This report presents the conceptual development of an off-road cargo trailer designed for usage in conjunction with bicycles when camping. The objective of the study is to address the limitations of existing cargo trailers and thereafter create a trailer that efficiently can navigate off-road terrains while carrying various types of cargo. The research includes collecting data regarding user behaviours and desired functions an optimal trailer should obtain and was translated into user requirements. The result demonstrates the successful development of an off-road cargo trailer on a conceptual level that offers innovative solutions and improved load-carrying capacity in comparison to the available market, while considering factors such as weight, manoeuvrability, and ease of use. This research contributes to the field by presenting data, which can be used in development and a comprehensive solution that expands the possibilities for bicycle-based cargo transportation in off-road environments. Future work can include further refinements to optimise the trailer’s performance and address additional user requirements based on the data presented.

Many engineering design optimization problems involve multiple conflicting objectives, which today often are obtained by computational expensive finite element simulations. Evolutionary multi-objective optimization (EMO) methods based on surrogate modeling is one approach of solving this class of problems. In this paper, multi-objective optimization of a disc brake system to a heavy truck by using EMO and radial basis function networks (RBFN) is presented. Three conflicting objectives are considered. These are: 1) minimizing the maximum temperature of the disc brake, 2) maximizing the brake energy of the system and 3) minimizing the mass of the back plate of the brake pad. An iterative Latin hypercube sampling method is used to construct the design of experiments (DoE) for the design variables. Next, thermo-mechanical finite element analysis of the disc brake, including frictional heating between the pad and the disc, is performed in order to determine the values of the first two objectives for the DoE. Surrogate models for the maximum temperature and the brake energy are created using RBFN with polynomial biases. Different radial basis functions are compared using statistical errors and cross validation errors (PRESS) to evaluate the accuracy of the surrogate models and to select the most accurate radial basis function. The multi-objective optimization problem is then solved by employing EMO using the strength Pareto evolutionary algorithm (SPEA2). Finally, the Pareto fronts generated by the proposed methodology are presented and discussed.

In this paper, an approach to generate surrogate modelsconstructed by radial basis function networks (RBFN) with a prioribias is presented. RBFN as a weighted combination of radialbasis functions only, might become singular and no interpolationis found. The standard approach to avoid this is to add a polynomialbias, where the bias is defined by imposing orthogonalityconditions between the weights of the radial basis functionsand the polynomial basis functions. Here, in the proposed a prioriapproach, the regression coefficients of the polynomial biasare simply calculated by using the normal equation without anyneed of the extra orthogonality prerequisite. In addition to thesimplicity of this approach, the method has also proven to predictthe actual functions more accurately compared to the RBFNwith a posteriori bias. Several test functions, including Rosenbrock,Branin-Hoo, Goldstein-Price functions and two mathematicalfunctions (one large scale), are used to evaluate the performanceof the proposed method by conducting a comparisonstudy and error analysis between the RBFN with a priori and aposteriori known biases. Furthermore, the aforementioned approachesare applied to an engineering design problem, that ismodeling of the material properties of a three phase sphericalgraphite iron (SGI) . The corresponding surrogate models arepresented and compared

The use of recommended S-N curves, presented in current literature, to analyse and determine the fatigue life of a part is common practice in, inter alia, the construction industry.However, the recommended S-N curves are generally created for larger components used in mainly the construction industry. Hence, the use of S-N curves for the evaluation of smaller parts, may result in over-dimensioning of such parts. For this reason, evaluation and designing of smaller parts could benefit from the development of an in house S-N curve specific for the part.

The purpose of this thesis is to generate and validate an in-house method for creating a S-N curve, for a specific part to be compared with recommended S-N curves in the literature. The specific part used for the generating of the method is a welded steel joint with the geometry of two steel pipes, welded together in a t-formation and which has been provided by Thule AB for the purpose of the thesis.

The method presented uses the results from 1) physical fatigue tests using a fatigue testing machine and 2) static FEA to derive a S-N curve for the specific part using the least squares method. A fatigue testing rig enables the gathering of data of the number of cycles to failure when the part is subject to a given cyclic load. The rig uses pneumatics to control the forces applied onto the part with the use of a cylinder. Furthermore, the fatigue testing rig was designed to be controlled by the applied force, meaning, that the rig ensured a homogeneous load cycle by measuring the force from a load cell and alternating the direction of the cylinder with an electrically controlled pressure valve. The performance of static FEA evaluations aim at locating stresses in the part. For this thesis the stresses were evaluated using the hot spot method due to the part's welded geometry.

The data gathered from the physical fatigue tests and the static FEA evaluations are subsequently combined deriving S-N curves applicable to the part.

From the fatigue tests and FEA evaluations for the t-shaped welded steel part, four S-N curves were derived of which two curves showed the results of a linear fitted curve whereas the other curves used the recommended slope of $-1/3$. The results showed that the S-N curves derived, using a set slope, resulted in similar curves to the recommended S-N curve provided by the literature. However, the linear fitted S-N curve showed that the part, according to the S-N curve, had a higher fatigue resistance than recommended.

 Due to limitations in the thesis work, the S-N curves derived within the framework of this thesis should be regarded as theoretical and have been strictly used to identify whether the method generated is applicable for deriving of S-N curves.

This thesis report aims to help the client developing their new product. The new product to be developed is a safety bracket for a safety system. The safety bracket connects different parts which create the safety system and it should be able to withstand impacts from moving objects. The client has a set of requirements that needs to be addressed during the product development process. One of the most important requirements that must be fulfilled is the given impact energy that the safety bracket must withstand. The methodology used during this thesis work is the product development processes (PDP). The product development process is used to find concepts that have the potential to answer the research questions and to fulfil the requirements. Some methods used in the product development process are brainstorming, brainwriting and combining working principles. The concepts were evaluated with a combination of Pugh´s matrix and weighting matrix. The three best concepts were selected for further development and tested with FEA simulation with Abaqus CAE. The impact simulation gave indications if the concepts could handle the impact energy and if they could fulfil the requirements. All three concepts could withstand the impact energy based on the simulations and most of the requirements could be fulfilled. The concepts with thinner profile walls had a reduction in stress and an increase in impact duration, where the kinetic energy is distributed throughout the impact. A protective shell helps with the reduction of stress and the energy absorption during the impact simulation.

Sammanfattning

Syfte – Syftet med studien är att ta fram en metod för att bevara ett stort antal verktyg för enstörre bearbetningsmaskin med en lösning för verktygsbyte. Frågeställningar sammanställdesgenom personlig kommunikation och kravspecifikationer som MFAB begärt.

Metod – För att ta fram och producera koncept användes flera metoder som beskrivs i Produktutveckling – Effektiva metoder för konstruktion och design av Johannesson, Perssonoch Pettersson. Koncepten som skapats värderas mot krav i form av en Pughs matris.

Resultat – I en informationssamling som utförs i förstudien samlas information om dagensvanligaste magasinlösning för fräs- och svarvmaskiner. Trum- och linjärmagasinet är devanligaste lösningarna för dagens bearbetningsmaskiner. Ett visuellt koncept beskrivs med hjälp CAD-programmet det är designat i samt en beskrivandetext för varje del. Det färdiga konceptet inkluderar:• En inhägnad för att hålla alla delar inom den förbestämda arbetsytan.• En serviceport för smidigt byte av verktyg utanför användning av magasinet.• Lösning för underhåll så att en person kan komma åt inuti magasinet.• Hyllor som agerar magasin då de håller verktygen som maskinen inte använder förtillfället.• En kedja som hyllorna är fästa på som roterar så att hyllorna kan nå dit de är behövda.• En linjärenhet som hämtar verktygen från hyllorna och lämnar vidare dem tillbufferten.• Bufferten som håller ett visst antal verktyg som maskinen är i behov av snart.• Restupplockning som tar hand om eventuellt skräp som kan förekomma på verktygen.Med dessa delar kan frågeställningarna besvaras.

Begränsningar – Två begränsningar i studien har påträffats. Den första begränsningen varatt i konstruktionen gick mer plats åt till magasinet än vad som ursprungligen hade beräknatsför. Nästa begränsning var att storleken av studien över den givna tiden som projektet varadebegränsade möjligheten att fullt utveckla det slutgiltiga konceptet.

Nyckelord – Bearbetningsmaskin, Automation, Magasin, Verktygshantering, Konstruktion, Skyddsinhägnad, Produktutveckling

Inter-project knowledge transfer is by scholars widely considered to be a crucial source of competitiveness for project-based organizations. Effective knowledge transfer not only brings economic benefits but also enhances firms’ environmental and social sustainability performance. However, to date, limited research has focused on ascertaining the prerequisites for effective knowledge transfer within the SME context. Correspondingly, through single-case study, this study aims to understand how interrelated organizational factors impact inter-project knowledge transfer in project-based SMEs. Aspects that were found to impact knowledge transfer could be grouped into three dimensions of organizational factors; project characteristics, organizational structure, and organizational culture. More specifically, project similarities, project complexity, horizontal differentiation, and strong interpersonal relationships were found to facilitate knowledge transfer. On the other hand, urgency, absence of formal project managers, low degree of formalization, centralization, low degree of vertical differentiation, and sense of ownership of knowledge were factors identified to hinder knowledge transfer. Furthermore, the present study discovered how the dimensions of organizational factors are interrelated in their impact on inter-project knowledge transfer. Based on the findings, academic and practical implications, and future research avenues are proposed.

The goal with this thesis is to find together with Saab Avionics Systems the correlation between applied current, air gap and forces that a brake with an electromagnetic release function have. This is achieved through theoretical calculations and practical tests.  

At the moment the brakes are used in electromechanical actuators that are applied in aircraft flap systems.

These brakes have been in Saab’s collection of products since a decade and to keep on being a competitive supplier they need to optimize their design process. However, there are difficulties regarding calculating the force of the magnetic field of these brakes since it is very complicated. To better understand how the design can be altered the current product Power Off Brake needs to be tested and analyzed.  

The test equipment that was developed is designed so that the brake dimension, air gap and current can vary alongside a change of surrounding temperature. After a test in room temperature it was found that the test equipment had a margin of error about 10%.

By testing Power Off Brake with the selected measuring method and test equipment Saab will get one step closer to better understand the relationship between theoretical calculations and practical tests. This can be used to reduce the safety margins when new brakes are to be developed since the test results provide insight about what happens when saturation in the material occur and how the brake perform in environmental conditions of an aircraft.

Furthermore, the authors leave recommendations for continued work and suggestions for improved design.

The increase of new and ever more stringent emission legislation has brought about with it a surge in the demand for more sustainable automotive solutions. This has particularly been the case for automobiles, including heavy-duty vehicles like trucks and buses, with internal combustion engines, which now require the design and manufacturing of more durable and reliable components. An important component of internal combustion engine automobiles, which helps achieve this target, is the exhaust after-treatment system. Exhaust after-treatment systems are usually equipped with some type of catalytic converter, treating the combustion gases from the engine exhaust manifold to reduce the concentration of pollutants. The catalytic converter assembly usually consists of an assembly of an outer metallic canning, an inner substrate and a packaging mat in between the two. The packaging mat, commonly known as the support mat, is an important component in the assembly, protecting the ceramic substrate from road induced and thermal loads, thereby preventing any damage to the latter. This thesis involves further development of a finite element model for the support mat that could be used in catalytic converter simulations with a reasonable degree of accuracy and reliability. In line with this objective, the characteristic mechanical response of the mat is first studied through a series of material tests: namely compression, friction, and shear tests. Different non-linear material models like hyperfoam, hyperelastic and viscoelastic models, are then created in ABAQUS to simulate the mat behaviour in the tests. The material model correlating most closely with the test is then implemented in the simulation of the assembly process, canning of a catalytic converter. This report includes the material tests conducted on the mats in new and aged condition, findings of the characteristic response of the mats in these tests as well as the constitutive material modelling and finite element simulations carried out for correlation with test data from the new mats. The most appropriate material model was also implemented in a canning assembly simulation to evaluate the efficacy of the material model in predicting the mat pressure, gap bulk density, and push-in force.

A hot isostatically pressed specimen of the A357 alloy in T6 condition has been tested for fatigue performance in situ. During testing, multiple small cracks were observed during the first cycle, both in proximity to and far from the stress concentration. These cracks have competed to form a propagating crack, forming multiple crack paths initially. Once the propagating crack has been established, it has chosen paths from multiple cracks that have opened around the tip to grow further. All small cracks observed to open have been attributed to bifilms, i.e., liquid metal damage. It is imperative to develop processes that minimize liquid metal damage to enhance the fatigue performance of aluminum alloy castings.

We construct a consistent multiplier free method for the finite element solution of the obstacle problem. The method is based on an augmented Lagrangian formulation in which we eliminate the multiplier by use of its definition in a discrete setting. We prove existence and uniqueness of discrete solutions and optimal order a priori error estimates for smooth exact solutions. Using a saturation assumption we also prove an a posteriori error estimate. Numerical examples show the performance of the method and of an adaptive algorithm for the control of the discretization error.

We suggest a finite element method for finding minimal surfaces based on computing a discrete Laplace–Beltrami operator operating on the coordinates of the surface. The surface is a discrete representation of the zero level set of a distance function using linear tetrahedral finite elements, and the finite element discretization is carried out on the piecewise planar isosurface using the shape functions from the background three-dimensional mesh used to represent the distance function. A recently suggested stabilized scheme for finite element approximation of the mean curvature vector is a crucial component of the method.

We construct a cut finite element method for the membrane elasticity problem on an embedded mesh using tangential differential calculus, i.e., with the equilibrium equations pointwise projected onto the tangent plane of the surface to create a pointwise planar problem in the tangential direction. Both free membranes and membranes coupled to 3D elasticity are considered. The discretization of the membrane comes from a Galerkin method using the restriction of 3D basis functions (linear or trilinear) to the surface representing the membrane. In the case of coupling to 3D elasticity, we view the membrane as giving additional stiffness contributions to the standard stiffness matrix resulting from the discretization of the three-dimensional continuum.

This master thesis investigates a redesign for a maintenance tube, used for both sampling and draining transformer oil from a tap changer compartment. With the current design, one can do one or the other of sampling and draining. The effect of this on a transformer site during maintenance means that personnel must bring extra equipment to do the maintenance routine. Along with the extra equipment, it also involves climbing the transformer an extra time to place the equipment for draining.

The project aims to address several issues in the context of the product. Redesigning the product to reduce maintenance time, and therefore downtime and electrical outages. Reducing the number of times that the transformer housing needs to be climbed in order to perform maintenance work. This with the purpose of improving working environment for maintenance personnel.

With the new design of the maintenance tube, draining and sampling can be done with the same pipe without the need for extra equipment. This is through a mechanism in the tube which allows the personnel to choose whether to drain oil from the bottom of the container or to take oil samples from an area in the tap-changer housing which gives more accurate results. The function of the mechanism can be described in the same way as a pen, where if you push the button, a tube will extract itself and close of the sampling inlets, enabling draining from the bottom. Push the button again and the same tube will retract, allowing you to take samples from the appropriate area again. The new design also adheres to the dimensional requirements needed for the design to fulfil the additional functions the tube has.

The project results in a design which would not only fill requirements of functions but also preserves some of the previous parts along with their interfaces. This means that the new design could be installed on current versions of tap-changer models when the next service interval is due.

We present a mixed method for the linearized elasticity equations with independent approximation of the curl of the displacements.The curl can be seen as a drilling degree of freedom allowing for coupling with rotating objects and the direct application of moments of force.

In this paper, we apply a rotated bilinear tetrahedral element to elastodynamics in R³. This element performs superior to the constant strain element in bending and, unlike the conforming linear strain tetrahedron, allows for row-sum lumping of the mass matrix. We study the effect of different choices of approximation (point- wise continuity versus edge average continuity) as well as lumping versus consistent mass in the setting of eigenvibrations. We also use the element in combination with the leapfrog method for time domain com- putations and make numerical comparisons with the constant strain and linear strain tetrahedra. 

A Galerkin finite element method for the membrane elasticity problem on a meshed surface is constructed by using two-dimensional elements extended into three dimensions. The membrane finite element model is established using the intrinsic approach suggested by Delfour and Zol´esio.

We develop a finite element method with continuous displacements and discontinuous rotations for the Reissner-Mindlin plate model on quadrilateral elements. To avoid shear locking, the rotations must have the same polynomial degree in the parametric reference plane as the parametric derivatives of the displacements, and obey the same transforma- tion law to the physical plane as the gradient of displacements. We prove optimal conver- gence, uniformly in the plate thickness, and provide numerical results that confirm our estimates. 

Second order buckling theory involves a oneway coupled coupled problem where the stress tensor from a plane stress problem appears in an eigenvalue problem for the fourth order Kirchhoff plate. In this paper we present an a posteriori error estimate for the critical buckling load and mode corresponding to the smallest eigenvalue and associated eigenvector. A particular feature of the analysis is that we take the effect of approximate computation of the stress tensor and also provide an error indicator for the plane stress problem. The Kirchhoff plate is discretized using a continuous/discontinuous finite element method based on standard continuous piecewise polynomial finite element spaces. The same finite element spaces can be used to solve the plane stress problem.

We construct a new Galerkin finite element method for the membrane elasticity problem on a meshed surface by using two-dimensional elements extended into three dimensions. The membrane finite element model is established using a tangential differential calculus approach that avoids the use of classical differential geometric methods. The finite element method generalizes the classical flat element shell method where standard plane stress elements are used for membrane problems. This makes our method applicable to a wider range of problems and of surface descriptions, including surfaces defined by distance functions. 

We develop a finite element method for a large deformation membrane elasticity problem on meshed curved surfaces using a tangential differential calculus approach that avoids the use of classical differential geometric methods. The method is also applied to form finding problems.

In this paper we derive a variational formulation for the static analysis of a linear curved beam natively expressed in global Cartesian coordinates. Using an implicit description of the beam midline during derivation we eliminate the need for local coordinates. The only geometrical information appearing in the final expressions for the governing equations is the tangential direction. As a consequence, zero or discontinuous curvature, for example at inflection points, pose no difficulty in this formulation. Kinematic assumptions encompassing both Timoshenko and Euler-Bernoulli beam theories are considered. With the exception of truly three-dimensional formulations, models for curved beams found in the literature are typically derived in the local Frenet frame. We implement finite element methods with global degrees of freedom and discuss curvature coupling effects and locking. Numerical comparisons with classical solutions for straight and curved cantilever beams under tip load are given, as well as numerical examples illustrating curvature coupling effects. 

In this paper, we propose a stabilized augmented Lagrange multiplier method for the finite element solution of small deformation elastic contact problems. We limit ourselves to friction-free contact with a rigid obstacle, but the formulation is readily extendable to more complex situations.

We propose a discontinuous finite element method for small strain elasticity allowing for cohesive zone modeling. The method yields a seamless transition between the discontinuous Galerkin method and classical cohesive zone modeling. Some relevant numerical examples are presented. 

ROL Ergo is a company that belongs to the ROL Group concern. They develop and manufacture products for the office furniture market and their main focus is on electrically height adjustable desk stands. They also develop products for personal use, often in collaboration with other companies.The products that ROL Ergo develop are all quite robust and stable, which are qualities often associated with weight. As the E-commerce is increasing in popularity, ROL-Ergo will have to adapt and further improve their products to keep up with it. This means that their product needs to decrease in weight, but without compromising their other qualities. To accomplish this, well thought-out weight reductions must be made on their components.The desktop stand that this report covers consists of many different components. However, the main components consist of the foot, leg, frame, and strut. There is also a motor housing, containing the electric engine used adjust the table, that connects the leg with the frame and strut. The foot, frame and strut are some of the heaviest and least complex components of the stand, and therefore suitable to perform weight reduction on.This report covers the work that was done to analyze the current components, as well as the design and development process to generate a new weight-improved design. To begin with, the analyzing of the current components consisted of getting an understanding of their purpose and what stresses they are subject to. Simulations were done to determine this, and the results from these were the basis as well as point of comparison for the new concepts.As the project finished, new weight improved concepts for the foot, strut and frame with new designs had been developed. Combined with the current remaining parts of the desk frame, it led to a significant total weight reduction. All the new components were compared to the already existing ones through simulations.

Decomposing and clarify “sustainability” implications in the same way as concrete targets on product functionality is challenging, mainly due to the problem of showing numbers and ‘hard facts’ related to the value generated by sustainability-oriented decisions. The answer lies in methods and tools that are able, already in a preliminary design stage, to highlight how sustainable design choice can create value for customers and stakeholders, generating market success in the long term. The paper objective is to propose a framework where Sustainable Product Development (SPD) and Value Driven Design (VDD) can be integrated to realize a model-driven approach to support early stage design decisions. Also, the paper discusses how methods and tools for Model-Based Decision Support (MBDS) (e.g., response surface methodology) can be used to increase the computational efficiency of sustainability- and value-based analysis of design concepts. The paper proposes a range of activities to guide a model-based evaluation of sustainability consequences in design, showing also that capabilities exist already today for combining research efforts into a multi disciplinary decision making environment.

Globe technologies is a company that sells products in the gardening market for both commercial and professional use. This study focuses on developing a battery powered accessory for autonomous mowers. The study investigates the possibility to use autonomous mowers in green spaces that do not have access to power by the grid. To provide the autonomous mower with power the study introduces a portable power supply that provides power to the mower.  The development of the portable power supply starts with a market analysis and that lays the foundation for the project. The report continues with the development of the actual product and finishes off with testing of a prototype. To get the product that is wanted relevant theories and methods is investigated and applied. During the thesis a number of iterations of the product are designed to meet the demands of the requirement specification.

The purpose of the thesis work given is to gain a better understanding of the degating process in high-pressure die casting components, as well as the effectiveness of the thermo-mechanical vibration technique for detaching cast components from the gating system. In addition, to evaluate and establish the most appropriate degating procedure in order to reduce labor, material costs, and processing time.In recent days, many investigators have been looking at an automated technique that can help optimize and streamline the casting process. VOLVO CE is also exploring on ways to assess and establish the most acceptable degating process in order to optimize cost towards labor, material expense, and processing time. To begin with, VOLVO CE wants to develop the full Finite Element Method (FEM) based approach prior to implementationThis thesis consists of a substantial amount of numerical work, demonstrating the effectiveness of thermo-mechanical vibration technique for degating the casting high-pressure die casting component. The dynamic behavior of the component was studied in ANSYS WB where the impact of thermal loading has been taken into consideration.The component studied in this thesis is a transmission component (oil distributor) from a Volvo construction equipment, VOLVO group. It is cast in Aluminum alloy with the material composition AlSi13Fe. A oil distributor is a component which is bolted on the back side (place where electric motor is connected to the casing through shaft) of the transmission casing.

Constantly growing demands from the costumers in the Automotive industry forces the subcontractors to seek alternative ways to compete. One parameter of quality is the components tolerance against NVH(Noise, Vibraion & Harshness) aspects. Kongsbergs Automotive has developed a new gear shifter platform (Shift-by-Wire) that is sold to Alfa Romeo and used in of their car models. However, the company is not pleased with the components sound quality, therefore the main purpose of this thesis is to develope a number of concepts that is supposed to enhance these NVH-aspects.

To get an understanding of the problem an analysis of the causes of the emitted sound has been done parallell to a product decomposition, function decomposition and a Ishikawa-diagram. Together with these methods has a litterature study been performed to get familiar with the physics of an impact and especially the emittment of noise. The concepts has been generated through a combined brainstorming and brainwriting session. A number of concepts has been developed that should reduce emitted noise. To evaluate the concepts generated has well proven methods for screening been used, such as: analysis of pros and cons, feasibility analyis and Go/No-Go.

The definite concept uses a method that absorbs the kinetic energy induced by the user through a built-on component and an energy absorbing foam. The idéa is that the built-on component and the foam should transform more of the kinetic energy to heat energy.

The consequenses of this study is that the company now has a fully applicable concept to evaluate the idés effectiveness regarding reduction of noise. Next step is to make a prototype and evaluate the idéa.

Since the making of a prototype has not been done, the biggest restriction in the thesis  is that the developed concept is not evaluated regarding its effectiveness of reduction of noise.

The present theoretical note shows how a naturalobjective function in stiffness optimization, including bothprescribed forces and non-zero prescribed displacements,is the equilibrium potential energy. It also shows how theresulting problem has a saddle point character that may beutilized when calculating sensitivities.

Stiffness topology optimization is usually based on a state problem of linear elasticity, and there seems to be little discussion on what is the limit for such a small rotation-displacement assumption. We show that even for gross rotations that are in all practical aspects small (<3 deg), topology optimization based on a large deformation theory might generate different design concepts compared to what is obtained when small displacement linear elasticity is used. Furthermore, in large rotations, the choice of stiffness objective (potential energy or compliance), can be crucial for the optimal design concept. The paper considers topology optimization of hyperelastic bodies subjected simultaneously to external forces and prescribed non-zero displacements. In that respect it generalizes a recent contribution of ours to large deformations, but we note that the objectives of potential energy and compliance are no longer equivalent in the non-linear case. We use seven different hyperelastic strain energy functions and find that the numerical performance of the Kirchhoff–St.Venant model is in general significantly worse than the performance of the other six models, which are all modifications of this classical law that are equivalent in the limit of infinitesimal strains, but do not contain the well-known collapse in compression. Numerical results are presented for two different problem settings.

This report, conducted at the School of Engineering in Jönköping within mechanical engineering: product development and design, focuses on the development of an exoskeleton for hedge trimmer operators. The project is aimed to create a mechanical solution to reduce the strain on hedge trimmer operator’s shoulders and upper bodies during long workdays.

Tasks involving hedge trimmers cause significant stress on the shoulder area, which can lead to long-term injuries. Exoskeletons have the potential to support users by redistributing the load to stronger parts of the body. The goal of the project was to design an exoskeleton specifically for hedge trimmer operators to reduce the risk of work-related injuries and improve the work environment.

The project began with a preliminary study that included market analysis, interviews with professional users, and testing of existing exoskeletons. A specification of requirements was formulated based on the collected data, and several concepts were generated through brainstorming. The final concept was selected using Pugh's matrix, where different options were compared against a reference product from Hilti.

The chosen design for the exoskeleton includes a spring-loaded mechanism placed on the user's back. The springs provide support at the right angle and reduce shoulder strain by transferring the load to the back and hips. The prototype was based on Husqvarna's existing harness, which contributed to reduced production costs and adaptability.

The prototype meets most of the requirements in the specification, such as providing mechanical support to the shoulders and the ability to adjust the force. However, further tests and adjustments are needed to optimize the design and ensure user-friendliness. Future research should include field tests with actual users and the implementation of adjustment options for the spring force.

This study lays the foundation for the future development of exoskeletons for hedge trimmer operators and potentially other tools, aiming to improve the work environment and reduce the risk of work-related injuries in the gardening and forestry industries.

This thesis is a cooperation with E.MIL Energi & Miljö, a company that mostly works with helping other companies to reduce and improve their usage of energy.

This project aims to develop a product which helps people, that due to different reasons, has reduced mobility to pick up belongings from the floor. It can be things like screws, pills and other stuff. The purpose of this project is to be able to produce a product that will solve this need without having the accuracy that is required by a gripper.

Two central questions have been addressed in the project:

1. How is the best way to produce a product that helps people to pick up things from the floor?

2. How does the design process look like when developing "Sugpellen"?

The methods that have been used is specifications for requirements, competitor analysis, screening, and finally the CAD model with 3D printed model and also a development of a prototype.

Two different kinds of solutions have been prepared which basically has the same ground functions. The product has a neck, filter, head, handle, fan and batteries. What separates the two alternatives with each other is that one of them has fifteen batteries which gives a more bigger and robust design. The other model has Lithium-Ion batteries that will be placed inside the handle and gives a smaller and more attractive design.

This product needs to be developed further before it is ready to enter the market. There are some things that still are missing before it is completely finished for instance strength analysis and material selection and also decide which types of batteries that should be used.

The purpose of the study is to develop a new cost-effective compost for Separett AB with a lower cost during transportation than the current product. The study began with gathering requirements from the company in a requirement specification. This specification provided a good basis of what was needed to include during the development. These requirements werealso supplemented by market research to understand what has been positive and negative with the current compost. To further develop the compost the market research and requirement specification was analyzed to create a functional analysis which helped to clarify what functions the compost should consist of and how it will operate at best.

To generate different solutions from these functions, a morphological matrix was used to create different concepts. These concepts consist of different functions from the analysis and when mixed they make whole concepts ideas. When whole concepts were made, they then got evaluated against the requirements to ensure that they are following the specification. These evaluations were done using two different matrices. The first was Go/No-Go and the second was Pugh’s matrix. The concepts were based of their ability to handle the different requirements, the concepts that performed the best was chosen to further develop in CAD to produce a working CAD prototype.

This concept was then presented at meetings with the company’s development team and the CEO of Separett. At the meetings the product received feedback and inputs, what is positive and less positive. The company recommended to proceed with an additional part that will hold the compost together and other small details such as screw holes, and list placement. This CAD will in turn then become the first prototype of Separett AB’s new compost. Everything that is in this project will be handed over to the development department at Separett where they will continue to get a new compost.

A forest harvester operator is today facing a stressful work environment with a high demand on coordination skills and effectiveness to run the operation with positive economical outcome. The learning phase is very long compared to similar work.The vision for this project was to transform the machine, through intuitive and innovative interface design, into an extension of the operator’s body. In this way it provides higher productivity as well as user friendliness, shorter learning phase and a healthier work situation.This was realized through the use of prior but yet not market available related research. Through market studies, applicable technology already available in other industries was found. The result is a complete seat with controls for a conceptual Gremo harvester realizable in the year 2023.

Foam materials are used in many structural applications, especially where impact loads are expected. A common application is to absorb energy and reduce the forces that would otherwise be transferred to vehicle occupants in the event of a collision. A structure or material that does this effectively is said to have a high crashworthiness. Foam materials with high crashworthiness are essential for protecting infants and young children in child safety seats, also known as Child Restraint Systems (CRS). Physical testing is time-consuming and costly, and accurate modeling is required to evaluate safety performance.

High-fidelity models and advanced methods in computational dynamics to predict acceleration-time response are crucial for evaluating human safety. This thesis investigates the constitutive behavior of foams within LS-DYNA for advanced material modeling and uses a deductive methodology to explore this. More specifically, the work focuses on constitutive modeling, finite elements, and parameter- fitting using optimization. The work contributes to the field of computational dynamics and solid mechanics. The thesis aims to improve the modeling of foams by providing an accurate, efficient, and robust framework.

The results consist of best practices for how foams should generally be modeled for FEM applications. This includes the choice of constitutive material models, finite elements, mesh-free methods, optimization for parameter-fitting, contact formulations in contact robustness and stability, and the necessary experiments for defining material parameters for constitutive extrapolation of strain rates. Two constitutive relations, Jeong's and Nagy's, are proposed for modeling strain rate effects used in dynamic impact tests. Besides that, we propose two extrapolation schemes to artificially extend the densification range for numerical stability based on the proposal of Paul Du Bois. Python code is also presented for automatic input compatible with LS-DYNA when set accuracy is achieved.

In the process of developing cast iron and cast aluminium components, a high level of co-operation between product development and production is of great importance. From an engineering standpoint, this co-operation is limited early in the product development phase by e.g. a lack of established methods for the consideration of local variations in the mechanical behaviour of a finished component.

This thesis aims to increase the possibilities for co-operation between product development and production during the product realisation process by introducing and studying the use of predicted local mechanical behaviour in structural analyses of cast components. A literature review of existing simulation methods and a work on characterisation of mechanical behaviour from microstructural features have been performed to identify important knowledge gaps. A simulation strategy has been formulated which is able to predict local mechanical behaviour throughout the entire component, and to incorporate this into a Finite Element Method (FEM) simulation of the structural behaviour of the component. In the simulation strategy, componentspecific microstructure-based mechanical behaviour is predicted using a casting process simulation. A computer program was developed to create FEM material definitions which capture the local variations in mechanical behaviour throughout the component. Using a material reduction technique, the local mechanical behaviour can be incorporated without increasing the FEM simulation time.

The relevance of the simulation strategy was experimentally verified on cast aluminium samples, where the strain field was observed using Digital Image Correlation (DIC). It was found that the local variations in mechanical behaviour cause a stress-strain distribution that deviates from that predicted by a homogeneous material description, indicating the importance of calculating with and including such variations in material behaviour in FEM simulations. Numerical investigations demonstrate the strategy’s relevance for predicting the behaviour of cast aluminium and ductile iron components.

The mechanical behaviour and performance of a ductile iron component is highly dependent on the local variations in solidification conditions during the casting process. Here we show a framework which combine a previously developed closed chain of simulations for cast components with a micro-scale Finite Element Method (FEM) simulation of the behaviour and performance of the microstructure. A casting process simulation, including modelling of solidification and mechanical material characterization, provides the basis for a macro-scale FEM analysis of the component. A critical region is identified to which the micro-scale FEM simulation of a representative microstructure, generated using X-ray tomography, is applied. The mechanical behaviour of the different microstructural phases are determined using a surrogate model based optimisation routine and experimental data. It is discussed that the approach enables a link between solidification- and microstructure-models and simulations of as well component as microstructural behaviour, and can contribute with new understanding regarding the behaviour and performance of different microstructural phases and morphologies in industrial ductile iron components in service.

The coupling between simulations of solidification, microstructure and local mechanical behaviour and simulation of stress-strain behaviour is studied by applying a recently developed simulation strategy to a high pressure die cast aluminium component. In the simulation strategy, named a closed chain of simulations for cast components, the mechanical behaviour throughout the component is determined locally by a casting process simulation. The entire casting process, including mould filling and solidification, is simulated to predict the formation of microstructure and residual stresses throughout the component, and material characterization models are applied to relate microstructural features to local elastic and plastic mechanical material behaviour. The local material behaviour is incorporated into a finite element method (FEM) stress-strain simulation of a realistic load case of the component in service.

In the current contribution the influences of local variations in mechanical behaviour and residual stresses on the component behaviour are investigated. The simulation results for local microstructure and mechanical behaviour are compared to experimental results, and the predicted local mechanical behaviour is incorporated on an element level into the FEM simulation. The numerical effect of the variations in mechanical behaviour is quantified by comparing the results achieved using local behaviour and homogeneous behaviour. The influence of residual stresses predicted by the casting process simulation on the component behaviour is also studied.

The casting process simulation is found to accurately predict the local variations in microstructure throughout the component, and the local variations in mechanical behaviour are well described. The numerical results show that casting process simulation and modelling of microstructure formation, material behaviour and residual stresses are important contributions to correctly predict the behaviour of a cast aluminium component in service. This motivates the use of the proposed simulation strategy, and show the importance of incorporating materials science and casting process simulations into structural analyses of cast components. It is discussed that integration of these areas, e.g. using the closed chain of simulations, is important in order to increase the accuracy of FEM simulations and the product development efficiency in the future.

Due to design and process-related factors, there are local variations in the microstructure and mechanical behaviour of cast components. This work establishes a Digital Image Correlation (DIC) based method for characterisation and investigation of the effects of such local variations on the behaviour of a high pressure, die cast (HPDC) aluminium alloy. Plastic behaviour is studied using gradient solidified samples and characterisation models for the parameters of the Hollomon equation are developed, based on microstructural refinement. Samples with controlled microstructural variations are produced and the observed DIC strain field is compared with Finite Element Method (FEM) simulation results. The results show that the DIC based method can be applied to characterise local mechanical behaviour with high accuracy. The microstructural variations are observed to cause a redistribution of strain during tensile loading. This redistribution of strain can be predicted in the FEM simulation by incorporating local mechanical behaviour using the developed characterization model. A homogeneous FEM simulation is unable to predict the observed behaviour. The results motivate the application of a previously proposed simulation strategy, which is able to predict and incorporate local variations in mechanical behaviour into FEM simulations already in the design process for cast components.

This project was a collaboration with C3 Scandinavian Lifestyle to create an induction percolator. Certain points had to be considered and explored. How can the copper coil be used in the percolator, and how can the new technology be turned off at the specified temperature?The report will begin with a theoretical foundation. This will include the type of study contained in this report. Every step made during the project will be explained in the procedure. The approach and implementation section will discuss how the work was done, as well as what methods were employed to get the outcomes. Last but not least, it concludes with conclusions and debate.

Despite composite materials are widely used in many applications, prediction on damage mechanism of the composite materials is still very difficult. Using the findings from the research on damage mechanism under fatigue loading, its transverse cracking and its crack opening and sliding displacement, a mathematical model has been developed. The model showed results closer to the real-time experimental results in crack initiation and growth. The aim of the thesis is to develop a computational tool using the mathematical model and effective stiffness concept of the layers with cracks to predict the degradation of the longitudinal young’s modulus and shear modulus of the composite laminate. In addition to that, graphical user interface is also created making the user control the tool easily. The tool developed shows promising results but still lacks the information on the effects of delamination on crack opening displacement and effective shear modulus.

In this thesis a further development of Orwak AB’s existing product, TOM, has been developed. The product is a trash bin that compresses the waste the user dumps to reduce the volume of the trash. A machine like this is called a waste compactor. The problems which had been revealed was that the user could not toss the waste during the compression process and the existing compression system was not optimally designed.The project started with a requirement specification that was made together with the company to create clear guidelines about what should be done. A GANTT-schedule was also made to know what and when everything was going to be performed. The work then proceeded with a pilot study, followed by a method called Brainstorming that is used to develop new ideas. The concepts was then screened through both feedback from the company and a method called Pughs matrix. Finally, only a few concepts remained and was further developed in the 3D-modelling program Solid Works.The final result became a new compression system and a new type of disposal hatch. The new compression system is driven by an electrical actuator that is connected to one of the arms in the so called “scissor lift solution”. By using this type of solution, the compression system became more compact and at the same time reduced the compression time due to the high gearing. The new disposal hatch looks like a type of garage door and occupies less space inside the machine. The hatch also has a magnetic switch that offers a safe solution to toss waste during the compression process.The project has only developed concept solutions in CAD that can be further developed by the company. No calculations or tests has been done on the concepts due to the limited time frame and an agreement with the company.

In this paper an efficient approach to simulate thermal stresses due to frictional heating of disc brakes is presented. Inthe approach thermal and stress analysis are performed sequentially. The frictional heat analysis is based on the Eulerianmethod, which requires significantly low computational time as compared to the Lagrangian approach. Completethree-dimensional geometries of a disc and a pad are considered for the numerical simulations. The contact forcesare computed at each time step taking the thermal deformations of the disc into account. The nodal temperaturehistory is recorded at each time step and is used in sequentially coupled stress analysis, where a temperature dependentelasto-plastic material model is used to compute the stresses in a disc brake. The results show that during hard braking,high compressive stresses are generated on the disc surface in circumferential direction which cause plastic yielding. Butwhen the disc cools down, the compressive stresses transform to tensile stresses. Such thermoplastic stress history maycause cracks on disc surface after a few braking cycles. These results are in agreement with experimental observationsavailable in the literature.

In this paper, an efficient sequential approach for simulating thermal stresses in brake discs for repeated braking is presented. First, a frictional heat analysis is performed by using an Eulerian formulation of the disc. Then, by using the temperature history from the first step of the sequence, a plasticity analysis with temperature dependent material data is performed in order to determine the corresponding thermal stresses. Three-dimensional geometries of a disc and a pad to a heavy truck are considered in the numerical simulations. The contact forces are computed at each time step taking the thermal deformations of the disc and pad into account. In such manner, the frictional heat power distribution will also be updated in each time step, which in turn will influence the development of heat bands. The plasticity model is taken to be the von Mises yield criterion with linear kinematic hardening, where both the hardening and the yield limit are temperature dependent. The results show that during hard braking, high compressive stresses are generated on the disc surface in the circumferential direction which cause yielding. But when the disc cools down, these compressive stresses transform to tensile residual stresses. For repeated hard braking when this kind of stress history is repeated, we also show that stress cycles with high amplitudes are developed which might generate low cycle fatigue cracks after a few braking cycles.