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On the use of heterogeneous thermomechanical and thermophysical material properties in finite element analyses of cast components
Jönköping University, School of Engineering, JTH, Materials and Manufacturing.ORCID iD: 0000-0003-1412-7988
Jönköping University, School of Engineering, JTH, Materials and Manufacturing.ORCID iD: 0000-0003-2671-9825
Jönköping University, School of Engineering, JTH, Materials and Manufacturing.ORCID iD: 0000-0003-0899-8939
2019 (English)In: IOP Conference Series: Materials Science and Engineering, Institute of Physics (IOP), 2019, Vol. 529, no 1, article id 012076Conference paper, Published paper (Refereed)
Abstract [en]

Cast components generally show a heterogeneous distribution of material properties, caused by variations in the microstructure that forms during solidification. Variations caused by the casting process are not commonly considered in structural analyses, which might result in manufacturing of sub-optimised components with unexpected in-use behaviour. In this paper, we present a methodology which can be used to consider both thermomechanical and thermophysical variations using finite element analyses in cast components. The methodology is based on process simulations including microstructure modelling and correlations between microstructural features and material properties. Local material data are generated from the process simulation results, which are integrated into subsequent structural analyses. In order to demonstrate the methodology, it is applied to a cast iron cylinder head. The heterogeneous distribution of material properties in this component is investigated using experimental methods, demonstrating local variations in both mechanical and physical behaviour. In addition, the strength-differential effect on tensile and compressive behaviour of cast iron is considered in the modelling. The integrated simulation methodology presented in this work is relevant to both design engineers, production engineers as well as material scientists, in order to study and better understand how local variations in microstructure might influence the performance and behaviour of cast components under in-use conditions. 

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2019. Vol. 529, no 1, article id 012076
Series
IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981 ; 529:1
Keywords [en]
Cast iron, Cutting tools, Cylinder heads, Microstructure, Refining, Solidification, Structural analysis, Experimental methods, Heterogeneous distributions, Integrated simulations, Material scientists, Microstructural features, Microstructure modelling, Strength-differential effects, Thermophysical material properties, Finite element method
National Category
Metallurgy and Metallic Materials
Identifiers
URN: urn:nbn:se:hj:diva-45335DOI: 10.1088/1757-899X/529/1/012076ISI: 000561759900076Scopus ID: 2-s2.0-85067891373OAI: oai:DiVA.org:hj-45335DiVA, id: diva2:1337190
Conference
Joint 5th International Conference on Advances in Solidification Processes, ICASP 2019, and 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining, CSSCR 2019, 17-21 June 2019
Funder
Knowledge FoundationAvailable from: 2019-07-12 Created: 2019-07-12 Last updated: 2021-09-28Bibliographically approved
In thesis
1. Process-Induced Local Material Variations in Finite Element Simulations of Cast and Fibre Reinforced Injection Moulded Components
Open this publication in new window or tab >>Process-Induced Local Material Variations in Finite Element Simulations of Cast and Fibre Reinforced Injection Moulded Components
2019 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The purpose of this thesis is to provide an overview of the methods used in the appended papers, in order to consider heterogeneous material properties in finite element simulations by using process simulations as input. The work deals with both injection moulded and cast components, and focuses on process-induced local material variations and their effect on component performance.

The influence of heterogeneous properties originating from the casting process as well as some other common simplifications, which are made in finite element analyses, are evaluated for a cast iron component. It is found that commonly neglected properties such as compressive strength, residual stresses, temperature dependency and heterogeneous properties have a non-trivial and potentially large influence on the simulation results.

Lastly, a computational method for fibre reinforced plastics is presented. The methodology enables designers to consider the non-linear anisotropic properties of fibre-reinforced polymers, due to the flow-induced fibre orientation predicted by injection moulding simulations. The method allows material data assignment in each integration-point of the structural mesh. The method is demonstrated to capture the behaviour of the full range of fibre orientations simultaneously with good accuracy.

Abstract [sv]

Syftet med denna avhandling är att översiktligt beskriva de metoder som används i de bifogade artiklarna. Dessa metoder möjliggör beaktandet av heterogena materialegenskaper vid hållfasthetsberäkningar med hjälp av finita element metoden (FEM), genom att först simulera tillverkningsprocessen. Arbetet behandlar både formsprutade och gjutna komponenter, och fokuserar på process-inducerade lokala materialvariationer, samt hur dessa påverkar komponenters prestanda.

En gjutjärnskomponent har studerats med syftet att undersöka inverkan av heterogena materialegenskaper från gjutprocessen, samt några andra vanligt förekommande förenklingar som görs i industriella hållfasthetsanalyser. Genom att försumma materialets kompressionsbeteende, eventuella restspänningar ifrån gjutprocessen, temperaturberoende, samt den heterogena fördelningen av materialegenskaper ifrån tillverkningsprocessen introduceras icke-triviala och potentiellt stora fel i simuleringsresultaten.

Slutligen presenteras en beräkningsmetod för fiberförstärkta formsprutade plaster. Initiala simuleringar av formsprutningsprocessen används för att prediktera den lokala fiberorienteringen, vilken används för att möjliggöra hållfasthetsberäkningar som tar hänsyn till det olinjära och anisotropa materialbeteendet hos formsprutade fiberförstärkta komponenter. Metoden möjliggör att materialdata kan appliceras i varje integrationspunkt i beräkningsnätet, och har utvärderats genom att demonstrera ett korrekt materialbeteende för flera fiberorienteringar samtidigt, med god noggrannhet.

Place, publisher, year, edition, pages
Jönköping: Jönköping University, School of Engineering, 2019. p. 21
Series
JTH Dissertation Series ; 045
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-54596 (URN)978-91-87289-48-4 (ISBN)
Supervisors
Available from: 2021-09-10 Created: 2021-09-10 Last updated: 2021-09-10Bibliographically approved
2. Multiscale Constitutive Modeling of Heterogeneous Engineering Materials
Open this publication in new window or tab >>Multiscale Constitutive Modeling of Heterogeneous Engineering Materials
2021 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This work deals with different methods used to determine heterogeneous constitutive model parameters for macro-scale finite element models, based on microstructural variations, caused by the manufacturing process. These methods could be applied to decrease modeling errors associated with the material behavior, improving the predictive capabilities of structural analyses in simulation-driven industrial product development. By providing engineers with more sophisticated tools and methods which lets them consider the complex relationships between the manufacturing process, the resulting microstructure and the final properties, manufactured components have the potential to be further optimized with respect to both weight and performance, reducing their cost and environmental impact.

An empirical approach for cast components is presented in Papers I & II, where material testing is used as a basis for constitutive model parameter extraction via optimization. Linear models were created for both thermo-mechanical and thermo-physical material properties, by characterizing specimens extracted from different regions in a lamellar graphite cast iron cylinder head. These models were used to generate heterogeneous constitutive model parameters for the cylinder head, based on the solidification time as predicted by casting process simulations. The influence of several commonly made casting-specific engineering simplifications were investigated, and it was shown that non-trivial errors of a potentially large magnitude are introduced by not considering e.g. the compressive behavior of the material, residual stresses from the casting process, the temperature dependency of the material, or the process-induced heterogeneity.

Paper III describes a statistical homogenization-based method, for modeling of anisotropic fiber reinforced materials. A non-linear anisotropic constitutive model was developed and implemented in commercial finite element codes, which is able to consider heterogeneous fiber orientations using only one material definition. The anisotropic elastic constitutive tensor is determined from fiber-matrix homogenization, and orientation averaging using second- and fourth order fiber orientation tensors provided by injection molding simulations. The plastic constitutive parameters are determined by optimization against experimental tensile tests using specimens with different fiber orientations. The method was demonstrated using a injection molded 50 wt.% short glass fiber reinforced plastic.

A pixel/voxel-based method is presented in Papers IV (2D) & V (3D), for simple and efficient generation of reduced numerical microstructure models using imaging data as input. The input micrograph or image stack is split into subdomains, which are evaluated individually using numerical or semi-analytical homogenization. The constitutive tensor of each subdomain is mapped to a new, reduced numerical model. The purpose of this approach was to support component level analyses, by representing process-induced microstructural imperfections like e.g. porosity on the macro-scale, in a computationally efficient way. The geometrical description of the microstructure can be retrieved from experimental imaging methods like Scanning Electron Microscopy (SEM) or X-ray based Computed Tomography (CT). Alternatively, it can be approximated from phase field or manufacturing process simulations. The method was demonstrated by reducing a 2D aluminium micrograph by 99.89%, with material property errors of less than 0.5% in Paper IV. Also, in paper V by reducing a complex high-resolution 3D aluminum shrinkage porosity by 99.2%, with a material property error of approximately 1%. The method significantly reduces the complexity of building finite element models of complex microstructures, where the pre-processing step is replaced by image segmentation.

Place, publisher, year, edition, pages
Jönköping: Jönköping University, School of Engineering, 2021. p. 45
Series
JTH Dissertation Series ; 065
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-54771 (URN)978-91-87289-69-9 (ISBN)
Public defence
2021-10-29, E1405 (Gjuterisalen), School of Engineering, Jönköping, 10:00 (English)
Opponent
Supervisors
Available from: 2021-09-28 Created: 2021-09-28 Last updated: 2021-09-28Bibliographically approved

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