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Digital Image Correlation and nanoindentation in evaluation of material parameters of cancellous bone microstructure

Kokot G., Skalski K., Makuch A., Ogierman W.

Archives of Materials Science and Engineering

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2017

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Vol. 83, nr 1

10--16

EN

Purpose: Purpose of this paper is to present the possibilities of the application of the two methods: Digital Image Correlation and nanoindentation in porous bone tissues testing. Firstly, as a tool in the evaluation process of material parameters for porous microstructures, such as bone tissues or other foams and, secondly, as validation and verification tools for finite element analysis of bone or foams structures. Those methods are helpful when the high accuracy of the mechanical parameters of porous microstructures is required. Design/methodology/approach: Two methods: Digital Image Correlation (DIC) and nanoindentation are used as an efficient approach in the evaluation process of material parameters or constitutive relationship of porous structures like bone tissues. Digital image correlation enlarges the accuracy of classical mechanical tests and the nanoindentation allows to look inside the microstructure. Findings: The proposed methods were found to be effective in experimental testing and material parameters evaluation process of some special materials. Among them are porous structures, such as bone tissue. Additionally, the DIC is an excellent tool for finite element model validation and results verification. Practical implications: The presented method based on the combination of the Digital Image Correlation and nanoindentation presents new possibilities in material testing fields, material behavior and parameters evaluation. They have great advantages, among others, in the field of testing of porous bone structure or determining the mechanical parameters of bone tissue. Originality/value: The paper presents methods for testing the complicated porous bone structures: evaluating mechanical behavior of the whole structure and evaluating mechanical properties of the single element of the structure. The mechanical parameters of human cancellous bone structures are presented as the preliminary research results.

2

Numeryczne modelowanie zjawiska wybuchu

Ogierman W.

Modelowanie Inżynierskie

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2014

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T. 20, nr 51

62--69

PL

W artykule przedstawiono metodykę numerycznego modelowania zjawiska wybuchu przy użyciu metody elementów skończonych (MES) oraz bezsiatkowej metody SPH (Smoothed Particle Hydrodynamic). Zaprezentowano i porównano wyniki symulacji otrzymane wymienionymi metodami. Wartości ciśnienia fali uderzeniowej wyznaczone numerycznie zostały porównane z istniejącymi w literaturze zależnościami empirycznymi. Możliwości metod numerycznych w analizie zjawiska wybuchu przedstawiono na przykładzie analizy oddziaływania fali uderzeniowej na przykładową konstrukcję.

EN

This article presents methodology of numerical modeling of explosion phenomenon by using the finite element method (FEM) and meshless SPH (Smoothed Particle Hydrodynamic) method. Obtained simulations results are presented and compared. Computed numerically shock wave pressure values were compared with existing empirical solutions. Testing the influence of blast wave on the exemplary structure is presented as an example of capabilities of numerical methods in modeling of the explosion phenomenon.

3

Particle shape influence on elastic-plastic behaviour of particle-reinforced composites

Ogierman W., Kokot G.

Archives of Materials Science and Engineering

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2014

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Vol. 67, nr 2

70--76

EN

Particle-reinforced composite materials very often provide unique and versatile properties. Modelling and prediction of effective heterogeneous material behaviour is a complex problem. However it is possible to estimate an influence of microstructure properties on effective macro material properties. Mentioned multi-scale approach can lead to better understanding of particle-reinforced composite behaviour. The paper is focused on prediction of an influence of particle shape on effective elastic properties, yield stress and stress distribution in particle-reinforced metal matrix composites. Design/methodology/approach: This research is based on usage of homogenization procedure connected with volume averaging of stress and strain values in RVE (Representative Volume Element). To create the RVE geometry Digimat-FE software is applied. Finite element method is applied to solve boundary value problem, in particular a commercial MSC.Marc software is used. Findings: Cylindrical particles provide the highest stiffness and yield stress while the lowest values of stiffness and yield stress are connected with spherical particles. On the other hand stress distribution in spherical particles is more uniform than in cylindrical and prismatic ones, which are more prone to an occurrence of stress concentration. Research limitations/implications: During this study simple, idealised geometries of the inclusions are considered, in particular sphere, prism and cylinder ones. Moreover, uniform size and uniform spatial distribution of the inclusions are taken into account. However in further work presented methodology can be applied to analysis of RVE that maps the real microstructure. Practical implications: Presented methodology can deal with an analysis of composite material with any inclusion shape. Predicting an effective composite material properties by analysis of material properties at microstructure level leads to better understanding and control of particle-reinforced composite materials behaviour. Originality/value: The paper in details presents in details an investigation of influence of inclusion shape on effective elastic-plastic material properties. In addition it describes the differences between stress distributions in composites with various inclusion shapes.

4

Mean field homogenization in multi-scale modelling of composite materials

Ogierman W., Kokot G.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 61, nr 2

343--348

EN

Purpose: The paper is focused on testing of the capabilities of the mean field homogenization scheme in numerical analysis of composite materials. Another goal of this research is an attempt of coupling of mean field homogenization procedure with finite element computations to carry out a multi-scale analysis Design/methodology/approach: This research is based on the application of the DIGIMAT software which is material modelling platform. The Mori-Tanaka homogenization scheme implemented in DIGIMAT code was applied to obtain the average composite’s mechanical properties. Additional aspect is coupling of DIGIMAT material modeller with finite element solver. Findings: Application of mean field homogenization allows to obtain the effective properties of heterogeneous material very efficiently. Process of assigning material parameters to each composite’s phase on the micro level is operative and fast. Coupling homogenization procedure with finite element solver leads to full multi-scale analysis where material nonlinearities can be taken into account Research limitations/implications: Mean field homogenization gives approximate results, therefore detailed stress and strain fields in microstructure can not be analysed. Practical implications: Methodology presented in present article shows efficient approach to finding effective composite properties and in addition allow to carry out nonlinear multi-scale analysis. Originality/value: The paper presents new methodology which is intensively developed in the field of numerical simulation of structures and materials. The material parameters are not treated as the constant input data, but are obtained as results of the material parameters modelling process on the micro-scale level.