Microscale Modeling of Deformation Response of Advanced High Strength Steels and Mechanical Behavior of Active Biopolymer Networks

chen, peng

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Year:: 2013
Contributor:: chen, peng (creator); Bower, Allan (Director); Kim, Kyung-Suk (Reader); Kumar, Sharvan (Reader); Hector, Louis (Reader); Brown University. ENGINEERING: Mechanics of Solids (sponsor)
Genre:: theses
Subject:: Low-carbon martensite; Dual-phase steels; Deformation; Micropillar; Finite element modeling; Active biopolymer networks; Crosslinks; Molecular motor; Strain stiffening; Microstructure
Extent:: xx, 127 p.
DOI: https://doi.org/10.7301/Z0639N24

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Abstract:: The nonlinear deformation response of two distinct materials was studied using finite element simulations. One is the hard Advanced High Strength Steels (AHSS) widely used in automobile vehicles. Another is the soft active biopolymer networks in plant and animal cells. For the hard AHSS, our proposed approach has successfully modeled the deformation response of two types of AHSS: fully martensitic steel and dual-phase steels. The measured flow curves for the martensite micropillars in the size-independent regime were used to determine material parameters in a dislocation-density-based crystal plasticity model of individual martensite blocks. The crystallographic orientation dependence of the flow strength in the ferritic micropillars was predicted successfully by a crystal plasticity model that accounts for the non-Schmid behavior. Full 3D crystal plasticity simulations, with material properties determined from micropillar compression tests, were then used to predict the macroscopic uniaxial stress–strain curves of the fully martensitic steel and dual-phase steels, which were in excellent agreement with experimental measurements. For the soft active biopolymer networks, we have studied the elastic response of actin networks with both compliant and rigid crosslinks by modeling molecular motors as force dipoles. Our finite element simulations show that for compliant crosslinkers such as filamin A, the network can be stiffened by two orders of magnitude while stiffening achieved with incompliant linkers such as scruin is significantly smaller, typically a factor of two, in excellent agreement with recent experiments. We show that the differences arise from the fact that the motors are able to stretch the compliant crosslinks to the fullest possible extent, which in turn causes to the deformation of the filaments. With increasing applied strain, the filaments further deform leading to a stiffened elastic response. When the crosslinks are incompliant, the contractile forces due to motors do not alter the network morphology in a significant manner and hence only small stiffening is observed.
Notes:: Thesis (Ph.D. -- Brown University (2013)

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chen, peng, "Microscale Modeling of Deformation Response of Advanced High Strength Steels and Mechanical Behavior of Active Biopolymer Networks" (2013). Mechanics of Solids Theses and Dissertations. Brown Digital Repository. Brown University Library. https://doi.org/10.7301/Z0639N24

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Mechanics of Solids Theses and Dissertations

Theses and Dissertations for the Mechanics of Solids department.
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