Robust Constitutive Model Research Articles

Constitutive modeling of polymer materials at impact loading rates

Starting from physical basis, a robust three-dimensional constitutive model for the finite strain response of amorphous polymers is briefly presented. This model accounts for the high strain rate and temperature effect. Intramolecular as well as intermolecular interactions under large elastic-inelastic behavior are considered for the mechanisms of deformation and hardening. In particular, it is found that the secondary relaxations of polymer chains play an important role in the deformation process for the high strain rates and low temperatures. For a wide range of temperature and strain rate, the proposed constitutive model has been validated in compression for three amorphous polymers: polymethylmethacrylate (PMMA), polycarbonate (PC) and polyamideimide (PAI).

Nonlinear Finite Element Analysis on Shear Failure of Structural Elements Using High Performance Fiber Reinforced Cement Composite

High-performance fiber reinforced cement composites (HPFRCC) are highly ductile and characterized by pseudo strain hardening in tension. High-level in structural performance through the application of HPFRCC is expected. However, many uncertainties remain regarding the influence of the tensile characteristic of HPFRCC on the shear resistance mechanism of structural elements utilizing HPFRCC. Though FEM analysis is an effective engineering tool to analyze the relationship between the material characteristics and the structural performance of elements, a robust constitutive model is indispensable for obtaining accurate results. This paper proposes constitutive models based on basic test results. The proprieties of the model are confirmed based on a comparison between the analytical simulation and the structural test results for shear failure behavior. The analytical results using the proposed model match reasonably well the experimental results of HPFRCC structural elements.

Study of magnetomechanical non-linear deformation of ferromagnetic materials: Theory and experiment

A robust constitutive model is desirable in order to guide the processing and development of ferromagnetism and for use in the design of ferromagnetic devices. In this paper, a non-linear constitutive model of soft ferromagnets is developed for general magnetomechanical loading histories. The experimental set-up and measured techniques, which were employed to measure the non-linear deformation of both the magnetostrictive materials and the soft ferromagnetic materials subjected to coupled magnetomechanical loading, are introduced. The general structure for the constitutive behaviour of ferromagnets including soft-ferromagnetic and hard-ferromagnetic materials is similar to the classical models of metal plasticity; i.e. a convex yield surface can be identified in a stress-magnetic field space, within which the deformation and magnetization are reversible, and increments of both remanent magnetization and remanent strains are normal to the yield surface. The state of materials is described in terms of the remanent strain and the remanent magnetization that are introduced as internal variables besides stress, strain, magnetic field and magnetization. The one-dimensional model is examined by numerical stimulations and the response of the ferromagnetic materials is discussed in comparison with the measured results. The macroscopic features of ferromagnets, such as hysteresis loop and magnetostrictive hysteresis, are predicted.

高靱性セメント系複合材料を用いた構造要素のせん断破壊挙動に関する非線形FEM解析

High-performance fiber reinforced cement composites (HPFRCC) are highly ductile and characterized by pseudo strain hardening in tension. High-level in structural performance through the application of HPFRCC is expected. However, many uncertainties remain regarding the influence of the tensile characteristic of HPFRCC on the shear resistance mechanism of structural elements utilizing HPFRCC. Though FEM analysis is an effective engineering tool to analyze the relationship between the material characteristics and the structural performance of elements, a robust constitutive model is indispensable for obtaining accurate results. This paper proposes constitutive models based on basic test results. The proprieties of the model are confirmed based on a comparison between the analytical simulation and the structural test results for shear failure behavior. The analytical results using the proposed model match reasonably well the experimental results of HPFRCC structural elements.

Simulation of Highly Ductile Fiber-Reinforced Cement-Based Composite Components Under Cyclic Loading

This research investigates ductile fiber-reinforced cement-based composites (DFRCCs) for new design as well as retrofitting of structures in seismic regions. DFRCC is highly ductile and is characterized by strain-hardening in tension to strains over 3% and by unique cycling loading behavior. In order to accurately predict the structural performance of DFRCC components under cyclic and seismic loading, a robust constitutive model is needed for structural-scale simulations. In this paper, a constitutive model based on total strain is proposed and applied to simulate structural component tests. The model in particular captures DFRCC's unique reversed cyclic loading behavior. Simulation results show that the implemented model is robust and reasonably accurate in simulating DFRCC structural components reinforced with steel and fiber-reinforced polymer bars.