An elastic-viscous-plastic constitutive model construction method considering complex nonlinear behaviors of a fiber reinforced composite material

Abstract

The invention discloses an elastic-viscous-plastic constitutive model construction method considering complex nonlinear behaviors of a fiber reinforced composite material, which comprises the following steps: constructing a viscoplastic potential function considering the influences of stretching, compression yield asymmetry and hydrostatic pressure of the composite material, and obtaining the viscoplastic strain in an incremental form through a non-associated flow criterion; Defining a dynamic yield surface based on an overstress function, and considering the difference of isotropic hardeningof the material under stretching and compression and the rate correlation effect of the dynamic yield surface; And considering the existence of lagging elastic deformation, defining the relationship between the overstress function at the loading stage and the relaxation stage and the equivalent viscoplastic strain rate, and forming an elastic-viscoplastic constitutive model for describing the complex nonlinear behavior of the composite material. The method can effectively describe the elastic-viscoplastic behavior of the fiber reinforced composite material, and can be applied to the scientificresearch and engineering technical fields of development of a continuous constitutive model of a commercial finite element software composite material, analysis and optimization of mechanical properties of a composite material engineering structure and the like.

Description

technical field [0001] The invention relates to the field of numerical modeling of mechanical behavior of composite materials, in particular to a method for constructing an elastic-viscoplastic constitutive model considering complex nonlinear behavior of fiber-reinforced composite materials. Background technique [0002] Compared with traditional metal materials, fiber-reinforced polymer matrix composites have higher specific stiffness and specific strength, and are widely used in weaponry, aerospace, vehicles and ships and other fields. Because the composite material exhibits certain elastic-viscoplastic behavior when it is loaded during use, until the material is damaged and degraded, it will affect the structural bearing capacity. Reliably grasping the nonlinear elasto-viscoplastic properties of composite materials before damage is of great significance for accurately predicting the damage failure of composite structures and optimizing the performance of composite structu...

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Problems solved by technology

Although this constitutive model can accurately predict the nonlinear elasto-viscoplastic behavior of composite materials, and uses hysteresis elastic deformation to describe the difference between loading and unloading behavior after dynamic yielding, it ignores the influence of hydrostatic pressure and loading rate on material yielding , the associated flow criterion used in the model makes it difficult to obtain the correct material plastic Poisson's ratio and bulk plastic strain (explained in the journal paper Modeling the inelastic deformation and fracture of polymercomposites-Part I: plasticity model)

Therefore, the model is difficult to apply to the prediction of nonlinear elasto-viscoplastic mechanical behavior of composite materials under different loading rates

[0004] In the existing commercial large-scale finite element software, there is no model that can directly provide users with the analysis of the above-mentioned complex nonlinear elasto-viscoplastic behavior of composite materials, and a suitable model can be used in finite element to accurately predict the nonlinear behavior of composite materials. The constitutive model of elasto-viscoplastic behavior is in short supply, which further increases the difficulty for engineers and technicians to analyze the nonlinear elasto-viscoplastic mechanical response of composite structures

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