A New And Direct Approach To Explicitly Characterizing Work-hardening Features Of Metals

A new finite deformation elastoplastic constitutive model is established in this dissertation.Based on this model,the whole process of the metal from the initial yielding up to strength limit is directly and explicitly simulated.At the same time,this paper proposes a new method to determine the yield strength of metallic materials,aiming to characterize the work-hardening behavior of the whole process of metallic materials from the initial yielding up to strength limit.The central issue in this regard is to determine the exact change law of yield strength during plastic deformation,that is,the change law of yield strength with plastic work needs to be determined.This method directly gives an explicit form of uniaxial stress-strain function.Firstly,this function is accurately conformed to the experiment,and then an explicit expression of plastic work is derived based on the function.Finally,the expression of plastic work and the given stress-strain function together explicitly determine the yield strength that changes with plastic work.The new idea takes monotonic axial strain as a parametric variable and gives explicit expressions of the aforementioned two functions as parametric variables.Together,they uniquely determine the yield strength as a function of plastic work,thereby solving the central problem of work hardening characterization.This method has the advantages of accuracy and explicitness,avoids the tedious trial and error steps and complicated calculations involved in solving the nonlinear elastoplastic rate equations,and can directly identify unknown parameters,It also avoids the limitation of giving only rough approximate results.The new method is used to numerically simulate the stress-strain data of the uniaxial tensile experiment.It can be found that the simulation results are in good agreement with the experimental data.At the same time,the relationship between the yield strength and the plastic work can be obtained.The new elastoplastic model can also be used to deal with the multiaxial stress-strain response of elastoplastic structures under various load conditions.