基于最小耗能原理的塑性应变流动法则

根据最小耗能原理,推导塑性应变流动法则的一般表达式.与传统塑性流动法则相比,该流动法则增加了一项交叉耦合项,可以很好地揭示准脆性材料剪胀效应的内在机理.同时在该流动法则下,推导弹塑性有限元增量迭代格式,由于其刚度矩阵的对称性,使得计算效率大大提高.对土试样塑性应变的演化过程进行追踪模拟,其破坏形式与实验现象非常接近,表明基于最小耗能原理框架下的流动法则是合理可靠的.最后,采用该流动法则下的弹塑性有限元对土质边坡的变形破坏过程进行模拟,破坏形式与实际情况相符,表明新的流动法则不仅合理可靠,而且具有广阔的应用前景.

Flowing Rule of Plastic Strain Based on Least Energy Dissipation Principle

Based on the assumption of least energy dissipation,a general expression of flowing criterion of plastic strain is derived.This formula has a cross couple term of current stress and a plastic softness increment matrix that do not exist in the classic plastic flowing criteria.Due to this cross couple term,the plastic deformation does not always flow along the normal direction of yield function surface,making the intrinsic mechanism of shearing dilation characteristics for quasi-brittleness material well discovered.With the plastic strain flowing equation,increment iteration is conducted.The evolvement process of plastic deformation for soil sample subject to axial and surrounding pressure is then simulated.The fracture form of the simulation is similar to the experimental results.Finally,the slippage fracture process of a soil slope is modeled with the flowing criterion of plastic strain.The fracture form conforms to the practical case,showing that the flowing rule is rational and reliable.Therefore the numerical method based on the new flow rule has a good prospect of applications.