应用Lyapunov指数研究混凝土阶段特征的稳定判据

根据混凝土材料的应力-应变试验研究,得出试验曲线呈明显的分段特征,曲线的离散性发生于应变软化阶段。通过对试验数据序列的混沌动力学分析得出:随着单向抗压强度的增加,混凝土材料全应力-应变过程的系统状态由较有序的定常态质变为低混沌态,进而逐渐演化到强混沌态;混凝土材料峰后应力-应变阶段曲线的线性性质增强,裂隙系统状态由强有序的定常态向弱混沌态演化;混凝土材料峰前阶段的裂隙系统基本呈现弱混沌状态。提出将LE1作为混凝土材料阶段特征的稳定判据,将LE1作为系统稳定度的表征量,并在实例计算中证明了该法确定的稳定判据符合实际情况。

Research on Stability Criterion of Concrete Feature in Different Stress Stage with Lyapunov Exponent

According to the research on whole curves of strain-stress of concrete materials,this paper finds there was an evident features of stages,and the discrete feature of curve is often in strain-softening stage.After data series of test being detected by dynamics of chaos,it presents that system of whole process of strain-stress evolutes from ordered steady state to low chaos state even high chaos state,system after compressive strength which curve of strain-stress is more linear one by one changes from strong ordered steady state to low chaos state;and joint system of concrete before compressive strength normally generates weak chaos state,with increase of uniaxial compressive strength of concrete materials specimens.The LE1 is proposed to be the stability criterion of concrete features in different stress stages,and the LE1 is regarded as the representative value of the system stability degree.The calculation of example shows that the stability criterion defined by the proposed method is consistent with the actual situation.