Chaboche随动硬化模型参数确定及棘轮效应

采用遗传算法确定不同Chaboche随动硬化模型的参数,得到的3种模型中,四分量模型对棘轮的预测与试验结果符合最好.增大应力幅值或应力平均值,都会使应变峰值增大,应变累积速度加快;利用确定的四分量模型研究加载顺序对棘轮的影响.结果表明,平均应力加载顺序对棘轮预测有较大影响,加载顺序高-低的累积应变低于加载顺序低-高的累积应变,而且先加载的平均应力越大,后加载的载荷产生的累积应变越小;而应力幅值加载顺序对应变累积几乎没有影响.

Parameter determination of Chaboche kinematic hardening models and ratcheting simulation

Chaboche kinematic hardening model is a powerful tool to evaluate the cyclic behavior and it can predict the ratcheting phenomenon. Parameters in three Chaboche kinematic hardening models were determined using genetic algorithm considering both hysteresis loop and ratcheting. In the three models, model with four nonlinear components has the best prediction for ratcheting compared with experimental results. Peak strain increases when increasing stress amplitude or mean stress, and strain accumulation rate accelerates at the same time. Ratcheting was simulated using Chaboche kinematic hardening model containing four components to study the effects of loading sequence on ratcheting. Results show that loading sequence of mean stress makes a difference on ratcheting. Accumulated strain under high-low loading sequence is lower than that under low-high loading sequence. The higher the former mean stress is, the lower the accumulated strain under the later load is. However, loading sequence of stress amplitude has little impact on accumulated strain.