冲击爆炸荷载作用下混凝土材料两类弹塑性损伤本构模型的对比分析

Comparative study on two kinds of elastic-plastic-damage constitutive models for concrete materials under impact and blast loadings

冲击爆炸荷载作用下,混凝土弹塑性损伤本构模型包含流体弹塑性模型和帽盖弹塑性模型。就本构理论而言,这两类模型在偏应力模型、压力-体应变关系和损伤模型三个方面存在本质的区别。模拟混凝土结构在不同荷载作用下的动力响应时,了解不同本构模型的特点并选择合适的模型进行数值模拟是获得合理预测结果的先决条件。文章探讨了这两类弹塑性模型的本构理论区别并给出两类模型的适用条件。选取弹体低速侵彻混凝土薄板和弹体高速侵彻混凝土厚板两个算例对两类弹塑性模型进行比较,结果表明,弹体低速侵彻下,两类模型预测结果接近并且均与试验结果吻合;弹体高速侵彻下,流体弹塑性模型预测结果与试验结果吻合,而帽盖弹塑性模型预测结果与试验结果差别很大。这一结果表明,在冲击荷载作用下,流体弹塑性模型可适用于低压力到高压力的不同情况,而帽盖弹塑性模型只适用于较低压力(约1GPa),不适用于高压力如弹体高速侵彻的情况。

Under impact and blast loadings,the concrete elastic-plastic-damage model comprises the elastic-plastic model in hydrocode and the elastic-plastic cap model.In terms of the constitutive theory,the two kinds of models differ in three aspects,i.e.,the deviatoric stress model,the relation between pressure and volumetric strain,and the damage model.To attain reasonable predictions,it is critical to know the features of different constitutive models and apply an appropriate one to simulating concrete structures subjected to different dynamic loadings.In this study,the differences in the constitutive theory for the two kinds of elastic-plastic models and their application scenarios were discussed.A thin concrete slab perforated by a low-velocity projectile and a thick concrete slab penetrated by a high-velocity projectile were simulated.Results indicate that for the impacts of low-velocity projectile,the predictions by the two kinds of models were close and consistent with the test results;whereas for the impacts of high-velocity projectile,the predictions from the elastic-plastic model in hydrocode were similar to the test data,but those from the elastic-plastic cap model were far from the test data.These findings suggest that under impact loadings,the elastic-plastic model in hydrocode can be used for those situations with low to high pressure,whereas the elastic-plastic cap model can only be used for the situations with low pressure(less than 1 GPa)and it is not suitable for the situations with high pressure such as impact cases of high-velocity projectile.