This paper investigates the failure strain as a dependence of the stress triaxiality and the Lode angle parameter for polyurethane rigid foams (PUR) of two densities (100 and \(300\,\hbox {kg/m}^{3})\). Tests were carried out in tension for various configurations, resulting in different states of stress triaxiality at various Lode angles in the critical areas. The failure strain was determined for each setup using finite element analysis, as the tests were replicated with numerical models. The displacement at failure recorded in the experiments was imposed for the models, determining the failure strain as a function of stress triaxiality and the Lode angle parameter. The results were validated through the analysis of the failure of sandwich structures with aluminium faces and PUR cores.

本文研究了两种密度（100和\（300 \，\ hbox {kg / m} ^ {3}）\）的聚氨酯硬质泡沫塑料（PUR）的破坏应变与应力三轴性和洛德角参数的关系。。在各种配置下进行了张力测试，从而在关键区域的不同洛德角下产生了不同的应力三轴状态。使用有限元分析确定每种设置的破坏应变，因为测试是通过数值模型进行的。对模型施加了在实验中记录的破坏时的位移，确定了破坏应变与应力三轴性和洛德角参数的关系。通过对带有铝面和PUR芯的夹心结构的破坏进行分析，验证了结果。