Specimens of sandwich plate with viscoelastic core for 3-points bending test appear delay debonding at interface after unloading.Theoretical and experimental approaches for sandwich plate with steel faceplates and polyurethane elastomer core were utilized here to study this phenomenon.Double Cantilever Beam(DCB) and Single Cantilever Beam(SLB) tests were conducted here to obtain strain energy release rate (SERR) between face plates and core.And the expression of critical SERR was deduced on condition of unchanged crack tip opening angle.Furthermore,critical crack length for two types of sandwich plate with different core was calculated.The results show that despite of some limitations,crack tip opening angle can illustrate the propagation of interface crack and reveal the characteristic of delay debonding of sandwich plate with polyurethane core and steel faceplate.%以聚氨酯弹性体钢夹层板为研究对象,对黏弹性夹芯夹层结构三点弯曲实验卸载后裂纹会沿层间方向继续扩展这一现象进行研究.开展了不同硬度夹芯的双悬臂梁(Double Cantilever Beam,DCB)实验和单悬臂梁(SLB)实验,测得了临界应变能释放率.在假设裂纹张开角度在开裂过程中不变的前提下,推导了临界应变能释放率的计算公式.并计算了软夹芯试件和硬夹芯试件的临界破坏的裂纹长度.结果表明,虽然存有一定的局限性,但是裂纹张开角度能够描述黏弹性夹层结构的层间裂纹扩展,获得的结果能够描述聚氨酯弹性体钢夹层板的层间延迟破坏的特点.
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