静压卸载后夹层结构界面蠕变失效特性分析

Analysis of Creep Interface Failure Mechanism of Sandwich Structural with Viscoelastic Core After Unloading

深水静压载荷作用下夹层复合材料结构上下表层弹性弯曲凹陷,其黏弹特性芯材将发生压缩形变,并随时间延长而产生蠕变形变,卸载后在表层弯曲刚度回复载荷作用下,表层与芯材界面将存在正应力σz。采用Maxwell模型建立芯层和界面层黏弹性材料本构模型,推导并得到了反映夹层结构界面层应变随时间变化规律的表达式;以最大正应变为界面层失效判据,综合分析了芯材与界面黏结材料的黏弹特征参数、表层弯曲刚度以及芯层厚度对界面层失效特性的影响规律。结果表明:芯层黏度系数ηc是影响模型蠕变的主要因素,表层弯曲刚度对模型蠕变的影响与达到最大正应变的时间有关,在材料选定后适当增加芯层厚度可减小界面层的应变。

Under deepwater static pressure, the surface of composite sandwich structure elastically bends to sink, and compression deformation of the viscoelastic core occurs to creep along the time. After unloa- ding, under elastically restoring force of the surface bending rigidity, normal stress σz exists between the surface and core interface. By use of Maxwell model, the constitutive model of the core layer and interface layer with viscoelastic materials was established, the variable patterns expression by time of strain with in- terface layer was deduced to receive. Take the biggest influence regulation of the core thickness, the surface normal strain as failure criterion of interface layer, bending rigidity and viscoelastic parameters of the core and interface adhesion material on interface failure mechanism were synthetically analyzed. The re- suits show that the core viscosity coefficient ηc is the main factors for the model creep and the influence of the surface bending rigidity for the model creep changes along the time reaching to the biggest normal strain, and increasing appropriately, the core thickness can decrease the interface strain after selecting the material.