Press Formability of the Steel/Resin/Steel Laminates Vibration Damping Sheets

研究了树脂芯剪切流动应力对钢/树脂/钢层合减振板压制成形性的影响。首先，对于具有不同芯材的几种类型的板，进行常规的金属板成形性试验，即简单拉伸试验、Swift杯试验和扩孔试验。结果表明，芯树脂的剪切流动应力越高，其抗撕裂和抗断裂性能越好。树脂芯的高剪切流动应力使蒙皮钢板的极限应变增大。这是因为流动剪应力限制了局部区域外蒙皮层应变的发展。对Marciniak和Kczinski提出的M-K模型进行了修正，使之能用于预测三层夹芯板在均匀双向平面应力状态下的极限应变。数值计算结果表明，流动剪切应力和弹性刚度的大小对极限应变有显著的影响。其次，采用J2-变形理论对V型弯曲过程中的双弯现象进行了分析，数值分析结果表明，树脂芯的流动剪切应力对双弯现象有一定的影响。它可以确定成形条件，确保不进行双弯V形弯曲操作。最后，为了确定树脂在简单剪切下的粘弹塑性性能，我们尝试构造了树脂芯夹层环试件扭转试验机。试验机能够进行任意指定路径剪切应变率的扭转试验。对几种树脂进行了加工硬化规律和应变速率敏感性试验。

Effects of the shear flow stress of resin core on the press formability of steel/resin/steel laminates vibration damping sheets were investigated. First, for several types of sheets with different core materials, conventional sheet metal formability tests, i.e. the simple tension test, Swift cup test and the hole expansion test, were performed. It mede clear that higher shear flow stress of the core resin gives more excellent press formability, both for wrinkling and fracture resistivity. The limit strain ,at which the skin steel sheet breaks, increased for high shear flow stress of resin core. Because the shear flow stress constrained the development of strain of the outer skin layer in the localized zone. M-K model,which had been proposed by Marciniak and Kczinski,was modified to predict the limit strain of the three layers sandwich sheet under uniform biaxial plane stress states. Results of numerical calculation gives the remarkable influence off the value of shear flow stress and elastic rigidity on the limit strain.Next, double-bent phenomenon in the V-type bending process was analyzed using J2-deformation theory and the results of numerical analysis make clear some effects of shear flow stress of the resin core on double-bent phenomenon. It could determine the forming condition that ensure to perform no double-bent V-bending operation. Finally, in order to decide the visco-elastic-plastic properties of resins under simple shear, we tried to construct the torsion testing machine for the sandwiched ring specimen with resin core. Trial machine is able to torsion test with any specified path of shear strain rate. For several types of resin, workhadening rules and strain rate sensitivities are decided by the test using the trial testing machine.