带中心孔形状记忆合金板在双轴加载下的响应研究

Analysis of a Shape Memory Alloy Plate with a Circular Hole Subjected to Biaxial Tension

为了研究复杂应力下多孔SMA的超弹性特性,用一热力学有限元模型对带中心孔宽板在双轴拉应力作用下孔临界区域的应力分布以及相变情况进行了有限元模拟计算。初始时,平板处于奥氏体状态,在载荷作用下,在圆孔边界处首先发生相变,并随着载荷的增加,相变区域逐渐向内部扩展。在计算中,两个加载方向同时加载,并采用了不同的加载比例R。随着加载比例的增大,圆孔周围完全发生马氏体相变的区域逐渐增大,等效应力分布也发生变化。随着2-方向加载水平的增加,1-方向的应力-应变滞后环位置逐渐逐渐降低,马氏体相变临界应力也逐渐减小。同时确立了应力空间(σ11,σ12)上的相变初始面。

In order to study the superelsticity of porous SMAs under complex loading,a thermo-mechanical model has been used to simulate the stress distribution and the phase transformation in the vicinity of the hole.The plate is in the austenitic phase prior to loading.However,as a result of tensile loading,stress-induced martensite forms,beginning from the boundary of the hole and extending into the interior,as the load continues to increase.The proportional loading is applied with different loading rates R.with the increasing of the loading rates,the regions of pure martensite around the hole increase.With the increasing of the 2-direction loading level,the stress-strain loops of the 1-direction descend,the critical stresses required for the martensitic transformation decrease and the slopes of the upper plateau in the stress-strain curves decline.Simultaneously,the initial surface of phase transformation under biaxial loading in the space(σ_(11),σ_(12)) has been determined.