芯棒锥面结构对孔冷挤压强化残余应力场的影响

为了在紧固孔周引入均匀的残余压应力,以延长紧固孔构件的疲劳寿命、提高其抗应力腐蚀性能,利用ANSYS有限元软件,建立了轴对称弹塑性有限元模型,对直接芯棒冷挤压强化过程进行了仿真,特别是对芯棒的前锥段曲线结构形式进行了设计与分析,研究了前锥段曲线形式对残余应力场分布的影响.结果表明:孔壁表面的周向残余应力分布复杂且不均匀,比较而言,外凸型正弦曲线型芯棒所产生的残余压应力沿孔壁深度方向分布更加均匀;几种曲线形式的芯棒在上表面近孔边区域均产生了径向残余拉应力,在孔的挤入段产生了轴向残余拉应力,但外凸型正弦曲线型芯棒在上述区域所产生的残余拉应力较小,且分布区域也较小.

Effects of cone surface profile of mandrel on residual stress distribution of cold expansion strengthening of hole

The residual stress field of fastening holes caused by hole cold expansion with different front cone structures of the mandrel was simulated by using Finite Element Analysis Software ANSYS, in order to introduce uniform residual stress around the fastener holes, thus the fatigue life could be increased and the stress corrosion resistance could be enhanced. The results show that circular residual stresses around cold worked fastener holes showed an uneven distribution. In contrast, residual stress caused by mandrel with bulgy sinusoidal structure was well distributed along depth direction of the hole. For all of the fastening holes using different mandrel structures, radial residual tensile stress was produced in the upper surface near the hole and axial residual tensile stress was produced in diapir of the hole. Yet residual stress caused by mandrel with bulgy sinusoidal structure was less, and stress distribution region was smaller.