2B25-T351压印强化残余应力场的有限元模拟与实验

Finite element simulation and experimental test on residual stress field by pressed strengthening

运用有限元软件ABAQUS建立压印强化残余应力场的三维有限元模型,模拟计算压印强化过程中2B25-T351铝合金构件的三维残余应力场分布,模拟结果表明,压印痕底部残余应力沿厚度方向呈梯度分布,与表面距离越远,压应力水平越小。孔周围的残余应力分布比较集中,压印痕端头附近,孔边为相对均匀的残余压应力,其他位置为自平衡的残余拉应力;使用X射线衍射应力分析技术测量实际试样的残余应力,结果表明,实验测量值与有限元模拟值吻合较好;对压印强化前后试样进行疲劳性能试验,结果表明,压印强化在试件表面引入残余压应力,可降低裂纹萌生的几率及裂纹扩展的速率,压印强化后材料的疲劳寿命提高了近1.5倍。

The residual stress field of 2B25-T351 aluminum alloy caused by pressed strengthening was simulated by FEM using ABAQUS . The results show that the residual stress around indentation flaw possesses a gradient distribution across the thickness . Far away from the surface , the residual compressive stress decreased towards a stable value . The residual compressive stress around hole shows a centralized distribution , and the self-balanced residual tensile stress is located in other regions . The residual stress of the specimen measured by the X-ray agrees well with the FE simulation result . Furthermore , the effect of the pressed strengthening as the mechanical surface treatment on high cycle fatigue performance was investigated . The results show that pressed strengthening leads to a significant improvement in the fatigue life , and the main reason was that the pressed strengthening causes the residual compressive stress layer by which the crack initiation rate and propagation rate were suppressed .