喷丸三维残余应力场的有限元模拟

SIMULATION OF 3D RESIDUAL STRESS FIELD OF SHOT PEENING BY DYNAMIC FINITE ELEMENT ANALYSIS

运用大型有限元计算软件ABAQUS建立了模拟喷丸残余应力场的三维有限元模型,预测了在相同喷丸强度下玻璃丸和钢丸两种类型弹丸喷射所产生的残余应力场。模拟过程中,分析了线性减缩积分单元的沙漏参数、材料的应变硬化率、喷丸覆盖率以及初始残余拉应力等因素对304不锈钢靶材残余应力分布的影响。从计算结果可以看出,钢丸喷丸产生的残余压应力层较深,但在高覆盖率时,玻璃喷丸产生的残余压应力的平均值比钢丸喷丸处理后产生的大。在有初始残余拉应力(250MPa)存在的情况下,两种类型的喷丸处理均能使304不锈钢靶材表面形成残余压应力层,这说明喷丸工艺可以提高奥氏体不锈钢焊接构件的抗应力腐蚀开裂能力。本研究成果为进一步探讨喷丸强化不锈钢焊接头抗应力腐蚀性能的机理奠定了基础。

The shot peening process is simulated by FEM using ABAQUS codes. The 3D linear reduced-integration elements are used to predict residual stress fields in the weldments peend by glass beads and steel shots under the same Almen intensity. The effect of Hourglass, dynamic hardening of target material, peening coverage and initial residual stress induced by welding are considered during the simulations. It can been seen from the results that steel-shots peening can produce deeper compressive residual stress layer, but in the condition of higher peening coverage glass-beads peening results in higher average residual compressive stress on the surface of weldments than steel shots. Numerical results also show that a residual compressive stress layer could be produced by shot peening even if there are welding residual tensile stresses existing in the weldments. Therefore, shot peening is an effective method for protecting weldments against stress corrosion crack. The above results provide the basis for studying the mechanism on prevention of stress corrosion cracking in weld joint of 304 type stainless steel by shot peening.