薄板激光冲击强化残余应力场的数值模拟与试验

Numerical simulation and experimental investigation of residual stress field for laser shock processing

激光冲击强化会在材料表面形成深度达到1 mm的残余压应力,而对于厚度小于1 mm的薄板,由于冲击时应力波的反射和叠加,其残余应力场的分布肯定不同于厚板。文章采用4种冲击方式(单面冲击、底面约束情况下的单面冲击、双面非同时冲击以及双面同时对冲)对2024铝合金薄板(厚度为1 mm)进行激光冲击强化,并应用有限元软件ANSYS/LS-DYNA对其进行数值模拟,系统分析经过4种不同的冲击方式,得到薄板的变形以及残余应力的分布情况。结果表明,双面同时对冲方式能够使薄板两面都产生很大的残余压应力,而且不会出现弯曲变形,是理想的冲击方式。

During laser shock processing the residual compressive stress may reach lmm under the surface. But for the sheet thinner than lmm, due to the reflection and superposition of shock stress wave, the distribution of residual stress field would be different from that of thick sheet. Four methods are introduced to impact 2024 aluminum alloy sheet lmm thick including single-sided impact not restrained; single-sided impact with the bottom restrained; non-simultaneous double-sided impact and simultaneous double-sided impact. Numerical simulation using FEM software ANSYS/LS-DYNA has been made. The distortion of the sheet and distribution of the residual stress after impact are analyzed. The results show that large residual stress would emerge on both sides during simultaneous double-sided impact and no bending distortion exist, so it＇s an ideal method.