振动时效对铝板表面应力松弛均匀性的实验设计与分析

通过对7075铝板进行振动时效（VSR）实验研究，观察其对材料表面应力松弛的影响。采用振动模态仿真和X-ray应力测试，对材料表面应力分布、应力释放状况及其均匀化应对策略进行实验分析。结果显示：VSR在振动台第5阶固有频率亚共振区开始，对试样造成表面应力松弛，在距离振幅最小的节线远端，应力释放率最大达到18.7%，而靠近节线处，应力松弛效果减弱，只有4.1%，说明振动时效下材料表面应力松弛出现不均匀。根据平台振型弯曲变形特点，本文提出位置交叉时效方法，以促使激振能均匀分配于材料表面。实验结果表明，铝板表面应力松弛波动由原来的14.6%降到了6.5%，应力分布不均匀得到明显改善，验证了位置交叉VSR方法的可行性，对VSR解决轻质结构零件应力均化问题具有参考作用。
Abstract： The effect of stress relaxation on the surface stress of materials was investigated by experiments of vibration stress relief (VSR) for a 7075 Al-base alloy thin plate.The surface stress distribution,stress relaxation uniformity and handling strategies were analysed by vibration simulations and X-ray stress measurements.The experiments show that the effective VSR starts from the sub-resonance region of 5th order natural frequency of the vibrating plate,and the VSR causes the surface stress relaxation which is of non-uniformity along the normal direction of pitch line of zero amplitude.The max stress relaxation ratio (SRR) is 18.7% in the places far away from the pitch line,but the min SRR is 4.1% in the places close to the pitch line.According to the harmonic character of vibration mode,the cross-position VSR method was proposed to balance the vibration energy on the surface of samples.The further experimental results show that the uniformity of stress relaxation is greatly improved,the fluctuation of SRR is reduced from previous 14.6% down to present 6.5%,which means the method is practical.The VSR method can also be applied to other lightweight thin-walled components. 