采用喷丸强化技术引入残余应力是一种广泛应用的疲劳寿命强化技术,特别是对于航空材料7075铝合金,但喷丸所引入的残余应力并不是稳定不变的,在交变工作载荷作用下会导致该残余应力的松弛和重分布,从而影响其强化效果.故开展喷丸残余应力松弛规律的研究是十分必要的.文章针对7075铝合金喷丸试件进行三点弯曲疲劳实验,探究循环次数、外载强度、初始喷丸强度和应力比对喷丸残余应力松弛的影响,结果表明:经喷丸处理后,会在工件表面和次表面形成残余压应力层;循环次数对残余应力松弛的影响主要是集中在前100次循环,在此之后,残余应力松弛达到稳定阶段,即残余应力基本不发生松弛;随着外载强度的增加,残余应力松弛越明显;初始喷丸强度越大,所引入的残余应力越大,松弛量也越大,但所剩残余应力值仍较大.应力比对残余应力松弛也会产生影响,随着应力比的增大,残余应力松弛量将随之减小.%The introduction of residual stress introduced by shot peening is widely used in fatigue life strengthening technique, especially for aerospace 7075 aluminum alloy, but the residual stress introduced by shot peening is not stable, which can be relaxed and redistributed, thus affecting its strengthening effect on fatigue life. Therefore, it is necessary to study residual stress relaxation. So the effects of cyclic number, loading strength, initial shot peening strength and stress ratio on shot peening stress relaxation are studied. The results show that a residual compressive stress layer is formed in surface and sub-surface of the work-piece after shot peening. The effect of cyclic number on residual stress relaxation is mainly concentrated on the first 100 cycles, then the residual stress reaches a stable stage. With the increase of loading strength, the residual stress relaxation will become more obvious. The greater the initial shot peening strength is, the grea-ter the residual stress and relaxation are, but the residual stress is still large. The stress ratio also influences the residual stress relaxation. As the stress ratio increases, the residual stress relaxation will decrease.
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