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试验研究了预先经历一定次数的低周疲劳(low cycle fatigue,LCF)对TA11合金高周疲劳(high cycle fatigue,HCF)强度的影响.考虑了LCF试验中循环最大应力、应力比和寿命比例等主要参数,根据步进法,利用旋转弯曲疲劳试验,研究了LCF预损伤对标准试件HCF强度的影响规律.结果表明:当循环最大应力为900MPa时,LCF载荷中靠前的循环产生的塑性应变大,因此加载较少的LCF预损伤也会降低该合金HCF强度;不同应力比的LCF预损伤都会降低HCF强度;当LCF预损伤的最大应力远小于材料的屈服强度时,LCF预损伤对HCF强度的影响较小,而当LCF预损伤的最大应力接近或大于材料的屈服强度时,则必须考虑LCF预损伤对TA11合金HCF强度的影响.
The effects of low cycle fatigue (LCF) on the high cycle fatigue (HCF) strength of TA11 alloy have been experimentally studied in this paper.Considering the maximum cyclic stress, the stress ratio and the life ratio in the LCF test According to the step-by-step method, the influence of LCF pre-damage on the HCF strength of the standard specimen was studied by the step-by-step method.The results show that when the maximum cyclic stress is 900 MPa, the plasticity Strain and large LCF pre-damage will reduce the alloy HCF strength; LCF pre-damage at different stress ratios will reduce the HCF intensity; when the maximum LCF pre-damage stress is far less than the yield strength of the material, LCF pre- HCF strength is less affected. However, when the maximum LCF pre-damage stress is close to or greater than the yield strength of the material, the effect of LCF pre-damage on the HCF strength of TA11 alloy must be considered.