航空7050铝合金孔挤压强化及其响应特征研究

doi:10.3969/j.issn.1007-2012.2023.09.027

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塑性工程学报 ›› 2023, Vol. 30 ›› Issue (9) : 217-225. DOI: 10.3969/j.issn.1007-2012.2023.09.027

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材料性能与变形理论

航空7050铝合金孔挤压强化及其响应特征研究

钟达智¹, 焦海涛¹, 徐颖珊², 刘晓鹏², 张岐良³

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Study on hole expansion strengthening and response characteristics of aerospace 7050 aluminum alloy

ZHONG Da-zhi¹, JIAO Hai-tao¹, XU Ying-shan², LIU Xiao-peng², ZHANG Qi-liang³

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摘要

为深入理解航空7050铝合金机械连接接头孔挤压强化的力学响应特性，提出了多个不均匀性指标，结合数值模拟定量评估了挤压强化参数对残余应力分布不均匀性的影响；在交变加载条件下，同时从应力水平和应力幅值两个维度，定量分析了挤压强化参数对结构应力响应的影响。结果表明：芯棒挤压后孔壁附近获得对疲劳性能有益的残余压应力，该应力沿厚度方向呈梯度分布，且当挤压量超过某临界值后其分布不均匀指标趋向平缓；纵向残余应力沿横向分布的特点是由孔壁附近较高的、存在大梯度变化且分布范围较窄的压应力转变为外侧的较低的、较为平缓且分布范围较宽的拉应力，且二者极值、残余压应力分布范围随挤压量的增大而增大；未经挤压试件的纵向加载应力由孔壁向外呈单调下降趋势，且孔壁应力集中系数高达3.7～4.1，而经孔挤压试件因挤压残余压应力效应其加载应力分布曲线不再是单调曲线，且高挤压量下孔壁应力甚至不及外侧应力的50%；高挤压量下卸载应力横向分布曲线与残余应力曲线几乎重合，但挤压量小于某临界值时孔壁附近的卸载应力低于残余应力；芯棒孔挤压只降低孔壁附近应力的大小，不改变其幅值。

Abstract

To deeply understand the mechanical response characteristics of the mechanical joint holes expansion strengthening of aerospace 7050 aluminum alloy,several uneven indexes were proposed,and the influence of expasion strengthening parameters on the uneven distribution of residual stress was quantitatively evaluated by numerical simulation. Under alternating loading condition,the influence of expasion-strengthening parameters on the structural stress response was quantitatively analyzed from two dimensions of stress level and stress amplitude.The results show that the residual compressive stress beneficial to fatigue properties is obtained near the hole wall after the mandrel expasion. The stress is distributed in gradient along the thickness direction,and the uneven distribution indexes tend to gentle when the expansion amount exceeds a critical value. The transverse distribution characteristics of the longitudinal residual stress are changing from the high compressive stress with large gradient change and narrow distribution range near the hole wall to the low,gentle tensile stress with wide distribution range on outside,and the extreme values and the distribution range of residual compressive stress increase with the increase of the expansion amount. The longitudinal loading stress of the unextruded specimen decreases monotonically from the hole wall to the outside,and the stress concentration coefficient of the hole wall is reach up to 3.7-4.1,while the loading stress distribution curve of the hole extruded specimen is no longer monotonic due to the effect of compressive residual stress,and the hole wall stress is even less than 50% of the external stress with high expansion amount. The transverse distribution curves of unloading stress almost coincide with those of residual stress under high expansion amount,but the unloading stress near the hole wall is lower than the residual stress when the expansionn amount is less than a critical value. The mandrel hole expansion only reduces the stress near the hole wall,but does not change its amplitude.

导出引用

钟达智, 焦海涛, 徐颖珊, 刘晓鹏, 张岐良. 航空7050铝合金孔挤压强化及其响应特征研究[J]. 塑性工程学报, 2023, 30(9): 217-225 https://doi.org/10.3969/j.issn.1007-2012.2023.09.027

ZHONG Da-zhi, JIAO Hai-tao, XU Ying-shan, LIU Xiao-peng, ZHANG Qi-liang. Study on hole expansion strengthening and response characteristics of aerospace 7050 aluminum alloy[J]. Journal of Plasticity Engineering, 2023, 30(9): 217-225 https://doi.org/10.3969/j.issn.1007-2012.2023.09.027

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