Lu Lei, Chen Hao, Ren Mingming, Xu Sha, Li Yongfang, Zhou Tianjun, Yang Yali
School of Mechanical and Automotive Engineering, Shanghai University of Engineering Science, Shanghai 201620, China.
Materials (Basel). 2024 Feb 29;17(5):1133. doi: 10.3390/ma17051133.
A certain number of hole-like defects will occur in aluminum alloys under cyclic loading. The internal holes will reduce the strength of the material and cause stress concentration, which will aggravate the development of fatigue damage. A classification method of defect features based on X-ray CT damage data is proposed. The random hole distribution model is established through the linear congruence method and the region division method. The hole parameter is introduced as the intermediate variable of the 3D reconstruction model of internal defects. In the mesoscopic stage, the function relationship between the distribution of random holes and the fatigue life is established based on the coupling relationship between the number and proportion of pores and the fatigue life. In the macroscopic stage, the relationship between the random holes and the macroscopic crack growth life is established by taking the crack length as the damage variable. The crack propagation rate decreased with the increase in the number of holes. The prediction model of the whole life stage is established using the life function from microcrack initiation to macroscopic crack propagation. Finally, the validity of the whole stage fatigue life prediction model is demonstrated through the comparison and verification of experiments, which provides a certain engineering value for the life estimation of 6061-T6 aluminum alloy materials.
铝合金在循环载荷作用下会出现一定数量的孔洞状缺陷。内部孔洞会降低材料强度并引起应力集中，进而加剧疲劳损伤的发展。提出了一种基于X射线CT损伤数据的缺陷特征分类方法。通过线性同余法和区域划分法建立随机孔洞分布模型。引入孔洞参数作为内部缺陷三维重建模型的中间变量。在细观阶段，基于孔隙数量和比例与疲劳寿命的耦合关系，建立随机孔洞分布与疲劳寿命的函数关系。在宏观阶段，以裂纹长度为损伤变量，建立随机孔洞与宏观裂纹扩展寿命的关系。裂纹扩展速率随孔洞数量的增加而降低。利用从微裂纹萌生到宏观裂纹扩展的寿命函数建立全寿命阶段的预测模型。最后，通过实验对比验证了全阶段疲劳寿命预测模型的有效性，为6061-T6铝合金材料的寿命估算提供了一定的工程价值。
