The present work is concerned with the numerical modelling of the cyclic behaviour of Ti-6Al-4V lattice structures. In the study, diamond structures of titanium alloy produced by the additive laser powder bed fusion (LPBF) method with different degrees of relative density were used. Realistic geometric models of the studied mesostructures were generated using computed microtomography, taking into account the imperfections of the material resulting from the manufacturing process. The numerical calculations also took into account the actual material hardening curve in the elastic-plastic strain range. One of the achievements of this work is the numerical modelling of cyclic loading of realistic mesostructures with their imperfections. The areas of the mesostructures most susceptible to fatigue cracking have been identified and analysed. True hysteresis loops and values of local stress and strain amplitude were determined at the locations of highest stress concentration in cyclically loaded diamond structures. The main achievement of the present work was the modelling of the macroscopic fatigue life of the investigated mesostructures based on the true values of stress and strain at the locations most exposed to fatigue cracking. For this purpose, a stress criterion for fatigue cracking of Ti-6Al-4V lattice structures fabricated by the additive LPBF method was proposed.

中文翻译：

---

增材制造 Ti-6Al-4V 晶格结构的循环行为建模

目前的工作涉及 Ti-6Al-4V 晶格结构循环行为的数值模拟。在研究中，采用了通过增材激光粉末床熔合（LPBF）方法生产的具有不同相对密度的钛合金金刚石结构。考虑到制造过程中产生的材料缺陷，使用计算机显微断层扫描生成了所研究的细观结构的真实几何模型。数值计算还考虑了弹塑性应变范围内的实际材料硬化曲线。这项工作的成就之一是对具有缺陷的现实细观结构的循环载荷进行数值模拟。已确定并分析了最容易出现疲劳裂纹的细观结构区域。真实的磁滞回线以及局部应力和应变幅值是在循环加载金刚石结构中应力集中最高的位置确定的。目前工作的主要成就是基于最容易发生疲劳裂纹的位置处的应力和应变的真实值，对所研究的细观结构的宏观疲劳寿命进行建模。为此，提出了采用加法LPBF法制备的Ti-6Al-4V晶格结构疲劳开裂的应力准则。