航空学报 > 2026, Vol. 47 Issue (8): 432553-432553   doi: 10.7527/S1000-6893.2025.32553

增材制造钛合金点阵超结构压缩疲劳断裂行为

孙文博1, 段旭朝2, 徐瑞阳3, 马玉娥2,4(), 张卫红1   

  1. 1.西北工业大学 机电学院,西安 710072
    2.西北工业大学 航空学院,西安 710072
    3.中国空空导弹研究院,洛阳 471009
    4.强度与结构完整性全国重点实验室,西安 710072
  • 收稿日期:2025-07-11 修回日期:2025-07-28 接受日期:2025-08-20 出版日期:2025-08-29 发布日期:2025-08-28
  • 通讯作者: 马玉娥 E-mail:ma.yu.e@nwpu.edu.cn
  • 基金资助:
    国家自然科学基金(12302103);国家自然科学基金(U2341238);国家自然科学基金(91860128);陕西省三秦英才特殊支持计划-科技创新领军人才

Fatigue fracture behavior of additively manufactured titanium alloy superstructures under compressive loading

Wenbo SUN1, Xuzhao DUAN2, Ruiyang XU3, Yu’e MA2,4(), Weihong ZHANG1   

  1. 1.School of Mechanical Engineering,Northwestern Polytechnical University,Xi’an 710072,China
    2.School of Aeronautics,Northwestern Polytechnical University,Xi’an 710072,China
    3.China Airborne Missile Academy,Luoyang 471009,China
    4.National Key Laboratory of Strength and Structural Integrity,Xi’an 710072,China
  • Received:2025-07-11 Revised:2025-07-28 Accepted:2025-08-20 Online:2025-08-29 Published:2025-08-28
  • Contact: Yu’e MA E-mail:ma.yu.e@nwpu.edu.cn
  • Supported by:
    National Natural Science Foundation of China(12302103);Shaanxi Province Sanqin Talent Special Support Plan for Scientific and Technological Innovation

摘要:

粉末床熔融(LPBF)增材制造超结构以优异的减重性能、可设计性,满足了航空航天飞行器高性能轻质一体化的要求。然而,增材制造产生的表面粗糙度、内部孔隙易使疲劳裂纹萌生,导致超结构提前失效。为研究表面粗糙度、孔隙对疲劳性能的影响机制,设计了增材制造体心立方(BCC)超结构试件,完成了5种载荷工况下的超结构疲劳试验,获取了应力-寿命(S-N)曲线。基于半经验公式计算表面粗糙度引入应力集中系数,结合有效承载面积参数修正孔隙、表面粗糙度的影响。通过三维重建模型的有限元仿真并验证其准确性后,代入Neuber-Kuhn公式求得了疲劳极限。在有效承载面积修正的研究基础上,建立了单杆的疲劳S-N曲线,构建了从单杆S-N到超结构S-N的映射方法,给出了修正的S-N曲线。结果表明:有效承载面积修正后的模型能更好地反映表面粗糙度、内部孔隙的耦合影响,从而提高超结构的疲劳极限、寿命的预测精度;单胞模型的周期性边界条件可以有效模拟整体结构的应力集中;采用修正的S-N曲线预测超结构疲劳寿命结果在3倍误差带内。

关键词: 增材制造, 超结构, 表面粗糙度, 孔隙, 疲劳寿命

Abstract:

Laser Powder Bed Fusion (LPBF) additively manufactured superstructures are highly promising for aerospace vehicles due to their excellent weight reduction performance and design flexibility, fulfilling the demand for high-performance, lightweight, and integrated components. However, surface roughness and internal porosity introduced by additive manufacturing tend to serve as initiation sites for fatigue cracks, potentially leading to premature failure of the lattice structures. To investigate effects of surface roughness and porosity on fatigue performance, Body Centered Cubic (BCC) lattice specimens were designed and fabricated by additive manufacturing. Fatigue tests under five different loading levels were conducted to obtain the corresponding Stress-Number of cycles (S-N) curves. A semi-empirical formula was used to calculate the stress concentration factor introduced by surface roughness. Additionally, the concept of effective load-bearing area was applied to account for the influence of both porosity and surface roughness. The accuracy of this method was verified through finite element simulations based on 3D reconstructed models, and the Neuber-Kuhn formula was used to estimate the fatigue limit. Based on the effective area correction, a fatigue S-N curve for a single strut was established, then a mapping method from the single-strut S-N curve to the lattice S-N curve was developed, and a corrected S-N curve was proposed. It is shown that the model incorporating effective load-bearing area correction more accurately reflects the coupled effect of surface roughness and internal porosity, and thereby it can improve the predictive accuracy of the fatigue limit and fatigue life of the lattice structures. The periodic boundary conditions in one unit lattice can be built and effectively simulate stress concentration in the whole structure. The corrected S-N curve is used to predict the fatigue life of the lattice, and its results fall within a scatter band of factor 3.

Key words: additive manufacturing, superstructure, surface roughness, pore, fatigue life

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