Research on Fatigue Life Prediction and Reliability of High Strength and Toughness Aluminum Alloys
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Research on Fatigue Life Prediction and Reliability of High Strength and Toughness Aluminum Alloys Haigen Jian
· Xiaomei Yang · Yedong Wang · Xinlei Lei · Wei Zhang · Chengji Mi
Submitted: 10 February 2020 © ASM International 2020
Abstract According to the fatigue test statistical analysis method, the median S–N curve and the p-S–N curve with 99.9% survival rate of smooth specimens of high strength and toughness Al–Zn–Mg–Cu alloy are obtained. Based on these curves, the reliability analysis of test data under different stress amplitudes was analyzed. The finite element technique is used to simulate the stress intensity factor K, combined with fatigue crack growth rate test, using K criterion to predict and evaluate the safety and reliability of alloy materials and to serve for the service life design and fracture control of structural materials in fatigue service. Keywords High strength and toughness aluminum alloy · Fatigue crack growth rate · Fracture toughness · K criterion · p-S–N curve
Introduction The high strength and toughness Al–Zn–Mg–Cu alloy studied is a heat-treatable strengthened aluminum alloy, which has the advantages of high specific strength, hot working property, good corrosion resistance and toughness,
H. Jian · X. Yang · Y. Wang · X. Lei · W. Zhang · C. Mi (&) College of Metallurgy and Material Engineering, Hunan University of Technology, Zhuzhou 412007, China e-mail: [email protected] H. Jian e-mail: [email protected]
and is widely used in aerospace, transportation and other fields [1–3]. In the course of using, as the main loadbearing structural material, the fatigue properties of high strength and toughness Al–Zn–Mg–Cu alloy had been paid more and more attention by material researchers [4, 5]. According to incomplete statistics, fatigue fracture accidents caused by alternating loads account for 95% of the total failures of mechanical structures. When fatigue analysis is carried out by deterministic method, the fatigue life obtained is a definite value. But structural fatigue is an extremely complex phenomenon which is affected by many uncertain factors. Therefore, according to the structural reliability theory, it is necessary to analyze the fatigue reliability of structural materials from the point of probability and statistics, which is a new scientific and rational method for structural fatigue reliability evaluation [6–9]. Defects in materials or structures are unavoidable, and the most serious form of them is cracking. Using the crack initiation life to control the fatigue life of alloy materials causes great waste. Facing the objective facts of the crack existence, rapid expansion of crack by K criterion based on fracture mechanics and the theory of fatigue crack expansion established based on the K criterion can reasonably evaluate the safety and reliability of structural materials, which provide a relatively reliable basis for anti-fracture design and fracture control [10–12]. Based on the above all, this paper keeps
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