PSI - Issue 19

Shinji Hashimura et al. / Procedia Structural Integrity 19 (2019) 204–213 Author name / Structural Integrity Procedia 00 (2019) 000–000

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rolling. And the reason that the influence of the mean stress on fatigue strengths for A6056 got disappeared was the strain hardening coefficient of A6056 was very low in comparison with that of A5056. Namely the stress at the root of the first thread couldn't increase with an increase in the local strain. In this study, although we used the stress-strain relationship for A6056 from the literature, we should investigate cyclic stress-strain relationship accurately in the experiments to reveal the mechanisms in detail. The results suggest that we have to change the tightening rule from that of the steel bolt when we use the aluminium alloy A5056 bolts. However we can tighten the bolts in the same manner as the steel bolt that when we use aluminium alloy A6056 bolts. 6. Conclusion The main conclusions obtained in this study are summarized as follows. 1. The fatigue strength for A5056 bolts decreases with an increase in the mean stress. 2. Although the fatigue strength for A6056 bolts decreases with an increase in the mean stress until exceeding 6 kN, the fatigue strength does not decrease if the mean load exceeds 6 kN. 3. The reason that the fatigue strength for A6056 bolts stop decreasing if the mean load was 6 kN or more is because the mean stress was released by the shakedown behavior generated due to the local plastic deformation at the root of the first thread. References Ureshino, Y., 2018, Evolution of material technology in car makers -1. Expectations to steel materials for weight reduction of automobiles, The special steel 67-5, 8-21. (in Japanese) Ufferman, B., Abke, T., Barker, M., Vivek, A., Daehn, G.S., 2018, Mechanical properties of joints in 5052 aluminum made with adhesive bonding and mechanical fasteners, International l Journal of Adhesion and Adhesives 83, 96-102. Hana, L., Thorntona, M., Shergoldb, M., 2010, A comparison of the mechanical behaviour of self-piercing riveted and resistance spot welded aluminium sheets for the automotive industry, Materials and Design 31, 1457-1467. Meschuta, G., Matzkea, M., Hoerholda, R., Olfermanna, T., 2014, Hybrid technologies for joining ultra-high-strength boron steels with aluminum alloys for lightweight car body structures, Conference on Assembly Technologies and Systems, Procedia CIRP 23, 19-23. Westphal, K., Mulherkar, T., Scheiding, W., 2005, Joining of Magnesium Components Using AL Fasteners, Light Metal Age 63, 42–44. Yoshimoto, I., 1983, A Hypothesis concerning Fatigue Strength of a Bolt-nut Joints, Journal of The Japan Society for Precision Engineering 49-6, 801-803 (in Japanese). Ishibashi, T., 1969, Fatigue of Metals and Prevention of Fracture (expanded/revised ed.), 52, Yokendo Tokyo (in Japanese). Nakamura, M., Tsuchiya, K., Hasunuma, S., Ogawa, T., 2016, Effect of Mean Stress and Stress Concentration Factor on Fatigue Limits of Middle and High Strength Steels, Journal of the Society of Materials Science, Japan 68-3, 228-232. (in Japanese) Htoo, A.T., Miyashita, Y., Otsuka, Y., Mutoh, Y., Sakurai, S., 2016, Variation of local stress ratio and its effect on notch fatigue behavior of 2024 T4 aluminum alloy, International Journal of Fatigue 88, 19-28. Schwerdt, D., Pyttel, B., Berger, C., 2010. Fatigue Strength and Failure Mechanism for The AluminiumWrought Alloy ENAW6056 in The VHCF region and Influence of Notches and Compressive Residual Stresses, Procedia Engineering 2, 1505-1514. Schwerdt, D., Pyttel, B., Berger, C., 2011. Fatigue Strength and Mechanisms of Wrought Aluminium Alloy in The VHCF-region Considering Material and Component Relevant Influencing Factors, International Journal of Fatigue 33, 31-41. Berger, C., Pyttel, B., Trossmann, T., 2006, Very High Cycle Fatigue Tests with Smooth And Notched Specimens And Screw Made of Light Metal Alloys, International Journal of Fatigue 28, 1640-1646. Gröber, D., Georgi, W., Sieber, M., Scharf, I., Hellming, R.J., Leidich, E., Lampke, T., Mayr, P., 2015, The Effect of Anodising on The Fatigue Performance of Self-tapping Alminium Screws, International Journal of Fatigue 75, 108-114. Hashimura, S., Miyashita, Y., Kurakake, Y., Yamanaka, S., 2012; Tightening Characteristics of Nonferrous Bolts and Usefulness of Magnesium Alloy Bolts, SAE International 2012-01-0476, doi:10.4271/2012-01-0476.