| Summary: | 碩士 === 國立中正大學 === 機械工程所 === 97 === In this paper, the global and local stress intensity factor solutions for spot welds in cross-tension specimens are investigated by finite element analyses. Three-dimensional finite element models are developed for cross-tension specimens to obtain accurate global and local stress intensity factor solutions. Based on the approach of Wang et al. (2005a, 2005b), various geometric factors of cross-tension specimens, sheet thickness, clamp width, clamp length, specimen width and specimen length are considered in this investigation. The computational results are compared with the analytical solutions of Zhang (1997) and Yuuki et al.(1986) and Swellam et al.(1993). The computational results provide some geometric functions to analytical solutions of Zhang (1997) for cross-tension specimens and suggest an appropriate specimen size. Next, based on the approach of Wang and Pan (2005), the effects of the kink length and the kinked crack location to the local stress intensity factor solutions for kinked crack are investigated. The computational results provide some geometric functions to local stress intensity factor solutions for a vanishing kink length. The computational results also indicate that as the kink length increases, the local stress intensity factor solutions increase and then decrease. As the kink length increases over 90% of the sheet thickness, the local stress intensity factor solutions become negative. In addition, the location of the kinked crack do not have significant effects on the local stress intensity factor solutions; however, when their locations are in a right angle, the mode III local stress intensity factor solution occurs.
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