Papers by Keyword: Multiple Site Damage (MSD)

Abstract: The MSD phenomenon is an active research topic of the academic and the aviation industry. This paper puts emphasis on the multi-crack propagation with interactive effects of MSD structure in 2524-T3 aluminium alloy. Material tests were accomplished for the crack growth parameters. The multi-crack propagation tests were conducted on specimens containing 5-similar-details, and the corresponding fatigue crack growth analysis with a fast prediction of crack growth life method were accomplished with finite element software. The comparison of crack tip position vs. load cycling from the test and the numerical simulation shows that the numerical simulation can give a good agreement to the experiment result.

Abstract: Abstract. This paper presents an investigation method of residual strength of Multiple Site Damage (MSD) panel. Both interaction between cracks and the effect of stable tearing are considered together. Dugdale model of collinear cracks is employed in the MSD panel model. Swift strip-yield criterion is used to judge whether the cracks linkup. Compared with the test results, numerical results of 9 different configuration MSD panels of 2024-T3 aluminum alloy are compared with the test results. The average relative error is -2.09％and root-mean-square error is 0.048. The agreement between analysis and experiment is shown to be reasonable.

Abstract: Many military aircraft have reached or exceeded their original design life, and have been subject to significant increase in maintenance and repair cost due to multiple site damage (MSD). In order to assessing the effects of MSD on the structural integrity of aircraft lap joints, the wing lap joint of certain model military aircraft with MSD was analyzed using special code FRANC2D/L. The rivet holes along the top row of the outer skin of lap joint were considered as the independent structural unit for the simulated MSD cracks. The stress intensity factors (SIFs) at each crack tip with different distribution loads at the rivet holes were computed and show that the analysis results have good coherence with the available literature data. It also shows that the SIF at each crack tip
s a function of crack length can be calculated by the crack growth simulation capability of FRANC2D/L. The SIF values are not sensitive to the rivet load distribution manner, which has seriously influence on MSD crack growth direction. Rivet loading can be best molded quadratic load distribution over one half of rivet hole relative to uniform load distribution and point load. As a result of this analysis, it is postulated that for MSD in aircraft lap joints, compliance measurements may provide a useful tool for assessing the structural integrity of the lap joints.

Abstract: Widespread Fatigue Damage (WFD) is a technical expression used in the certification of aircraft. The paper presents a set of issues which may influence the probability that a structural item exhibits WFD. The paper mainly follows the line of a stochastic approach to these subjects, and includes the influence of realistic parameters - like manufacturing - and tries to assess what may be the impact of new technologies.