Abstract:

The residual strength tests of unstiffened aluminum alloy LY12CZ panels with multiple site damages (MSD) were carried out. The lead crack and the small cracks at rivet holes were simulated by saw cuts. Each specimen was subjected to a monotonically increasing tensile load perpendicular to the crack surface until failure occurred. The residual strengths of these panels with different crack sizes were obtained. The experimental results showed that the residual strengths of the panels would decrease as the lead crack length increased and for the same lead crack size,the residual strengths of the panels would decrease as the distance b between the lead crack tip and the adjacent MSD crack tips reduced.The residual strengths of the panels with multiple site damage were evaluated by five different failure criteria respectively.Compared with the experimental results,it is shown that for panels with different lead crack sizes and different b values,the average error for net section yield criterion and K-apparent criterion was too great,while the average error for plastic zone link up criterion and improved K-apparent criterion were 22.17% and 16.98% respectively,and that for improved plastic zone link up criterion was 8.27%,suggesting a notable improvement in prediction with the improved model.

Key words: multiple , site , damage,  , residual , strength,  , lead , crack,  , failure , criterion