Basic Studies on the Crashworthiness of Structural Elements (Part 5)

Abstract

The mean crushing loads, plastic buckling loads and crushing strokes in the axisymmetric collapse mode for circular cylinders of various radius-to-thickness ratios were analytically and experimentally investigated. The finite element analysis (using axisymmetric solid elements) and the crush tests were conducted for 8 mild steel cylinders with different R/t ratios. The results obtained are summarized as follows : (1) The plastic buckling loads due to Gerard's theory agree well with the maximum loads obtained in the experiments with R/t>20. But if R/t is below 20, Gerard's solutions underestimate the loads.(2) The mean crushing loads which the present finite element code predicted, agree well with the experimental results and are improved solutions in comparision with the existing rigid-plastic solutions and the empirical formula. The above numerical results confirmed that the thin-walled assumption can not be maintained for relatively thick cylinders which are considered approximately thin in the linear problem.(3) For the mean crushing load in case of axisymmetric collapse the modified Alexander's solution is in better agreement with experimental results with R/t>30 than the other existing theories and the empirical formula. When the axisymmetric and the non-axisymmetric collapse are both considered, Magee's empirical formula is sufficiently accurate for the thin to thick walled range.(4) The crushing half wavelengths and crushing strokes are in good agreement with the solutions of the tangent modulus theory and the modified Alexander's theory respectively, confirming the results of Ref. (2).