Zhaolong Yu

Dynamic behaviour of aluminium alloy plates with surface cracks subjected to repeated impacts

ABSTRACT This paper investigates the behaviour of aluminium alloy plates with and without initial cracks under repeated impacts. Three series of impact tests were conducted to study the behaviour of circular plate that do not have any cracks (series B), have surface cracks with varying length (series L), and have cracks varying depths (series D). A hammer was dropped from the same height with a constant initial striking energy 60J for all tests. It was observed that plates with larger cracks carried smaller impact forces and assumed larger deformations. With the increase in impact number, the effects of crack lengths and depths on the dynamic behaviour became much more significant. Predictions using a rigid-plastic theoretical model were compared with these test results. With the stresses determined based on the true strain-stress curve obtained by standard tension test, the refined analytical formula provides better predictions that agree well with the lab tests.

Numerical investigations of the dynamic response of a floating bridge under environmental loadings

ABSTRACT Floating bridges across wide and deep fjords are subjected to the environmental wind and wave loadings. In this study, the dynamic response of floating bridges under such loadings is investigated. A floating bridge concept, which consists of two cable-stayed spans and 19 continuous spans, is selected. An eigenvalue analysis is first conducted and it is found that the period of the first mode is typically in the order of one minute or more. This implies that the amplified response effect should also be evaluated for the second-order wave load in addition to the first-order wave load. By performing a nonlinear time domain dynamic analysis, the bridge dynamic responses from wind and wave loadings are obtained. The effects of the wind load, first-order and second-order wave loads are studied considering different load combinations. Structural responses including girder displacements, accelerations and moments are investigated for each load combination.

Design of offshore tubular members against excessive local indentation under lateral impacts

High speed vessels are constructed according to the high speed craft codes. These codes enable very light ship structures, which are necessary for effective operation of fast vessels without taking ...