Ultimate strength and post ultimate strength behaviors of hull plates under extreme longitudinal cyclic load

Abstract

The present paper aims at making a research on the ultimate strength and post ultimate strength behaviors of hull plates under extreme longitudinal cyclic load. The cyclic load is controlled by displacement at the load edge of the plate to reach both ultimate strength and post ultimate strength stages. Two load patterns are considered for cyclic compressive and cyclic tensile-compressive load. The ultimate strength of intact plates in each cycle are found to be close to the unloading points of the previous cycle. It is found that not only the overall residual deformation but also the local residual stress and strain formed in cyclic loads will lead to a reduction of the ultimate strength of plates. Accumulated plastic damage and low-cycle fatigue crack damage arisen from the extreme cyclic load are discussed in present study. The combined effect of accumulated plastic damage and low-cycle fatigue crack damage on the ultimate strength and post ultimate strength as well as the load path of hull plates is obtained. It can be seen as a coupling effect of the two individual ones. The mechanical mechanism of strength behaviors in each condition of cyclic loading is analyzed.