Study On The Element Failure Strain By Simulating Hull Fracture

Crack which can cause structural damage is one of the main types ofthe ship and ocean engineering structural failure, and the numericalsimulation is the important method to study this problem. This thesisfocuses on macroscopic crack growth and the whole mechanical behaviorof structures, and then the determination method of the element failurestrain is studied to provide basis for lucubrating the ship and oceanengineering structural failure and getting ultimate strength of thestructures using numerical simulation method. The contents completed inthis thesis are as follows:1Developing a series of tensile tests of cracked plates. Designcracked plates size, prefabricate initial length of the cracks and determinethe loading method according to the requirements of specification andtensile test apparatus. Displacement-load curves, maximum load anddisplacement which can token macroscopic mechanical behavior of thecracked plates are got by developing different tensile tests of the crackedparameters. 2The determination of element failure strain. Based on themaximum load, displacement and energy of the tensile tests separately, theeffects of element size to element failure strain are analyzed and thedetermination method of element failure strain is studied by the finiteelement program MSC.Dytran, then the deviation of results by failurestrain of the different criterions is discussed.3Rationality of the selection of element failure strain is verifiedby examples. Based on the failure strain on maximum load, displacementand energy criterion separately, the difference of results betweensimulation and tests is analyzed, at the same time the rationality ofselection of element failure strain is verified.4The tensile fracture characteristics of deck grillage are analyzesby numerical simulation. Getting the element failure strain of certainelement scale according to the element failure strain curves, the effects ofresidual strength of deck grillage under the tensile load are studied whencrack length, location and combine position are different, getting theultimate strength of grillage, observing the crack propagation path,structural failure mode, deformation and failure characteristics, etc.