Development Of VUMAT In ABAQUS And Application Of VUMAT In The Experiments Of Crashworthiness Of Ship Side Structure

Although continuous efforts are being made to prevent the occurrence of ship collision and grounding accidents it is certain that these accidents will continue to occur. With an ever-increasing societal demand for safety, further research on improving crashworthiness of ships is pressing. The collision resistant performance of plates and the stiffened plates which were the basic members of ship side structures were studied by medium and small scale experiments of crashworthiness of ship side structures and finite element method combining with the VUMAT developed in ABAQUS.First of all,status and trends in development of experimental method and finite element method within the territory of ship collisions. Various ductile fracture models were classified and summed up, then the failure criterion adopted in this thesis was determined.Secondly, the existing tests were used for reference and medium and small scale experiments of crashworthiness of ship side structures were designed and conducted. In the medium scale tests of collision resistant performance of ship side structures, the effects of the thickness of the shell, the sizes of stiffeners, strong transverse stiffeners and location of penetration on crashworthiness of stiffened plates were studied; in the small scale tests of collision resistant performance of ship side structures, crashworthiness of the square plates was compared to that of the stiffened plates and circular plates and the effects of the sizes of square plates and boundary conditions on crashworthiness of square plates were studied.Thirdly, the RTCL fracture criterion was implemented into an explicit finite element code(ABAQUS/Explicit), together with a user-defined material model with a constitutive material algorithm based on J2 flow theory with a radial return algorithm and isotropic hardening. Several small scale experiments available in the literature were simulated to validate the RTCL failure criterion for varisized structures which were in various stress status. The finite element results corresponded well with the experimental results, which proved the usefulness of the RTCL failure criterion for the simulation of rupture for varisized structures.which were in various stress status.Then, crashworthiness of test models was simulated in ABAQUS/Explicit with the VUMAT of RTCL failure criterion. Data curves and damage phenomena of finite element simulations were in accordance with that of experiments. It demonstrated that not only were pre-processings of finite element models quite reasonable, but the crashworthiness of test models could be predicted well by finite element method with RTCL failure criterion.Finally, conclusions were given and recommendations for future work were proposed.