Interfacial Crack Propagation And Prevention Of Metal-based Polymer Composites Pressure Vessel

Metal-based polymer multilayer composites have been widely used in engineering practice over the past few decades and in many cases have replaced traditional engineering materials.Metal-based polymer multilayer composite pressure vessels are difficult to characterize and predict due to their unique microstructures,including matrix cracking and interlaminar cracking.Establishing the operating process conditions-material performance parameters-structural morphology-crack propagation correlation theory,can clarify the direct driving force of its key control parameters and interface crack propagation,and reveal the mechanism of interface crack propagation,based on the crack propagation mechanism,it can establish a preventive design criterion for the interface crack propagation failure of metal-based polymer multilayer composite pressure vessels.Based on the cohesive force contact model,the crack propagation behavior of metal-based polymer two-layer composite pressure vessel under vacuum condition was studied.The reason for the rapid crack propagation was that the vacuum load exceeded its critical value,and the stress concentration at the crack tip was also the driving force of crack propagation.By studying the simulation of the layered interface crack propagation process of metal-based PMMA,PTFE and PC lining composite pressure vessels,the evolution law of interface crack propagation length with vacuum load loading time is studied systematically.A method for predicting the critical vacuum pressure load of failure was put forward.The relationship between interfacial crack propagation characteristics-initial crack morphology-operational process parameters-material secondary damage initiation stress and fracture toughness is studied.The results show that the interface crack propagation length is linear positive correlation with the initial crack length,operating temperature and vacuum load.The cooperative coupling curve between the critical strain energy release rate and the damage initiation stress under the condition of equivalent vacuum pressure load constraint control and equivalent initial crack length constraint control is constructed,and the design criterion for preventing interface crack propagation failure is constructed..The results show that with the increase of vacuum pressure load and initial crack length,the synergistic coupling curve of critical strain energy release rate and damage initiation stress moves upwards,and the critical strain energy release rate of material sub-interface required to prevent interface crack instability expansion Increase,so to increase the equivalent vacuum pressure load and the initial crack length,it is necessary to increase the fracture toughness of the material interface by the synergistic coupling correlation curve,and to prevent the expansion failure of the interface crack.The innovation research results can provide theoretical basis for material selection and residual life evaluation of metal-based polymer composite pressure vessel design and manufacture.The vacuum loading condition of the metal-based polymer composite pressure vessel during the cooling and cooling process is a dangerous condition.For this purpose,a simulation platform for the interface crack propagation process based on thermo-mechanical coupling is established,and the interface under the thermo-mechanical coupling is established.The comparative analysis of the crack propagation behavior shows that the critical vacuum with rapid propagation of interfacial cracks under thermo-mechanical coupling is 40.8% smaller than the critical vacuum for rapid propagation of interfacial cracks without thermo-mechanical coupling.Thermo-mechanical Coupling accelerates the propagation failure of the interface crack.Based on the co-simulation simulation of cohesive force contact model and extended finite element method,a numerical simulation method for the crack propagation of polymer-lined micro-cracks in metal-based polymer two-layer composite pressure vessel during service is proposed,which leads to interface crack propagation failure.It has been found that the crack propagation on the polymer liner is due to the fact that the crack of the pressure vessel during the pressure-bearing process is difficult to resist the circumferential stress,and the bond strength between the metal matrix and the polymer liner is insufficient,and the stress concentration at the crack tip is induced.The crack in the polymer liner is continuously opened,eventually causing the failure of the pressure vessel.