Creep behavior analysis of conical observation window for human occupied vehicle based on ABAQUS

  Objectives  The observation window is the most important component of a human occupied vehicle (HOV) for personnel and structural safety. As such, it is extremely important to accurately calculate its creep performance under long-period loads.

  Methods  First, based on the tensile specimen creep test data, when the specimen and observation window material is polymethyl methacrylate (PMMA), the basic parameters of the age hardening creep model are determined using a multi-parameter comparison and optimization method with reference to the test curves. The observation window structure is then modeled through ABAQUS. Coupled with the age hardening model and structural contact, the creep performance of the window structure is analyzed. Finally, based on the presented finite element model, the creep behavior of the observation window structure under the multi-parameter structure and different loading rates is carried out respectively.

  Results  The calculation results show that the numerical and experimental test results are in good agreement under both the calculation verification model and physical observation window structure, revealing the reliability of the observation window structure creep model under high-pressure load. Based on age hardening, the numerical results of the creep model are in higher agreement with the real mechanical behavior of the observation window structure and actual engineering applications. The structure of the observation window with a conical angle of 70° under parametric optimization is more reasonable and optimized, and the stress level and creep performance of the structure are better. Under high pressure, the phenomena of "pits" near the center of the high-pressure surface of the observation window and "peeling" inside the window are the result of the structural creep response.

  Conclusions  The results of this study on the creep behavior of the observation window structure based on the ABAQUS creep model are accurate and reliable, providing theoretical references for the design optimization and life analysis of manned submersibles.