Load spectrum for creep-fatigue life prediction of viewport used in human occupied vehicle
Yiting Kang1, 2, Yali Feng3, Jinggao Lin4, Wenming Zhang1
1School of Mechanical Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Beijing 100083, China
2CONCAVE Research Centre, Department of Mechanical & Industrial Engineering, Concordia University, Montreal, Canada
3School of Civil and Environmental Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Beijing 100083, China
4China Ocean Mineral Resources Research & Development Association, 1 Fuxingmenwai Street, Beijing 100860, China
Acrylic plastic, polymethylmethacrylate (PMMA), are widely employed as the material for the viewports of human occupied vehicle (HOV) which usually dives into deep sea. The service life of viewport is critical to the reliability and safety of HOV. In order to predict life of viewport in design stage, mathematical statistics method is applied to establish the load spectrum for viewport. It is found that ALVIN (America) HOV’s dive-depth data is in a skewed distribution, and a piecewise function combined Gumbel and Weibull distributions is proposed for data fitting. HOV undertakes long-term and cyclic load in service, which will cause damage on viewport, so a creep-fatigue load spectrum is established and applied for JIAOLONG (China) HOV’s viewport, which integrates both the dive-frequency of each depth range and the duration that maximum stress acts. The proposed method for determination of creep-fatigue load spectrum could thus be considered to be employed for failure analysis and life prediction of modern HOV’s viewport.