Temperature and stress-level effects on the long-term performance of deep-sea acrylic observation windows

Excessive deformation of the observation windows during service of a deep-sea Human Occupied Vehicle (HOV) may result in critical structural failure of the manned cabin. In the present study, the temperature-dependent compressive properties, including elastic modulus and yield strength, are experimentally studied considering a range of temperature from 3°C to 30°C and stress levels from 20% to 60% of yield strength. Deformation over time under different temperatures and stress levels shows strain accumulation with a sustaining load. A modified time-hardening creep model is then proposed to describe these effects. Numerical analyses are performed according to the modified time-hardening creep model and the comparison to test results validates the accuracy of the modified time-hardening model in analysing the long-term response of the acrylic structures. The research results suggest that the analysis for the acrylic window should consider the temperature effect.