Finite element analysis of viscoelastic creep behaviors of deep-sea manned submersible viewport windows

Liu, P.F.; Li, J.X.; Wang, S.B.; Leng, Jianxing

doi:10.1016/j.ijpvp.2020.104218

Cited by 12 publications

(5 citation statements)

References 12 publications

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“…Li et al [13] employed a viscoelastic damage model to predict the viscoelastic behavior of the PMMA observation window through the entire operational process at varying water depths. Liu et al [14] examined the creep and damage behavior of the PMMA observation window under constant seawater pressure and analyzed its creep-fatigue life using finite element analysis. Li et al [15] proposed an evaluation method of stress accumulation and recovery of observation windows based on polarization imaging, which can provide new possibilities for stress detection of observation windows.…”

Section: Introductionmentioning

confidence: 99%

Life Assessment of Deep-Sea Observation Windows under Different Design Considerations

He,

Wang,

Zhang

et al. 2024

JMSE

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As a key component of deep-sea manned submersibles, the observation window is usually constructed with polymethyl methacrylate (PMMA) material. During the design of the observation windows, the consideration of actual lifespan and its influential factors is insufficient. There are no clear provisions in the widely applied specifications. In this paper, based on the continuum damage mechanics model, combined with the viscoelastic relationship of PMMA material, a series of calculations were performed on the PMMA observation window. The parametric analysis of the fatigue crack-initiation life of the observation window at various thickness-to-diameter ratios (1.6, 1.4, 1.2, and 1.0), different friction coefficients (0.1, 0.2, and 0.3), and different transition arc radii (4000 mm and 6000 mm) was carried out. The calculated crack positions in the numerical mode used for validation closely align with those in the tested window. And simulation results show that the fatigue life of the observation window gradually decreases with the decrease in the thickness–diameter ratio and the increase in the friction coefficient. However, the increase in the transition arc radius will prolong the fatigue life of the observation window, which is higher than that of the original structure.

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Section: Introductionmentioning

confidence: 99%

Life Assessment of Deep-Sea Observation Windows under Different Design Considerations

He,

Wang,

Zhang

et al. 2024

JMSE

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“…Increased displacement could potentially lead to the complete destruction of the observation window. Given this scenario, multiple researchers have explored the displacement and stress in observation windows through the incorporation of theoretical calculation methods, parametric analysis, and experimental research [18][19][20]. However, the predominant method for the long-term analysis of PMMA windows is based on tensile tests, despite the fact that PMMA windows are predominantly subjected to complex compression states.…”

Section: Introductionmentioning

confidence: 99%

Parametric Analysis on Creep Deformation of Deep-Sea PMMA Observation Window

He,

Wang,

Wang

et al. 2024

Applied Sciences

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Observation windows are core components of the submersible manned cabins. The strength and stiffness of the observation window during the loading and load-sustaining process are crucial to ensure the safety of the equipment and personnel inside the manned cabin. It is extremely important to accurately calculate the structural creep performance of the observation window under a long-period sustaining load in seawater. In the present study, finite element analyses based on a temperature-dependent time-hardening creep model are conducted to investigate the performance of the observation window. The mesh convergence is studied first and the parametric analysis is accordingly carried out, taking different combinations of temperatures from 2~30 °C, different loading rates of 2.3 MPa/min, 4.5 MPa/min, 6 MPa/min, and 8 MPa/min, and different friction coefficients of 0.05, 0.1, 0.15, 0.2, 0.25, and 0.3 into account. The results show that the displacement in the y-axis direction of the center point of the lower surface of the viewport window increases with the increasing temperature and loading rate. On the contrary, the axial displacement of the observation window gradually decreases with the increase of the friction coefficient, and the axial displacement is the largest when the lowest friction coefficient is applied. This study aims to offer a more unified analysis and design methodology for the creep deformation of PMMA structures in underwater facilities.

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“…Li et al predicted the cyclic creep behaviors and lifetime of conical/spherical viewport windows by FEM simulation, in considerations of velocity, time, depth and sequence for diving (Li et al, 2021). Liu et al developed characterization method on PMMA material properties by employed the ABAQUS-UMAT package (Liu et al, 2020). Wang et al proposed an explicit formula to calculate the axial displacement of PMMA frustums with different ratios of thickness to diameter under different holding-time and pressures, to provide guidelines on the preliminary design of deep-sea window (Wang et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Failure analysis on fully-transparent deep-sea pressure hulls used at 2,500 m depth

Luo

et al. 2023

Front. Mater.

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Fully-transparent deep-sea pressure hulls have been attracted attention in recent years with the increasing demand for underwater observation. So far, public researches on design rule and failure modes for fully-transparent deep-sea pressure hulls are limited and the relevant experience cannot meet the requirements of new cabin design. In this study, the compression test is carried on, in which the material samples are subjected to quasi-static compressive load until failure in tests at different loading rates, and the hyperelastic finite element model is established in LS-DYNA software to simulate the failure process. Simulation results of material properties in finite element analysis on the cylindrical samples are compared with the experimental data, including the characteristic points of the mechanical properties in elastic stage and hardening stage, the ultimate load and failure mode of the samples. Mesh convergence analysis is conducted, and the appropriate mesh quality is accordingly selected in simulation of fully-transparent deep-sea pressure hulls. An equation for prediction of instability-type failure is described, which is derivation based on the classical analytical expression of elastic instability, thus, when 5 times of safety factor is taken, the wall thickness of the pressure hull is calculated to be t/R0 = 0.0685 at 2,500 m depth. Ultimate strength and failure mode of a typical fully-transparent deep-sea pressure hull are simulated. First, the first-order linear buckling modal analysis is carried out to simulate initial geometric imperfections. Then, simulations for the loading and collapse process of two fully-transparent pressure hulls respectively with one opening and two openings are conducted, and the ultimate load of 126 MPa and 128 MPa for the two kinds of hulls are obtained. Finally, simulation of a scaled pressure hull is carried out and simulation results are compared with the experimental data in reference, which are basically consistent. The calculated failure strength shows that the spherical hulls satisfy the safety factor requirement of 5 times. The provided simulation procedure can be referred for failure analysis of fully-transparent pressure hulls.

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Finite element analysis of viscoelastic creep behaviors of deep-sea manned submersible viewport windows

Cited by 12 publications

References 12 publications

Life Assessment of Deep-Sea Observation Windows under Different Design Considerations

Life Assessment of Deep-Sea Observation Windows under Different Design Considerations

Parametric Analysis on Creep Deformation of Deep-Sea PMMA Observation Window

Failure analysis on fully-transparent deep-sea pressure hulls used at 2,500 m depth

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