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Abstract

Liquified natural gas (LNG) is increasingly used as fuel in marine industry. For transportation and storage purposes it is kept at -163 °C under atmospheric pressure. When LNG gets in contact with a plate, pipe or a tank, it causes very significant thermal load on the structure which has, until that point, been kept at environmental temperature. The current study presents the nonlinear transient thermoelastic response of circular/annular plates which experience sudden cryogenic thermal load. This is the first time that thermoelastic analysis has been presented for any structure under such condition. The material is composed of stainless steel (SUS304) and lowcarbon steel (AISI 1020) and is functionally graded through the thickness. The novel material configuration proposed in this study has been used for the first time in cryogenic and low-temperature applications. Material properties are evaluated based on available experimental data and assumed to be temperature dependent. The nonlinear governing equations and boundary conditions are obtained with the von Kármán assumption and the first order shear deformation theory. The governing equations are discretized and solved with the Generalized Differential Quadrature Method (GDQM) and Newton-Raphson iterative method. The temporal evolution of the temperature field is obtained by solving Fourier-type heat conduction equation using GDQM and Crank-Nicolson scheme. The results have been validated with axisymmetric FEM models using solid elements. A detailed parametric study has been carried out to investigate the effect of temperature dependency, material distribution, thermal/mechanical boundary conditions, geometrical nonlinearity, and plate size on the thermoelastic response. The results show that transient thermoelastic response of plates under sudden cryogenic cooling can be very different than steady state response. Significant deflections occur in a fraction of a second because of the sudden thermal load and decrease over time. The highest stresses appear predominantly in the initial phase, but can also appear later depending on the plate geometry and boundary conditions. For certain thermal boundary condition, the response of a plate under low-temperature thermal load can qualitatively differ from high-temperature thermal load.