Efficient thermo-mechanical modelling of cyclic loading with Chaboche type constitutive law coupled with damage

This paper describes a numerical modelling approach to study the
behaviour of a solar receiver tube subjected to cyclic thermomechanical loading. The Lagamine finite element (FE) code was utilized along with a Chaboche
type material law and a Lemaitre's unified damage model to simulate the material behaviour under fatigue, creep, and corrosion. The cycle jump procedure is
evaluated, as it is a method for efficient computation of long-term evolution of
material behaviour under cyclic loading. The procedure involves computing a
number of cycles in the FE code, then extrapolating the results from these cycles over a number of cycles. This alternating process is repeated until the end
of the computation. A parametric study was achieved to assess the effects of
different strategies within the cycle jump. It was observed that the strong evolution of the material behaviour for the first cycles (around 100 cycles) of the
computation prevented the use of the cycle jump during that period. Also, a sufficient number of cycles (minimum 4) must be computed with the FE code between the jumps to ensure reaching a stable solution. With the optimum parameters, the cycle jump permitted to significantly decrease the computation time
(factor 10), while having a limited impact on the accuracy of the results (lower
than 1%).