Studies of implicit and explicit solution techniques in transient thermal analysis of structures
Abstract
Studies aimed at an increase in the efficiency of calculating transient temperature fields in complex aerospace vehicle structures are reported. The advantages and disadvantages of explicit and implicit algorithms are discussed and a promising set of implicit algorithms with variable time steps, known as GEARIB, is described. Test problems, used for evaluating and comparing various algorithms, are discussed and finite element models of the configurations are described. These problems include a coarse model of the Space Shuttle wing, an insulated frame tst article, a metallic panel for a thermal protection system, and detailed models of sections of the Space Shuttle wing. Results generally indicate a preference for implicit over explicit algorithms for transient structural heat transfer problems when the governing equations are stiff (typical of many practical problems such as insulated metal structures). The effects on algorithm performance of different models of an insulated cylinder are demonstrated. The stiffness of the problem is highly sensitive to modeling details and careful modeling can reduce the stiffness of the equations to the extent that explicit methods may become the best choice. Preliminary applications of a mixed implicitexplicit algorithm and operator splitting techniques for speeding up the solution of the algebraic equations are also described.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 August 1982
 Bibcode:
 1982STIN...8231646A
 Keywords:

 Aerospace Vehicles;
 Algorithms;
 Analysis (Mathematics);
 Heat Shielding;
 Heat Transfer;
 Structural Analysis;
 Computer Programs;
 Finite Element Method;
 Numerical Integration;
 Spacecraft Shielding;
 Transient Heating;
 Fluid Mechanics and Heat Transfer