DIAL Finite Element System

Abstract

DIAL is a general purpose 2D and 3D finite element system consisting of a family of independently executable modules called processors; these communicate with each other through a common database (Figure 1). Each processor is driven by a free field command language that allows data statements, arithmetic expressions, looping, and conditional and unconditional branching similar to FORTRAN. User-written FORTRAN subroutines also are allowed for maximum flexibility, in which case the subroutine must be compiled and the processor linked to obtain an executable element. DIAL can perform nonlinear static and transient response structural analysis, extract frequencies and mode shapes for modal analysis, and perform bifurcation buckling analysis. The bifurcation buckling and vibration analyses can be performed from either a linear or nonlinear prestress state. In linear problems, unsymmetric vibration modes, buckling modes, or response under unsymmetric loading can be obtained using the method of Fourier decomposition. The unsymmetric vibration or buckling modes can be computed only from an axisymmetric state of prestress.

The total Lagrangian formulation is used to include the effects of geometric nonlinearities and finite strains.

The element library consists of a full set of modern multiorder isoparametric solid elements along with the corresponding degenerate curved shell and plate elements. Gap and contact elements, constraint elements, straight and curved beam elements, and lumped nonlinear springs and dashpots are also provided.

The material library consists of general anisotropic linear materials along with isotropic elastic-plastic, nonlinear elastic orthotropic, isotropic incompressible, isotropic high temperature creep, and incompressible hyperelastic materials. All materials are temperature dependent.

Restart capability is provided at almost any point in the analysis along with extensive post-processing and plotting. Because of the modular database architecture, user control is very versatile and economical. Large problems can be solved in an interactive environment. The system is operational on the UNIVAC 1100 series, CDC Cyber 175, and VAX 11/780 computers.