T-elements analysis of plated on unilateral elastic Winkler-type foundation
This paper presents a hybrid–Trefftz finite element algorithm designated as fictitious load approach. Its originality resides in the formulation and practical application of concepts which make it possible to account for the unilateral contact conditions of a plate without modification of the finite element mesh. To reach this aim, the approach allows the movable interface between the contact and non–contact parts of the plate to travers any finite element subdomain. The adjustments are confined to fictitious load dependent terms, while the element stiffness matrices remain unchanged during the whole iterative process. Several numerical examples are analysed to assess the effectivity of the T–element algorithm and to compare it with some of the existing solutions of the same problem.
Structural analysis program SAFE — special features and advanced finite element models
Abstract Program SAFE (Structural Analysis by Finite Elements) — an advanced industrial version of a former academic prototype (ELFIN) — is a comparatively large FE system including nearly 20 families of elements, automatic mesh and data generators, free format input with simple command language and extensive graphical pre- and post- processing. The program is written in FORTRAN 77, has a modern modular architecture and is easy to modify. A large part of the program's element library is formed by essentially conventional assumed displacement elements, some of which present various improvements and particularities (e.g. an original technique to represent accurately stress concentrations or singularities in the vicinity of concentrated loads). The most attractive feature of the program is, however, its non-conventional concept of using the so-called large finite elements. This concept presents an elegant possibility to solve efficiently, complex engineering problems involving various stress concentrations and singularities and is ideally suited for implementation on low capacity computers. Practical efficiency of the program is illustrated by some examples.
Implementation of a C1 triangular element based on the P-version of the finite element method
Abstract The implementation of a computer code CONE (for C1 continuity) based on the p-version of the finite element method is described. A hierarchic family of triangular finite elements of degree p ≥ 5 is used. This family enforces C1-continuity across inter-element boundaries, and the code is applicable to fourth order partial differential equations in two independent variables, in particular to the biharmonic equation. Applications to several benchmark problems in plate bending are presented. Sample results are examined and compared both with theoretical predictions and with the computations of other programs. Significant improvements are shown for the results obtained using CONE.