Showing papers by "Grant P. Steven published in 1995"

A study of fabric deformation using nonlinear finite elements

Abstract: Fabric deformation characterized by large displacements and rotations but small strains is analyzed using a geometric nonlinear finite element method. The fabrics are modeled by shell/plate elements. Special considerations for applying the finite element method to fabric analysis are discussed and several examples of fabric deformation presented. The results from the finite element model are compared with experimental data and are in good agreement.

Postbuckling behaviour of hat-stiffened thin-skinned carbon-fibre composite panels

Abstract: The results of a combined experimental and numerical study of hat-stiffened co-cured carbon-fibre composite panels loaded in uniaxial compression are presented. All panels consisted of two integrated stiffeners separated by an eight-ply thick skin bay of lay-up [*45/0190], . The effects of a 100 mm circular cutout in the skin was also investigated. The ultimate strength of all panels was governed by the load carrying capacity of the stiffeners. A change in the skin's buckling mode-shape was also observed for all panels loaded deep in the postbuckling region. The strains induced at the interior free-edge were not found to be critical. Non-linear finite element results correlated well with the prebuckling and initial postbuckling strain and displacements results obtained by experiment.

Analytical solutions of mass transport problems for error estimation of finite/infinite element methods

Abstract: In order to make an exact estimation of discretization error for finite/infinite element methods, it is necessary to develop analytical solutions for some transient mass transport problems in infinite media These transient mass transport problems may be viewed as the benchmark problems for the discretization error estimation of a new numerical method so that they generally have the following characteristics: (1) their initial and boundary conditions can be exactly modelled by the finite/infinite element method; (2) their solutions can be rigorously expressed in a closed form In this paper, several of the aforementioned problems have been constructed and solved mathematically for transient mass transport problems in both 1D and 2D infinite media

Shape Optimisation of Metallic Inserts in Composite Bolted Joints

Abstract: A simple evolutionary procedure for structural optimisation was modified to allow for the shape optimisation of metallic inserts into composite materials. The aim of the shape optimisation of inserts is to reduce the high stress concentration factor present in mechanically fastened composite joints to increase the bearing strength of pin loaded and bolted joints. Both optimised shape aluminium inserts obtained from the evolutionary structural optimisation package achieved a reduction in compressive stress concentration of approximately 46% when compared to a 2 mm circular insert, and a reduction of 67% when compared to a laminate without metallic insert. A comparison of the reduction of compressive stress at the interface per unit mass of test specimen shows that the optimum shapes developed by means of this process are approximately 40% more efficient than a 2 mm circular aluminium insert. A testing program is under way to prove the concept.

Error Estimation for General Finite Element Eigenvalue Problems

Abstract: The solution to a finite element analysis involving an eigenvalue/eigenvector extrapolation generally requires the eigenvalue solution as the design parameter. The eigenvector solution merely gives a visual representation of the deforming structure. Buckling and free vibration analyses are of this type, where the eigenvalue is related to the buckling load factor and natural frequency of the structure respectively. The eigenvector shows the buckled or vibrating shape of the structure.