β Scribed by Harald Osnes; Alfred Andersen
No coin nor oath required. For personal study only.
It is well known that geometric nonlinear effects have to be taken into account when the ultimate strength of single lap composite joints are studied. In the present paper we investigate for which level of loads or prescribed end displacements nonlinear effects become significant and how they appear. These aspects are studied by comparing finite element results obtained from geometric nonlinear models with the results from the linear ones. The well-known software package ANSYS is applied in the numerical analysis together with a self-implemented module in the CΓΎΓΎ library Diffpack. Some of the results are also compared with classical analytical theories of idealized joints showing significant differences.
The joints examined are made of cross-ply laminates having 0 or 908 surface layers. A combined cross-ply/steel joint and an isotropic joint made of steel are also studied. All the models except the all-steel one are assembled with adhesives, while the latter is welded.
Through the investigation a considerable departure from linear behavior has been detected for a large regime of prescribed end displacements or external loads. Geometric nonlinear effects begin to develop for external loads that produces stresses which are far below ultimate strength limits and for average longitudinal strains that are less than 0.5%. It has also been detected that the distribution of materials within the joint has some influence on the nonlinear behavior. Thus, geometric nonlinear methods should always be applied when single lap (or other non-symmetric) composite joints are analyzed.
π SIMILAR VOLUMES
An analytical model for determining the strain energy release rate due to a prescribed crack in an adhesively-bonded, single-lap composite joint with thick bondlines and subjected to axial tension is presented. An existing analytical model for determining the adhesive stresses within the joint is us