STATIC, FREE AND FORCED VIBRATION ANALYSIS OF ARBITRARY NONUNIFORM SHELLS WITH TAPERED STIFFENERS

The behaviour of the stiffened plates and shells having varying thickn esses both in the skin, as well as in the stiffening members, has been investigated under various static and dynamic loading conditions by e mploying a new higher order arbitrarily stiffened triangular shallow s hell finite element which includes thickness variations. The shell ele ment can accommodate arbitrary disposition of any number of stiffeners , which in turn allows the irregular mesh generation scheme independen t on the alignment of the stiffness in the stiffened shell structures. The quadratic variation of thickness both in the shell element and th e stiffeners have been considered. Before carrying out the investigati on on the dynamic response analysis in the time domain, the undamped f ree vibration of the same to compute the natural time period of oscill ation has also been performed. A number of problems of bare plates and shells of varying thickness have been analyzed and the comparison of the numerical results with the available theoretical and/or experiment al results shows close agreement, even with the coarse finite element mesh scheme. The convergence test with element gridwork refinement for each analysis has also been carried out to show the monotonic and exc eedingly rapid convergence. The new results for the above analyses of the stiffened plates and shells, where the thickness is varying for bo th the plate/shell and the stiffeners have also been presented, which will be valuable for future researchers in this field. Copyright (C) 1 996 Elsevier Science Ltd.