LARGE SCALE BUCKLING EXPERIMENT AND VALIDATION OF PREDICTIVE CAPABILITIES

摘要

A 9m long airfoil blade section, designed to fail in buckling, has been build and tested destructively in a four-point bending configuration. The purpose of the test was to verify capabilities for predicting buckling of an airfoil section subject to bending. First an analytical method to calculate the critical bifurcation-buckling load of a generally laminated cylindrical shell is presented. The analytical approach is intended for used in the early design phase as a quick estimate of the buckling strength of the design. And also it has been used in the present paper in a structural design optimization scheme presented at the end of the paper, where the critical buckling load is maximized. Secondly a finite element approach is adopted. The commercial finite element package MSC.Patran and MSC.Nastran is used. A set of Patran Command Language routines has been written to automate the very time consuming task of building a finite element model of a blade section. Both geometry and layup data is read directly from ASCII files, which are generated by an in-house developed software, BladeStructure. The data in the ASCII files are then translated to a finite element model of the blade section via the set of PCL routines. Results obtained with the analytical method and the finite element approach are presented and compared with the test data. Finally an example of a gradient based structural design optimization is presented. The critical buckling load is maximized using the orientation of the plies in the layup as design variables.