| The frictional contact problem has been studied for bolted joints of finite composite plates. This includes the effects of bolt clearance and variations in material and geometry, and the use of either an isotropic or orthotropic insert. Full-field displacements were measured by high sensitivity moire interferometry. Considerable effort was expended to develop a loading frame, relevant fixturing and monitoring capability to ensure that the plate was loaded uniformly through its thickness, particularly at the bolt hole. Numerical techniques were prepared for processing the optical fringe data.;A reliable finite element model for a bolted joint was also formulated. The FEM code, which is capable of handling finite geometry, as well as friction and/or clearance at the loaded hole, has been validated analytically, experimentally and numerically. The FEM analysis uses a new numerical scheme to formulate 3-node symmetric contact element stiffness matrices. The accuracy of this scheme is comparable to that given by conventional unsymmetrical contact element stiffness matrices, but it uses only half of the computing time and half of the storage device of the latter conventional method.;Among other results, the use of an insert can reduce the peak stresses in the composite plate by 75%. |
