Experiments Into the Inertial Deformation of Clamped Rectangular, Square and Triangular Diaphragms

Summary

An experimental investigation is described which was carried out to study the behaviour of fully-clamped rectangular, square and triangular diaphragms when subjected to uniformly distributed transverse initial velocities. A machine for the forming of metal diaphragms under the action of pure inertia forces was used for the investigation. The range of kinetic energy imparted to the diaphragm, corresponding to initial velocities between 3.5 and 23.5 m/s in 5 stages, was sufficient to cause plastic flow and to secure maximum permanent polar deflections of from 6 to nearly 40 times the diaphragm thickness. Interesting features were observed regarding the hinge phenomenon and bending wave effects. Observations also included ‘curling’ of the free inner edges when testing diaphragms having central holes of corresponding shapes. The test equipment is briefly described and results are presented showing deformed diaphragms and illustrating how the profile, strain distribution, polar deflection and polar radius of curvature of the formed specimens varies with initial velocity. Results for inertially deformed diaphragms are also compared with those from the hydraulic bulging operation.