Volume 23, Issue 4 (July 1995)
A Pneumatic Pressure Bag Testing Machine for Applying a Uniform Load to Panels and Pallets
Methods for applying uniformly distributed loads to structures are evaluated. A detailed description is presented for a pneumatic pressure bag (airbag) testing machine built by researchers at Virginia Polytechnic Institute and State University. A 48 in. (1.219 m) square steel plate with an average thickness of 0.498 in. (0.01265 m) was tested to determine whether the machine delivers a true uniformly distributed load. Experimental results are compared to an analytical solution obtained using the ABAQUS finite element program.
Results show that the deflection pattern of the plate along its length at midspan is parabolic, with deflections being greatest at the free edges and least at the plate center. Errors range from 0.6% at one free edge to 3.8% at the other. The error at the plate center is 1.4%. The close agreement between finite element and experimental values indicates that the load applied by the airbag testing machine is a good approximation of a truly uniform load.