A PNEUMATIC PRESSURE BAG TESTING MACHINE FOR APPLYING A UNIFORM LOAD TO PANELS AND PALLETS

Methods for applying uniformly distributed loads to structures are eva luated. A detailed description is presented for a pneumatic pressure b ag (airbag) testing machine built by researchers at Virginia Polytechn ic Institute and State University. A 48 in. (1.219 m) square steel pla te with an average thickness of 0.498 in. (0.01265 m) was tested to de termine 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 deflec tion pattern of the plate along its length at midspan is parabolic, wi th 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 fi nite element and experimental values indicates that the load applied b y the airbag testing machine is a good approximation of a truly unifor m load.