On twisting of orthotropic plates in a large deflection regime

The paper analyzes the large deflection behavior of an orthotropic square plate subjected to pure twisting moments distributed at all four edges of the plate supported at two opposite corners from below and at a third corner from above. The load is applied at the fourth corner. An expression relating load to deflection is derived by applying the principle of total potential energy. This expression is used to plot load-deflection curves, neglecting the contribution of self weight, for isotropic (aluminum), glass-epoxy, graphite-epoxy, and boron-epoxy plates. It is shown that the load-deflection curve is linear up to deflections of the order of plate thickness. This means that for the four cases considered, small deflection theory is adequate to predict the deflections as long as these are of the order of plate thickness. The load-deflection expression can be used to determine the shear modulus of plates by measuring deflections in the large deflection range