Transient heating effects on the bending strength of integral aluminum-alloy box beams

Richard A. Pride, John B. Hall, Jr.
naca-tn-4205
Mar 1958


Twenty-five square-tube beams made of aluminum alloy were tested to failure under various combinations of bending moment and transient heating. Two types of heat input were used so that the effect of thermal stresses could be separated from effects of material properties. Two sizes of square tubes were tested so that both elastic and plastic buckling stresses would be obtained. Good agreement was found between the buckling loads determined experimentally for both types of heat input and local buckling loads calculated according to a theory that incorporates the .effects of material properties and thermal stress in both the elastic- and the plastic-stress ranges. A marked reduction in buckling strength was observed as a result of thermal stress. Failure of the compression side of the beam occurred in all tests. The maximum loads when plotted as a function of temperature appeared as a single scatter band for both types of heat inputs and correlated well with the loads calculated by a maximum-strength theory based solely on material properties without consideration of thermal stresses. These results indicate that thermal stresses which influence the magnitude of the buckling load are largely alleviated in the interval between local buckling and maximum load. This limited study indicates that both local buckling and maximum bending strength appear to be essentially independent of the sequence of loading and heating.

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