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ABSTRACT--This study investigates heat generation in metals during plastic deformation. Experiments were designedto measure the partition of plastic work into heat and stored energy during dynamic deformations under adiabatic conditions. A servohydraulic load frame was used to measure mechanical properties at lower strain rates, 10 -3 s -1 to 1 s -1. A Kolsky pressure bar was used to determine mechanical properties at strain rates between 103 s -1 and 104 s -1. For dynamic loading, in situ temperature changes were measured using a high-speed HgCdTe photoconductive detector. An aluminum 2024-T3 alloy and c~-titanium were used to determine the dependence of the fraction of plastic work converted to heat on strain and strain rate. The flow stress and 13 for 2024-T3 aluminum alloy were found to be a function of strain but not strain rate, whereas they were found to be strongly dependent on strain rate for c~-titanium.

A simultaneous numerical and experimental investigation is undertaken to assess three dimensional effects and HRR dominance near a crack front in a ductile 3-point bend specimen. In parallel to the 3-D numerical calculations, a plandIstrain and a plane-'stress analysis of the same in-plane specimen geometry is performed to obtain upper and lower bounds for the 3-D calculation. The radial, angular and thickness variation of the stresses and displacements are studied in great detail from contained yielding, to fully plastic conditions. The results indicate that the plane strain HRR field prevails in the interior of the specimen very near the crack front even for moderate extents of yielding. On the other hand, for distances from the crack tip exceeding about half a specimen thickness, plane stress conditions are approached. The calculations presented here model a series of laboratory experiments involving three independent experimental techniques. Details regarding the experiments and comparisons of the experimental measurements with numercial calculations and theory are emphasized in Part II of this work.

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