98 J.L. Smith et al. The calculation of the fraction of mechanical energy converted to thermal energy during this test can be calculated as we have synchronous measurements for force, strain and temperature. This fraction of plastic work dissipated as heat is usually denoted by ß and has been theorized and calculated by researchers in the past. Rosakis et al. [3] first presented the theoretical thermodynamic foundations illustrating the plastic strain and strain rate dependence of ß. Hodowany et al. [4] then expanded on these tests by measuring the temperature of Al2024-T3 and ’-Titanium at strain rates of 1 s 1 and 3000 s 1. From these test he concluded that the Al2024-T3 had a plastic strain but not strain rate dependent ß while the ß for ’-Titanium was both plastic strain and strain rate dependent. ß was calculated in the preceding tests with the following equation: ˇ D cP P"p where is the mass density, c is the specific heat, P is the change in temperature, is the component of stress and P"p is the change in plastic strain. In the present paper, simultaneous full-field strain and temperature measurements, using 2D DIC and a high-speed IR camera, respectively, are made in tensile tests at a strain rate of 1 s 1. The results show the evolution of strain and temperature during the uniform deformation in the early part of the test and in the necking region during the localization. Calculations of the partition of plastic work converted to heat based on the measurements of force, strain, and temperature are presented. Practical and theoretical issues related to the emissivity of the specimens, calibration of infrared cameras, as well as the current limitations of the infrared techniques, such as the limited temperature range of measurements at a constant exposure time are discussed. 16.2 Experimental Procedures and Techniques Tensile tests on flat thin stainless steel 316 specimens are conducted at a strain rate of 1 s 1. Full-field deformation and fullfield temperature are measured simultaneously and synchronously during the tests. The deformation is measured using DIC on one side of the specimen, and the temperature is measured on the opposite side with an IR camera. Since the specimen is thin, it is assumed that the deformation and temperature are uniform through the thickness. The quasi-static test is completed using a servo-hydraulic MTS load frame as shown in Fig. 16.1 below. 16.2.1 Specimen Geometry and Material Tests at high strain rates require specimens with a short gage length, and in order to eliminate possible effects of the specimen geometry on the results, the gage section geometry of the specimens used in the quasi-static tests is the same. A drawing of the specimen used in the high strain rate tests is shown in Fig. 16.2. The specimens are made of stainless steel AISI 316. Fig. 16.1 Testing configuration on the MTS frame
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