| dc.description.abstract | This thesis focuses on ABS, which is used in TV set manufacturing with injection molding process, vacuum thermoforming etc. The cost is too high in injection molding process, so we used vacuum thermoforming. The advantage of using a thermoforming process is the cost effective molding in tackling large sized and complex shaped products such as a surfing board, a large size TV set back cover etc.
The combined effects of strain-rate, strain-hardening, and temperature on the elongation deformation behavior of ABS material at a high temperature was proposed. In the vacuum thermoforming process, there will be flow stress at the mold cavity of the ABS plastics, and stress, temperature, strain and strain rate will affect the ABS plastics deformation. The hot deformation behaviors and constitutive analysis of injection molded ABS plastics were systematically investigated by hot tensile tests in the temperature range of 95-110 °C and strain rate range of 1 x 10-3 to 5.6 x 10-2 s-1. Power law and hyperbolic sine constitutive relation was adopted and the constitutive parameters, strain rate ε ̇, stress exponent n, strain rate sensitivity exponent m, material constants (K, A), activation energy Q, and temperature T in the constitutive equations were calculated as a function of strain. By using the two functions, we can compare the calculated flow stresses and experimental ones and get average absolute relative error.
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