Non-destructively Analyzing Residual Stress based on using Thermoelastic Stress Analysis

• Main Authors: HSIEH, YOU-RU, 謝侑儒
• Other Authors: LIN, SHIANG-JIUN
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/56074498618542201438

碩士 === 國立高雄應用科技大學 === 模具工程系 === 105 === Thermoelastic Stress Analysis (TSA) is a non-contacting and non-destructive technique. This technique can provide the full-field stress information throughout the surface of a loaded object. Theoretically, when the material is stressed, the surface will produce a temperature change. That is, when the material is subjected to a tensile load, the temperature will be reduced. On the contrary, when the material is subjected to a compressive load, the material temperature will rise. This reaction is called thermoelastic response which can be represented by the theory of thermoelastic effect. The temperature change due to thermoelastic behavior can be very small and even approximately reach the order of . Based on the traditional TSA theory, a plane-stressed elastic body under adiabatic and reversible conditions gives that the rate of temperature change of a cyclically loaded member is linearly proportional to the stress amplitude. This proportionality is defined to be thermoelastic constant. Nowadays, the equipment of TSA applying array infrared detectors is able to rapidly capture the tiny temperature change over the entire surface of the material. This temperature change is related to the sum of principal stresses or isopachic stress. However, recent studies revealed that the loaded member of thermal response is not only a function of stress amplitude but the mean stress. Therefore, the thermoelastic coefficient is revised and expressed as stress dependence but not a constant. In addition, according to mechanics aspect, mean stress as well as residual stress are represented the static part of the stress. Hence, residual stresses is able to detected by using TSA technique. This study attempts utilizing TSA technique and analyzing the thermoelastically measure results to investigate the residual stress within the 2024 aluminum alloy plate.