Measurement of Microscopic Residual Stress by Using Indentation Method

残余应力是评价疲劳、应力腐蚀开裂或脆性断裂等断裂现象的重要参数。微观区域晶体结构的非均质性与残余应力分布的关系影响断口特征。因此，通过数值分析方法和直接测量方法，微观残余应力评估对材料设计和断裂行为机理研究是有效的。我们挑战压痕技术的微观残余应力测量。采用维氏压头和努普压头获取整个加载和卸载过程中的载荷-位移关系，然后从理论上计算残余应力。利用该方法可以精确地计算残余应力的方向和分量。

Residual stress is an important parameter for evaluating fracture phenomena such as fatigue, stress-corrosion cracking, or brittle fracture. Relationship between heterogeneity in microscopic region of crystal structures and residual stress distribution affects fracture characteristics. Microscopic residual stress evaluation is therefore effective for materials design and mechanism study of fracture behavior, by using not only numerical analysis approach but also direct measurement. We challenge indentation technique for microscopic residual stress measurement. Both of Vickers-type and Knoop-type indenters are used for obtaining load-displacement relationship during whole loading and unloading processes, then residual stress is theoretically calculated. Directions and components of residual stress are precisely evaluated by using the proposed method.