FATIGUE LIMIT ESTIMATION METHOD

To provide a method for accurately estimating the fatigue limit of an object to be measured based on a dissipation energy distribution of the object to be measured that is measured by using an infrared imaging apparatus.SOLUTION: A method according to the present invention has: a relationship calculation step S1 of picking up an image of an object to be measured by using an infrared imaging apparatus while sequentially adding repeated loads different in load width P to the object to be measured, thereby measuring a temporal change of the temperature distribution of the object to be measured for each of the repeated loads, based on the temporal change, calculating the dissipation energy distribution of the object to be measured for each of the repeated loads, and based on the dissipation energy distribution, calculating the relationship between the load widths P and dissipation energy q; and a fatigue limit estimation step S2 of estimating, as the fatigue limit of the object to be measured, the load width P at which the maximum value of at least one parameter is obtained, the parameter of three parameters: a first-order differential value d for each of the load widths P obtained by performing first-order differentiation on the relationship at the load width P; a second-order differential value d2 for each of the load widths P obtained by performing second-order differentiation; and the product dα of the first-order differential value d and the second-order differential value d2 for each of the load widths P.SELECTED DRAWING: Figure 2 【課題】赤外線撮像装置を用いて測定した被測定物の散逸エネルギー分布に基づき、被測定物の疲労限度を精度良く推定する方法を提供する。【解決手段】本発明に係る方法は、被測定物に荷重幅Ｐの異なる繰り返し荷重を順次付加しながら、赤外線撮像装置を用いて被測定物を撮像することで、繰り返し荷重毎に被測定物の温度分布の時間的変化を測定し、これに基づき、繰り返し荷重毎に被測定物の散逸エネルギー分布を算出し、これに基づき、荷重幅Ｐと散逸エネルギーｑとの関係を算出する関係算出ステップＳ１と、前記関係を荷重幅Ｐで１階微分して得られる荷重幅Ｐ毎の１階微分値ｄ、２階微分して得られる荷重幅Ｐ毎の２階微分値ｄ２、及び、荷重幅Ｐ毎の１階微分値ｄと２階微分値ｄ２との積ｄαの３つのパラメータのうち、いずれか１つのパラメータの最大値が得られた荷重幅Ｐを被測定物の疲労限度として推定する疲労限度推定ステップＳ２と、を有する。【選択図】 図２