PURPOSE: To make it possible to estimate the time of occurrence of fatigue damage readily and in high evaluating accuracy by obtaining the fluctuating width of the strain of an object structure based on the time of breakdown of a thin wire.
CONSTITUTION: The thin wire of a material 2, whose fatigue strength is lower than the fatigue strength of an object structure and has the known fatigue strength, is attached to the structure. The time of the breakdown of the thin wire is detected. The fluctuating width of the strain of the object structure is obtained based on the time of breakdown of the thin wire. The time of the occurrence of a crack in the object structure is further obtained from the fluctuating width of the strain. The attached material 2 indicates the lower fatigue strength in comparison with the material 2 used in the actual structure. Therefore, breakdown occurs in the attached material 2 before the occurrence of fatigue damage in the actual structure. The time of the occurrence of the fatigue damage can be estimated based on the time of breakdown, i.e. the life when fatigue occurs. When the kinds of the estimating wires (material 2) are changed and a plurality of the lines are used, the estimation of the fatigue damage can be performed in high accuracy.
FUJII MASANAO
MURAI RYOSUKE
