Fatigue damage detection sensor for structural materials and mounting method thereof

A method of mounting a fatigue damage detection sensor to a structural material for sensing the level of fatigue damage caused to the structural material when the structural material is subjected to an external stress, the method comprising the steps of:

• (a) providing a rectangularly configured, panel-shaped sensor body having a specified width and a predetermined length;
• (b) forming a notched portion which defines a tip in the sensor body;
• (c) forming a fatigue pre-crack in the sensor body at the tip of the notched portion;
• (d) relieving a residual stress from the sensor body resulting from the formation of the fatigue pre-crack in step (c), the relief of the residual stress increasing a mean stress of the sensor body;
• and
• (e) mounting the sensor body to the structural material.

A method for mounting a fatigue damage detection sensor to a structural material for sensing the level of fatigue damage caused to the structural material when the structural material is subjected to an external stress, the method comprising the steps of:

• (a) providing a rectangularly configured, panel-shaped sensor body having a specified width and a predetermined length;
• (b) forming at least one notched portion which defines a tip in the sensor body;
• (c) positioning a means for crack detection on the sensor body adjacent the tip of the notched portion;
• and
• (d) mounting the sensor body to the structural material via a spaced pair of fixing portions such that the sensor body has a length 2H between the fixing portions, with the length 2H being set so as to cause a crack propagation rate d(a)/dN to be proportional to H0.5m, (a) being the length of a crack that propagates from the tip of the notched portion, N being the number of times that the external stress acts on the structural material, H being one-half the length 2H, and m being a constant determined by the structural material.