Method of making a device for monitoring fatigue life

A method of making a device for monitoring the fatigue life of a member fabricated of a particular material comprising the steps of:

• obtaining a thin sheet of the material from which the member is fabricated;
• cutting a plurality of generally parallel elongated coupons from the thin sheet of material;
• cutting a predetermined stress concentrating notch pattern comprised of at least one pair of notches into each coupon, one notch of the notch pair being disposed on each of the longitudinal sides of a coupon, the notches of the notch pair being substantially geometrically the same and substantially aligned with each other, the notch pattern of each of the coupons varying in intensity from mild in which the edge surfaces of the notches are generally smooth and continuously curved, to severe, in which the edge surface of each of the notches exhibits a sudden change to form two portions which are in different planes, the two portions meeting to form a line so that upon the application of the same strain to all of the coupons, each coupon has a different fatigue life, the fatigue life of each coupon being a percentage of the fatigue life of the member being monitored.