Abstract: A device for monitoring the fatigue life of a structural member is comprised of at least one and preferably a plurality of substantially flat, elongated coupons which are fabricated of the same material as that of the member being monitored. The coupons are secured in parallel to the member so that they all experience the same strain history as the member. Each of the coupons includes a different stress concentrating notch pattern so that the application of the same strain to all of the coupons results in the development of different stress concentrations within the coupons. The development of different stress concentrations within the coupons causes each coupon to have a different fatigue life, the fatigue life of each coupon being a predetermined percentage of the fatigue life of the structural member being monitored.

Abstract: A device for monitoring the fatigue life of a structural member is comprised of at least one and preferably a plurality of substantially flat, elongated coupons which are fabricated of the same material as that of the member being monitored. The coupons are secured in parallel to the member so that they all experience the same strain history as the member. Each of the coupons includes a different stress concentrating notch pattern so that the application of the same strain to all of the coupons results in the development of different stress concentrations within the coupons. The development of different stress concentrations within the coupons causes each coupon to have a different fatigue life, the fatigue life of each coupon being a predetermined percentage of the fatigue life of the structural member being monitored.