Abstract: The invention relates to a fatigue indicator for mechanical parts subjected to repeated stresses, which comprises two thick elements spaced apart from one another and joined together by a thin web having a slit, these two elements being incorporated in the part or fixed thereto so as to move with respect to one another upon application of stress on the mechanical part in a plane which is parallel to the plane of the web, the thin web being thus subjected to a shearing stress in its plane, and wherein the slit of the thin web extends from one of the edges of the web in the direction of relative movement to a blind end so that, when the part is stressed, two cracks appear from corners of the blind end of the slit, extend progressively in the web and finish by reaching the opposite edge of the web or joining cracks coming from this opposite edge, the web thus being detached or practically detached.

Abstract: The present invention relates to an improved fatigue damage indicator for a echanical member subjected to repetitive stress, comprising two thick elements which are spaced from one another and are connected one to the other by a thin web or plate formed with a slot and at least one pair of free opposite edges, the two elements being so connected with the mechanical member or fixed to the latter so that they are displaceable relative to one another in a plane parallel to the plane of the thin plate, the thick elements being disposed so as to be separated from one another in a direction substantially perpendicular to their direction of relative displacement by such stress, the thin plate being placed under shear force in its plane by such relative displacement, the slot of the thin plate extending from one of the edges of the web in the said direction and terminating short of the opposite edge in a blind end of the slot having two corners so that, with application of stress, two cracks develop at corners of the

Abstract: A fatigue damage indicator includes a thin plate mounted between or integral with two members to which a stress is to be applied, the disposition of the two members being such that the thin plate is stressed in shear.Slots extending in the direction of the applied stress may be provided to ensure that cracks formed by fatigue stress propagate in a desired direction and the crack propagation is designed to ensure that a part of the plate becomes detached or is bent substantially away.