Abstract: The invention relates to a device for viewing tension loss in a structure, by engagement with a threaded rod, being carried out, for example, by a bolt made up of a screw, a nut, and consisting of two non-deformable washers comprising an inner face, an outer face, an outer peripheral wall and an inner peripheral wall delimiting a central opening and a diametrically deformable viewing ring sandwiched between the two non-deformable washers, characterized in that the ring is crush-resistant and the thickness of at least one of the washers decreases from the center of the washer towards the peripheral end thereof, the smallest thickness thus being located towards the peripheral end of at least one washer.

Abstract: The invention relates to a device for viewing tension loss in a structure, by engagement with a threaded rod, being carried out, for example, by a bolt made up of a screw, a nut, and consisting of two non-deformable washers comprising an inner face, an outer face, an outer peripheral wall and an inner peripheral wall delimiting a central opening and a diametrically deformable viewing ring sandwiched between the two non-deformable washers, characterized in that the ring is crush-resistant and the thickness of at least one of the washers decreases from the center of the washer towards the peripheral end thereof, the smallest thickness thus being located towards the peripheral end of at least one washer.

Abstract: Arrowhead (1) for a target, comprised of an arrowhead body (2) having three portions, including a front portion (2a), a central portion (2b), and a rear portion (2c), the front portion constituting the point for penetrating into the target, comprising mechanisms for facilitating the removal of the lodged arrow, such mechanisms being formed by at least one projecting profile (3), characterized in that the projecting profile(s) is/are in the form of a portion of a sphere.

Abstract: Arrowhead (1) for a target, comprised of an arrowhead body (2) having three portions, including a front portion (2a), a central portion (2b), and a rear portion (2c), the front portion constituting the point for penetrating into the target, comprising mechanisms for facilitating the removal of the lodged arrow, such mechanisms being formed by at least one projecting profile (3), characterized in that the projecting profile(s) is/are in the form of a portion of a sphere.

Abstract: A device (1) for displaying the correct tightening force for a nut (7) intended for assembling two elements (2, 3) of a structure (4) by co-action with a threaded rod (60), assembly being effected, for example, by way of a bolt (5) constituted by a screw (6), a nut (7), at least one nondeformable washer, and a display washer made of elastically deformable material such as a synthetic rubber, a natural rubber, an elastomer, or a polyurethane plastic material, wherein at least one of the nondeformable washers has on its inner face a projection (103) whose inner face (101) is intended, after tightening, to abut against the inner face of another washer or against the element to be assembled; and the deformable washer protrudes peripherally as it is crushed, constituting an indicator of proper tightening.