Experimental Study of the Loosening Phenomenon of an Assembly with Multi Fixations Under Vibration in the Transversal Direction

The majority of structures are subject to dynamic loads resulting from vibrations and shocks. Studies conducted by the researchers show that transversal loads are the main causes of the loosening phenomenon. The purpose of this paper is to expose an experimental study of the loosening phenomenon of an assembly subjected to dynamic transversal load resulting from vibration. The assembly will be the subject to vibrations resulting from a shaker. It consists of an inertial mass, bolted on a bracket attached to the shaker, which is animated with a vertical sinusoidal movement at a fixed frequency. The inertia of the mass will be exploited to generate its sliding. In fact, under the influence of the imposed acceleration, the inertial mass is subject to a shear load that overcomes the friction one. Sliding of the mass will cause the loosening phenomenon. The Assembly will be instrumented by a high-speed camera to track the rotation of parts during the vibration; an accelerometer for measuring the imposed acceleration and a load washer for measuring the screw preload. Results obtained from this study showed the loosening phenomenon for an assembly with one and two fixations. A parametric study will be elaborated in order to identify the critical case for the loosening phenomenon.