Abstract: In the current investigation numerical and radial basis function neural network (RBFNN) are adopted for diagnosis of fault in a cantilever composite beam structure present in form of transverse cracks. The presence of cracks a severe threat to the performance of structures and it affects the vibration signatures (Natural frequencies and mode shapes). The material used in this analysis is graphite fiber reinforced polyimide composite. The Numerical analysis is carried out by using commercially available software package ANSYS to find the relation between the change in natural frequencies and mode shapes for the cracked and un-cracked composite beam. Which subsequently used to the design of smart system based on RBFNN for forecast of crack depths and locations following inverse technique. The RBFNN controller is developed with relative natural frequencies and relative mode shapes difference as input parameters to calculate the deviation in the vibration parameters for the cracked dynamic structure. The output from the RBFNN controller is relative crack depth and relative crack location. Results from numerical analysis are comparing with experimental results having good agreement to the results predicted by the RBFNN controller.

Abstract: In the last few decades, a considerable amount of research has been done by many researchers around the world on the possibility of understanding mechanisms of brake squeal noise in order to improve vehicle users’ comfort and reduce the overall environmental noise level. Despite these efforts, still no general solution exists. Therefore, it is one of the most significant issues that require a detailed and in-depth study for realizing mechanisms of squeal generation in order to design silent brakes. The aim of this review paper is to gain insight into the disc brake squeal mechanisms that lead to audible noise. The principal mechanisms will be introduced to explain the brake squeal phenomenon namely; stick-slip, sprag-slip, modal coupling and hammering excitation mechanism. As more experimental evidence and simulation results become available, it is found that none of the above mechanisms alone can explain all events related to the squeal noise.

Abstract: This paper investigates the unidirectional motion of an object forced to move on the ground due to an attached inertial drive which comprises counter-rotating eccentric masses on the horizontal plane. The study deals with the case in which the motion is generated by motors rotating at high speed, preferably constant. This inertial propulsion eventually enables the body to travel a limited maximum distance, which was found to be proportional to the square of the motor speed and inversely proportional to the coefficient of sliding (kinetic) friction. Other significant parameters such as the ratio of rotating masses over the object mass, as well as the initial position of these masses when the object is released to move and the magnitude of eccentricity, are discussed. The simulation is based on the combination of analytical formulas with the numerical solution of Single-DOF nonlinear ordinary differential equations for the unidirectional motion of the object to which the rotating masses are attached.

Abstract: The composite materials are well known by their excellent combination of high structural stiffness and low weight. The main feature of these anisotropic materials is their ability to be tailored for specific applications by optimizing design parameters such as stacking sequence, ply orientation and performance targets. Finding free torsional vibrations characteristics of laminated composite beams is one of the bases for designing and modeling of industrial products. With these requirements, this work considers the free torsional vibrations for laminated composite beams of doubly symmetrical cross sections. The torsional vibrations of the laminated beams are analyzed analytically based on the classical lamination theory, and accounts for the coupling of flexural and torsional modes due to fiber orientation of the laminated beams are neglected. Also, the torsional vibrations of the laminated beams analyzed by shear deformation theory in which the shear deformation effects are considered. Numerical analysis has been carried out using finite element method (FEM). The finite element software package ANSYS 10.0 is used to perform the numerical analyses using an eight-node layered shell element to describe the torsional vibration of the laminated beams. The rotary inertia and shear deformation effects of the element are taken. The influence of fiber directions and stacking sequences of laminates on torsional natural frequencies were investigated. Also, the effects of boundary conditions are demonstrated. Numerical results, obtained by the ANSYS 10.0, classical lamination theory, and shear deformation theory are presented to highlight the effects of fibers orientation and layers stacking sequence on torsional frequencies of the beams. The results obtained by ANSYS are compared against the classical lamination theory, as well as shear deformation theory.