Dynamic behavior to fatigue crack initiation of a glass/epoxy laminate

This paper based to study of the dynamic and fatigue behaviors with numerical and experimental parts of a composite material manufactured by stacking two layers of E-glass fiber in different angle orientations (0°/90°) immersed in polyester resin with total thickness 1.39mm. In Finite Element Analysis (FEA) using ABAQUS was used to evaluate the maximal (displacement, strain and stress) and the natural frequencies (mode shapes) of composite behavior under crack initiation condition. In the experimental part the laminate plate specimen with two layers is tested under one types of cyclic load in fully reversible tensile at (R=0), the fast fracture occur phenomenon and the fatigue life are presented, the fatigue testing exerted in INSTRON 8801 machine

An advanced dynamic repair of edge crack aluminum plate with a composite patch

In this work, repaired crack in 2024 T3 aluminium plate with composite patch is presented, the problem is handled in plane stress condition under tensile Mode I crack growth. In the numerical simulation, firstly we determine the displacement, strain and stress, also the first six mode shapes of the plate, secondly we compare the first results with result of a cracked plate, thirdly we repair the crack with composite patch for different materials (Glass, Boron, carbon) and for (2 layers, 4 layers). Finally the comparison of stress, strain, displacement and six first natural frequencies between uncracked, crack initiation and composite patch repair crack. The best offer operating according to the need is selecte

Numerical and experimental investigation of the dynamic behavior of a vertical rotor

The present study deals with the identification and evaluation of some dynamic features of a laboratory designed and manufactured rotor. The rotor, embedded-free type, rotates in a vertical position. In the free side of the rotor, a disk with defaults is fixed to simulate some physical and aerodynamic phenomena. A dynamic unbalance which simulates a known specific critical regime is imposed to the structure. This type of aeroelastic dynamic instability, called gyroscope wavering, is characterized by a precession movement of the rotor which develops fatigue and increases loads on the structure. Identification and estimation of features inherent to the vibratory behaviour of the rotor, in this regime, are determined by two approaches: Finite elements and Rayleigh-Ritz method

Crack growth diagnostic of ball bearing using vibration analysis

It is known that supported ball bearings have great effects on the vibrations of the gear transmission system, above in all the presence of local faults as well as the crack growths. For this purpose, this paper focuses on shock and vibration crack growth diagnostic of ball bearing using vibration analysis. Our work is devoted first to a study the static behaviour of the ball bearing by determining the stress, strain and displacement, then its dynamic behaviour by determining the first four natural frequencies. Secondly, a dynamic analysis study of the bearing was carried with defects as a function of crack size and location. The obtained results clearly show that the natural frequencies decrease in a non-linear way with the growth of the length of the crack, on the other hand the stress increases with the presence of the singular points of the crack. Finally, this residual decrease in natural frequencies can be used as an indicator of the state of failure, as well as a parameter used for the diagnosis and screening, and to highlight the fatigue life of the bearing