A gear is a critical component and can be found in many industrial applications. This investigation develops a three dimensional finite element spur gear model to calculate the contact stress on the gear tooth surfaces. Contact stress is one of the main factors that is used to decide the gears tooth surface strength. In addition there are other important factors such as frictional forces and micro-pits that influence the gear tooth surface. Different analytical techniques have been used to calculate the contact stress of the gear surfaces namely; Hertzian theory and AGMA standards. The analytical results have been compared to the numerical analysis to verify the spur gear finite element model.

Fibre reinforced polymer composite have been utilised in applications that require high strength-to-weight ratio and durability like automotive and spacecraft components. The literatures has indicated that there is a gap of knowledge in fatigue failure mechanism, and reliable prediction of fatigue life for glass and carbon fibre laminates. This study is to address experimentally the stress level dominated the composite failure mode and how to avoid stress concentration in fatigue design. In addition, it contributes to the scientific knowledge and to further increase the understanding the fatigue behaviour of composite materials structures. To accomplish this investigation goals, three types of materials were fabricated and tested; glass/epoxy, carbon/epoxy, and chopped glass/epoxy. Traditional hand layup technique for composite processing was used to fabricate the composite specimens. It involves manually positioning the reinforcement woven roving in an open mould and pouring, brushing, the resin onto the composites. This study details the experimental results of the ultimate tensile strength and high cycle fatigue, with a stress ratio of 0.1, using ASTM. Results showed that carbon fibre composite had the highest ultimate tensile strength. The power curves conducted from this paper were used to estimate the number of cycles which the material can endure.

Application of gear in heavy industry is extremely challenging with the exposure to high load and high speed during transmission. These exposures produce an unfavourable condition in the gear operation as they induce crack. Induced crack might not only causes machine failures but catastrophic incidents that cost lives. Provided that the crack does not grow towards the shaft, the gear might still functioning but at a lower efficiency. Vice versa, the gear will tear into parts and causes catastrophic damages. Therefore, the study of crack propagation pathway was conducted by analysing the crack tip behaviour. The crack tip behaviour was indicated using the stress intensity factor (SIF) by identifying the potential fracture mode of the crack gear model. The analysis had implemented the application of extended finite element method (XFEM) in ABAQUS to avoid the need of re-meshing as in finite element method (FEM). The simulation outcomes show that the cracked gear model is experiencing a significant compressive in-plane shear than tensile stress. It also allows the witnesses of crack propagation along the tooth.