Papers by Keyword: Life Prediction

Abstract: Currently the fatigue testing of bevel gears are being done by using non rotating type of fixtures that applies fatigue load on a single tooth, which does not resemble the actual loading condition in an automotive differential gear box. This paper discusses the experimental setup with the noise and vibration analysis approach to determine the signature of failures of spiral bevel gears. The proposed experimental setup seems promising for further research and development in the fatigue testing of spiral bevel gears. The Crown pinion and wheel assembly is used for the testing. The pinion is connected to the electric 3 phase AC motor of 75HP with a suitable coupling and the crown wheel is mounted on the half axle shaft, which in turn is connected to an electric dynamometer. The speed/torque of electric motor and the load applied by the dynamometer can be varied. The acoustic sensor is mounted near the differential gear box and the accelerometers are mounted on the Pinion bearing, Crown wheel bearing and the half axle bearing. A four channel data acquisition system is used to log data in time domain (raw data) by three accelerometers and an acoustic sensor. The variations of sound pressure(dB) v/s time, sound Pressure(FFT-(RMS)) amplitude v/s Frequency, Acceleration v/s Time, Octave analysis i.e., Band power v/s Frequency, Noise spectrum Power v/s Frequency, Histogram, Power density v/s Time can be obtained. These data are then used to plot vibration and SPP levels in frequency domain to develop the noise and vibration signature of that crown pinion for given cycles of operation. The tests on Bevel pinion and gear set were performed in the BEC, Bagalkot NVH lab facility. The gear set run successfully at double the rated torque for 30 million pinion cycles. And the signature of pinion failure was obtained. The results demonstrated the suitability of using the given bevel crown pinion and gears set for specified speed, high load application in differential gear box of an automobile.

Abstract: A continuum damage mechanics model was proposed to predict the high cycle fatigue life. In order to consider mean stress effects, the Walker correction was introduced in proposed model. The model was verified by experimental data on LC4 and LY12CZ aluminum alloy under high cycle fatigue loading. The results showed that the predicted life of proposed model well correlated with experimental data.

Abstract: The objective of this paper is to obtain fatigue properties of API X65 steel using the stress life (S-N) approached. In this method S-N curve was established by relating the applied load and the number of cycles to failure. The sets of data were successfully constructed within the range of high and low cycle domains. The fully reversed loading was employed to generate the most severe damage condition. The experiment data lies approximately within correlation boundaries of 1:2 and 2:1. The mean square error was performed to evaluate the goodness of experiment to the simulated data. Therefore, with a 21% of accuracy it was concluded the presented data taken from actual measurements can be used for life prediction of X65 steel.

Abstract: A failure of eyes bar or pin leads to the collapse of the whole structure. For this reason, inspection and maintenance are important, but also very difficult. In addition there is also the problem of corrosion. Generation of small cracks shows that during the remaining life for bar eyes is quite low, indicating in terms of the rules that the item has high possibility of failure, and a failure of this element may lead to a collapse of the structure.

Abstract: Based on the random vibration theory and numerical analysis method, the paper presents a process of carrying out the fatigue life prediction for pipeline of a rocket engine under random excitation. The numerical analysis adopt the power spectrum density of acceleration as random loads. The material parameters of the simulation contains two straight lines in double logarithmic coordinate. The location of danger points is found and the root mean square stress, fatigue life of it is acquired in different excitation directions. The results show that the root of the ball head is the location of danger points, whose fatigue life is 3763 seconds. Furthermore, the location of danger points and its fatigue life obtained from numerical analysis are consistent with the test.

Abstract: The low cycle fatigue damage of turbine disc which is made of GH901 material is systematic analyzed and studied in the article that is based on the theory of continuum damage mechanics and fatigue testing, we improved the common Lemaitre’s low cycle fatigue damage mechanics model, the damage evolution law that the model describes is in good agreement with the test results throughout the course of the fatigue damage. The simplified analysis method for low cycle fatigue damage evolution and life prediction is proposed based on the GH901 low cycle damage features, the practical method of getting damaged material’s constants by existing data is proposed as well.

Abstract: On the analysis of main factors influencing on carbonation of concrete is a stochastic model and criterion of carbonation life prediction of bridge protection layer of concrete carbonation depth. Detection results with long age of railway bridges, the minimum requirements for concrete bridge in northern area of the design strength and thickness of protection layer.

Abstract: In order to study the residual fatigue life of 500 kv transmission tower under load conditions, a multi-scale finite element model of transmission tower is established. By simulating time course of wind load, using Miner fatigue cumulative damage theory and linear S-N curve, the calculation method of transmission towers fatigue life is established. The research shows that the multi-scale model can better simulate the stress and strain state of the transmission tower, and can predict the remaining service life of the transmission tower .The research has important significance and application value for the safe operation of the transmission lines.

Abstract: In this paper, the key technique involved in life prediction of aeroengine’s high temperature component for creep and fatigue/creep interaction, namely, the life prediction methods for high temperature component are discussed systematically. The essential thinking、features and development direction of the theories are commented in detail. All the results obtained are valuable to engineering applications.

Abstract: This paper presents an integrated creep-fatigue (ICF) theory to describe the non-linear creep-fatigue interaction during thermomechanical loading. The ICF theory recognizes the damage evolution as a holistic process consisting of nucleation and propagation of surface or subsurface cracks in coalescence with internally distributed damage, leading to final fracture. In a polycrystalline material under combined cyclic and dwell loading, crack nucleation and propagation occurs by fatigue or oxidation mechanisms, whereas internally distributed damage often occurs in the form of grain boundary cavities or microcracks due to creep or dwell effects, particularly at high temperatures. Based on the above mechanism, a damage evolution equation is mathematically derived, and the generality of the above physical mechanisms warrants the applicability of the ICF theory over a wide range of stresses and temperatures. This paper uses Mar-M 509, a cobalt base superalloy, as an example to illustrate how the ICF theory describes creep and low cycle fatigue (LCF).