scholarly journals Reliability and Random Lifetime Models of Planetary Gear Systems

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Peng Gao ◽  
Liyang Xie ◽  
Wei Hu
Keyword(s):  
Load Distribution ◽  
Planetary Gear ◽  
Working Process ◽  
Random Load ◽  
Working Mechanism ◽  
Dynamic Reliability ◽  
Reliability Models ◽  
Process Failure ◽  
Failure Dependence ◽  
Gear Systems

Conventional reliability models of planetary gear systems are mainly static. In this paper, dynamic reliability models and random lifetime models of planetary gear systems are developed with dynamic working mechanism considered. The load parameters, the geometric parameters, and the material parameters are taken as the inputs of the reliability models and the random lifetime models. Moreover, failure dependence and dynamic random load redistributions are taken into account in the models. Monte Carlo simulations are carried out to validate the proposed models. The results show that the randomness of the load distribution is obvious in the system working process. Failure dependence has significant influences on system reliability. Moreover, the dispersion of external load has great impacts on the reliability, lifetime distribution, and redundancy of planetary gear systems.

Dynamic reliability models of mechanical load-sharing parallel systems considering strength degradation of components

2014 ◽  
Vol 229 (13) ◽  
pp. 2484-2495 ◽  
Author(s):  
Peng Gao ◽  
Liyang Xie
Keyword(s):  
Failure Rate ◽  
Mechanical Load ◽  
Parallel Systems ◽  
Load Sharing ◽  
Strength Degradation ◽  
Random Load ◽  
Dynamic Reliability ◽  
Reliability Models ◽  
Load Redistribution ◽  
Mechanical Components

Conventional reliability analysis of load-sharing parallel systems is mainly based on failure rate of components, in which failure dependence of components and load redistribution are also characterized by specified failure rates. However, the failure rate of mechanical components always varies with time, which is difficult to measure. Therefore, in this paper, quantitative dynamic reliability models of mechanical load-sharing parallel systems are developed in terms of stress parameters and strength parameters rather than failure rate of components, which consider the degradation mechanism of mechanical components. The proposed models take into account the strength degradation path dependence (SDPD) of a component, the strength degradation process dependence between different components in a system, and the random load redistribution. In addition, Monte Carlo simulation is carried out to verify the proposed models. The results show that SDPD and the load-sharing effect have considerable influences on dynamic reliability of mechanical load-sharing parallel systems.

scholarly journals Fuzzy Dynamic Reliability Models of Parallel Mechanical Systems Considering Strength Degradation Path Dependence and Failure Dependence

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Peng Gao ◽  
Liyang Xie
Keyword(s):  
Path Dependence ◽  
Mechanical Systems ◽  
Strength Degradation ◽  
Sensitivity Function ◽  
Bolted Joint ◽  
Paper Strength ◽  
Dynamic Reliability ◽  
Reliability Models ◽  
Proposed Model ◽  
Failure Dependence

Fuzzy dynamic reliability models of mechanical parallel systems with respect to stress parameters and strength parameters are developed in this paper. Strength degradation path dependence (SDPD) and failure dependence of components in the system are two main problems to be addressed in developing fuzzy dynamic reliability of mechanical systems, which are taken into account in the proposed reliability models. In addition, the SDPD sensitivity function and the failure dependence sensitivity function are defined to analyze the influences of the fuzzy characteristics of stress on the effects of SDPD and failure dependence of mechanical components on dynamic reliability. The bolted joint systems for connection between launch vehicle and satellite are chosen as illustrative examples to demonstrate the proposed model. Moreover, Monte Carlo simulations are carried out to validate the effectiveness of the proposed models. The results show that SDPD and failure dependence of components have significant impacts on fuzzy dynamic reliability of mechanical systems. Besides, the influences of the fuzzy characteristics of stress on SDPD sensitivity and that on failure dependence sensitivity are different.

scholarly journals Reliability Evaluation Based on Different Distributions of Random Load

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Peng Gao ◽  
Liyang Xie
Keyword(s):  
Dynamic Change ◽  
Strength Degradation ◽  
Longitudinal Distribution ◽  
Reliability Model ◽  
Random Load ◽  
Dynamic Reliability ◽  
Initial Strength ◽  
Reliability Models ◽  
Model Based ◽  
Definition Of

The reliability models of the components under the nonstationary random load are developed in this paper. Through the definition of the distribution of the random load, it can be seen that the conventional load-strength interference model is suitable for the calculation of the static reliability of the components, which does not reflect the dynamic change in the reliability and cannot be used to evaluate the dynamic reliability. Therefore, by developing an approach to converting the nonstationary random load into the random load whose pdf is the same at each moment when the random load applies, the reliability model based on the longitudinal distribution is derived. Moreover, through the definition of the transverse standard load and the transverse standard load coefficient, the reliability model based on the transverse distribution is derived. When the occurrence of the random load follows the Poisson process, the dynamic reliability models considering the strength degradation are derived. These models take the correlation between the random load and the strength into consideration. The result shows that the dispersion of the initial strength and that of the transverse standard load coefficient have great influences on the reliability and the hazard rate of the components.

scholarly journals Dynamic Reliability Analysis Method of Degraded Mechanical Components Based on Process Probability Density Function of Stress

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Peng Gao ◽  
Liyang Xie
Keyword(s):  
Probability Density Function ◽  
Probability Density ◽  
Density Function ◽  
Solar Array ◽  
Dynamic Reliability ◽  
Reliability Models ◽  
Practical Engineering ◽  
Mechanical Components ◽  
Reliability Computation ◽  
Probability Density Function Pdf

It is necessary to develop dynamic reliability models when considering strength degradation of mechanical components. Instant probability density function (IPDF) of stress and process probability density function (PPDF) of stress, which are obtained via different statistical methods, are defined, respectively. In practical engineering, the probability density function (PDF) for the usage of mechanical components is mostly PPDF, such as the PDF acquired via the rain flow counting method. For the convenience of application, IPDF is always approximated by PPDF when using the existing dynamic reliability models. However, it may cause errors in the reliability calculation due to the approximation of IPDF by PPDF. Therefore, dynamic reliability models directly based on PPDF of stress are developed in this paper. Furthermore, the proposed models can be used for reliability assessment in the case of small amount of stress process samples by employing the fuzzy set theory. In addition, the mechanical components in solar array of satellites are chosen as representative examples to illustrate the proposed models. The results show that errors are caused because of the approximation of IPDF by PPDF and the proposed models are accurate in the reliability computation.

Touch Screen Technology and its Driver Design in uCLinux

2013 ◽  
Vol 303-306 ◽  
pp. 2397-2402
Author(s):  
Shu Wu
Keyword(s):  
State Transition ◽  
Touch Screen ◽  
The State ◽  
Working Process ◽  
Working Mechanism ◽  
Input System ◽  
Microcontroller Unit ◽  
Screen Touch

Touch screen input system about hardware connection and driver design in uCLinux were presented in this work. With the respect of hardware, it introduced working mechanism of four-wire resistive touch screen and method of calculating coordinate. Then it presented the hardware connection of touch screen input system including touch screen, touch screen control chip and Microcontroller Unit. With respect of software, it analyzed the characteristic of driver design in uCLinux. Then it divided touch screen working process into six states which were ‘start’, ‘idle’, ‘wait’, ‘read’, ‘error’, ‘end’ and defined the state transition. On this basis, Touch screen driver design was introduced, which mainly included initialization function, clean function, device-opening function, device-releasing function, coordinates-reading function and parameters-setting function. It also gave the arithmetic converting touch screen coordinate to application coordinate.

Effect of the bearing clearance on vibrations of a double-row planetary gear system

2019 ◽  
Vol 234 (2) ◽  
pp. 347-357
Author(s):  
Jing Liu ◽  
Shizhao Ding ◽  
Linfeng Wang ◽  
Hongwu Li ◽  
Jin Xu
Keyword(s):  
Contact Stiffness ◽  
Planetary Gear ◽  
Gear Ratio ◽  
Gear System ◽  
Double Row ◽  
External Torque ◽  
Bearing Clearance ◽  
Gear Systems ◽  
Planetary Gear System ◽  
Stiffness And Damping

The bearing clearance, external torque, and input speed can greatly affect vibrations of the planetary gear system. The double-row planetary gear systems are commonly used in the gearbox of special vehicles, which are the key parts to obtain a larger gear ratio. Although many works have been presented to study those factors on vibrations of the single-row planetary gear system, a few works were focused on vibrations of the double-row planetary gear system with the bearing clearance. To overcome this problem, a multi-body dynamic model of a double-row planetary gear system with six planet bearings and one supported bearing of the sun gear is presented. This model is the main part of a gear box transmission system. The new model is developed for studying the effect of the bearing clearance on the planetary system. The meshing stiffness and damping between the gears are obtained by current methods in the listed references, as well as the contact stiffness and damping in bearings. The liner stiffness and damping model is used. The effects of the bearing clearance, external torque, and input speed on vibrations of the system are analyzed. The results show that vibrations of the ring gear and sun gear decrease with the increment of the external torque and increase with the increment of the input speed. Moreover, a reasonable bearing clearance can be helpful for reducing system vibrations for some mating external torque and input speed conditions. The results can provide some guidance to find new method to reduce vibrations and increase the service life of planetary gear systems.

Sign in / Sign up

Export Citation Format

Share Document