scholarly journals Gear Contact Fatigue Reliability Analysis for Wind Turbines Under Stochastic Dynamic Conditions Considering Inspection and Repair

2014 ◽  
Author(s):  
WenBin Dong ◽  
Torgeir Moan ◽  
Zhen Gao
Keyword(s):  
Time Series ◽  
Wind Turbine ◽  
Reliability Analysis ◽  
Wind Turbines ◽  
Contact Fatigue ◽  
Crack Size ◽  
Contact Forces ◽  
Stochastic Dynamic ◽  
Fatigue Reliability ◽  
Gear Contact

Reliability is one of the most important features of the wind turbine gearbox, especially in offshore wind turbines (OWTs). This paper describes a general way to perform gear contact fatigue reliability analysis for wind turbines considering inspection and repair. A simplified predictive surface pitting model for estimating gear fatigue lives is applied to establish the ‘so-called’ limit stated functions. The National Renewable Energy Laboratory (NREL)’s 750kW land-based wind turbine is used to perform time domain simulations considering different wind speeds that the turbine will experience, whose occurrence frequencies are described by a generalized gamma distribution. The time series of the torques in the main shaft are obtained from the global dynamic response analysis of the wind turbine. The time series of the gear contact forces are obtained from the dynamic analysis of the gearbox through multi-body simulation. The 2-parameter Weibull distribution is used to fit the long-term probability distribution of the gear tooth contact pressures. The reliability analysis is based on fracture mechanics (FM) analysis of crack growth. Finally the sensitivity of the reliability index and failure probability on initial crack size, critical crack size, detectable crack size, crack size after repair, material property and environmental loads is estimated considering the effect of inspection.

Tooth Surface Contact Fatigue Reliability Analysis of Cycloidal Gear Based on Monte-Carlo

2012 ◽  
Vol 605-607 ◽  
pp. 811-814 ◽  
Author(s):  
Tian Min Guan ◽  
Jiang Bo Li ◽  
Lei Lei
Keyword(s):  
Monte Carlo ◽  
Fatigue Strength ◽  
Reliability Analysis ◽  
Contact Stress ◽  
Contact Fatigue ◽  
Tooth Surface ◽  
Fatigue Reliability ◽  
Contact Fatigue Strength ◽  
Design Variables ◽  
Distribution Laws

All sorts of design variables and parameters are often regarded as fixed values in the traditional design, it cannot describe quantitatively how well the products are safe. It is necessary to make a reliability analysis of cycloidal gear, which is the key part of FA pin-cycloidal transmission, this paper uses Monte-Carlo method to simulate and test the distribution laws of the contact stress and the contact fatigue strength of cycloidal gear, which indicates that the contact stress obeys the normal distribution and the contact fatigue strength obeys the lognormal distribution, besides, makes a sensitivity analysis of the random parameters, all these work lay the foundation for the reliability analysis of the whole reducer.

Evaluation of Contact Fatigue Life of a Wind Turbine Gear Pair Considering Residual Stress

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Heli Liu ◽  
Huaiju Liu ◽  
Caichao Zhu ◽  
Haifeng He ◽  
Peitang Wei
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Stress State ◽  
Wind Turbine ◽  
Axial Stress ◽  
Contact Fatigue ◽  
Tooth Surface ◽  
Gear Pair ◽  
Contact Fatigue Life ◽  
Gear Contact

Contact fatigue is a main fatigue mode of gears such as those used in wind turbines, due to heavy duties occurring in engineering practice. The understanding of the gear contact fatigue should be based on the interaction between the local material strength and the stress state. Under the rolling–sliding motion, the multi-axial stress state makes the gear contact fatigue problem more complicated. A numerical contact model is proposed to evaluate the contact fatigue life of an intermediate parallel gear stage of a megawatt level wind turbine gearbox. The gear meshing theory is applied to calculate the geometry kinematics parameters of the gear pair. The gear contact is assumed as a plane strain contact problem without the consideration of the influence of the helical angle. The quasi-static tooth surface load distribution is assumed along the line of action. The elastic mechanics theory is used to calculate the elastic stress field generated by surface tractions. The discrete convolute, fast Fourier transformation method is applied to estimate the subsurface stresses distributions. In order to describe the time-varying multi-axial stress states during contact, the Matake, Findley, and Dang Van multi-axial fatigue criteria are used to calculate the critical planes and equivalent stresses. Both the statistic and the deterministic fatigue life models are applied by choosing the Lundberg–Palmgren (LP), Zaretsky models, respectively. The effect of the residual stress distribution on the contact fatigue initiation lives is discussed. In addition, the crack propagation lives are estimated by using the Paris theory.

Continuous damage-based Voronoi finite element analysis of contact fatigue of a wind turbine gear

2019 ◽  
Vol 233 (10) ◽  
pp. 1483-1495
Author(s):  
Peitang Wei ◽  
Huaiju Liu ◽  
Caichao Zhu ◽  
Haifeng He
Keyword(s):  
Finite Element ◽  
Wind Turbine ◽  
Mechanical Response ◽  
Fatigue Behavior ◽  
Maximum Shear Stress ◽  
Contact Fatigue ◽  
Damage Mechanism ◽  
Mechanical Transmission ◽  
Element Analysis ◽  
Gear Contact

Contact fatigue failures of gears, especially those used in heavy duty conditions such as wind turbine gears, become important issues in mechanical transmission industry. In the present work, a continuous damage mechanism and Voronoi-based finite element model is developed to investigate the contact fatigue of a wind turbine gear. Plane strain assumption is adopted to simplify the gear contact model. Voronoi tessellations are utilized to represent the microstructure topology of the gear material, and continuous damage mechanism is implemented to reflect the material degradation within critical substrate area. With the developed framework, the contact pressure distribution, intergranular mechanical response and the progressive fatigue damage at the grain boundaries during repeated gear meshing are evaluated and discussed in detail. The depths of the maximum shear stress reversal and the crack initiation agree well with previously reported findings. The influence of microstructure on the gear contact fatigue behavior is also investigated.

Reliability Analysis of Sub Assemblies for Wind Turbine at High Uncertain Wind

2012 ◽  
Vol 433-440 ◽  
pp. 1121-1125 ◽  
Author(s):  
T. Sunder Selwyn ◽  
R. Kesavan
Keyword(s):  
Wind Turbine ◽  
Reliability Analysis ◽  
Failure Rate ◽  
Wind Turbines ◽  
Mountain Pass ◽  
Brake System ◽  
Operating Period ◽  
Onshore Wind ◽  
Normal Operating ◽  
Wind Turbine System

The wind energy plays a vital role in the world renewable energy scenario. The modern wind turbine system has a complex and repairable components due to sophistication and centralized control. The failure characteristics of the onshore wind turbines depend on the terrain conditions. In the main mountain pass and hill area, there is a heavy uncertainty in the wind that is due to the frequent change in the direction of wind and the change in the velocity. It causes a rapid failure in the individual sub assemblies. There is a substantial need for improving the reliability in the stages of design, manufacturing, operation and maintenance. Normally the infant mortality failures are more in the onshore wind turbine and the failure rate is constant during normal operating period. It is a surprise that the failure rate has rapidly increased during normal operating period of the wind turbines placed exactly in the mountain pass and hilly area due to the high uncertainty in the wind. This paper deals with reliability analysis of major components of wind turbine system and its sub system such as rotor system, gear box, brake system, generator, hydraulic system and yaw system. This paper also investigates the reliability of wind turbines and its sub assemblies placed at Aramboly pass in India by using Weibull software as reliability tool for a grid connected 250 kW wind turbine. This analysis yields some surprising results about some sub assembly like yaw system, brake system and generator which are most unreliable.

Reliability Analysis and Risk-Based Methods for Planning of Operation and Maintenance of Offshore Wind Turbines

2017 ◽  
Author(s):  
John Dalsgaard Sørensen
Keyword(s):  
Wind Turbine ◽  
Reliability Analysis ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Offshore Wind ◽  
Special Focus ◽  
Life Cycle Approach ◽  
Structural Components ◽  
Safety Factors ◽  
Partial Safety Factors

Reliability analysis and probabilistic models for wind turbines are considered with special focus on structural components and application for reliability-based calibration of partial safety factors. The main design load cases to be considered in design of wind turbine components are presented including the effects of the control system and possible faults due to failure of electrical / mechanical components. Considerations are presented on the target reliability level for wind turbine structural components. Application is shown for reliability-based calibrations of partial safety factors for extreme and fatigue limit states are presented. Operation & Maintenance planning often follows corrective and preventive strategies based on information from condition monitoring and structural health monitoring systems. A reliability- and risk-based approach is presented where a life-cycle approach is used. An example with wind turbine blades is considered using the NORCOWE reference wind farm.

scholarly journals Reliability Analysis on Gear Contact Fatigue Strength Considering the Effect of Tolerance

2014 ◽  
Vol 8 (1) ◽  
pp. 630-635 ◽  
Author(s):  
Guowei Li ◽  
Weijian Mi ◽  
Kailiang Lu ◽  
Weiguo Zhang
Keyword(s):  
Finite Element ◽  
Fatigue Strength ◽  
Reliability Analysis ◽  
Gear Tooth ◽  
Contact Fatigue ◽  
Tolerance Allocation ◽  
Product Performance ◽  
Gear Pump ◽  
Contact Fatigue Strength ◽  
Gear Contact

Tolerance allocation influences product performance especially for miniature precise assembly device. The purpose of this paper is to explore an approach to optimize manufacturing tolerances by combining the reliability of product performance indicators under actual working condition. The paper describes the principle and ways of tolerance handling in the finite element control equations for the displacement and stress, and then introduces the implementation of Monte-Carlo Finite Element Analysis method. We illustrate this method on a gear-tooth of port-cleaning-equipment gear pump and carry out the reliability analysis on gear contact fatigue strength considering the effect of manufacturing tolerance, and a sensitivity analysis is also performed to identify the key tolerances and improve them in order to attain the expected reliability.

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