Effects of thermal and mechanical combined load on blade stress and fatigue life characteristic

The turbine blade is the most important component in the heavy-duty gas turbine. The common fatigue failures of the blade include the thermal fatigue and mechanical fatigue. Firstly, the finite element simulation of the blade is carried out in the working condition including the centrifugal load, high frequency vibration load and thermal load. According to the simulation results of the combined load, the stress distribution of the blade body is reasonable in the working condition load; the stress level on the blade suction surface is higher than the pressure surface; in the blade body, the maximum Von Mises stress is 699.87 MPa, and the location of the minimum fatigue life is close to the blade shroud. Above simulation results is very useful for the structural design and fatigue experiment. Secondly, the blade fatigue experiment is realized by building a thermo-mechanical combined fatigue experiment system. The stress and thermo-mechanical fatigue life characteristic are both analyzed with this experiment system. Through the dynamic stress experiment under the high and low cycle combined load, the stress-time history in the blade body is obtained; through the thermo-mechanical fatigue experiment, the fatigue crack of the blade first appears in the middle of the blade exhaust side. Based on these experiment results, the dynamic stress experiment data and the combined fatigue failure mode are obtained. Lastly, a nonlinear Gauss fitting expression between the fatigue life cycle number and the vibration frequency of the high cycle load is given for the fatigue life prediction. These results are significant for the blade fatigue failure in the future.

[1]  E. Hajjari,et al.  Failure Assessment of the First Stage Blade of a Gas Turbine Engine , 2017, Transactions of the Indian Institute of Metals.

[2]  Robert L. Amaro,et al.  Thermomechanical fatigue and bithermal–thermomechanical fatigue of a nickel-base single crystal superalloy , 2012 .

[3]  Yeon-Sun Choi,et al.  Investigation of blade failure in a gas turbine , 2010 .

[4]  Weiwen Peng,et al.  Probabilistic Physics of Failure-based framework for fatigue life prediction of aircraft gas turbine discs under uncertainty , 2016, Reliab. Eng. Syst. Saf..

[5]  Dianyin Hu,et al.  Thermo-Mechanical Fatigue Experiments of Single Crystal Hollow Turbine Blades , 2012 .

[7]  Kais Ammar,et al.  Multiaxial high-cycle fatigue criteria and life prediction : Application to gas turbine blade , 2016 .

[9]  B. S. Adair.  Characterization and modeling of thermo-mechanical fatigue crack growth in a single crystal superalloy , 2013 .

[10]  Chen Dong,et al.  Failure analysis of the 1st stage blades in gas turbine engine , 2013 .

[11]  M I Wood.  Gas turbine hot section components: The challenge of ‘residual life’ assessment , 2000 .

[13]  A. Weidner,et al.  Small-scale specimen testing for fatigue life assessment of service-exposed industrial gas turbine blades , 2016 .

[14]  Alaaeldin H. Mustafa.  Characterization of Failed First-Stage Turbine Blade Cooling Passage of Gas Turbine Engine , 2015, Journal of Failure Analysis and Prevention.

[15]  Esmaeil Poursaeidi,et al.  Failure analysis of a second stage blade in a gas turbine engine , 2008 .

[16]  Tord Kjellstrom,et al.  Climate change and Occupational Health and Safety in a temperate climate: potential impacts and research priorities in Quebec, Canada. , 2013, Industrial health.

[17]  J. Xu,et al.  Tensile and bending thermo-mechanical fatigue testing on cylindrical and flat specimens of CMSX-4 for design of turbine blades , 2008 .

[18]  Uwe Gampe,et al.  Advancement of Experimental Methods and Cailletaud Material Model for Life Prediction of Gas Turbine Blades Exposed to Combined Cycle Fatigue , 2012 .

[19]  Nie Jing-xu.  Experimental study on fatigue curve law of turbine blade under combined high and low cycle loading , 2011 .

[20]  Lianshan Lin,et al.  Investigation on Material's Fatigue Property Variation Among Different Regions of Directional Solidification Turbine Blades—Part I: Fatigue Tests on Full Scale Blades , 2014 .

[21]  I. Rychlik.  A new definition of the rainflow cycle counting method , 1987 .