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1 – 10 of 255Zhixun Wen, Naixian Hou, Baizhi Wang and Zhufeng Yue
The purpose of this paper is to found a life model for the single crystal (SC) turbine blade based on the rate‐dependent crystallographic plasticity theory.
Abstract
Purpose
The purpose of this paper is to found a life model for the single crystal (SC) turbine blade based on the rate‐dependent crystallographic plasticity theory.
Design/methodology/approach
This life model has taken into consideration the creep and fatigue damages by the linear accumulation theory. A SC blade was taken from an aero‐engine, which had worked for 1,000 hours, as the illustration to validate the life model.
Findings
The crystallographic life model has a good prediction to the life and damage of the SC turbine blade. In the mean time, the micro damage study of the miniature specimens showed that creep damage has more serious influence on the material performance in the blade body but it is fatigue damage in the blade rabbet.
Originality/value
The life model can reflect the crystalline slip and deformation and crystallographic orientation of nickel‐based SC superalloys.
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Zhenwei Li, Zhixun Wen, Cheng Wang, Ying Dai and Peng Fei He
This paper aims to provide SIF calculation method for engineering application.
Abstract
Purpose
This paper aims to provide SIF calculation method for engineering application.
Design/methodology/approach
In this paper, the stress intensity factors (SIFs) calculation method is applied to the anisotropic Ni-based single crystal film cooling holes (FCHs) structure.
Findings
Based on contour integral, the anisotropic SIFs analysis finite element method (FEM) in Ni-based single crystal is proposed. The applicability and mesh independence of the method is assessed by comparing the calculated SIFs using mode of plate with an edge crack. Anisotropic SIFs can be calculated with excellent accuracy using the finite element contour integral approach. Then, the effect of crystal orientation and FCHs interference on the anisotropic SIFs is clarified. The SIFs of FCH edge crack in the [011] orientated Ni-based single crystal increases faster than the other two orientations. And the SIF of horizontal interference FCHs edge crack is also larger than that of the inclined interference one.
Originality/value
The SIFs of the FCH edge crack in the turbine air-cooled blade are innovatively computed using the sub-model method. Both the Mode I and II SIFs of FCHs edge crack in blade increase with crack growing.
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Describes the evolution in manufacture of jet engine turbine blades from wrought steel to directional solidification and single crystal growth. Reports on SCORPIO, the single…
Abstract
Describes the evolution in manufacture of jet engine turbine blades from wrought steel to directional solidification and single crystal growth. Reports on SCORPIO, the single crystal orientation rapid processing and interpretation operation, developed by Rolls‐Royce for blade inspection to ensure that each is formed from a single crystal grain with the correct orientation. Also reports the improvement in performance that has been achieved in blade performance.
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The purpose of this paper is to evaluate the effect of film cooling holes on the vibration characteristics of a turbine blade, and provide the design basis for the blade, which…
Abstract
Purpose
The purpose of this paper is to evaluate the effect of film cooling holes on the vibration characteristics of a turbine blade, and provide the design basis for the blade, which may reduce computing costs.
Design/methodology/approach
Modal analysis of the blades with and without film cooling holes is performed to evaluate the effect of film cooling holes on its natural frequency. Harmonic analysis of the blade is performed to calculate the stress concentration factors of film cooling holes for different modes.
Findings
The frequency differences between two blades with and without film cooling holes are insignificant, while the differences of the vibration stress cannot be neglected. For the first three modes of the blades, the stress concentration factor is sensitive to the hole’s shape and position on the blade. With the help of the stress concentration factor defined in this work, the concentration of stresses induced by different film cooling holes can be accurately described when evaluating HCF life of the turbine blade.
Originality/value
The effect of film cooling holes on a turbine blade's natural frequencies was confirmed to be insignificant and the stress concentration factors around the holes are calculated. Therefore, the simplified model of the blade without film cooling holes can be used to evaluate the natural frequencies and vibration stress, which saves a lot of time and cost.
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Xing Ai, Shuaishuai Wang, Fenghua Luo, Haiqing Pei and Zhenwei Li
The purpose of this study is to describe the mechanism of single-crystal high-temperature creep deformation, predict the creep life more accurately and study the creep…
Abstract
Purpose
The purpose of this study is to describe the mechanism of single-crystal high-temperature creep deformation, predict the creep life more accurately and study the creep constitutive and lifetime models with microstructure evolution.
Design/methodology/approach
The mechanical properties of nickel-based single-crystal superalloy are closely related to the γ' phase. Creep tests under four different temperature and stress conditions were carried out. The relationship between creep temperature, stress and life is fitted by numerical method, and the creep activation energy is obtained. The creep fracture surface, morphology and evolution of strengthening phase (γ') and matrix phase (γ) during different creep periods were observed by scanning electron microscope. With the increase of creep temperature, the rafting time is advanced. The detailed morphology and evolution of dislocations were observed by transmission electron microscope (TEM).
Findings
With the increase of creep temperature, the rafting time is advanced. The detailed morphology and evolution of dislocations were observed by TEM. Dislocations are mainly concentrated in the γ channel phase, especially at high temperature and low stress.
Originality/value
A creep constitutive model based on the evolution of γ' phase size and γ channel width was proposed. Compared with the experimental results, the predicted creep life is within 1.4 times error dispersion band.
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OPERATING to increasingly severe noise and NOx emission levels and at the lowest Specific Fuel Consumption (SFC) attainable, current turbofan engines represent considerable…
Abstract
OPERATING to increasingly severe noise and NOx emission levels and at the lowest Specific Fuel Consumption (SFC) attainable, current turbofan engines represent considerable advances in all respects on powerplants of only a few years ago. Nevertheless, the demand for even larger engines has meant that the major manufacturers are making considerable efforts to develop operating cycles and improved components to attain optimum performance for the foreseeable future.
Furnaces have been used by man since he discovered fire, which he contained in certain types of earth and stones. In the early metal age man found a material more workable than…
Abstract
Furnaces have been used by man since he discovered fire, which he contained in certain types of earth and stones. In the early metal age man found a material more workable than the brittle flint tools and brittle furnace materials he had used.
Mr. Derek Kingsbury, 55, has been appointed group chief executive of Fairey Holdings with effect from April 5 and chairman of the group subsidiaries, Fairey Automation, Fairey…
Abstract
Mr. Derek Kingsbury, 55, has been appointed group chief executive of Fairey Holdings with effect from April 5 and chairman of the group subsidiaries, Fairey Automation, Fairey Engineering, Fairey Hydraulics, Fairey Marine, Fairey Nuclear, Faircy Winches and the Fairey Filtration Division. He is joining the Fairey group from the Dowty Group which he joined in 1976 as a director and deputy chief executive.
Guijian Xiao, Tangming Zhang, Yi He, Zihan Zheng and Jingzhe Wang
The purpose of this review is to comprehensively consider the material properties and processing of additive titanium alloy and provide a new perspective for the robotic grinding…
Abstract
Purpose
The purpose of this review is to comprehensively consider the material properties and processing of additive titanium alloy and provide a new perspective for the robotic grinding and polishing of additive titanium alloy blades to ensure the surface integrity and machining accuracy of the blades.
Design/methodology/approach
At present, robot grinding and polishing are mainstream processing methods in blade automatic processing. This review systematically summarizes the processing characteristics and processing methods of additive manufacturing (AM) titanium alloy blades. On the one hand, the unique manufacturing process and thermal effect of AM have created the unique processing characteristics of additive titanium alloy blades. On the other hand, the robot grinding and polishing process needs to incorporate the material removal model into the traditional processing flow according to the processing characteristics of the additive titanium alloy.
Findings
Robot belt grinding can solve the processing problem of additive titanium alloy blades. The complex surface of the blade generates a robot grinding trajectory through trajectory planning. The trajectory planning of the robot profoundly affects the machining accuracy and surface quality of the blade. Subsequent research is needed to solve the problems of high machining accuracy of blade profiles, complex surface material removal models and uneven distribution of blade machining allowance. In the process parameters of the robot, the grinding parameters, trajectory planning and error compensation affect the surface quality of the blade through the material removal method, grinding force and grinding temperature. The machining accuracy of the blade surface is affected by robot vibration and stiffness.
Originality/value
This review systematically summarizes the processing characteristics and processing methods of aviation titanium alloy blades manufactured by AM. Combined with the material properties of additive titanium alloy, it provides a new idea for robot grinding and polishing of aviation titanium alloy blades manufactured by AM.
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Zhixun Wen, Fei Li and Ming Li
The purpose of this paper is to apply the concept of equivalent initial flaw size (EIFS) to the anisotropic nickel-based single crystal (SX) material, and to predict the fatigue…
Abstract
Purpose
The purpose of this paper is to apply the concept of equivalent initial flaw size (EIFS) to the anisotropic nickel-based single crystal (SX) material, and to predict the fatigue life on this basis. The crack propagation law of SX material at different temperatures and the weak correlation of EIFS values verification under different loading conditions are also investigated.
Design/methodology/approach
A three-parameter time to crack initial (TTCI) method with multiple reference crack lengths under different loading conditions is established, which include the TTCI backstepping method and EIFS fitting method. Subsequently, the optimized EIFS distribution is obtained based on the random crack propagation rate and maximum likelihood estimation of median fatigue life. Then, an effective driving force based on anisotropic and mixed crack propagation mode is proposed to describe the crack propagation rate in the small crack stage. Finally, the fatigue life of three different temperature ESE(T) standard specimens is predicted based on the EIFS values under different survival rates.
Findings
The optimized EIFS distribution based on EIFS fitting - maximum likelihood estimation (MLE) method has the highest accuracy in predicting the total fatigue life, with the range of EIFS values being about [0.0028, 0.0875] (mm), and the mean value of EIFS being 0.0506 mm. The error between the predicted fatigue life based on the crack propagation rate and EIFS distribution for survival rates ranges from 5% to 95% and the experimental life is within two times dispersion band.
Originality/value
This paper systematically proposes a new anisotropic material EIFS prediction method, establishing a framework for predicting the fatigue life of SX material at different temperatures using fracture mechanics to avoid inaccurate anisotropic constitutive models and fatigue damage accumulation theory.
Details