Based on the nonlinear continuum damage model （CDM） developed by Chaboehe, a modified model for high cycle fatigue of TC4 alloy was proposed. Unsymmetrical cycle fatigue tests were conducted on rod specimens at room...Based on the nonlinear continuum damage model （CDM） developed by Chaboehe, a modified model for high cycle fatigue of TC4 alloy was proposed. Unsymmetrical cycle fatigue tests were conducted on rod specimens at room temperature. Then the material parameters needed in the CDM were obtained by the fatigue tests, and the stress distribution of the specimen was calculated by FE method. Compared with the linear damage model （LDM）, the dam- age results and the life prediction of the CDM show a better agreement with the test and they are more precise than the LDM. By applying the CDM developed in this study to the life prediction of aeroengine blades, it is concluded that the root is the most dangerous region of the whole blade and the shortest life is 58 211 cycles. Finally, the Cox propor- tional hazard model of survival analysis was applied to the analysis of the fatigue reliability. The Cox model takes the covariates into consideration, which include diameter, weight, mean stress and tensile strength. The result shows that the mean stress is the only factor that accelerates the fracture process.展开更多
Due to the excellent performance of carbon fiber-reinforced polymer(CFRP),they are widely used in the world’s aircraft manufacturing industry,including aeroengine blades.During aircraft service,engine blades are ofte...Due to the excellent performance of carbon fiber-reinforced polymer(CFRP),they are widely used in the world’s aircraft manufacturing industry,including aeroengine blades.During aircraft service,engine blades are often impacted by foreign objects such as breakstone,seriously affecting the airworthiness and safety of aircraft.Therefore,studying the impact resistance of carbon fiber composite materials is crucial for improving aircraft safety.In this paper,ABAQUS is used to establish a simulation model for impacting composite blades with breakstone.The VUMAT user subroutine is compiled to predict the damage of inner layer elements based on 3D-Hashin failure criterion and stiffness reduction scheme;cohesive elements based on the bilinear model are inserted between adjacent laminas to predict the delamination damage of the composite material.The damage initiation of cohesive elements is judged by QUADS criterion,and the damage evolution is performed using the B–K criterion of the energy method.Finally,based on the simulation results,the impact force,failure mode,and energy transformation during the impact process are analyzed.展开更多
As crucial parts of an aeroengine,blades are vulnerable to damage from long-term operation in harsh environments.The ultrasonic surface rolling process(USRP)is a novel surface treatment technique that can highly impro...As crucial parts of an aeroengine,blades are vulnerable to damage from long-term operation in harsh environments.The ultrasonic surface rolling process(USRP)is a novel surface treatment technique that can highly improve the mechanical behavior of blades.During secondary machining,the nominal blade model cannot be used for secondary machining path generation due to the deviation between the actual and nominal blades.The clamping error of the blade also affects the precision of secondary machining.This study presents a two-sided USRP(TS-USRP)machining for aeroengine blades on the basis of on-machine noncontact measurement.First,a TS-USRP machining system for blade is developed.Second,a 3D scanning system is used to obtain the point cloud of the blade,and a series of point cloud processing steps is performed.A local point cloud automatic extraction algorithm is introduced to extract the point cloud of the strengthened region of the blade.Then,the tool path is designed on the basis of the extracted point cloud.Finally,an experiment is conducted on an actual blade,with results showing that the proposed method is effective and efficient.展开更多
基金Supported by National Natural Science Foundation of China(No.60879002)Key Technologies R and D Program of Tianjin (No.10ZCKFGX03800)
文摘Based on the nonlinear continuum damage model （CDM） developed by Chaboehe, a modified model for high cycle fatigue of TC4 alloy was proposed. Unsymmetrical cycle fatigue tests were conducted on rod specimens at room temperature. Then the material parameters needed in the CDM were obtained by the fatigue tests, and the stress distribution of the specimen was calculated by FE method. Compared with the linear damage model （LDM）, the dam- age results and the life prediction of the CDM show a better agreement with the test and they are more precise than the LDM. By applying the CDM developed in this study to the life prediction of aeroengine blades, it is concluded that the root is the most dangerous region of the whole blade and the shortest life is 58 211 cycles. Finally, the Cox propor- tional hazard model of survival analysis was applied to the analysis of the fatigue reliability. The Cox model takes the covariates into consideration, which include diameter, weight, mean stress and tensile strength. The result shows that the mean stress is the only factor that accelerates the fracture process.
基金funded by Aeronautical Science Foundation of China(2019ZA057003).
文摘Due to the excellent performance of carbon fiber-reinforced polymer(CFRP),they are widely used in the world’s aircraft manufacturing industry,including aeroengine blades.During aircraft service,engine blades are often impacted by foreign objects such as breakstone,seriously affecting the airworthiness and safety of aircraft.Therefore,studying the impact resistance of carbon fiber composite materials is crucial for improving aircraft safety.In this paper,ABAQUS is used to establish a simulation model for impacting composite blades with breakstone.The VUMAT user subroutine is compiled to predict the damage of inner layer elements based on 3D-Hashin failure criterion and stiffness reduction scheme;cohesive elements based on the bilinear model are inserted between adjacent laminas to predict the delamination damage of the composite material.The damage initiation of cohesive elements is judged by QUADS criterion,and the damage evolution is performed using the B–K criterion of the energy method.Finally,based on the simulation results,the impact force,failure mode,and energy transformation during the impact process are analyzed.
基金The authors gratefully acknowledge the financial support extended by the National Natural Science Foundation of China(Grant Nos.51975214,51725503,and 51575183)the 111 Project.Zhang X C is also grateful for the support by the Major Program of the National Natural Science Foundation of Shanghai(Grant No.2019-01-07-00-02-E00068).
文摘As crucial parts of an aeroengine,blades are vulnerable to damage from long-term operation in harsh environments.The ultrasonic surface rolling process(USRP)is a novel surface treatment technique that can highly improve the mechanical behavior of blades.During secondary machining,the nominal blade model cannot be used for secondary machining path generation due to the deviation between the actual and nominal blades.The clamping error of the blade also affects the precision of secondary machining.This study presents a two-sided USRP(TS-USRP)machining for aeroengine blades on the basis of on-machine noncontact measurement.First,a TS-USRP machining system for blade is developed.Second,a 3D scanning system is used to obtain the point cloud of the blade,and a series of point cloud processing steps is performed.A local point cloud automatic extraction algorithm is introduced to extract the point cloud of the strengthened region of the blade.Then,the tool path is designed on the basis of the extracted point cloud.Finally,an experiment is conducted on an actual blade,with results showing that the proposed method is effective and efficient.
