A method of imparting deep compressive residual stress to an aerofoil, the method involves determining a stress map for the aerofoil for stress generated by Foreign Object (FOD) impact, a stress map for the aerofoil of high cycle fatigue, a stress map for the aerofoil of low cycle fatigue and determ
A method of imparting deep compressive residual stress to an aerofoil, the method involves determining a stress map for the aerofoil for stress generated by Foreign Object (FOD) impact, a stress map for the aerofoil of high cycle fatigue, a stress map for the aerofoil of low cycle fatigue and determining a combined stress map by combining the stress map of FOD impact, the stress map of high cycle fatigue and the stress map of low cycle fatigue. A zone is then defined on the aerofoil from the combined stress map for receiving the deep residual compressive stress, and compressive residual stress imparted to the defined zone.
대표청구항▼
1. A method of imparting deep compressive residual stress to an aerofoil, the method comprising the steps of: a) determining a stress map for the aerofoil for stress generated by Foreign Object (FOD) impact,b) determining a stress map for the aerofoil of high cycle fatigue,c) determining a stress ma
1. A method of imparting deep compressive residual stress to an aerofoil, the method comprising the steps of: a) determining a stress map for the aerofoil for stress generated by Foreign Object (FOD) impact,b) determining a stress map for the aerofoil of high cycle fatigue,c) determining a stress map for the aerofoil of low cycle fatigue,d) determining a combined stress map by combining the stress map of FOD impact, the stress map of high cycle fatigue and the stress map of low cycle fatigue,e) defining a zone on the aerofoil from the combined stress map for receiving the deep residual compressive stress, andf) imparting compressive residual stress to the defined zone. 2. A method according to claim 1, wherein the step of determining a stress map for FOD impact includes the steps of determining the impact location of foreign objects on the aerofoil at a selected operating condition of the aerofoil and the stress imparted to the blade by the impact. 3. A method according to claim 2, wherein the selected operating condition is at takeoff. 4. A method according to claim 1, wherein the step of determining the stress map for the aerofoil of high cycle fatigue includes the steps of applying finite element analysis to the aerofoil for at least one major excitation mode of the aerofoil. 5. A method according to claim 1, wherein the step of determining the stress map for the aerofoil of high cycle fatigue includes the steps of applying finite element analysis to the aerofoil for a selected engine cyclic load. 6. A method according to claim 5, wherein the selected engine load is the acceleration to maximum take off speed. 7. A method according to claim 1, wherein the step of determining the combined stress map for the aerofoil includes the steps of applying a goal seeking algorithm to calculate the maximum stress from the LCF deflection at a given velocity or acceleration summed with the HCF deflection and FOD impact stress. 8. A method according to claim 1, wherein the step of defining a zone on the aerofoil comprises the steps of providing a first zone for higher deep residual stress (DRS) which encompasses the stressed areas on the combined stress map which exceed the material limit of the aerofoil and a second zone for lower deep residual stress which encompasses the levels of combined stress that are at 90% or more of the material limit of the aerofoil. 9. A method according to claim 8, wherein the step of defining a zone includes a third zone which blends between the higher deep residual stress zone and the lower deep residual stress zone. 10. A method according to claim 8 wherein a zone is defined for a pressure surface of an aerofoil and a zone is defined for a suction surface of an aerofoil and determining the effect of applying deep residual stress to the zones, wherein when the effect inducing twist or distortion of the aerofoil outside a predetermined threshold adjusting the zone on either or both of the pressure or suction surfaces. 11. A method according to claim 10, wherein the adjustment is selected from a group including varying the area of the zone, the spacing of the zone, and/or the depth of the zome. 12. A method according to claim 1, wherein the compressive residual stress is imparted by peening. 13. A method according to claim 12, wherein the peening is shot peening or High Intensity Shot Peening (HISP). 14. A method according to claim 12, wherein the peening is laser shock Peening. 15. A method according to claim 12, wherein the peening is cavitation or water jet peening. 16. A method according to claim 12, wherein the peening is ultrasonic peening. 17. A method according to claim 12, wherein the peening is electro shock Peening. 18. A method according to claim 12, wherein the compressive residual stress is imparted by burnishing. 19. A method according to claim 12, wherein the compressive residual stress is imparted by roller burnishing or deep cold rolling. 20. A method of imparting deep compressive residual stress to an aerofoil, the method comprising the steps of a) providing a defined zone on an aerofoil for receiving the deep residual compressive stress from a combined stress map provided from a stress map for the aerofoil for stress of Foreign Object (FOD) impact, a stress map for the aerofoil of high cycle fatigue, and a stress map for the aerofoil of low cycle fatigue, andb) imparting compressive residual stress to the defined zone.
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이 특허에 인용된 특허 (4)
Hansen Kurt L. (Cincinnati OH) Cornell Jay L. (Hamilton OH) Schilling Jan C. (Middletown OH), Hollow airfoil impact resistance improvement.
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