Bimaterial turbine blade damper
A turbine blade damper includes an outer part for damping vibration of the blade airfoil and a supporting inner part. The two parts are formed of different materials for the different performance required thereof in the blade.
1. A damper for a turbine blade including a hollow airfoil joined at a platform to a supporting dovetail, said damper comprising:
an outer part sized to extend inside said airfoil from said platform;
an inner part affixed to a proximal end of said outer part and extending therebelow for being retained in said blade below said platform; and
said parts being formed of different materials for effecting frictional damping inside said airfoil and tensile support below said platform.
2. A damper according to claim 1 wherein said outer part comprises a first material having a greater frictional wear resistance than a different second material in said inner part.
3. A damper according to claim 2 wherein said second material in said inner part has a greater tensile strength than said first material in said outer part.
4. A damper according to claim 3 wherein said outer part is generally straight, and said inner part includes a bend.
5. A damper according to claim 4 wherein said outer and inner parts are coextensive and terminate at a mounting block at the proximal end of said inner part.
6. A damper according to claim 5 wherein said inner part bends laterally from said outer part below a joint therewith.
7. A damper according to claim 6 wherein said joint is disposed closer to said block than to the distal end of the said outer part.
8. A damper according to claim 4 further comprising a pair of said outer parts affixed at corresponding joints to a common fork in said inner part.
9. A damper according to claim 8 wherein said inner part further includes a stem integrally joined to said fork.
10. A damper according to claim 8 wherein said fork is stemless.
11. A turbine blade damper comprising a longitudinally elongate outer part formed of a first material affixed coextensively end-to-end to a longitudinally shorter inner part formed of a different second material.
12. A damper according to claim 11 wherein said outer part includes longitudinally opposite distal and proximal ends, and said proximal end is affixed to a distal end of said inner part at an integral joint therewith.
13. A damper according to claim 12 wherein said first material in said outer part has a greater frictional wear resistance than said second material in said inner part.
14. A damper according to claim 13 wherein said second material in said inner part has a greater tensile strength than said first material in said outer part.
15. A damper according to claim 14 wherein said outer part is generally straight, and said inner part includes a bend.
16. A damper according to claim 15 wherein said inner part terminates at a mounting block at the proximal end thereof.
17. A damper according to claim 16 wherein said inner part bends laterally from said outer part below said joint.
18. A damper according to claim 14 further comprising a pair of said outer parts affixed to a common inner part.
19. A damper according to claim 18 wherein said inner part includes a fork affixed to said pair of outer parts at corresponding joints between said first and second materials.
20. A damper according to claim 19 wherein said inner part further includes a stem integrally joined to said fork.
21. A damper according to claim 19 wherein said fork is stemless.
22. A damper according to claim 19 wherein said fork has straight legs joined to said outer parts.
23. A damper according to claim 19 wherein said fork is bulbous.
24. A method of making said damper according to claim 14 comprising:
forming said outer part in said first material;
forming said inner part in said second material; and
bonding said outer and inner parts at said integral joint therebetween to form a unitary damper.
25. A method according to claim 24 further comprising:
firstly casting said parts and secondly bonding together said cast parts; and
machining excess material from said parts to form said damper.
26. A method according to claim 25 further comprising hot forming said bonded parts to bend said inner part.
27. A turbine blade stick damper comprising an outer rod joined longitudinally end-to-end with a supporting inner shank with correspondingly different adjoining materials.