Shim for a turbomachine blade

Abstract

A shim ( 20 ) for a turbomachine blade ( 14 ), the shim comprising two branches ( 20 A) for coming against bearing surfaces ( 16 A) of the blade rotor ( 16 ), and a base part ( 20 B) interconnecting the branches. The shim presents, at least in its branches ( 20 A), a multilayer structure having at least three layers ( 31, 32, 33 ) that are fastened to one another and superposed in the following order: a first layer ( 31 ) of a first material; a second layer ( 32 ) of a second material; and a third layer ( 33 ) of a third material that is optionally different from the first material, said first and third materials presenting respective first and third Young's moduluses of values E and E′ at any arbitrary operating temperature in the operating temperature range of the shim, and said second material presenting a second Young's modulus of value lying in the range E/20 to E/5 and in the range E′/20 to E′/5 at said operating temperature.

1 . A shim for a turbomachine blade, the shim comprising two branches for coming against bearing surfaces of the blade rotor, and a base part interconnecting the branches, the shim presenting, at least in its branches, a multilayer structure having at least three layers that are fastened to one another and superposed in the following order: a first layer of a first material; a second layer of a second material; and a third layer of a third material that is optionally different from the first material, said first and third materials presenting respective first and third Young's moduluses of values E and E′ at any arbitrary operating temperature in the operating temperature range of the shim, and said second material presenting a second Young's modulus of value lying in the range E/20 to E/5 and in the range E′/20 to E′/5 at said operating temperature. 
   
   
       2 . A shim according to  claim 1 , in which said first and third materials are identical. 
   
   
       3 . A shim according to  claim 1 , in which said first and third materials are metal alloys or organic matrix composite materials, while the second material is non-metallic. 
   
   
       4 . A shim according to  claims 1 , in which said second material presents viscoelastic behavior in the operating temperature range of the shim. 
   
   
       5 . A shim according to  claim 1 , in which said first, second, and third layers also extend in the base part of the shim. 
   
   
       6 . A turbomachine rotor assembly comprising: a rotor disk presenting slots in its outer periphery; blades fastened by their roots in said slots; and shims according to any preceding claim, each branch of each shim being disposed between the bearing surface of a blade root and the corresponding bearing surface of the disk. 
   
   
       7 . A turbomachine rotor assembly according to  claim 6 , in which the base part of each shim extends under each blade root. 
   
   
       8 . A turbomachine rotor assembly according to  claim 6 , in which the base part of each shim extends over the outer periphery of the disk, between two adjacent slots. 
   
   
       9 . A turbomachine comprising a rotor assembly according to  claim 6 .