Process for determining a remaining life for a part

Abstract

A process for determining a remaining life of a part, such as an airfoil in a gas turbine engine, comprising the steps of establishing the boundary conditions that act on the part, determining the material properties of the part, creating a 3D finite element model of the part and determining the residual stresses on the part, observing the actual part for at least one crack, and comparing the location of the crack to the residual stresses determined on the model at the crack location. If the residual stress at the crack location passes into the wall of the part beyond a predetermined length, then the part is rejected for further use.

1 . A process for determining a remaining life of a part, the process comprising the steps of:
 Establishing one or more boundary conditions for the part;   Determining the material properties of the part;   Determining residual stresses in the part;   Observing the actual part for at least one crack;   Comparing the location of at least one observed crack with the residual stresses at the crack;   Establishing a maximum level of crack propagation at the crack; and,   Rejecting the part if the residual stress at the crack is beyond the maximum level of crack propagation.   
   
   
       2 . The process for determining a remaining life of a part of claim I, and further comprising the step of:
 The step of establishing one or more boundary conditions for the part comprising establishing the temperature acting on the part, or establishing the pressure acting on the part, or establishing the loads that act on the part.   
   
   
       3 . The process for determining a remaining life of a part of  claim 1 , and further comprising the step of:
 The step of determining residual stresses in the part comprises creating a 3D finite element model of the part and applying the established boundary conditions on the part.   
   
   
       4 . The process for determining a remaining life of a part of  claim 1 , and further comprising the step of:
 The step of establishing a maximum level of crack propagation at the crack comprises determining if the crack has reached a stable size.   
   
   
       5 . The process for determining a remaining life of a part of  claim 1 , and further comprising the step of:
 The step of establishing a maximum level of crack propagation at the crack comprises determining if the crack passes through a wall of the part.   
   
   
       6 . The process for determining a remaining life of a part of  claim 1 , and further comprising the step of:
 The part is an airfoil for use in a gas turbine engine.   
   
   
       7 . The process for determining a remaining life of a part of  claim 1 , and further comprising the step of:
 Comparing the locations of a plurality of observed cracks with the residual stresses at the plurality of cracks; and,   Rejecting the part is the residual stress at a particular crack is beyond the maximum level of crack propagation.