Slitting

There are several names in the open literature given to the technique for measurement of residual stress by performing an incremental cut such as: crack compliance method, fracture mechanics approach, successive cracking method, slitting method, etc. The technique is similar to the compliance method for measuring crack length in a fatigue or fracture specimen where a known load is applied to a cracked specimen and the resulting strain is measured to determine the crack length. In the slitting method the crack length is known and the measured strain is employed to determine the residual stress.
The method itself involves three steps:

  • Cutting a narrow slot of progressively increasing length into a body using a notionally stress-free cutting technique (this relaxes residual stress at the cut surfaces and redistributes the residual stress field within the entire body)
  • measuring the changes in strain associated with progressive cutting at suitable locations
  • Analysing the measured data to infer the initial residual stress distribution.

 
 

 
 
 
 
 x
 y
 
 a
Crack length
 
 
Top face strain gauge
Back face strain gauge

 
Figure 4 Schematic drawing of the slitting method.