PSI - Issue 2_B

R. Seddik et al. / Procedia Structural Integrity 2 (2016) 2182–2189 Seddik. R/ Structural Integrity Procedia 00 (2016) 000–000

2184

3

    

pl                   0   

m







   

  

  

T T 

 

pl n

room

(1)

A B( ) 1 CLn  

1

   



melt T T 

 

Where A is the yield stress, B is the coefficient of strain hardening, n is the strain hardening exponent, C is the strain rate sensitivity coefficient, T melt is the melting temperature, and m the thermal softening coefficient . Static FEM analysis has been adopted using energy equivalence between a dynamic impact and static indentation Johnson (1983). During the impact, it is assumed that the difference between the incident and the restored kinetic energies multiplied by the efficiency of the impact i K W. Johson (1972) is equal to the plastic dissipated energy. For the case of normal impact ( 90    ), we have the following relation Cao et al. (1995):

2 i 1 w K w mV (1 e )K 2      p i i r

(2)

Where w   is the difference between the incident and the restored kinetic energies, k is the efficiency of shock, m is the mass of the shot particle, i V is the speed of the incident shot particle, r e is the coefficient of restitution shot/material and  the angle of impingement.

Fig. 2. Applied thermo-mechanical loading

Assumptions The principal assumptions employed in the shot peening FE model are:  The shot particles are considered rigid spheres of uniform radius.  The shot is supposed impacting the target surface at normal incidence

90    .

 The area density of impact is considered uniform.