13th International Conference on Fracture June 16–21, 2013, Beijing, China -5The value of a/ R1 is increased from 0.1 to 1.6 by 0.1 while the others are fixed, K1 can be modified as K2=K1*g( a/ R1),where g( a/ R1)=-0.1285*( a/ R1) 2+0.3059*( a/ R1)+0.8228 (13) The value of R2/ R1 is increased from 1.5 to 3 by 0.1 while the others are fixed, K2 can be modified as K3=K2*f( R2/ R1), where f( R2/ R1)=-0.1654*( R2/ R1) 4+1.6326*( R2/ R1) 3-6.0293*( R2/ R1) 2+9.9046*( R2/ R1)-5.1399 (14) The value of R1 is increased from 5 to 20 by 1 while the others are fixed, the function h( R1) can be obtained as h( R1)= 0.99, it is obvious that the effect of R1 on SIF is less than the other parameters. Finally we can obtain the modified straight attachment lug’s SIF equation as K=K3*h( R1), the SIF equation of straight lug (Figure 10) is obtained as blows. a F K ⋅ = ⋅ ⋅ π σ . (15) Where t P 2c =σ , (16) 2 1 R R c= − , (17) r fw ar f f f F ⋅ ⋅ = , (18) ( ( ) ) / 0.6762 0.8734 / 0.3246 2 1 0.3857 0.31711 1.971 1.98 1.33734 1 1 2 + + + ⋅ ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ + ⋅ = R a R a R R far , (19) ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ − + ⋅ = a R a R ffw 2 1 2 2 2 sec π , (20) ⎟ ⎟ ⎠ ⎞ ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ ⋅ ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ ⋅ ⎜ ⎜ ⎝ ⎛ ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ ⋅ ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ ⋅ = -5.1399 +9.9046 -6.0293 +1.6326 -0.1654 1 2 2 1 2 3 1 2 4 1 2 R R R R R R R R fr . (21) Scope of application： 1.6 0.1 1 ≤ ≤ R a , 3 1.5 1 2 ≤ ≤ R R , 20 5 1 ≤ ≤ R . In the same way, considering the load degrees β additionally, the SIF equation of the straight attachment lugs subjected to oblique pin-load less than 45 degrees can be obtained as below. a F K ⋅ = ⋅ ⋅ π σ (22) where t P 2c =σ , (23) 2 1 R R c= − , (24) rr fw ar ar f f f f f F ⋅ ⋅ ′ ⋅ ⋅ = β , (25) 1.05 0.0092469 10 8.4026 10 -3.7107 2 -5 3 -6 ⋅ + ⋅ + × ⋅ + × = β β β βf , (26) ( ) ( ) / ) 0.6762 0.8734/(0.3246 2 1 / 0.3857 0.31711 1.971 1.98 1 1.33734 1 1 2 + + + ⋅ + ⋅ = R a R a r R far , (27) 0.94853 0.067224 -0.063305 1 2 1 ⋅ + ⎟⎟ + ⎠ ⎞ ⎜⎜ ⎝ ⎛ ⋅ ′ = R a R a far , (28)
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