PSI - Issue 10

D.G. Ntritsos et al. / Procedia Structural Integrity 10 (2018) 288–294 D.G. Ntritsos et al. / Structural Integrity Procedia 00 (2018) 000 – 000

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The dynamic loading stress concentration factor K f is derived from Eq.(3):

(3)

1 ( 1)    f t K q K

where the notch sensitivity factor q for CK45 and the given geometry is 0.68 for according to Peterson (1953). Substituting K t with K f in Eq.(2) the fatigue stress is obtained as:

32 ( 2 )  M π D h

 σ K

(4)

D f

3

3.2. Stress concentration factor of keyway

For keyways the fatigue concentration factor K f is given for profiled keyway, according to Madayag (1969), equal to 1.6. According to Fessler et al. (1969), the K t factor for keyways is equal to 2.2 which gives K f =1.48 applying Eq.(3) for q=0.4 for CK45 and the keyway geometry. Subsequently the and stresses are calculated as follows

M

32

(5)

( ) σ K  s D

t f

( )

3

πD

3.3. Numerical analysis

Since there are no literature references for stress concentration in areas with conjuring notches, the Finite Element Analyses were launched. The purpose of the Numerical Approach is to determine the maximum static bending stresses due to the lack of a mathematical model that adequately specimen behavior. The mathematical model of the specimens was created with Inventor Autodesk solid modeler and simulated using finite element analysis Nastran solver for the estimation of the maximum stresses, typical results shown in Fig.3a.

ax: 757.8

Max: 757.8

Fig. 3. (a) Typical FEA results for double notched shaft; (b) plan view of stress concentration regions.