IBMMAE – 3- Machine Elements
1
Static & Fatigue loading
Forces, stress, resistance criteria
Figure 1 Tableau 1
One considers the cylindrical bar represented in figure 1. It is clamped in O. The bar and the arm are rigidly coupled.
A force F is applied in C.
Static loading
a. Define and determine the stress state at points A and B.
b. With the values indicated in table 1 and F=Fmax, check the static resistance of the bar and determine the safety factor
c. In the case of a hollow cylindrical bar, which maximum inner diameter could be used (here, the shear stress due to the shear load will be neglected) ?
Fluctuating load, fatigue
a. The load F is assumed to be varied sinusoïdally between Fmin et Fmax. Determine the mean and amplitude stress in A and B
b. Determine the fatigue safety factor using the Soderberg or/and Goodmann criteria.
d
40 mm
l 300 mm
a 200 mm
Fmin -1000 N Fmax 1500 N σE,Y 325 MPa σr,u 450 MPa
σD 160 MPa
bar
arm