Part (a) of the figure below shows a knuckle (rotatable) joint with a pin inside it....

 

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Part (a) of the figure below shows a knuckle (rotatable) joint with a pin inside it. It is subject to a fluctuating load F varying between 0 N and 8000 N in tension. The loading on the pin is modeled as a concentrated force as shown in part (b) of the figure (Free-body-diagram). The shaft is made from AISI 1030 hot-rolled steel that was machined to its final diameter. The fatigue stress concentration factor is 1.6 a) By considering the stresses at the cross-section A, determine: 1) The pin diameter which will provide a factor of safety of 1.8 guarding against yielding [5 marks] 2) The endurance limit [3 marks] b) For the pin diameter found in part 1), calculate the factor of safety guarding against fatigue using: 3) Morrow fatigue failure criteria [3 marks] 4) Gerber fatigue failure criteria [3 marks] 5) ASME-elliptic fatigue failure criteria [3 marks] 6) Smith-Watson-Topper failure criteria [3 marks] -10- -20- -10- Dimensions in mm F/2 F A F/2 Part (a) of the figure below shows a knuckle (rotatable) joint with a pin inside it. It is subject to a fluctuating load F varying between 0 N and 8000 N in tension. The loading on the pin is modeled as a concentrated force as shown in part (b) of the figure (Free-body-diagram). The shaft is made from AISI 1030 hot-rolled steel that was machined to its final diameter. The fatigue stress concentration factor is 1.6 a) By considering the stresses at the cross-section A, determine: 1) The pin diameter which will provide a factor of safety of 1.8 guarding against yielding [5 marks] 2) The endurance limit [3 marks] b) For the pin diameter found in part 1), calculate the factor of safety guarding against fatigue using: 3) Morrow fatigue failure criteria [3 marks] 4) Gerber fatigue failure criteria [3 marks] 5) ASME-elliptic fatigue failure criteria [3 marks] 6) Smith-Watson-Topper failure criteria [3 marks] -10- -20- -10- Dimensions in mm F/2 F A F/2