Answer:
Explanation:
We have the following data:
Mass = 2 kg
R.V = 10 Grms
g = 9.8 m/s^2
edge of cube = 10 cm = 0.1 m
Assume that the force is divided between the four bolts, the restraint force will be:
Total Restraint Force = 196.2
Force on each bolt:
Assume the bolt material as metric class 4.6 with:
Proof strength = 225 MPa
Tensile strength = 400 MPa
Yield strength = 240 MPa
The load can be either horizontal or vertical, thus we check for tension and shear.
<u>Tenison:</u>
Assume that the load is on the bolts.
Maximum and Minimum bolt load is =
<u>Stress:</u>
<u>(</u>where stress concentration factor = 2.2)
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Mean stress:
Stress amplitude:
<u>Fatigue Strength:</u>
The rotating beam fatigue strength is:
Assume machined thread, the surface condition factor will be:
Size factor:
Loading factor:
Temperature factor:
Reliability factor:
Fatigue strength for infinite cycles:
Using modified Goodman relation with assumed factor of safety:
Shear Failure:
Axial load of the bolt is 49.05 N.
Principal stress are:
We know,
Using endurance strength values:
The bolt is safe in shear.
We will need to check:
1. Natural frequency of supporting system
2. Range of excitation frequencies