Answer to Question #268070 in Mechanical Engineering for Amat

Question #268070

A rigid flange coupling is used to connect a 45KW 1440rpm electric motor to a centrifugal pump. The starting torque of the motor is 225% of the rated torque. There are 8 bolts and their pitch circle diameter is 150mm . The bolts are made of steel 45C8 (sigma yt 380N/mm2 ) the factor of safety is 2.5 . Determine the diameter of the bolts. Assume (sigma sy 0.577 sigma yt) . Assume that the bolts are finger tight is reamed and ground holes.

1
Expert's answer
2021-11-19T00:07:30-0500

Permissible shear stress,τ=sSyFS\tau=\frac{s_{Sy}}{FS}

=0.577sst2.5=87.7N/mm2=\frac{0.577s_{st}}{2.5}=87.7N/mm^2

Direct shear stress in bolt

P1=P2=PNumber of boltsP_1'=P_2'=\frac{P}{Number\ of\ bolts}

=451038=5625N=\frac{45*10^3}{8}=5625N

Shear area of 8 bolts=8(πd24)mm28(\frac{πd^2}{4})mm^2

P=8(πd24)τ8(\frac{πd^2}{4})*\tau

d2=4510348π87.7d^2=\frac{45*10^3*4}{8*π*87.7}

d2=81.664d^2=81.664

d=9.03mmd=9.03mm

Hence standard size of bolt is M10


Need a fast expert's response?

Submit order

and get a quick answer at the best price

for any assignment or question with DETAILED EXPLANATIONS!

Comments

No comments. Be the first!

Leave a comment