Torsion bar is machined from AISI 4130 annealed steel. The centre section of the
ID: 1860342 • Letter: T
Question
Torsion bar is machined from AISI 4130 annealed steel.
The centre section of the bar is fine turned with a diameter of D=30mm and with a drilled transverve hole of d=3mm diameter.
The mounting sections of the bar are D=50mm and the shoulder fillet radius is r=1.5mm
Find
a) Calculate the maximum allowable fully reversed torque, Tn permissible if the torsion bar must have a life in excess of 10^6 load reversals.
b) Calculate the maximum allowable fully reversed torque, T3 permissible if the torsion bar is only required to last for 10^3 load reversals.
c) In normal service , the torque condition in the bar fluctuates between values in a generally random manner, but with some observable trends as indicated in table 1. Machine usage patterns (operating loads) cause the torque to be a proportion of the T3, valve that you determined in part b.
Estimate the life of the torsion bar in normal service.
Explanation / Answer
(a) 320 N-m
(b) 160 N-m
(c) 12 days