MTS Series 215 Rotary Actuator - Manual (Page 45)

Test Setup Using No Flexures
Series 215 Rotary Actuator Product Manual Operation 45
The value of 862 lbf is the side load (P) imposed on the test specimen and
actuator by base plate twist.
Calculate bending
moment
Calculate the bending moment (M) on the test specimen with no flexures
installed by using the following formula:
The value of 4310 lbf-in. is the bending moment exerted on the actuator shaft and
specimen.
For this example, P = 862 or 12% of side load capacity, and M = 4310 or 10% of
bending moment capacity. The sum is less than 100% at capacity, so flexures are
not necessary.
Calculate specimen
stress
Calculate S
B
as the final step:
The value 5488 psi represents the amount of stress experienced by the specimen
under test. Typically, in a torsion test, stress caused by reaction base or T-slot
table twist should be zero or as close to zero as possible. In the sample
calculation, the excessive specimen stress loading introduces unfavorable loads