Dynamometer

Evaluation

Background: A Dyno test was performed.

A Dynamometer shaft as shown in the picture has a torque of 15 inch-pounds.

The factor of safety (FOS) and torsion stress on the shaft were unknown (FOS = yield strength/applied stress)

Test to Modeling Procedure

Design (Replicate)

the Dynamometer

shaft using CAD.

Applied ground (hold)

boundary condition on

drum and applied the

measured torque to

get simulation results

The results

of the

stress test

showed that

most of the

stress was

on the thin

shaft and

was

torsional in

nature (not

bending).

Model Results

Model results

The shaft

had a

factor of

safety of

152.39

(w/o the

key way

cut)

Material Change and Re-simulate The material

was changed

to 6061 Alloy

Aluminum

The New

factor of

safety was

13.55

(instead of

152!)

Design Change and Re-simulate

The Key Hole was put into the part.

The final factor of safety was 8.73 with aluminum. (Note with steel the FOS was 98.13)

Conclusion

Modeling on CAD is a very accurate and efficient

way to get FOS and stress results

Adding the key made the shaft significantly

weaker by raising the stress level in the notch.

Alloy steel is stronger than 6061 Aluminum.