Torsion Spring Creep
Torsion Spring Creep
(OP)
Hello Forum,
I'm using a rectangular wire torsion spring in a safety device to indicate applied torque. The assembly environment is outdoors and cycles in lifetime < 500.
min tensile strength (not min yield) = 256 ksi
max design stress = 167 ksi
preload stress = 110 ksi
I just wanted to verify some things I've heard with the bright people on this forum.
1. Creep (relaxation) for torsion springs <5%
2. Max design stress should be < 75% of min Tensile stress
Thank you
I'm using a rectangular wire torsion spring in a safety device to indicate applied torque. The assembly environment is outdoors and cycles in lifetime < 500.
min tensile strength (not min yield) = 256 ksi
max design stress = 167 ksi
preload stress = 110 ksi
I just wanted to verify some things I've heard with the bright people on this forum.
1. Creep (relaxation) for torsion springs <5%
2. Max design stress should be < 75% of min Tensile stress
Thank you





RE: Torsion Spring Creep
Provided the ratio of mean coil dia to wire dia is less than 8 then 75% of UTS as a design stress is used particularly if its a spring that operates only infrequently.
I would use a design stress of abou 40-50% personally.
Creep will depend on material used and whether its at an elevated temperature, at room temp your 5% is reasonable.
desertfox