Question

How does “surface roughness” affect the “fatigue stress endurance limit?

What is the effect of pre-setting on stresses during loading of helical compression springs?

Discuss elevated temperature effects on loading of helical compression springs

Answer 1

1.when the surface finish is poor,there are scratches and geometrical irregularities on the surface. These surface scratches serves as stress raiser and result in the stress Concentration at these scratches.

The surface finish factor takes into account the reduction in endurance limit due to variation in the surface finish between the specimen and actual components.

2.Due to pre- setting of helical spring the load carrying capacity in spring is increased.It is done by making the spring longer than needed and compressing it to it's solid height.

3.In many applications compression and expansion spring are subjected to elevated temperature at high stress which can result in relaxation or loss of load