1.  GLOSSARY

Helix angle of a spring: angle of the plane of the body coils with the horizontal.

Austenitization: heating steel to a temperature above 850°C to make it formable with less effort, and hardenable after rapid cooling. The structure of the steel at this temperature is austenite, hence the name austenitization. Hardening (≍ 850°C $\to$ ≍ 100°C) transforms this austenite into martensite, which is very hard and brittle.

B10: number of fatigue cycles for which 10% of specimens fail with a probability of 50%.

Banana (banana spring): name given to a spring with a slightly curvilinear axis, giving a resultant force in compression that is offset from its geometric axis.