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Relaxation
- The opposite of stress or tension

Remove set - The process of closing to a solid height a compression spring which has been coiled longer than the desired finished length, so as to increase the elastic limit.

Set - Permanent distortion which occurs when a spring is stressed beyond the elastic limit of the material.

Shaft - This parameter describes the maximum diameter of spring shaft in industrial applications

Shear modulus G - Is defined as the ratio of shear stress to the shear strain.

Shear strain - Is the components of a strain at a point that produce changes in shape of a body (distortion) without a volumetric change

Shear stress - Is caused when a force is applied to produce a sliding failure of a material along a plane that is parallel to the direction of the applied force e.g. when cutting paper with scissors or a steel bolt with a bolt cutter.

Shot peening - A cold-working process in which the material surface is peened to induce compressive stresses and thereby improve fatigue life.

Shot peening - Is a process used to modify mechanical properties of metals, It entails impacting a surface with shot (round metallic particles) with force sufficient to create dimples and with enough shot that those dimples overlap

SI - International System of Units. SI is sometimes referred to as the metric system.

Slenderness ratio - Ratio of spring length to mean coil diameter.

Solid height - Length of a compression spring when under sufficient load to bring all coils into contact with adjacent coils.

Spiral springs - Formed of flat strip wound in the form of a spiral (clock or power springs), such springs are loaded by torque about an axis normal to the plane of the spiral.

Spring index - Ratio of mean coil diameter to wire diameter.

Spring rate (R) - This parameter determines spring's resistance, while it is working. It is measured in 1 DaN/mm = 10 N/mm.

Squared ends = Closed ends.

Squareness of ends - Angular deviation between the axis o a compression spring and a normal to the plane of the other ends.

Stiffness - Is the resistance of an elastic body to deflection by an applied force. Stiffness is typically measured in Newton’s per meter.

Strain - Deformation caused by the action of stress on a solid material. Strain therefore expresses itself as a change in size and/or shape.

Stress - The force that is exerted on a solid material from the outside. The SI unit for stress is the Pascal (symbol Pa); in US Customary units, stress is expressed in pounds per square inch (PSI). See also"

Stress range - The difference in operating stresses at minimum and maximum loads.

Tensile strength (Rm) - Te maximum amount of stretching stress a material can withstand before it tears. Materials rated at a high tensile strength are durable and difficult to tear.

Tensile stress - Is a loading that tends to produce stretching on a material by the application of axially directed pulling forces. Materials can withstand some tensile loading, but if enough force is applied, they will eventually break into two pa

Torque - A twisting action in torsion springs which tends to produce rotation, equal to the load multiplied by the distance (or moment arm) from the load to the axis of the spring body.

Torsion-bar Springs - These are essentially straight bars under torsion, the load usually being applied through splined ends.

Total number of coils - Number of active coils plus the coils forming the ends.

Yield point - See Yield strength

Yield strength - The amount of strain that a material can undergo before moving from elastic deformation into plastic deformation. The stress felt by a material given a certain strain is defined by linear relationship, with a slope defined by the m

Young's modulus - Is a measure of the stiffness of a given material, That is how hard it is to stretch chemical bonds that bind the atoms of a material together