# What is meaning of Elastic Stretch of wire?

Elastic stretch is the ability of the individual wires to elongate under load due to their elastic properties. Providing the rope is not subjected to loads beyond its elastic limit, the rope will return to its original length after removal of the load – original, that is, from whatever point in permanent stretch had been attained earlier.

The formula for calculating the elastic stretch requires the knowledge of mainly four aspects.

• The load on the rope.
• The working length of the rope,
• The cross-sectional area of the rope, and
• Modulus of elasticity of wire.

Elastic stretch (mm) = (WL/ AE)

Where, W is the load on the rope in kg f
L is the length of the rope under load in mm
A is the metallic cross-sectional area of the rope in mm2
E is the modulus of elasticity of the rope in kgf/mm2.

###### Note :

For 16mm dia. wire rope – Elastic stretch under load, expressed as a percentage of the length of the wire under load, will be:-

Wire
6 x 12 = Load (in tonne f)/6 — % stretch
6 x 19 = Load (in tonne f)/lO — % stretch
6 x 24 = Load (in tonne f)/8 — % stretch.

For 18mm dia. wire rope –  Elastic stretch under load, expressed as a percentage of the length of the wire under load, will be:-

Wire
6 x 12 = Load (in tonne f)/7.7 – % stretch
6 x 19 = Load (in tonne f)/l3.0 — % stretch
6 x 24 = Load (in tonne f)/l0.4 — % stretch 