Factors affecting
elasticity
Dr D. Arun Kumar
Assistant Professor
Department of Physical Sciences
Bannari Amman Institute of Technology
Sathyamangalam
General Objective:
• To explain the factors affecting elasticity
Specific Objective:
1. list five factors affecting the elasticity (S)
2. analyse the effect of stress and temperature on
the elastic properties (S, E)
3. identify the role of impurities, heat treatment
and metal processing (S, T)
4. illustrate the effect of crystal defects (S)
Factors affecting elasticity
Effect of stress
• Constant stress – loses elastic property even within
elastic limit.
• Loaded repeatedly or subjected to large no. of
cycle of stress – tired or ruptured.
• Elastic fatigue – loss of strength of the material
caused by repeated stress on it.
Factors affecting elasticity
Effect of temperature
• Elasticity decreases with increase of temperature.
• eg. Carbon
• Lead at room tempt – plastic and at low tempt. – elastic.
• Invar – to make pendulums.
• Creep resistance – property of the material which can
withstand its elastic property without fracture at high
temperature.
Factors affecting elasticity
Effect of impurities
• The elastic properties may increase or decrease due
to the addition of impurities.
• eg Carbon in molten iron, potassium in gold
increases elastic property.
• Addition of impurities distorts lattice structures –
decreases elastic property
Factors affecting elasticity
Effect of heat treatment and metal processing
• Annealing – decreases the elastic properties of materials
due to the formation of large crystal grains.
• Hammering and rolling – increase of elastic property
Effect of crystal defects
• Single crystal form – elastic
• Poly crystal form – comparatively less
Mind map
Summary:
Factors affecting elasticity

Effect of stress

Effect of temperature

Effect of impurities

Effect of heat treatment and metal processing

Effect of crystal defects
Stimulating question
• Why bridges are declared as unsafe after long
use?
Thank you……