Page 84 - CITS - WCS - Mechanical

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Pascals (Pa)

The units of modulus of elasticity are pressure units, as it is defined as stress (pressure units) divided by strain
(dimensionless). Most commonly the units are Pascals (Pa) which is the SI unit, or pounds per square inch (psi)
depending on the industry or geographical location.
There are three different types of elastic modulus
• young’s modulus.
• shear modulus.

• bulk modulus.
• The greatest known modulus of elasticity (Young’s modulus) is found in diamonds. ...
• The elasticity of a material is determined by its modulus of elasticity, commonly referred to as elastic modulus
or simply modulus.
• A material’s resistance to elastic, or non-permanent, deformation is measured by its elastic modulus.

The symbol of absolute value is represented by the modulus symbol, ꞌꟾ ꟾꞌ, with the numbers between it. For
example, the absolute value of 9 is denoted as |9|.

Poisson ratio is the ratio of transverse contraction (or expansion) strain to longitudinal extension strain in the
direction of stretching force. Tensile deformation is considered positive and compressive deformation is considered
negative.

Poisson's ratio = – Lateral strain / Longitudinal
Formula
strain
Range -1.0 to +0.5

Units Unit less quantity

Scalar / Vector Scalar quantity

Rubber has one of the highest values of Poisson’s ratio at 0.4999, which is evident in its physically noticeable
reaction to axial stretching.

The equation for calculating Poisson’s ratio is given as v=(-εtrans)/ε axial. Transverse strain (ε_trans) is measured
in the direction perpendicular to the applied force, and axial strain (ε_axial) is measured in the direction of the
applied force.

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CITS : WCS - Mechanical - Exercise 7