Introduction to Basic Manufacturing Processes and ... - always yours

Porperties and Testing of Metals 125
Locking
Lever
Hand
Wheel
Lower
Cross-
Head
Column
Square Threaded
Screw
Compression
Plates
Beds
Test P iece
Table
Fig. 7.8 Schematic compression test set up on a universal testing machine
Tensile Strain
The ratio of increase in length to the original length is known as tensile strain.
Compressive Strain
The ratio of decrease in length to the original length is known as compressive strain.
Modulus of Elasticity
The ratio of tensile stress to tensile strain or compressive stress to compressive strain is
called modulus of elasticity. It is denoted by E. It is also called as Young’s modulus of elasticity.
E = Tensile Stress/Tensile Strain
Modulus of Rigidity
The ratio of sheer stress to shear strain is called modulus of rigidity. It is denoted by G.
G = Shear Stress/Shear Strain
Bulk Modulus
The ratio of direct stress to the volumetric strain (ratio of change in volume to the
original volume is known as volumetric strain) is called Bulk modulus (denoted by K).
K = Direct stress/volumetric strain
Linear and Lateral Strain
When a body is subjected to tensile force its length increases and the diameter decreases.
So when a test specimen of metal is stressed, one deformation is in the direction of force
which is called linear strain and other deformation is perpendicular to the force called lateral
strain.