Belonging to the same family of mechanical properties of materials, that contain the elasticity, resilience; is another quantity, called toughness, refers to the ability of a manner to absorb energy (strain energy) without fracturing.
Actually, when a material is deformed beyond the proportional limit by the dynamic loadings, accurate theoretical predictions of energy observed would be much more difficult to obtain owing to the non linearity between stress and strain. However a knowledge of the capacity of a material to absorb energy before fracture can be determined experimentally and this quantity is termed the “toughness of the material”.
Since it is the energy it is allocated the symbol U.
The examples of toughness condition are the impact loadings
• Ice berg striking the ship
• A bird colliding to the aero plane to higher altitudes.
MODULUS OF THOUGHNESS:
Toughness is ability of material to resist fracture
The corresponding modulus is called modulus of toughness, and the modulus of toughness UT is actually the strain energy density where material is stressed to the point of failure.
It is equal to the area by the entire stress-strain curve.
The higher the modulus of toughness greater the ability of the material to absorb energy without failing high modulus of toughness is therefore important when the material subject to impact loads.
The unit of modulus of toughness is Joules/m3 and its symbol is UT.
FACTORS AFFECTING MODULUS OF TOUGHNESS:
The general factors, affecting the toughness of a material are: temperature, strain rate, relationship between the strength and ductility of the material and presence of stress concentration (notch) on the specimen surface
FORMULATION OF MODULUS OF TOUGHNESS
Graphically the Modulus of toughness can be calculated by the area under the STRESS-STRAIN curve fig 1. Let us define this in details
An approach to calculate the modulus of...