Torsion Test on Mild Steel and Cast Iron - Lab Report
To perform Torsion Test on
Procedure of the Test:
Observations and Calculations:
Twisting effect of couple or force is called as torque. It is denoted by double head arrow.
Torque applied in a plane perpendicular to the longitudinal axis of a member is called as
t, Shearing stress in MPa
The geometric rigidity of the X-sec is termed as polar moment of inertia. It is the resistance against twisting, summation of 2 moment of area about x-axis.
For Hollow Shaft:
Torsional Rigidity / Modulus of Rigidity / Modulus of Elasticity in Shear:
"When material is subjected to pure twist loading, the slope of shear stress verses shear strain curve is termed as modulus of rigidity ( modulus of elasticity in shear, torsional rigidity)
The ratio of lateral strain to longitudinal strain when material is subjected to axial loading and always less than 1.
The relationship between yield stress in simple tension and that in pure shear can be found from VON MISES for a yield criteria.
Angular displacement of specimen caused by specified torque in torsion test. It is equal to angle of twist in radians divided by gauge length or effective length.
Strain corresponding to specified torque in torsion test. It is equal to torsional deformation multiplied by the radius of the shaft. It's units are radians.
Shear stress developed in a material subjected to a specified torque in torsion test for a circular shaft. It can be calculated using the expression.
Fracture in torsion for ductile materials generally occur in the plane of maximum shear stress perpendicular to the axis of bar where as for the brittle material failure occurs along 45° hilux to the axis of bar due to tensile stress across that plane.