how to calculate twisting moment?
Join TheConstructor to ask questions, answer questions, write articles, and connect with other people. When you join you get additional benefits.
Log in to TheConstructor to ask questions, answer people’s questions, write articles & connect with other people. When you join you get additional benefits.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Calculation of twisting moment:
When we try to rotate a steel bar then that moment is nothing but the bending moment.
The twisting moment is a special case of a bending moment.
The twisting moment is also called a torsional moment or torque
When we twist the end of the bar either clockwise or counterclockwise then bending moment will form.
T= (G x angle ) x J/ L
T – Torque
J- polar moment of inertia
L – length
G – Modulus of rigidity
Torque, T = F x r x sin (theta), where r=distance between the rotation axis and the point of force applied, F =force applied and theta= angle between F and r.
T = (shear stress X polar moment of inertia) / r.
Torsion is the twisting of a beam under the action of a torque (twisting moment). It is systematically applied to screws, nuts, axles, drive shafts etc, and is also generated more randomly under service conditions in car bodies, boat hulls, aircraft fuselages, bridges, springs and many other structures and components. A torque, T , has the same units (N m) as a bending moment, M . Both are the product of a force and a distance. In the case of a torque, the force is tangential and the distance is the radial distance between this tangent and the axis of rotation.
All torsion problems can be solved using the following formula:
T/J = shear stress/ r = (G * angle)/ L
T = torque or twisting moment, [N×m, lb×in]
J = polar moment of inertia or polar second moment of area about shaft axis, [m4, in4]
τ = shear stress at outer fibre, [Pa, psi]
r = radius of the shaft, [m, in]
G = modulus of rigidity (PanGlobal and Reed’s) or shear modulus (everybody else), [Pa, psi]
θ = angle of twist, [rad]
L = length of the shaft, [m, in]