how to calculate twisting moment?

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## nikeetasharma

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

where:

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]

## Komal Bhandakkar

This answer was edited.## Calculation of twisting moment:

When we try to rotate a steel bar then that moment is nothing but the

bending moment.Thetwisting moment is a special case of a bending moment.The twisting moment is also called a

torsional moment or torqueWhen we twist the end of the bar either clockwise or counterclockwise then bending moment will form.

Formula:T= (G x angle ) x J/ LWhere,

T – Torque

J- polar moment of inertia

L – length

G – Modulus of rigidity

Thank You.

## AdityaBhandakkar

Hi,

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.Twisting moment,T = (shear stress X polar moment of inertia) / r.