Torsion in Shaft Calculator
Calculate torque, shear stress, and angle of twist in circular shafts under torsion. Step-by-step formulas included for solid and hollow shafts.

Torsion in shafts calculator
This Torsion in Shafts Calculator can be used to find the max shear stress, torque capacity, and angle of twist of solid and hollow shafts. Input torque, shaft size, and material. There are step-by-step calculations that indicate the stress distribution and rotational deformation along the shaft.
Torsion in shafts Tool Formula:
Shear Stress (τ)
\[ T = \frac{T \times r}{J} \]
(where τ = shear stress, T = applied torque, r = radius, J = polar moment of inertia)
Polar Moment of Inertia for Solid Circular Shaft (J):
\[ J = \frac{\pi \times d^{4}}{32} \]
(where d = diameter of the shaft)
Angle of Twist (θ):
\[ \theta = \frac{T \times L}{J \times G} \]
(where θ = angle of twist, T = applied torque, L = length of shaft, J = polar moment of inertia, G = modulus of rigidity)
Torsion in Shafts Calculator is an engineering, student, and educational tool used to analyze circular shafts when it is subjected to torsional loads. Torsion causes shear stress in the material used in that shaft, and it creates an angle of twist in the length of the shaft that is vital in rotating machines, power transmission shafts, and drive systems.
There is the ability of the user to input torque (T), the shaft length (L), the shaft diameter (d), and material properties (shear modulus G). The calculator takes solid and hollow shafts, calculating the highest shear stress (τ = T × r / J), the angle of twist (θ = T × L / G × J), and the polar moment of inertia (J). The calculation is step-by-step to demonstrate the formulae and intermediate values, hence easy to understand the torsional behavior.
SI units are acceptable: N·m, mm, m, Pa/MPa. The tool is suitable for mechanical engineers, structural engineers, students, and educators in the analysis of the shaft strength, torsional deformation, and rotational design both academically and professionally.
⚡ Work & Installation Input to Output:
Input:
- Torque applied (T)
- Shaft type: solid or hollow
- Shaft length (L)
- Shaft diameter (d) or inner/outer diameters for hollow shaft
- Material properties: shear modulus (G)
- Units: N·m, mm, m, Pa/MPa
Processing:
- Compute polar moment of inertia (J): A. Solid shaft: J = π × d⁴ / 32 B. Hollow shaft: J = π × (d_o⁴ − d_i⁴) / 32
- Compute maximum shear stress (τ_max): τ = T × r / J, r = outer radius
- Compute angle of twist (θ): θ = T × L / (G × J)
- Optional: compute required shaft diameter for a given torque and allowable shear stress
Output:
- Maximum shear stress (τ_max)
- Angle of twist (θ)
- Polar moment of inertia (J)
- Step-by-step formulas and intermediate calculations
- Optional solid/hollow shaft comparison and printable results
Testing and Final Adjustments
Test common scenarios:
- Solid steel shaft, T = 1000 N·m, d = 50 mm, L = 1 m, G = 80 GPa → compute τ_max, θ
- Hollow aluminum shaft, T = 500 N·m, d_o = 50 mm, d_i = 30 mm → validate J, τ_max, θ
- Edge cases: zero torque, very long shaft → check formula consistency
- Units validation: N·m ↔ kN·m, mm ↔ m, Pa ↔ MPa
- Step-by-step clarity for students and professionals
- Mobile/desktop UX: numeric keypad, labels, error messages
- Include preset materials: steel, aluminum, brass
- SEO metadata: "Torsion in Shafts Calculator," "Shaft Shear Stress," "Angle of Twist," schema markup
Frequently Asked Questions - Torsion in Shaft Calculator:
What is torsion in a shaft?
Torsion is the twisting of a shaft due to an applied torque, producing shear stress and angle of twist along its length.
How do I calculate maximum shear stress?
τ_max = T × r / J, where T is torque, r is outer radius, and J is polar moment of inertia.
How do I calculate angle of twist?
θ = T × L / (G × J), where L is shaft length, G is shear modulus, and J is polar moment of inertia.
Can this calculator handle hollow shafts?
Yes, it supports solid and hollow circular shafts.
Which units are supported?
Torque in N·m, lengths in mm or m, stress in Pa or MPa.
What is the polar moment of inertia?
J is a geometric property of the shaft cross-section, used to calculate shear stress and angle of twist.
Can it calculate required shaft diameter?
Yes, you can compute the diameter for a given torque and allowable shear stress.
Who should use this calculator?
Mechanical and structural engineers, students, and educators designing shafts under torsion.
Is step-by-step solution available?
Yes, formulas and intermediate calculations are shown clearly.
Why is angle of twist important?
It indicates rotational deformation of the shaft, critical for machinery alignment and performance.
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