Engineering Formula Library
Verified formula records with variables, conditions, sources and direct links to deterministic calculators.
FORMULA RECORDS
Open a formula to inspect its calculation basis.
Every published record states units, assumptions, source metadata and a related calculator. Formula records cover stated preliminary conditions—not final design-code compliance.
Solid circular shaft torsion
Relates torque, selected allowable shear stress and diameter for a solid circular shaft under pure torsion.
T = πτd³ / 16Open formula detail →Hollow circular shaft torsion
Relates torque to outside/inside diameter for a hollow circular shaft in pure torsion.
T = (πτ/16)((Do⁴ − Di⁴)/Do)Open formula detail →Power, speed and torque
Converts transmitted mechanical power and rotational speed to torque.
T = 60P/(2πN) = 9550P(kW)/N(rpm)Open formula detail →Sheet-metal bend allowance
Neutral-axis arc-length estimate for one bend, using radians for angle.
BA = θ(R + Kt)Open formula detail →Preliminary press-brake air-bend force
Preliminary metric air-bending estimate with explicitly entered tensile strength, thickness, bend length and V-opening.
F = 1.42Rm t²L/(V × 1000)Open formula detail →Newton’s Second Law
Net force from mass and acceleration.
F = maOpen formula detail →