Machine design formula sheets for mechanical engineers. Reference guides for stress, strain, gears, and more.
Reference
Machine Design Formula Sheets
7 sheets
Stress and strain
Formula reference for mechanical engineering interviews. Every relation assumes linear elastic, isotropic, homogeneous material unless the note says otherwise.
Torsion
Formula reference for mechanical engineering interviews. The Tr/J form assumes a circular, prismatic, linear elastic shaft. Non-circular sections warp and need the separate relations in section 03.
Buckling
Formula reference for mechanical engineering interviews. Buckling is a stability failure, so yield strength does not appear in the Euler equation at all. Check slenderness before choosing a formula.
Bending and deflection
Formula reference for mechanical engineering interviews. Bending stress in a determinate beam is independent of material; deflection is not. Check both, and say which one governed.
Fatigue
Formula reference for mechanical engineering interviews. Fatigue happens below yield, starts at the surface, and is governed by geometry, surface condition and mean stress rather than by material strength alone.
Gearbox calculations
Compound, planetary and harmonic drives. Ratio multiplies torque and divides speed, but it divides reflected inertia by the square, and that is usually the reason the gearbox is there.
Rotational motion
Formula reference for mechanical engineering interviews. Moment of inertia is about mass distribution, not mass. Take moments only about a fixed axis or about the centre of mass.