Machine Design by Hand: Stress Transformation & Mohr's Circle, Combined Shaft Loads, Von Mises, Fatigue & the Goodman Line, Shaft Sizing, Bearing Life, Gear Forces, Springs & Bolt Preload

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

• Turn four fictional plane stress states into the centre and radius of Mohr's circle, the principal stresses and the maximum shear, find the principal angle with ATAN and a quadrant correction, and chart how the stresses on a face change as one state is turned.
• Calculate the bending and torsion stress at the surface of a solid shaft for four diameters, combine them into the von Mises stress, and compare it with a fictional yield strength to get the yield factor of each size.
• Correct a fictional endurance limit with surface, size and reliability factors from lookup tables, split four load cycles into mean and alternating stress, calculate their Goodman factors and draw the Goodman line.
• Check a fictional list of standard shaft sizes for fatigue and yield, solve both requirements for the minimum diameter in closed form and pick the smallest standard size that meets both with MINIFS – without any solver.
• Look up e and Y from a fictional factor table, turn a radial and an axial load into the equivalent bearing load, calculate the L10 life in hours for five catalogue bearings, and pick the smallest bearing that reaches the target life.
• Turn motor power and speed into torque, follow speed and torque through a two-stage gear train with losses, and calculate the tangential and radial tooth forces of the first gear pair from its pitch diameter and pressure angle.
• Calculate the rate, index and corrected shear stress of three fictional helical springs, turn a tightening torque into bolt preload and find the external load at which the bolted joint would separate.
• Complete a drive-train table with the life factor of one bearing, find the weakest element with MIN and INDEX/MATCH, choose the cheapest upgrade that brings it up to its target and chart achieved against required factors.