Technical concepts explained simply — from fluid dynamics to material properties.
Fatigue strength is the stress a material survives for a stated number of cycles. See the formulas, S-N curves, endurance limit and worked steel examples.
The tip speed ratio is blade tip speed divided by wind speed. See the TSR formula, worked examples, optimal values by rotor type and what it means for power.
Torque is the turning effect of a force about an axis. See the formula, units such as N·m and lb·ft, its link to power, gears and bolt preload, with examples.
Stress is force per area and strain is relative deformation. Learn to read the stress-strain curve, find yield and ultimate strength, and use Hooke's law.
Strain is change in length divided by original length. See the formula, why it has no units, microstrain, true strain, strain gauges and worked examples.
Young's modulus measures how stiff a material is: stress divided by strain. See the formula, units, values by material, how to measure it and worked examples.
Shear stress is force acting parallel to a surface, divided by area. See the formula, units, bolt shear, torsional and beam shear, and fluid shear examples.
Factor of safety compares a part's strength with the stress it carries. Learn how it differs from design factor, why the lowest mode governs and who sets it.
The Reynolds number compares inertia with viscosity and predicts laminar or turbulent flow. See the formula, units, pipe limits and worked examples.
Thermal expansion is the change in a material's size with temperature. See the formula, coefficients by material, examples and what blocked expansion does.
Poisson's ratio is how much a material narrows as it stretches. See the formula, typical values, the limits of 0.5 and −1, and where engineers really need it.
A bending moment is the internal turning effect that bends a beam. Learn the formula, units, maximum moment cases and step-by-step beam examples.
Heat transfer is energy moving because of a temperature difference. Learn the three modes, their formulas and units, key properties and worked examples.
Viscosity is a measure of a fluid's resistance to flow. See the definition, symbols μ, η and ν, units such as cP and cSt, the formula and worked examples.
Specific gravity compares a density with water's. Learn the formula, why it has no units, how to read a tank's SG rating and how to convert it to density.
Surface roughness is the fine texture left by machining. See Ra, Rz and other parameters, how roughness is measured, cut-off lengths and typical Ra values.
Heat treatment changes a metal's properties through controlled heating and cooling. Compare annealing, normalizing, hardening, tempering and case hardening.