ENGINEERING FORMULA LIBRARY

Verified Engineering Formula Library

Fundamental mechanical equations across 9 categories derived from Shigley, Machinery's Handbook, Roark's Formulas, and ISO/ASME standards. Every equation includes derivation steps, symbols, and unit conventions.

10 formulas
9 categories
10 linked calculators

Strength of Materials

Fundamental stress, strain, and deflection equations for beams, shafts, and structural elements.

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EQU-001

Beam Bending Stress Formula (Flexure Equation σ = My/I)

Calculate normal flexural and maximum beam bending stress (σ = My/I = M/S) in beams, shafts, and structural shapes per Euler-Bernoulli beam theory.

beam bending stressbending stress formulaflexural stress formula+6

Related:

beam-deflectionshaft-bending-torsionshaft-design-basics+2
EQU-002

Torsional Shear Stress in Shafts

Calculates the maximum and radial torsional shear stress (τ = T·r/J) in solid and hollow circular shafts under torsional moments.

torsional shear stresstorsional shear stress formulashaft shear stress+4

Related:

shaft-diametershaft-bending-torsionshaft-design-basics

Machine Design

Combined loading criteria, fatigue analysis, and sizing equations per ASME and Shigley methods.

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EQU-003

ASME Shaft Sizing Formula (ASME B106.1M)

Standard ASME B106.1M governing equation for transmission shaft diameter sizing under combined steady torque and reversed bending fatigue loads.

ASME shaft sizingASME shaft diameter formulaASME B106.1M+4

Related:

shaft-diametershaft-bending-torsionshaft-design-basics

Mechanics

Kinematics, dynamics, power transmission, and rotational motion relationships.

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EQU-004

Torque, Speed & Power Relation (P = Tω = 2πNT/60)

Calculate mechanical power, motor torque, and rotational speed (RPM) across SI (kW, N·m) and Imperial (HP, lbf·ft) engineering units.

torque power relationtorque power speed formulatorque RPM power+5

Related:

shaft-diametershaft-bending-torsionshaft-design-basics+1

Fluid Mechanics

Pipe flow, head loss, friction factors, and fluid power equations.

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Thermodynamics

State equations, gas laws, and thermodynamic property relationships.

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EQU-006

Ideal Gas Equation of State

Relates pressure, volume, temperature, and substance amount for ideal gas systems.

ideal gasstate equationgas constant+2

Related:

unit-converterengineering-materials-guide

Manufacturing

Forming, machining, and fabrication calculation formulas.

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Materials

Elasticity, plasticity, and material property relationships.

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EQU-008

Hooke's Law (1D Stress-Strain Relation)

Defines the linear elastic proportional relationship between normal stress and resulting strain in materials.

Hooke's Lawelastic modulusstress strain ratio+2

Related:

material-weightcolumn-bucklingengineering-materials-guide+3

Fasteners

Bolt preload, torque, joint analysis, and thread engagement formulas.

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Bearings

Fatigue life, load ratings, and selection criteria per ISO 281.

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TRANSPARENT EQUATIONS, ASSUMPTIONS, AND REFERENCES

Built for Professional Mechanical Design

  1. Standard-Sourced

    Every formula cites Shigley, Machinery's Handbook, Roark's, or ISO/ASME standards.

  2. Symbol Defined

    All variables include symbol, unit conventions, and applicability limits.

  3. Derivation Linked

    Step-by-step derivation paths connect to textbook chapter references.

  4. Calculator Linked

    Related design calculators provide immediate numerical evaluation.

Need a formula derivation that isn't listed? Check our calculators or submit a request via GitHub.