Examples#

This gallery walks through every public feature of engineeringkit.mechanical_engineering, one breakthrough per script: rigid-body dynamics, gears and belts, screws, bearings, bolts and springs, linkages and robot arms, vibration, normal modes and absorbers, and the whirling and balanced rotor.

Units, assumptions and numerical validation gives the physical validity limits. Each script is self-contained and can be run directly with python examples/mechanical_engineering/<section>/<script>.py.

Sections#

  • dynamics – Huygens’s moment of inertia, Coriolis’s work and kinetic energy and Lagrange’s equations.

  • transmission – Euler’s involute gear, the Euler-Eytelwein belt-friction law and Lewis’s gear-tooth bending.

  • machine_elements – Coulomb’s power screw, Petroff’s and Sommerfeld’s journal bearings, the L10 life of rolling bearings, Rötscher’s bolted-joint diagram and Wahl’s spring factor.

  • mechanisms – Reuleaux’s slider-crank, Grashof’s condition, Freudenstein’s synthesis, Denavit-Hartenberg kinematics and Aronhold and Kennedy’s instant centres.

  • vibration – Rayleigh’s free and forced vibration, Frahm’s absorber, Holzer’s torsional method, Bernoulli’s normal modes and Dunkerley’s whirling shafts.

  • rotordynamics – the Jeffcott rotor and its critical speed, and Dalby’s balancing of rotating masses.

Dynamics#

Moments of inertia, work, kinetic energy and power, and Lagrange’s equations.

Huygens’s compound pendulum and the parallel-axis theorem (1673)

Huygens's compound pendulum and the parallel-axis theorem (1673)

Coriolis’s work and kinetic energy (1829)

Coriolis's work and kinetic energy (1829)

Lagrange’s equations of motion (1788)

Lagrange's equations of motion (1788)

Machine elements#

Power screws, journal bearings, rolling bearings, bolted joints and helical springs.

Coulomb’s friction and the power screw (1785)

Coulomb's friction and the power screw (1785)

Petroff’s law of bearing friction (1883)

Petroff's law of bearing friction (1883)

Reynolds and Sommerfeld: hydrodynamic lubrication (1886-1904)

Reynolds and Sommerfeld: hydrodynamic lubrication (1886-1904)

Lundberg and Palmgren’s rolling-bearing life (1947)

Lundberg and Palmgren's rolling-bearing life (1947)

Rötscher’s bolted-joint diagram (1927)

Rötscher's bolted-joint diagram (1927)

Wahl’s curvature factor for helical springs (1929)

Wahl's curvature factor for helical springs (1929)

Mechanisms#

Slider-cranks, four-bar linkages and their velocities and accelerations, and serial robot arms.

Reuleaux’s kinematics of machinery: the slider-crank (1875)

Reuleaux's kinematics of machinery: the slider-crank (1875)

Grashof’s condition for four-bar linkages (1883)

Grashof's condition for four-bar linkages (1883)

Freudenstein’s equation for four-bar synthesis (1954)

Freudenstein's equation for four-bar synthesis (1954)

Denavit and Hartenberg’s link parameters (1955)

Denavit and Hartenberg's link parameters (1955)

Aronhold and Kennedy’s theorem of three centres (1872-1886)

Aronhold and Kennedy's theorem of three centres (1872-1886)

Rotordynamics#

Unbalanced rotors, critical speeds and balancing.

Jeffcott’s rotor and the critical speed (1919)

Jeffcott's rotor and the critical speed (1919)

Dalby’s balancing of rotating masses (1902)

Dalby's balancing of rotating masses (1902)

Transmission#

Gear trains, gear-tooth strength and belt drives.

Euler’s involute gear tooth (1765)

Euler's involute gear tooth (1765)

The Euler-Eytelwein belt-friction law (1769)

The Euler-Eytelwein belt-friction law (1769)

Lewis’s gear-tooth bending formula (1892)

Lewis's gear-tooth bending formula (1892)

Vibration#

Free and forced vibration, normal modes, frequency bounds, vibration absorbers and torsional modes.

Rayleigh’s Theory of Sound: free vibration (1877)

Rayleigh's Theory of Sound: free vibration (1877)

Frahm’s vibration absorber and Den Hartog’s tuning (1909)

Frahm's vibration absorber and Den Hartog's tuning (1909)

Holzer’s method for torsional vibration (1921)

Holzer's method for torsional vibration (1921)

Rayleigh’s Theory of Sound: forced vibration and resonance (1877)

Rayleigh's Theory of Sound: forced vibration and resonance (1877)

Daniel Bernoulli’s superposition of normal modes (1753)

Daniel Bernoulli's superposition of normal modes (1753)

Dunkerley’s whirling shafts and Rayleigh’s bound (1894)

Dunkerley's whirling shafts and Rayleigh's bound (1894)

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