Slow Cheetah

Mechanical Engineering Design Learning notes

(Reference: Shigley’s Mechanical Engineering Design Textbook)

Manufacturing cost is highly dependent on tolerance. In my previous experience, when estimating the facility cost, we normally convert that into a value equalling to a coefficient times the cost of the metals.

The heat Treatment of Steel

  1. Annealing: soften a material and make it more ductile, to relieve residual stresses, and to refine the grain structure.
  2. Quenching: rapid cooling, prevent phase-changing.
  3. Tempering: stress relieving.

Key properties: Young’s modulus (stress/strain), density, strength(MPa)

Temperature effects

Thermal expansion, change the normal strain.

Failure analysis

for ductile behaviour: distortion-energy theory (Coulomb-Mohr method)

Crack modes: opening crack propagation (Most common), sliding, tearing.

Fatigue failure (Could combine with liquid-soild interaction simulation? How to determine failure criterion? Frequency? Humidity? etc.)

Fatigue-life methods: stress-life, strain-life, linear-elastic.