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MACHINE DESIGN 2 - COMPENDIUM
- Constraints
PVW
dS = ∫ Aon dA ⋅ X ⋅ dx where A: FX on
A = N according to the load
Force method
Simple bending diagrams
Stress tensor
Principal stresses:
- det |(σx - θp) τxy τxz | = 0
- τyx (σy - θp) τyz
- τzx τzy (σz - θp)
Plane case:
- θ̅1,2 = ⌊σx+σy⌋ ± √{(σx-σy)2 + 4τxy2}
- tg2φ = 2τxy / (σx-σy)
Strain gauge rosette
εi = εxcos2θi + εysin2θi + τxycosθisinθi
Hooke's Law
εi = 1/E [(1 - ν) (σx+σy)]
τij = 2(1+ν)/E τij
G = E/2(1+ν)
Stress concentration factor
σmax = kt ⋅ σnom
σuiex = ke ⋅ τnom
σuxx = kt ⋅ τnom (only normal)
Polar coordinates (plane case)
θ = σx + θx - θy / 2 ⋅ cos2θ + τxysin2θ
θ = σx + θx - θy / 2 ⋅ cos2θ - τxysin2θ
τθ = τxy ⋅ sin2θ + σxcos2θ
Fatigue
σ̅m = σuxx+σuim/2
σa = σuxx-σuim/2
r = σuim/σuxx
σa = A ⋅ Nfb
r3o = 0.4; 0.6; 0.75 bending (FE 0.5; Re,Ti Ou)
r3e = 0.3; 0.5; 0.6 axial
r3e = 0.2; 0.3; 0.5 torsion