5.5 Deformation and stiffness

5.5.1 Skeletal structures and types of load

@Le2004

  • Bending
  • Axial Loading
    • Tension
    • Compression
  • Torsion

5.5.2 Stiffness

  • Stiffness is a structural relationship between deflection and load

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  • The slope of the load-deflection curve (\(k\)) is the structural stiffness
  • Two factors influence the stiffness
    • Material response
    • Geometry

5.5.3 Structural properties

Material Properties

  • Elastic modulus (\(E\) and \(G\))
  • Yield stress (\(\sigma_Y\))
  • Toughness (brittle/ductile) (\(K\))

Independent of shape!

Geometric Properties

  • Material distribution
    • Cross sectional area (\(A\))
    • Area moment of inertia (\(I\))
    • Polar moment of inertia (\(J\))

Independent of material!

Structural Properties

  • Axial Stiffness (\(E A\))
  • Bending Stiffness (\(E I\))
  • Torsional Stiffness (\(G J\))

Depends on shape and material!