mechanical property

• Stress


  A measure of an applied mechanical load or force, normalized to take into account cross-sectional area
• Engineering stress


  One of the two different stress parameters defined
• True stress


  One of the two different stress parameters defined
• Strain


  The amount of deformation induced by a stress
• Engineering strain


  One of the two different strain parameters used
• True strain


  One of the two different strain parameters used
• Stress-strain tests


  • Tension
  • Compression
  • Torsion
  • Shear
• Elastic deformation


  Nonpermanent deformation where stress and strain are proportional
• Modulus of elasticity


  The constant of proportionality between stress and strain in tension and compression
• Shear modulus


  The constant of proportionality between stress and strain when the stress is shear
• Poisson's ratio


  The negative ratio of transverse and longitudinal strains
• Yielding


  The onset of plastic or permanent deformation
• Yield strength


  The stress at which plastic deformation begins, determined by a strain offset method
• Tensile strength


  The maximum tensile stress that may be sustained by a specimen
• Ductility


  The amount of plastic deformation that has occurred at fracture, measured by percent elongation and reduction in area
• Resilience


  The capacity of a material to absorb energy during elastic deformation
• Modulus of resilience


  The area beneath the engineering stress-strain curve up to the yield point
• Static toughness


  The energy absorbed during the fracture of a material, taken as the area under the entire engineering stress-strain curve
• Hardness


  A measure of the resistance to localized plastic deformation
• Hardness testing


  A small indenter is forced into the surface of the material, and an index number is determined on the basis of the size or depth of the resulting indentation
• For many metals


  Hardness and tensile strength are approximately proportional to each other
• Measured mechanical properties are not exact and precise quantities, there will always be some scatter for the measured data
• Typical material property values are commonly specified in terms of averages, whereas magnitudes of scatter may be expressed as standard deviations
• Design/safety factor


  A ratio used for design purposes to account for uncertainties in measured mechanical properties and in-service applied stresses
• Safe stress

  For ductile materials, the ratio of the yield strength and the factor of safety