MECHANICS OF DEFORMABLE BODIES

• Simple Strain


  Also known as unit deformation, strain is the ratio of the change in length caused by the applied force, to the original length
• Strain


  ε = δ/L, where δ is the deformation and L is the original length
• Yield Point


  The point at which the material will have an appreciable elongation or yielding without any increase in load
• Ultimate Strength


  The maximum ordinate in the stress-strain diagram, also known as tensile strength

  
• Rupture Strength


  The strength of the material at rupture, also known as breaking strength
• Modulus of Resilience


  The work done on a unit volume of material as the force is gradually increased from O to PL, in Nm/m^3
• Creep is the slow and continuous deformation of a material under a constant stress, usually at high temperatures
• Fatigue is the progressive and localized damage of a material under cyclic or fluctuating stress, usually at low or moderate temperatures
• Hooke's Law


  The law of elasticity discovered by the English scientist Robert Hooke in 1660, which states that, for relatively small deformations of an object, the displacement or size of the deformation is directly proportional to the deforming force or load

  
• Elastic Limit


  The limit beyond which the material will no longer go back to its original shape when the load is removed, or it is the maximum stress that may developed such that there is no permanent or residual deformation when the load is entirely removed
• Hooke's Law


  σ = Eε
• Under Hooke's Law conditions, the object returns to its original shape and size upon removal of the load
• Calculating total elongation of the rod


  1. Due to axial load

  2. Due to self-weight