Introduction to Engineering-Solid Mechanics 2.Stress and Strain Elongation and Strain The stretch or elongation 4L is one way to describe how the rod lengthens when F is applied If a second rod has the same cross-sectional area,but is shorter The stress within it would be the same as for the first rod The shorter rod would stretch by a smaller amount - Strain(a.is the amount of stretching per unit of length. △L = L Strain is a dimensionless quantity.Strain is generally very small. Introduction to Engineering 11 H.ShaoIntroduction to Engineering Introduction to Engineering —— Solid Mechanics Solid Mechanics Introduction to Engineering Introduction to Engineering H. Shao 11 2. Stress and Strain Elongation and Strain – The stretch or elongation ΔL is one way to describe how the rod lengthens when F is applied – If a second rod has the same cross-sectional area, but is shorter • The stress within it would be the same as for the first rod • The shorter rod would stretch by a smaller amount – Strain (), is the amount of stretching per unit of length. – Strain is a dimensionless quantity. Strain is generally very small. L0 L  