2009+8-2StressStrain - Introduction to Solid Mechanics...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
1 SJTU Introduction to Solid Mechanics -Vm211 Chapter 8 Stress and Strain Chapter 8 Stress and Strain SJTU Introduction to Solid Mechanics -Vm211 STRAIN Today’s Objectives: a) Understand the concept of normal and shear strain, and b) Apply the concept to determine the strains for various types of problems SJTU Introduction to Solid Mechanics -Vm211 Deformation ± Occurs when a force is applied to a body ± Can also occur when temperature of a body is changed DEFORMATION SJTU Introduction to Solid Mechanics -Vm211 Deformation ± Can be highly visible or practically unnoticeable ± Is not uniform throughout a body s volume, thus change in geometry of any line segment within body may vary along its length DEFORMATION SJTU Introduction to Solid Mechanics -Vm211 To simplify study of deformation ± Assume lines to be very short and located in neighborhood of a point ± Take into account the orientation of the line segment at the point DEFORMATION SJTU Introduction to Solid Mechanics -Vm211 Normal strain ± Defined as the elongation or contraction of a line segment per unit of length ± Consider line AB in figure below ± After deformation, Δ s changes to Δ s STRAIN
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 SJTU Introduction to Solid Mechanics -Vm211 Normal strain ± If normal strain ε is known, use the equation to obtain approx. final length of a short line segment in direction of n after deformation. ± Hence, when is positive, initial line will elongate, if is negative, the line contracts Δ s’ (1 + ) Δ s STRAIN SJTU Introduction to Solid Mechanics -Vm211 Normal strain ± Defining average normal strain using avg (epsilon) ± As Δ s 0, Δ s’ 0 avg = Δ s Δ s’ Δ s = Δ s Δ s’ Δ s lim B A along n STRAIN SJTU Introduction to Solid Mechanics -Vm211 Units ± Normal strain is a dimensionless quantity , as it s a ratio of two lengths ± But common practice to state it in terms of meter/meter (m/m) STRAIN = Δ s Δ s’ Δ s lim B A along n SJTU Introduction to Solid Mechanics -Vm211 Units ± is small for most engineering applications, so is normally expressed as micrometers per meter ( μ m/m) where 1 m = 10 6 m ± Also expressed as a percentage
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 08/09/2011 for the course EE 211 taught by Professor Liuxila during the Summer '09 term at Shanghai Jiao Tong University.

Page1 / 7

2009+8-2StressStrain - Introduction to Solid Mechanics...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online