strain - I. Basic Concepts A. Strain Defined 1. Strain =...

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

View Full Document Right Arrow Icon
114 I. Basic Concepts A. Strain Defined 1. Strain = deformation of material in response to stress a. deformation = change in size and shape (1) change in length, diameter, volume of material b. Extensional Strain = lengthening/stretching c. Compressional Strain = shortening/flattening d. Rotational vs. nonrotational strain B. Types of Strain 1. Homogeneous: changes in size and shape are proportionately identical from smaller scale to larger scale in rock body a. planar surfaces remain planar after deformation b. lines remain straight c. parallel lines remain parallel 2. Inhomogeneous: changes in size and shape vary from place to place in rock body a. straight lines become curved b. planes become curved c. parallel lines are not parallel after deformation d. Example Folding: (1) On large scale: inhomogeneous ductile deformation (2) On small scale: homogeneous strain C. Other Terms and Concepts of Strain 1. Progressive Deformation: time series of motion that carries body from undeformed state to final deformed state a. strain path: steps or path of progressive deformation b. strain state: any given instant of strain, final strain state yields no information about strain path 2. 3-D strain: examination of shape/size changes in 3-dimensions 3. Plane Strain: examination of shape/size changes in 2-dimensions 4. Material objects used to identify 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
115 a. bedding planes b. fossils, oolites, nodules II. Measures of Strain A. Linear Strain (change in length during deformation, strain in 1-dimension) 1. volume of material: measure of size of material, that may be subject to change during strain a. volume of cube = l x l x l (e.g. cu. cm) 2. Stretching: measure of ratio deformed length (L2) to original length (L1) Sn = L2/L1 3. Extension: measure of ratio of change in length (dL) to original length (L1) e = dL/L1 = (L2-L1)/L1 = Sn - 1 a. Positive value of extension = lengthening b. negative value of extension = shortening B. Volumetric Strain (change in volume during deformation, i.e. change in length in 3-D) 1. volumetric stretch: Sv = v2/V1 2. volumetric extension: Ev= dV/V1 = (V2-V1)/V1 = Sv-1
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 10/02/2011 for the course GEOLOGY 406 taught by Professor Taylor during the Spring '11 term at Western Oregon University.

Page1 / 7

strain - I. Basic Concepts A. Strain Defined 1. Strain =...

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