# Lab_12_2011 - GG303 Lab 12 11/15/11 1 DEFORMATION AROUND A...

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GG303 Lab 12 11/15/11 1 Stephen Martel Lab12-1 University of Hawaii DEFORMATION AROUND A HOLE The objective of this lab is to develop insight into the stress and strain fields around a hole, and to see how those fields are related. Part 1 (Strain in Lycra sheet) a “Exploration” Stretch the Lycra sheet with a hole in it, and observe how the circles and the grid deform. Observe the regions near the hole and far from the hole. The attached page shows traced scans of the grid lines and some of the holes from one quadrant of an actual experiment. The grey circles are the original undeformed circles, and the dashed ellipses are their deformed counterparts, the strain ellipses. b For each of the 22 strain ellipses 1 On page 2, neatly draw the orientations of the major (2a) and minor (2b) axes of the strain ellipses in the first quadrant. Use one color for the major axes and a second color for the minor axes . (5 pts) 2 On page 3, neatly draw the vectors showing the displacement of the centers of the circles. (5 pts) 3 Describe in words the displacement field of question (b2) (5 pts) c For the 4 strain ellipses A, B, C, and D 1 Measure the length of the ellipses to the nearest 0.1 mm, and from those measurements calculate the principal strains to two significant figures. (16 pts total) Strain ellipse Length of major axis 2a (mm) Length of minor axis 2b (mm) Greatest principal strain ( ε 1 ) Least principal strain ( ε 2 ) A B C D 2 Why are the values of ε 1 at C and D similar? (1 pt) 3 At which ellipse is ε 1 the largest? (1 pt) 4 At which ellipse is ε 2 the smallest? (1 pt) 5 What is the ratio of ε 2 at B to ε 2 at C? (1 pt) 6 What is the ratio of ε 1 at A to ε 1 at C? (1 pt) 7 What is the direction of the greatest principal strain at A? (1 pt) 8 What is the direction of the least principal strain at B? (1 pt)

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GG303 Lab 12 11/15/11 2 Stephen Martel Lab12-2 University of Hawaii
GG303 Lab 12 11/15/11 3 Stephen Martel Lab12-3 University of Hawaii

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GG303 Lab 12 11/15/11 4 Stephen Martel Lab12-4 University of Hawaii Part 2 (Photo-elastic analysis) a “Exploration” Take a sample with no hole it, place it horizontally between cross polarizers, and flex it
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## This note was uploaded on 12/05/2011 for the course GEOLOGY 300 taught by Professor Stephenmartel during the Fall '11 term at University of Hawaii, Manoa.

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Lab_12_2011 - GG303 Lab 12 11/15/11 1 DEFORMATION AROUND A...

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