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Department of Materials Science and EngineeringUNIVERSITY OF CALIFORNIA^ College of Engineering
This is a and no reference materials are permitted. Please use only the pages given here, and write your closed book Exam. You must work independently, answers in the spaces provided.
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Department of Materials Science and EngineeringUNIVERSITY OF CALIFORNIA^ College of Engineering
Midterm #
NAME:______________________________________ (Please Print Clearly) This is a independently, and no reference materials are permitted. closed book Exam. You must work Please use only the pages given here, and write your answers in the spaces provided.
Question 1 The mechanical normalized parameters. Choose the properties of materials are described in engineering terms using simple concepts and best answers from those presented below for 2 points each. a. The data at right could have been obtained from a uniaxial tensile test three-point bend test Brinell hardness test b. This data reveals that the sample had a yield strength of 350 MPa 400 MPa 450 MPa c. Necking would have been observed in this sample when the stress reached 350 MPa 400 MPa 450 MPa d. Dislocations began to move in this sample when the strain exceeded 0.0475 0.
e. The construction at right represents percent elongation to failure estimate of toughness modulus of elasticity
E45•Midterm #1, 2001 NAME:_______________________________
0 0.02 ε0.04 0.
Question 3 Identify the lattice directions and lattice planes shown in the sketches below for 3 points each. intercepts. Note especially the scale markings and use them to precisely identify any fractional Be sure that your answer satisfies the special requirement of the four-index Miller-Bravais notation that h + k = -i.
a. b. c. d. e.
f. g. h. i. j.
E45•Midterm #1, 2001 NAME:_______________________________
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Question 4 An alloy of copper and gold forms a special “ordered” crystal structure known as L1 Strukturbericht at the face centers. notation. It has a cubic unit cell with Au atoms at the corners and Cu atoms 2 in the
x
z
y a. Draw and label the contents of the unit cell (5 points) b. Show how to count all of the atoms in the unit cell and use your result to specify the chemical formula of this ordered alloy? (5 points)
c. Now specify a Bravais lattice ( ordered L1 2 crystal structure.5 points) AND a motif (5 points) that appropriately describe this
E45•Midterm #1, 2001 NAME:_______________________________
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Professor R. Gronsky Department of Materials Science & EngineeringUNIVERSITY OF^ College of Engineering^ CALIFORNIA Fall Semester, 2005
Engineering 45 Midterm 01
LATTICE seatingCLOSED BOOK format .................. (^) ...... All you need are writing instruments and a straightedge. Please store all books, reference matePlease be seated with rials, calculators, PDAs, cell phones (OFF), and iPods. occupied^ INSTRUCTIONS seats to your front and back, vacant seats to your left and right.- NO DISRUPTION rulePROFESSIONAL protocol ......... (^) ... Questions cause too much of a disturbance to others in the room. Instead of asking questions, write any concerns or alternative interpretations in your answers.Engineers do not cheat on the job and they certainly don’t cheat on exams.
Name: (Please print)
(^1) Mark Two (. Mechanical Properties (20 points) (^) +2 ☒ (^) ) points for correct answers,the ballot box corresponding to the -1 if wrong, best answer 0 if blank.. ( shown below is defined by which expression? a ) The compressive stress induced in the volume element
l w t
☐ ☐ ☐ σσσ === PPP ((( wll ×× × wt (^) ) t )) ( below is defined by which expression? b ) The shear stress induced in the volume element shown l w t
☐ ☐ ☐ σσσ === PPP ((( wll ×× × wt (^) ) t )) ( plot to a stress essential. ☐ c ) In order to convert the data from a load the cross-sectional area of the sample vs strain plot, the following information is vs elongation ☐ ☐ the yield strength of the samplethe geometry of the sample ( ☐ ☐ ☐ d ) Elastic deformation is________? linearrecoverabletime-dependent ( standard uniaxial tensile test ☐ ☐ e ) The gage length of a metallic alloy sample used in the has the smallest cross-sectional areaestablishes the initial length of the sample ☐ calibrates the sample’s elongation to failure
( ☐ ☐ ☐ f ) “True” stress differs from “engineering” stress in the way tensile test data is collectedin the way tensile test data is reportedin the way tensile test data represents the actual sample ( carbon steel sample indicates that g ) The following data from a uniaxial tensile test of a low (^2000)
(^0) Strain,0.01_!_ (mm/mm) 0.
Stress,^ " (MPa) ☐ ☐ ☐ it has a lower yield point of 450 MPait has an 0.2% offset yield point of 450 MPAit fractured at precisely 0.02% offset ( room would have observed necking in the sample ☐ ☐ h ) For the same steel sample as above, an observer in the justjust before the sample fractured atwhen the sample yielded at 500 MPa 400 MPa ☐ ( i ) An aluminum alloy produced the following stress-strain just as the stress exceeded 600 MPa plot during a uniaxial tensile test. Its yield strength is (^2000)
(^0) Strain,0.01_!_ (mm/mm) 0.
Stress,^ " (MPa) ☐ ☐ ☐ 400 MPa450 MPa500 MPa ( Al alloy sample, it can be concluded that ☐ ☐ j ) Comparing the above plots from a steel sample and an the Al alloy has greater elastic recovery after fracturethe Al alloy has a larger elastic modulus ☐ the Al alloy deforms more before it fails
E 45 Midterm 01, 2005 Initials:
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(^3) The triangles drawn here are sections of planes through cubic and hexagonal lattices. Identify the relevant planes by their Miller indices or Miller-Bravais indices.. Lattice Planes (20 points) Four ( 4 ) points for correct answers in the boxes provided.
x
z
y ( a )
x
z
y ( b )
x
z
y ( c ) c a 3 a 1
a (^2) ( d ) c a 3 a 1
a (^2) ( e )
E 45 Midterm 01, 2005 Initials:
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(^4) Identify the following directions through both cubic and hexagonal lattices using the appropriate Miller index or Miller-Bravais index notation.. Lattice Directions (20 points) Four ( 4 ) points for correct answers in the boxes provided.
x
z
y ( a )
x
z
y ( b )
x
z
y ( c ) c a 3 a 1
a (^2) ( d ) c a 3 a 1
a (^2) ( e )
E 45 Midterm 01, 2005 Initials:
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No points will be given or deducted for work shown here. Please enter answers in the spaces provided. Worksheet
Problem # 1 Possible Points 20 Your Score (^23 ) (^45 ) Total 100
E 45 Midterm 01, 2005 Initials:
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