Exam2KeyW06 - ENGR 213 Winter 2006 Exam 2 Name Instructions 1 2 Do not open the exam until you are told to do so There are 4 problems on this exam

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Unformatted text preview: ENGR 213 Winter 2006 Exam 2 Name: Instructions: 1. 2. Do not open the exam until you are told to do so There are 4 problems on this exam . This is a partial credit exam. All work must be shown in the space provided and must be legible for credit to be awarded. . The exam is 50 minutes long, so budget your time accordingly . You are permitted two 8.5 x 11 equation/note sheets No worked problems are permitted on equation/note sheet Write your name on your equation/note sheets and hand them in with your exam Do not write in this space I) For the stress state shown below, answer the following questions using the 2-D analytic expressions as necessary for stress transformation (NOT Mohr’s circle). a) What is the maximum normal stress for rotations in the x-y plane? (5 pts) b) What is the minimum normal stress for rotations in the x—y plane? (5 pts) c) What is the name given to these stresses? (5 pts) d) At what element rotation angle (from the horizontal) do these stresses first occur? (5 pts) e) What is the shear stress in this orientation? (5 pts) YA ._ 14’ NV]; ‘2) 0;“ Rama (y 96/ :Wt . /z{‘( (1) PRINL 9% 577255555 xb X47 W (9’ ) ‘2’ _ o a ‘v abefémdmgig =1 9.2 l g 1133” 2) a) For the strain state shown, plot Mohr’s circle, labeling the axes and points P and Q<§ts> _ P+r P PW} mm” ay=0.003 5x=0~001 M Q l, .‘ F; 5 ‘ “009 ourng H 3 (bf/MAJ rag/2::O‘OD3 .- yxy = 0.006 ex 0.002 b) A state of strain and its corresponding Mohr’s circle representation is shown below (the usual conventions were followed in drawing the Mohr’s circle representation). Draw on the Mohr’s circle representation the strain state corresponding to a 30 degree counter—clockwise rotation of the element. 5’ +5. yxy = 0.004 (0, -0002) 8X 0.010 c) A given strain state, 8,: 0.010, sy=0,yxy= 0.004 is shown on Mohr’s circle below (the usual conventions were followed in drawing the Mohr’s circle representation). Calculate, using basic geometry and trigonometry, the strains (8,, eygyxy) resulting from a 45 degree clockwise rotation on Mohr’s circle (15 pts.) In order to save you some time, I have calculated the following for you; é a [j Center ofthe circle: (0.0050) 4 U 55" 6 Radius of the circle: 0.0054 ’1 l/IN / 1 I Mb' Angle 20p = - 21.8 degrees (a w {b é‘“ [1 [:0 007/ V?” ’= = 0.00577» 0:90:41” ’ ' g {X CK + R cosfii -— ’ 49544054532 0,0029 \7 g):- CX ’ 726054: - amps—0 3) a) The 3-D stress state shown below can be evaluated using 3—D Mohr’s circle. Explain why. (5 pts) if b) Using Mohr’s circle, determine the principal stresses ()0 pts) 0) Using Mohr’s circle, determine the absolute maximum shear stress ( pts) 3. 2.9 x / 00 &A\\\ at - 60 z a; ‘3 “M0 /—- 40 20 Nxaf’ _;& MPa i L F— or ‘20 60 MPa 7 / xv“) 7W0 ‘firfiflflé, SAW page; MA Eel-{‘0 4) Two thin-walled pressure vessels, one spherical and one cylindrical, of identical inside radius (R = 24—in) and wall thickness (t = 0.125-in.) are connected by a tee fitting to the same pressurized input line (i.e. both experience the same internal and external pressure). Both vessels are constructed of a material having a strength of 100 000 psi. Assuming failure will occur when the maximum nomial stress in the vessel exceeds the material strength, answer the following: :1) Which vessel will fail first? Why? (no credit without explanation) (10 pts.) b) If the inside radius of both vessels remains 24-in., and the wall thickness of the spherical vessel remains 0.125-in., what wall thickness of the cylindrical vessel will cause both vessels to fail simultaneously. (15 pts.) \\ a) 72:34 ,5: was - 9 Mo 000 P50 17 —’EE “at ll 07mm 5F)» %\m3mu~i a, . in) 77,Q.;\$ ti‘lt‘S/ MA'Y‘ dw%$ m lmaer n vavw‘i') 9 R=94“ \\ 165 0,135 Far flmul+nn£W5 gfibm‘ 03AM :. 02am SFhl . 6% ...
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This test prep was uploaded on 04/08/2008 for the course ENGR 213 taught by Professor Keil during the Spring '06 term at Oregon State.

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Exam2KeyW06 - ENGR 213 Winter 2006 Exam 2 Name Instructions 1 2 Do not open the exam until you are told to do so There are 4 problems on this exam

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