**Unformatted text preview: **éiiéﬁfﬁ/Ligﬁfr 155;_ofCompos:tes QUIZ No.1 Fall 2012 "if? I. Answer the foilowing (5 points each) 56/6? 1' BLEﬂK describe the thee major PIOCCSSES for. ﬁlament extrusion « I I; .- III . P .. III, I Mag-PI Sgig’ﬁﬁﬂﬂl .I. WII-Pm‘; Iii-P2. PIPI n22: “£5"? PIP-“PP II P 52¢. IIIIIIIPIIII .
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I iI-P‘P I IMQEEZ'IE 3. What is the approximate range of diameters of a sinwgment in advanced ﬁber—polymer composites?
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E: ‘9?ng £651” Pom .— Srlygss cleareages: wiren a {DRE-$2914" SPﬁ'agm ES mﬁﬂa‘ﬁéd; WV a bra Wise! of aim / 7. To account for the Poisson’s effects in the micromechanics models for transverse modulus E2, one has to
replace the Young’s modulus of matrix Em by (circle the correct answer) 3.. Em (l—Uf) )K 53.. “ fwﬁy Wm Fﬁg—Eaa‘g ErM-fjgwm’j‘ ”(9:5 Em
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Material Figs-ﬁg / _ 10. Name the three major constituents of ﬁber-polymer composites and state the function(s) of each
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11 [T(—9)] :[T] ./FALSE /
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V. Vd4.3’t[T ]¢l TRUE 13. The micromechanjcs models for stiffness of composite assume EY'S’EFT' $9ij - between ﬁber and II. A unidirectional lamina made 0fIM6G/3501—6 is subjected to stresses {6x37} as shown in the ﬁgure below. _
Compute the strain {812} in the local co—ordinate system. (15 points) y 5; [ﬁ 0 xpo Fm
750/" { j}: g 50}
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£512} 7— Eglzj~i57z3 ”“' ESELJLFE—j‘ir “3:; 6‘9} ii if as} >< M W W; 50533 3 III. A unidirectional composite is made up of isotropic ﬁbers with Young’s modulus EE and matrix with Young’s
modulus Ern (assume that E is greater than Em). With a ﬁber volume fraction of 50%, the longitudinal and
transverse Young s modulii fof the composite were experimentally measured as E =3OOGP2, and E2 2.20GPa 0. Estimate the ﬁber and matrix modulii using the rule of mixtures (10 points){ E! ; 300 = E; (019* Em ((05)‘ 11g, ﬁvha’c wquld be the '.15an
W5“ wmi' IV. Given the basic lamina properties E1, E2“ 1' V
mrﬁ" “ " 3 limitng value of the shear modulus GB, for the case of a h1g6 stiffness 13151113. orieIiEdr at 9=45° t0 the x- axis [0
(10 points) 1 [E 753 MECHANICS OF COMPOSITES
QUIZ N0. 2 l. A balanced 8; symmetric laminate is subjected to bending load Mk [f the twisting curvature of the laminate
has to be zero, what additional bending load IVL _ has to be applied to the laminate (4 points) 4". a _. m ’ """ r
i M? EM {it} 2. a laminate is fabricated using AS4/3501--6 maiéﬁgli‘éeﬁﬁ £"§£5é’1§ﬁ§”§"é&iﬁéﬁéé b'f""’[d790]1he 131}? thickness is 0.005 inches. Determine the component DSS of the [D] matrix for the laminate ( 6 points) £2 [4 .’ Fall 2012 pn—l 5. A AS4/ 3501-6 lamina shown below (refer to'help sheet for elastic properties) is subjected to global stress
Ux=+p. Using the Maximum Strain failure theory, (30 points) a. determine the angle 9 at which the failure mode transitions from a transverse tensile failure to a
matrix shear failure. b. What is the value of ‘p’ for this angle at failure? a? F1, = 300.5ksi EC = 250.5ksi
1+; = 10.80ksi F26 = 35.7ksi
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Fall 2012 ' 4’8 0 2 4. For the laminates listed in the table below, a. check the boxes corresponding to the components of [A] and [D] manices, whose value will be ZERO b. List the total number of plies for each laminate . I
55/,9/w/{9/f9/L9/493 [+/—
Fay/#3923928? +6 LAMINATE 7923] /—3(9] Am 537K525 0%ngﬁefzs/o ] [o / +25 / 90 / ‘25]; [
[0/+9l—9/1,80] [+QI—QL
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II a» NOTE: 6 :2 0 or 90 (same applies] tot? thickness CEO/.30 /;a/— 30‘5/423 /$0//30/3aj Fall 2012 1 , (92) ; All Xplies are made of same material and have same ply 5. ANSWER THE FOLLOWING QUESTIONS (8X5 points each) @? a. The in—plane normal strains and in—plane shear strains in a lamina are uncoupled when
ﬁg: : ﬂgﬁ 3' 0 (/L/ b. The bending and twisting deformation in a laminate are uncoupled when
“Dr 3 . _ =4 § 5/ c. The in—plane normal strains and iniplane shear strains in a laminate are coupled when ﬁxer A“: 9 f
d. The ability to predict failure modes is desirable for conducting Qfogﬁﬁsi V3 ’éf/Wﬁ farm £73k . e. The shear strength Of a lamina is associated with the following loading (circle your choice) f. HashimeRotern criterion is a (circle the correct answer)
i. Independent criterion
ii Interactive criterion V"
iii Both in ependent and interactive
iv. None of the above g. List 5 assumptions of the classical laminated plate theory I Sires/9mg 5’6”}?th ﬁt? a mem am,- exymﬁec! 9% “b9”?
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@7556 it} £VJ€WWWA§¢W? :12 plying. Sac-£2996 Feﬂnm‘rj Pi4n6./ h- Give two CXMFPIES of laminates for which the bending & twisting deformation can be decoupled. L +£55z—967 , Sig; =0
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- Spring '14
- SureshR.Keshavanarayana