Lecture 13

Today’s objectives-Composite Applications and Discontinuous (short) fibers ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Optimal fiber length ,[object Object],[object Object],[object Object],Poorer fiber efficiency Better fiber efficiency fiber diameter shear strength of fiber-matrix interface or the matrix itself (whichever is smaller) fiber strength in tension

Review for Long Fibers (L>L c ): ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Problem 16.16 ,[object Object],[object Object],[object Object],And, solving for Vf yields, Vf = 0.418 = 1440 MPa 76 3 Nylon 6,6 3400 72.5 Glass fiber σ * (MPa) E (GPa) And, to calculate the transverse strength:

Fiber composite strengthening mechanisms ,[object Object],[object Object],[object Object],[object Object],[object Object]

Fiber composite failure as a f(load orientation) ,[object Object],[object Object],[object Object],http://www.matter.org.uk/matscicdrom/manual/co.html#_Toc360435310

What if fibers are short (<30L c =“discontinuous”)? ,[object Object],[object Object],[object Object],• Examples: disk brakes, gas turbine exhaust flaps, nose cones. Adapted from F.L. Matthews and R.L. Rawlings, Composite Materials; Engineering and Science , Reprint ed., CRC Press, Boca Raton, FL, 2000. (a) Fig. 4.24(a), p. 151; (b) Fig. 4.24(b) p. 151. (Courtesy I.J. Davies) Reproduced with permission of CRC Press, Boca Raton, FL. (b) (a)

Strength for aligned fibers of various lengths ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],F F F

E for Discontinuous and random fibers ,[object Object],[object Object],[object Object],1 Parallel to fibers Parallel 0 Perpendicular Parallel 3 / 8 Any in-plane direction Random, uniform, in plane 1 / 5 Any direction Random, uniform, in all directions K Stress Direction Fiber Orientation

Summary of fiber orientation effects ,[object Object],[object Object],[object Object],[object Object]

Polymer matrix composites ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

More polymer matrices ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Carbon-Carbon composites ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Ceramic Matrix Composites ,[object Object],[object Object]

Transformation Toughening ,[object Object],[object Object],[object Object]

(Mostly) uniaxial fiber composite fabrication ,[object Object],[object Object],[object Object],http://www.netcomposites.com/news.asp?2714 ,[object Object],[object Object],[object Object],[object Object],[object Object]

Start to finish http://www.owenscorning.com/ http://www.acp-composites.com/ACP-CAT.HTM

More (mostly) uniaxial fiber composite fabrication ,[object Object],[object Object],[object Object],[object Object],http://www.acmanet.org/pic/products/description.htm

Fiber composite fabrication, not uniaxial ,[object Object],[object Object],[object Object],[object Object],http://www.owenscorning.com/

Hybrids ,[object Object],[object Object],[object Object],[object Object],http://www.owenscorning.com/

Structural Composites ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

SUMMARY ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Lecture 13

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Lecture 13