Effective fiber length matrix modulus

A7.1.2 Effect of Matrix Modulus on Effective Fiber Length... 

A7.1.3 Effect of Fiber-to-Matrix Modulus Ratio on Effective Fiber Length/Diameter Ratio... 

Eiber lengths between 5 and 10 mm are conveniently selected for the microindentation test (111). Eor a carbon fiber/epoxy system, as the fiber volume fraction increases from 10 to 50 vol%, the indentation displacement distance decreases from 44 to 36 pm but the interfacial shear strength increases from 33 to 46 MPa. When the interphase-to-matrix modulus ratio increases from 1.0 to 7.5, the interfacial shear stress increases by only 10%. Likewise, the interphase thickness and fiber diameter have marginal effects on the interfacial shear stress. Three types of thermoplastic polymers (polyester, polyamide, and polypropylene) were tested for their interfacial shear strength to the glass fiber by Desaeger and... 

Folkes and Wong [79], in their study of adhesion between fiber and matrix of thermoplastic composites, noticed that the formation of transcrystalline morphology around glass fibers in polypropylene has an effect on the critical fiber length, probably through the change in local interphase modulus. 

The discrete atomic nanotube structure replaced the effective hollow cylinder having the same length and outer diameter as a discrete nanotube with effective Young s nanotube modulus determined from atomic structure [7], The stress transfer between fiber and matrix in RVE was determined using modified shear-lag model [8], For example, in the region laxial component of stress tensor (dimensionless form) for fiber matrix has the following form... 

In this expression, Ef and Em are the Young modulus of respectively the fiber and the matrix, and f is the fiber volume fraction. //0 is the fiber orientation factor this factor is equal to 1 for perfectly oriented fibers and 1/6 for a random orientation, tj, is the so-called effective length coefficient (10), which mainly depends on the aspect ratio of the fiber. Indeed ... 

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