Minimum Fiber Length

Nearly all micromechanics models for short-fibers filled systems consider the same basic assumptions  

In short-fibers composites, loads are transferred from the matrix to the fibers in a zone near the fiber end, so that how the stress is distributed aroimd a fiber is an important aspect. A basic approach to this problem is the classical 

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The critical fiber length, /c, is the minimum fiber length that will allow tensile failure of the fiber rather than shear failure of the interface. It can be calculated from Eq. (15.46) ... 

Fiber length, critical Minimum fiber length required for shear loading to its ultimate strength by the matrix. 

The value of / is 1 when the fibers are aligned and /j when the fibers are randomly oriented, i.e., isotropic composites. The value of /is decreased when the length of the fiber is less than the critical length (minimum chain length required for entanglement of the polymer chains). 

The improved mechanical properties of reinforced plastics require that the fiber length exceed a certain minimum value. The aspect ratio (length/diameter) of the fibers should be at least about 100 for the full benefits of reinforcement. This is why particulates like carbon black are reinforcements only for hydrocarbon elastomers, but not for plastics generally. 

Average Fiber Length V Minimum Distance between Fibers... 

The minimum effective length for short fibers can be calculated with Equation 7.3. 

The shear-lag analysis of fiber-reinforced composites considers that below a certain length, a fiber is no longer effective in supporting the transfer of load from the matrix. There is thus a minimum effective fiber length that can... 

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