Short Fiber Composites

Whisker and Short Fiber Composites. Whiskers and short fibers tend to align during forming, lea ding to anisotropic properties and large... 

Short-fiber composites fabrication of, 26 766 Short fiber metal-matrix composites, casting process for, 76 168 Short fiber web layering systems, 77 504 Short oil alkyds, 2.T48 Short random fiber reinforcement,... 

Aboudi, J. (1983). The effective moduli of short fiber composites. Int. J. Solids Struct. 19, 693-707. 

Toughness maps for short fiber composites can also be established in a similar manner, but no such maps have been reported. The difficulty stems from the large number of material and process variables that are used to fabricate these... 

In short fiber composites, energy absorption mechanisms, such as interfacial debonding and matrix cracking, most often occur at the fiber ends (Curtis et al., 1978). The damage model proposed by Bader et al. (1979) assumes that short fiber composites fail over a critical cross-section which has been weakened by the accumulation of cracks, since the short fibers bridging this critical zone are unable to carry the load. In fatigue loading, sudden fracture takes place as a direct result from the far-field effect of the composite, rather than due to the near field of the crack tip... 

It is assumed that the maximum stress in the next fiber located at a distance dj away is approximately equivalent to the composite tensile strength, cr. It follows then that the damage zone size, cq, for aligned short fiber composites is given by (Lauke et al., 1985)... 

Agarwal, B.D. and Glare, G..S. (1982). Influence of the properties of the matrix material on the fracture toughness of short fiber composites. Mater. Sci. Eng. S2, 139-145. 

Sato N., Kurauchi T., Sato, S. and Kamigaito O. (1988). Reinforcing mechanism by small diameter fiber in short fiber composite. J. Composites Mater. 22, 850-873. 

Mitaka, Y. and Taya, M. (1986). Thermal stress in a coated short fiber composites. J. Appi. Mech. 53, 681-689. 

Unlike short-fiber composites, modulus and strength in long-fiber composites are little affected by the interface. However, the interface does affect off-axis properties, such as compressive modulus, and the toughness and shear strength are affected. As shown in Eigure 5.107, a reduction in the interfacial strength, such as through the... 

Lang RW (1984) Applicability of linear elastic fracture mechanics to fatigue in polymers and short-fiber composites. PhD-Dissertation, Lehigh University, Bethlehem, PA... 

Short Fiber Composites Problem Sets References... 

Figure 2. Minimum creep rate (a) and time to fracture (b) versus stress for the monolithic alloys and their short fiber composites.

There are no standard test methods specific for discontinuous fiber (or short fiber) reinforced thermoplastics. It is also not clear whether a geometry-independent fracture parameter can be measured for these nonuniformly inhomogeneous materials. However in spite of these reservations there has been considerable work conducted towards characterizing short fiber composites for fracture toughness using the standard and other procedures outlined in the previous sections. The investigators have recognized that fracture mechanics data provide much more reliable information than the customary alternative tests for material selection and also a service performance indicator for components. 

Short fiber composites are used in many apphcations. They are not as stiff or as strong as composites with continuous fibers, but they can be formed economically by injection molding or by in situ polymerization. Choice of an optimal fiber length can result in improved toughness, due to the predominance of fiber pull-out as a fracture mechanism. 

---