A study of the impact behavior of chopped fiber reinforced composite

Abstract

The impact behavior of sheet molding compound (SMC) plaques was determined by using an instrumented Instron puncture test machine and the failure mechanism was qualitatively assessed by examining the damage. The impact response of SMC in terms of the load‐deflection curve is fairly consistent and shows the characteristics of a composite, intermediate between a brittle and a ductile material. At the speed of 2 m/s (about 5 miles per hour) the fracture energy, i.e., energy to break, was determined to be about 10 J for a regular 3 mm thick R‐25 SMC panel. This value decreases exponentially with a decrease in the thickness of the panel (power of 2.7). The failure process could also be affected by the material factors (resin and fibers used in the composite). For instance, an examination of the length distribution of the fibers in the damage region indicates that a combination of fiber pull‐out and severe fiber breakage have contributed to the impact resistance. Also, the fiber length in the composite could alter the failure modes. With the 25 mm fibers, the damage consists of an even mixture of fiber breakage and fiber pull‐out, but with a mixture of equal numbers of longer (38 mm) and shorter (13 mm) fibers in the composite, the damage is shifted to predominantly breakage of the longer fibers.

Pretreatments of natural fibers and their application as reinforcing material in polymer composites—A review

“…Impact resistance is the ability of a material to resist breaking under a shock loading or the ability to resist fracture under stress applied at high speed. A lot of work has already been done on the impact resistance of short fiber reinforced composites [190][191][192] and it depends on fiber rigidity, interfacial stress resistance and fiber aspect ratio. The strength of the matrix, the weakest part of the material, should be related to the failure process.…”

Trends in Real Estate Research, 1988–2001: What’s Hot and What’s Not

“…The ®gure reveals that papers in REE are more highly cited on average than papers in JREFE, a result con®rmed by regression. 6 In an attempt to ascertain how much of this difference is attributable to the expected lower citation rates for papers in the early years of JREFE before it had established its presence in the real estate community as an important research outlet, Figure 1(b) presents the synthetic life cycle of citations per year ignoring the period from 1988 to 1992. Although the time period is rather limited, the graph reinforces the view that the citation performances of the two journals are converging in recent years.…”