Improvement of Vibration Damping Capacity and Fracture Toughness in Composite Laminates by the Use of Polymeric Interleaves

Abstract

It is shown that, under certain conditions, simultaneous improvement of vibration damping capacity and interlaminar fracture toughness in composite laminates can be achieved by using polymeric interleaves between the composite laminae. The specific case of Mode II interlaminar fracture toughness and flexural damping capacity of interleaved composite laminates is studied. Graphite/epoxy, E-glass/epoxy and E-glass/polyetherimide composite laminates with polymeric interleaves of several different thicknesses and materials were tested using both the end notch flexure (ENF) test for Mode II fracture toughness and the impulse-frequency response test for flexural damping capacity. The Mode II energy release rate GIIc for all three composites increased linearly with increasing interleaf thickness up to a critical thickness, then dropped off with further increases in thickness. The damping loss factor η for all three composites increased linearly with increasing interleaf thickness up to the maximum thickness. Analytical models for predicting the influence of interleaves on GIIc and η are developed, along with a hypothesis for the critical thickness effect with regard to fracture toughness.

A Method to Extract Interface Stress Intensity Factors for Bimaterial Problems using Interlayers

“…Such interlayers are also at times deliberately introduced between plies of composite laminates. This technique, called interleaving, sometimes increases the toughness of the interface (Carlsson and Aksoy, 1991;Davidson and Hu, 1995;Hu and Abatan, 1999;Gibson et al, 2001). The universal relation developed in this paper, can be of use in the analysis of such material systems.…”

Palliatives for Low Velocity Impact Damage in Composite Laminates

“…This technique of interleaving enhances growth of crack-tip yield zone in the region between the plies [145]. Frequently used interleaving materials include thin thermoplastic films such as PEEA/PA film [146,147], bisphenol A based epoxy [145], FM 300 epoxy resin [148,149], PEI films [149], poly(ethylene-co-acrylic acid) PEAA [150,151], polyethylene based films [152], epoxy modified with carboxyl-terminated butadiene acrylonitrile (CTBN) and polyurethane (PU) [153], cyanate ester/epoxy resin film [154], glass/epoxy softening strips [155], and nitride rubber modified epoxy interleaves [156]. However, degradation of hot/wet properties and inferior handling characteristics such as drape and tack have restricted the usage of this technology [157].…”

Improvement of the impact and crack resistance of epoxy thermosets and thermoset-based composites with the use of thermoplastics as modifiers

“…The resulting semifinished products are sometimes called multilayer prepregs. This modification makes it possible to improve various characteristics of PCMs, including, for example, the vibration dampening capacity [90]. At the same time, the interrelationship of various mechanical characteristics of PCMs and their dependence on the structure of the intermediate layer may be very complex [91].…”