Fractography

About: Fractography is a research topic. Over the lifetime, 5043 publications have been published within this topic receiving 86068 citations.

A Progressive Damage Methodology for Residual Strength Predictions of Notched Composite Panels

Abstract: The translaminate fracture behavior of carbon/epoxy structural laminates with through-penetration notches was investigated to develop a residual strength prediction methodology for composite structures. An experimental characterization of several composite materials systems revealed a fracture resistance behavior that was very similar to the R-curve behavior exhibited by ductile metals. Fractographic examinations led to the postulate that the damage growth resistance was primarily due to fractured fibers in the principal load-carrying plies being bridged by intact fibers of the adjacent plies. The load transfer associated with this bridging mechanism suggest that a progressive damage analysis methodology will be appropriate for predicting the residual strength of laminates with through-penetration notches. A progressive damage methodology developed by the authors was used to predict the initiation and growth of matrix cracks and fiber fracture. Most of the residual strength predictions for different panel widths. notch lengths, and material systems were within about 10 percent of the experiemntal failure loads.

Nanoparticle-induced enhancement in fracture toughness of highly loaded epoxy composites over a wide temperature range

Abstract: The fracture toughness of an epoxy molding compound (EMC) has been enhanced over a wide temperature range by the addition of a very low volume fraction of silica nanoparticles to the EMC filled with micro-silica particles, which induces macroscopic crack deflection and plastic deformation in front of the crack tip. To evaluate the fracture toughness (GIC) of these materials, the single edge notched bending (SENB) test was performed for a wide range of temperatures (from ambient temperature to 230°C). The fracture toughness of the nano-silica filled EMCs was found to be improved in this temperature range by as much as a factor of two. Investigation of the fracture surfaces revealed that the micro-silica particles are covered with deformed matrix materials, which implies that the silica nanoparticles induced the crack to move into the interface between the micro-silica particles. Fractography results suggest that the silica nanoparticles act as surface modifiers of the micro-silica particles, which results in crack deflection and plastic deformation.