Multiwalled carbon nanotubes of 0.2% weight fraction are used as a sensory network for detecting and characterizing the damage of particulate epoxy composites under shear loading conditions. Three different weight fractions of carboxyl-terminated butadiene acrylonitrile copolymer rubber [10 parts per hundred of epoxy resin (phr), 20 phr, and 30 phr] are used for toughening a thermoset epoxy composite. The electrical response of the specimens is measured, nearest the central shearing plane, using a four-circumferential ring probe technique in conjunction with a high-resolution data acquisition system. A collection of the electromechanical response results are reported with respect to the shear strain. The resistance changes observed under shear loading are related to nonlinear deformation mechanisms, void initiation, and growth around rubber particulate. With increasing rubber content, the strength of the material decreases and a greater drop in resistance is recorded as a result of decreased distance between neighboring carbon nanotubes (CNTs) due to declustering and straightening of molecular chains of host matrix. In the end, a comparison for 30 phr composites under shear loading with that of tensile and compression loading conditions is presented. For initial deformation, there is no change in resistance under shear loading condition; however, the significant resistance change can be noticed under both tension and compression. The specimen under shear loading conditions experiences smaller decrease in resistance when compared with both tension and compression. However, the decrease in resistance is higher for compression due to higher decrease in distance between neighboring CNTs. POLYM. COMPOS., 37:360-369, 2016.
In the early days of aviation, maintenance requirements were determined by a few experienced mechanics with assistance from the Original Equipment Manufacturer (OEM). As aircraft became more complex, a more sophisticated method of developing an aircraft maintenance program was needed. The approach aimed for a data driven maintenance philosophy. Just as sequential aircraft designs introduced new enhancements, each revision to the maintenance logic improved the maintenance approach in terms of effectiveness. The latest approach to this maintenance philosophy is known by the acronym MSG-3, for Maintenance Steering Group 3. As scheduled maintenance requirements for aircraft continue to change, the procedures need to be effective, reliable, and economically reasonable. The approach and benefits of an MSG-3 program are discussed in reference to the Bell 525, a new fly-by-wire, 16-passenger commercial helicopter under development at Bell Textron Inc. The development of the 525's MSG-3 maintenance program and its benefits to operators are discussed. The MSG-3 process schedules aircraft maintenance tasks necessary to maintain the stated levels of reliability and safety, reducing direct maintenance costs by 30% while maximizing aircraft availability (Ref 1).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.