1,721,064 research outputs found
Novel processes to reinforce the piezoelectric actuator interface with carbon nanotubes
No full textA study was performed to develop a novel technique to enhance the bond strength between a piezoelectric (PZT) actuator and a hosting structure. The bond interface has been considered to be a critical linkage between the structure and the surface-mounted actuators. The loss of interface integrity can have a detrimental effect on the performance of the PZT actuators. The key feature of the proposed technique is to embed a high-density array of oriented carbon nanotubes (CNTs film) into the adhesive layer between the structure and the actuators to enhance the interfacial strength. This presentation focuses primarily on the two fabrication techniques that were developed during the investigation: one is to grow the CNTs directly on the PZT surface at elevated temperatures and the other is to grow the CNTs film on a substrate and then transfer it into the bonding layer at significantly lower temperatures. The latter method is a cost-effective and easy technique which has the potential to be used for structural (as the one proposed here) and for high-performance electronic applications. Through a microscopic examination of the adhesive, it was found that CNTs were uniformly dispersed and aligned into the bonding adhesive. Mechanical tests were performed to investigate the shear strength of the adhesive layer with the embedded CNTs film. Preliminary results show that an increase of the bondline strength up to nearly 300% could be achieved. However a wide data dispersion was also observed and might be attributable to the ratio between the length of the CNTs and the actual PZT-structure gap [1]
HIBRID VEHICLE PROVIDED WITH THE SYSTEM “FUEL CELL-FLYWHEEL ENERGY STORAGE” FOR URBAN PUBLIC TRANSPORTATION
No full textSYSTEM OF ABOVEGROUND URBAN PUBLIC TRANSPORTATION WITH POINT TO POINT ELECTRICALLY POWERED BUSES
No full textCharacterization Method of the V-shaped High-Temperature Superconducting Maglev Module for Transport System Applications
Full text linkIt is now recognized that high-temperature superconducting (HTS) technology has a significant potential for future magnetic levitation (Maglev) transit system applications due to the advantages of self-stable levitation, being free of electric power and magnetic drag to the vehicle motion, and system simplicity. This article provides a characterization method of the experimental transport system Maglev levitation module developed at the University of L’Aquila (Italy). More specifically, the lifting and guiding behavior of a single V-shaped Maglev module, which is unique for this type of application, is analyzed and tested. Its working principle is based on the interaction between HTS “skate” onboard of the vehicle and the magnetic field generated by the permanent magnets distributed on the guideway (PMG). A single scaled levitation module was built and tested under quasi-static conditions using dedicated measuring equipment by varying system parameters such as vertical gap, lateral offset, and field cooling height. The latter determines the amount of interacting magnetic field that is trapped in the HTS core during its transition from the resistive to the superconducting state and which, in turn, interacts with the field generated by the PMG to create the suspension phenomenon. The Maglev module’s dual behavior due to the double phenomenon of repulsion and attraction has been verified and tested in terms of vertical and lateral forces by varying system parameters. The dual “push and pull” force allows the phenomenon of vehicle driving to be enhanced
RESTRUCTURING NORTH AMERICAN METROPOLITAN AREAS USING THE POLYCENTRIC TOWN PLANNING CRITERION
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Self-activated morphing carbon fiber composites via cyclic internal stresses
No full textAn innovative concept to exploit self-activated morphing composite materials is presented and demonstrated experimentally. In this design, shape changes of a carbon fiber composite are achieved by combining two key ingredients: fibers orientation and temperature-sensitive epoxy resin. When the fibers are properly oriented in each layer, internal stresses can be induced or gradually released by hardening or softening, respectively, the hosting epoxy resin. The epoxy resin stiffness is controlled with the help of internal heaters (e.g. the carbon fibers as demonstrated in this paper). The proposed mechanism results in a large scale and cyclic shape-changing capability which, together with the corresponding tunable stiffness, represent the fundamental features of morphing structural materials
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