Advanced non-linear dynamics, finite element computational methods and tools are utilized in order to assess the blast wave mitigation potential of the fluid–structure interaction phenomena involving rigid and deformable structures. The employed computational methods and tools are verified and validated by first demonstrating that they can quite accurately reproduce analytical solutions for a couple of well-defined blast wave propagation and interaction problems. Then the methods/tools are used to investigate the fluid–structure interaction phenomena involving deformable structures while accounting for both the interaction of the incident blast wave with the structure and for the structure-motion induced blast wave (at the back-face of the structure). To assess the role of the structure deformability, i.e. the role of the shock waves generated within the structure, the results obtained are compared with their rigid structure counterparts. This comparison established that no additional structure-deformability-related blast-mitigation effects are observed in the case of fully supported blast wave loading while, under exponentially decaying blast wave loading, such effects are observed but only under conditions when the shock wave propagation time within the structure is comparable with the incident wave decay time.

The limitations posed by batteries have compelled the need to investigate energy harvesting methods to power small electronic devices that require very low operational power. Vibration based energy harvesting methods with piezoelectric transduction in particular has been shown to possess potential towards energy harvesters replacing batteries. Current piezoelectric energy harvesters exhibit considerably lower power to weight ratio or specific power when compared to batteries the harvesters seek to replace. To attain the goal of battery-less self-sustainable device operation the power to weight ratio gap between piezoelectric energy harvesters and batteries need to be bridged. In this paper the potential of integrating lightweight honeycomb structures with existing piezoelectric device configurations (bimorph) towards achieving higher specific power is investigated. It is shown in this study that at low excitation frequency ranges, replacing the solid continuous substrate of conventional bimorph with honeycomb structures of the same material results in a significant increase in power to weight ratio of the piezoelectric harvester. At higher driving frequency ranges it is shown that unlike the traditional piezoelectric bimorph with solid continuous substrate, the honeycomb substrate bimorph can preserve optimum global design parameters through manipulation of honeycomb unit cell parameters. Increased operating lifetime and design flexibility of the honeycomb core piezoelectric bimorph is demonstrated as unit cell parameters of the honeycomb structures can be manipulated to alter mass and stiffness properties of the substrate, resulting in unit cell parameter significantly influencing power generation.

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Purpose -This paper aims to utilize purpose advanced fluid-structure interaction, non-linear dynamics, finite-element analyses in order to investigate various phenomena and processes accompanying blast wave generation, propagation and interaction and to assess the blast-wave-mitigation potential of a piston-cylinder assembly placed in front of the target structure. Design/methodology/approach -The employed computational methods and tools are verified and validated by first demonstrating that they can quite accurately reproduce analytical solutions for a couple of well-defined blast wave propagation and interaction problems. Findings -The methods/tools are used to investigate the piston-cylinder blast-mitigation concept and the results obtained clearly reveal that significant blast-mitigation effects can be achieved through the use of this concept. Furthermore, the results showed that the extent of the blast-mitigation effect is a sensitive function of the piston-cylinder geometrical parameters. Specifically, the mass of the piston and the length of the cylinder are found to be the dominant factors controlling the extent of the blast-wave-mitigation. Originality/value -The work demonstrates that, when assessing the blast-wave-mitigation potential of the piston-cylinder concept, it is critical that loading experienced by the piston be defined by explicitly modeling (fluid/structure) interactions between the blast wave(s) and the piston. IntroductionWithin the present work, advanced fluid-structure interaction (FSI) computational methods and tools are utilized in order to assess the blast-wave-mitigation potential of a piston-cylinder based assembly placed between the incident blast wave(s) and the target structure/personnel. Thus, the main aspects of the present work include:

This paper proposes Wireless Power Transfer (WPT) system, consisting of transmitter-receiver coils along with some conditioning and stabilizing circuits. The transmitter circuit is designed with a simple H bridge circuit to supply the pulses to source coil. The efficiency variation or performance with respect to the coil size has been demonstrated in this paper, which is not well demonstrated experimentally in the past. It is about an inductive link efficiency calculation as a function of the geometrical dimensions. The efficiency has been derived analytically, and analytical results are validated experimentally. From the results observed the effect of geometrical dimensions (area, distance, shape, and size) is explored. The performance analysis evaluated analytically against experimentally, infers that the inductive coupling with same sized coil has achieved maximum power transfer wirelessly, for a shorter distance with applied ▻ View in search results format All Export