30 research outputs found
Structural flax/PLA biocomposites: understanding of their thermo-mechanical behaviour.
The extended use of bio-composites for the manufacturing of vehicle components would largely benefit the industry. However, the properties of biocomposites, their mechanical performance under different environments and the effect of different loading conditions are still unclear. Systematic studies have been conducted on flax/PLA biocomposites, to determine the phenomena dominating their mechanical behaviour and their potential use in structural automotive applications
Electronic and optical properties of beryllium chalcogenides/silicon heterostructures
We have calculated electronic and optical properties of
Si/BeSeTe heterostructures by a semiempirical
tight-binding method. Tight-binding parameters and band bowing of
BeSeTe are considered through a recent model for highly
mismatched semiconductor alloys. The band bowing and the measurements of
conduction band offset lead to a type II heterostucture for
Si/BeSeTe with conduction band minimum in the Si layer and
valence band maximum in the BeSeTe layer. The electronic
structure and optical properties of various (Si/(BeSeTe [001] superlattices have been considered. Two
bands of interface states were found within the bandgap of bulk Si. Our
calculations indicate that the optical edges are below the fundamental bandgap
of bulk Si and the transitions are optically allowed.Comment: 16 pager, 7 figure
Tannin-based flax fibre reinforced composites for structural applications in vehicles.
Innovation is often driven by changes in government policies regulating the industries, especially true in case of the automotive. Except weight savings, the strict EU regulation of 95% recyclable material-made vehicles drives the manufactures and scientists to seek new 'green materials' for structural applications. With handing at two major drawbacks (production cost and safety), ECHOSHELL is supported by EU to develop and optimise structural solutions for superlight electric vehicles by using bio-composites made of high-performance natural fibres and resins, providing enhanced strength and bio-degradability characteristics. Flax reinforced tannin-based composite is selected as one of the candidates and were firstly investigated with different fabric lay-up angles (non-woven flax mat, UD, [0, 90°]4 and [0, +45°, 90°, −45°]2) through authors' work. Some of the obtained results, such as tensile properties and SEM micrographs were shown in this conference paper. The UD flax reinforced composite exhibits the best tensile performance, with tensile strength and modulus of 150 MPa and 9.6 MPa, respectively. It was observed that during tension the oriented-fabric composites showed some delamination process, which are expected to be eliminated through surface treatment (alkali treatment etc.) and nanotechnology, such as the use of nano-fibrils. Failure mechanism of the tested samples were identified through SEM results, indicating that the combination of fibre pull-out, fibre breakage and brittle resins failure mainly contribute to the fracture failure of composites
Nested Topology Optimization Methodology for Designing Two-Wheel Chassis
Weight reduction has always been a challenge for the automotive industry, mainly to reduce consumption but also improve handling. In electric vehicle design, the battery packs, their shape and positioning are critical aspects that determine the overall weight, weight distribution and, as a consequence, the efficiency, dynamics and stability of the vehicle. This presented a new challenge, to manage this necessary and inflexible weight and volume, developing the vehicle chassis around it and in the best possible way, without compromising the overall efficiency and behavior. In this work, a methodology for nested topology optimization has been developed which combines structural topology optimization and battery pack shaping and positioning. The new methodology is implemented without limiting its applicability, into the framework of the commercial software Hyperstudy by Altair
Highly anisotropic room-temperature sub-half-micron Si reactive ion etching using fluorine only containing gases
Visible luminescence from one- and two-dimensional silicon structures produced by conventional lithographic and reactive ion etching techniques
Performance evaluation of a Radio over Fiber (ROF) system subject to the transmitter's limitations for application in broadband networks
The increasing demand for high data rates in wireless networks indicates Radio-over-Fiber (RoF) as an excellent candidate for physical layer infrastructure in the development of future broadband communication systems. In this work, a thorough investigation on the performance of an intensity-modulation direct detection (IM-DD) RoF system utilizing orthogonal frequency division multiplexing (OFDM) is performed, emphasizing on the transmitter's impairments, and to what extend the above limitations are compensated by typical demodulation techniques implied in OFDM technology. It is shown that an acceptable performance is depicted up to 5.8GHz carrier frequency, by a proper adjustment of the laser's current RF amplitude level. © 2008 IEEE