94 research outputs found
A novel design and manufacturing method for compliant bistable structure with dissipated energy feature
No full textIn this paper, a novel design concept and manufacturing method for the compliant bistable structure is proposed. The pulsed laser technique is utilized as the manufacturing method for both the fabrication and the introduction of desired pre-stresses, simultaneously. Based on this concept, a novel bistable structure consisted of one pre-compressed main beam, and a pair of supporting beams is designed and fabricated. The deformation difference between the main beam and the supporting beams induced by laser heating residual stress make the main beam to buckle under the constraints of two supporting beams and possess a bistable feature. The bistable structures can be implemented into other devices in the form of cantilevers thanks to the internal integration of the buckled beam and the boundary conditions. The characteristics of this new bistable structure, including its stable shape and snap-through response, are investigated both experimentally and numerically. During the snap forth and back process with the snapping load of 19 mN and the required energy of 77 mN·mm, an impressive energy dissipation with a loss factor value of 0.3 exists. Finally, a parametric study was carried out to find the critical performance parameters.Mechatronic Systems Desig
In-situ damage mechanism investigation and a prediction model for delamination with fibre bridging in composites
No full textCarbon-fibre reinforced composites are susceptible to delamination. Fibre bridging is an important shielding mechanism frequently observed in delamination. The presence of these bridging fibres can significantly increase interlaminar resistance, making it critical to represent this phenomenon for delamination characterization in composite laminates. To this end, in-situ SEM examinations were carried out to thoroughly explore damage mechanisms around delamination front as well as in bridging fibres. It was found that micro-cracks initiated at fibre–matrix interface can gradually develop and coalesce into micro-delaminations ahead of the main crack. The accumulation of these micro-delaminations can finally cause macro delamination propagation. The performance of bridging fibres can be summarized as three typical stages, i.e. bending, fibre–matrix peeling and final breakage with crack opening. Subsequently, theoretical discussions on bridging stress distribution were conducted in accordance with these bridging mechanism examinations, contributing to a new traction-separation constitutive to represent fibre bridging performance. A FEA prediction model was finally developed to characterize delamination behavior with fibre bridging. The simulation results can agree well with the experimental data in the entire delamination, demonstrating its effectiveness in fibre-bridged delamination representation. This study also demonstrated the importance of having in-depth understanding on fibre bridging mechanisms to appropriately represent bridging performance during delamination growth in composite laminates.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Structural Integrity & Composite
Zhong-Lab-UCSD/Genomic-Interactive-Visualization-Engine: Code refactoring, issue fixing and others
No full text<ul>
<li>Better documentation</li>
<li>Refactored code to make path simpler</li>
<li>Other major and minor fixes</li>
</ul>
Zhong-Lab-UCSD/Genomic-Interactive-Visualization-Engine: Release fixing issues
No full text<ul>
<li>Fixed issue with new genome assemblies;</li>
<li>Fixed some issue with UI.</li>
</ul>
GIVE: portable genome browsers for personal websites
No full textAbstract Growing popularity and diversity of genomic data demand portable and versatile genome browsers. Here, we present an open source programming library called GIVE that facilitates the creation of personalized genome browsers without requiring a system administrator. By inserting HTML tags, one can add to a personal webpage interactive visualization of multiple types of genomics data, including genome annotation, “linear” quantitative data, and genome interaction data. GIVE includes a graphical interface called HUG (HTML Universal Generator) that automatically generates HTML code for displaying user chosen data, which can be copy-pasted into user’s personal website or saved and shared with collaborators. GIVE is available at: https://www.givengine.org/
Low-frequency vibration absorption of magnetic quasi-zero-stiffness structures with lever mechanism
No full textDynamic vibration absorbers (DVAs) are widely employed in diverse engineering systems for their capacity to mitigate structural vibrations. However, traditional absorbers exhibit sensitivity to natural frequencies and present challenges in tuning within the low-frequency range. This study introduces a lever mechanism to enhance the low-frequency vibration absorption performance of magnetic quasi-zero-stiffness structures, resulting in a lever-type DVA (L-DVA). We elucidate the design philosophy behind the proposed L-DVA. An analytical model is derived based on the Lagrange equation and the frequency-response relationship is determined using the harmonic balance method. We conduct numerical and experimental analyses to assess the impact of the lever ratio, mass ratio, frequency ratio, nonlinear stiffness coefficient ratio, and damping ratio on vibration absorption performance. Furthermore, we fabricate a prototype of the L-DVA with an adjustable magnetic quasi-zero-stiffness structure, and the experimental results align with simulation outcomes. The result shows that this study is the ease of customization in the vibration absorption capabilities of magnetic quasi-zero-stiffness structures, achieved by adjusting the lever ratio. An increase in the lever ratio and tip mass effectively shifts the anti-resonant peak to a lower frequency. The decrease in the frequency ratio leads to a reduction in the anti-resonant frequency. This study validates the efficacy and feasibility of utilizing the L-DVA for low-frequency vibration absorption
Rhombus-type magnetic-levitation structure for low-frequency vibration isolation
No full textThis paper presents a rhombus-type magnetic-levitation structure (RMLS) to achieve effective low-frequency vibration isolation performance. The design philosophy behind the proposed RMLS integrates the motion of permanent magnets (PMs) with geometric nonlinearities to achieve high-static-stiffness-and-low-dynamic stiffness. A theoretical model for RMLS is developed, and the displacement transmissibility is determined using the harmonic balance method. Both numerical simulations and experimental verifications are conducted to examine the effects of various factors on vibration isolation performance, including the initial angle, the configuration and the parameters of PMs, the length of rods and the equilibrium position of RMLS. The experimental results demonstrate that the proposed RMLS exhibits lower peak transmissibility and isolation frequency compared to an equivalent rhombic-type vibration isolator. The RMLS offers adjustable quasi-zero stiffness (QZS) region, which effectively broadens the range of vibration isolation frequencies. Low-frequency vibration isolation performance can be further improved by reducing the distance between the fixed PMs and adjusting the initial angle of the rhombic structure. Additionally, the maglev structure enhances the load-bearing capacity of RMLS. Under a larger load, the position of the PMs can be adjusted to maintain a wider QZS region, ensuring effective vibration isolation. This study provides a valuable guidance for the design of low-frequency QZS vibration isolators
Cancer core modules identification through genomic and transcriptomic changes correlation detection at network level
No full textRobust diagnosis framework based on sliding least squares estimate and directional discrepancy
No full text- …
