Recent Submissions

  • Improving Dielectric And Magnetic Properties Of (Cr, Fe, Ni)-Doped Sic Microwaves Absorbents: A Dft Study

    Merabet, Boualem (2021-05-24) [Poster]
    In wireless telecoms, EM waves absorbers become important if applied outside special fields like rooms, radar systems, and military application. Composite materials allow convenient use on surfaces, good control over mechanical properties, variation of EM properties with proper selection of matrix material and different inclusions. Wide frequency range, zero external magnetic field, thin absorption layer (required for absorbers) limit FM materials for microwave frequency range. In absorber composites, and FM inclusions reduce impedance mismatches at front interface of absorbers and increase absorption of EM waves (V. B. Bregar, IEEE Transactions on Magnetics (2004) 40, 3). Cr4+ transition metal ions provide a rich set of optically active defect spins in wide bandgap semiconductors, and produce in SiC a spin-1 ground state with a narrow, spectrally isolated, spin-selective, near-telecom optical interface (B. Diler, npj Quantum Inf (2020) 6, 11). Cr4+ are detected by placing the device into a photonic cavity to reduce the excited state lifetime by Purcell enhancement: large fraction of indistinguishable photons in near telecom ZPL would be further enhanced (A. M. Dibos et al., Phys. Rev. Lett. (2018) 120, 243601). A metallic character shown by (Ni, Cr)-codoped 4H–SiC, and a FM order mainly due to Cr impurities, originating from a strong FM coupling due to p-d hybridization interaction, allow us using our alloys in microwave circuits as absorbers. 4H-SiC (P63mc hexagonal structure of a =b =3.081 Å, c = 10.096 Å (B. Song, et al., J. Am. Chem. Soc. 131 (2009) 1376–1377)). To avoid EM pollution caused by electronic and telecom systems, Cr-doped 4H–SiC are used. Cr behaves as donor or acceptor and the dielectric properties of SiC can be changed through n- or p-type doping in the microwave range, where enhanced dielectric loss and improved EM matching are beneficial to get excellent microwave absorption performancee.(Justo JF, MachadoWVM, Assali LVC. Physica B 2006;378:376).
  • Effect Of Infill Density And Build Orientation On The Mechanical Properties Of Pla Cf & Petg Cf Composites In 3D Printing

    Said, Ahmed A.; Aljafari, Mutaz (2021-05-24) [Poster]
    Abstract An important aspect of additive manufacturing is reducing the weight while maintaining the mechanical properties of the material. While the properties of the additive manufactured specimen depend on the type of the materials used for the filament, the settings of printing also affect the properties of specimen. Consequently, this work is about the investigation of the effect of 3D printing settings on the weight reduction and the mechanical properties of the specimen between two different filament materials and to achieve an optimum compromise between the two. The infill density and the build orientation and pattren of the printed layers are the variables being considered while all other setting remain constant in all tests. Experiments are performed using two different filaments materials types; PLA Carbon fiber and PETG Carbon fiber composites. Ahmed Abdulrahman Said King Abdulaziz University Email:
  • Ultrasensitive Wireless Strain Sensor For Structural Health Monitoring

    Nesser, Hussein (2021-05-24) [Poster]
    Objective: Embedding a monitoring system including :sensor, cable, and interface circuit is a hindrance for some structures. Our project aims to develop new generations of strain sensors that are ultra-sensitive, have wireless communication of data and energy, low consumption of power, easy installation in-situ structures. Methods: The data and energy,  from and to LRC tag, will be transmitted remotely by an inductive coupling between the internal inductance of the sensor and an external readout coil. The external strain is detected by following the variation on the quality factor of the resonance frequency of the LRC circuit resulting from the variation of resistance of cracked electrodes. Results: -Microfabrication method, alternative to silicon technology, is used in the fabrication of our sensor. -Durable, flexible and thin materials like polyimide or PET, are used in the fabrication of our sensor which facilitates the process of integrating the sensor. -High crack density is created in a nonmetric metal electrodes (Cr/Au). -High-sensitivity (GF= 6657) and low strain detection (<0.1% strain). à Working towards following the resonance frequency by an external readout coil.
  • Strategy For Toughening Interfaces In Adhesively Bonded Composite Joints

    Tao, Ran (2021-05-24) [Poster]
    Objective: Surface patterning strategy was proposed to facilitate the formation of adhesive ligaments using pulsed CO2laser irradiation, in order to enhance fracture toughness and arrest the crack propagation within adhesively bonded composite joints. Methods: Arrest regions (highlighted in green in the video), with higher interfacial strength but lower fracture toughness than the uniformly laser ablated (LA) baseline surface, are alternatively placed on the top and bottom CFRP/adhesive interface. Mode I fracture toughness was assessed through the double cantilever beam (DCB) configuration. Results: The proposed patterning strategy is promising to trigger adhesive ligaments and hold the separating arms, promoting a R-curve-like response of the bonded joint, where the energy release rate keeps increasing as the crack propagates. The proposed patterning strategy shed light to the design of reliable and safety adhesively bonded CFRP joints.
  • Laser-Based Pre-Treatment Of Secondary Bonded Composite T-Joints For Improved Energy Dissipation

    Hashem, Mjed (2021-05-24) [Poster]
    Enhanced composite T-joint energy dissipation using laser patterning strategy M. Hashem, A. Wagih, G. Lubineau Introduction Internal aircraft structures such as ribs, spars and stringers are required to be connected and must be able to transfer loads to the skin. Metallic joints require bolts and rivets which cause weight penalties and stress concentration. Composite T-joints allows the connection of structural components while maintaining low weight and high toughness. Objectives â ¢Investigate the efficacy of a novel CO_2 laser pre-treatment on the toughness of CFRP T-joints. â ¢Understand the failure mechanisms in toughened CFRP T-joints considering different surface ply orientations.   Methods CFRP T-joints were manufactured by using unidirectional carbon fiber prepregs composed of toughened epoxy resin and carbon fibers. After a general peel-ply treatment, the adherents experienced CO_2 laser treatment. We applied laser treatment with two different energy, low and high, to create laser pattern of cleaning, LC, and ablation, LA, treatment as shown in Fig. 1.  Upon the laser treatments the stiffeners and skins were secondary bonded using an Araldite 420 A/B adhesive and mechanical tested using pull-off tests. The baseline joint, where peel ply treatment was applied is nominated as â PPâ . The laser patterned joint, where the alternative high and low laser power was applied, is nominated as â B5G5â . Results High surface roughness profile fluctuations were noticed at LC treated regimes, but low profiles were observed at LA regimes. SEM shows how the high fluence LA treatment exposed fully the fibers as compared to LC which minorly removed contaminants from the surface. PP baseline resulted in catastrophic failure at low extensions (4 mm). However, the laser treated T-joints showed progressive failure with improved toughness and extensions. The maximum load and extension for B5G5 joint reach 1712 N and 17.8 mm, respectively, compared to  805 N and 4 mm for PP joint. Discussion The enhancement observed for B5G5 T-joints was related with the creation of adhesive ligaments between the top and bottom adhesive layers (Fig. 5). The adhesive ligaments were generated at the transition between LA and LC treatment due to the difference in roughness between both treatments as shown in Fig. 2, which arrest the crack propagation at one interface allowing crack migration to the other interface. The effect of laser patterning was optimised when a 0° ply fiber direction was placed at the interface.   Owing to the crack migration, the ligament formation and breakage during testing, progressive failure occurred in B5G5 T-joints with larger improvements in the energy dissipation (toughness) reaching 12 times larger than the conventional PP treatment. Conclusions   â ¢Laser pre-treatment provided enhanced toughness and energy dissipation as compared to PP.   â ¢Laser patterning resulted in up to ~12x enhanced energy dissipation by the activation of non-local damage mechanisms which produced progressive failure indicating safter joints.
  • A Multiscale Computational Framework To Predict The Nonlinear Response Of Fibre-Reinforced Polymer Composites

    Ullah, Dr Zahur (2021-05-24) [Poster]
    Objective: Development of multi-scale computational framework for the prediction of nonlinear micro/meso response of the fibre-reinforced polymer (FRP) composites. Methods: The multi-scale computational framework provides the macroscopic constitutive behaviour of the structures based on its microscopically heterogeneous representative volume element (RVE). Two dominant damage mechanisms 1: Matrix plasticity (using pressure-dependent paraboloidal yield criterion). Fibre-matrix decohesion (using zero thickness cohesive interface elements). Yarns/fibres as transversely isotropic materials (calculation of fibre directions using potential flow analysis) 2. Generalised imposition of the RVE boundary conditions which allows convenient switching between displacement, traction and periodic boundary conditions 3. Adoption of hierarchic finite elements, which permits the use of arbitrary order of approximation 4. Implementation of the computational framework in an open-source finite element software MoFEM (Mesh Oriented Finite Element Method) and is designed to take advantage of the high-performance computing 5.
  • A Compact Thermofluidic Soft Actuator

    Chellattoan, Ragesh (2021-05-24) [Poster]
    A compact thermo-fluidicactuator Objective: Soft actuators producing large motion in a short time is mainly based on stretchable polymers actuated by pneumatic pressure. But such systems consist of bulky components like motor, pump/compressor, tubes and valves. Here, we developed a fast-responding large-amplitude soft actuator based on a liquid-gas phase transition, resulting in a compact system.    Methods: The required pressure is generated solely by the electrically induced phase transition of a fluid in a cavity. We pay special attention to design variables to improve the response time and propose a new design for the electrodes which are the most critical components.    Results: Our bending actuator produces large motion in less than 7 seconds using a low voltage source (less than 50V), which is much faster than previously reported soft actuator based on phase transition.
  • Smartphone-Based Single-Camera Stereo-Vision System

    Yu, Liping; Bekdullayev, Nurlat; Lubineau, Gilles (2021-05-24) [Poster]
    Stereo-digital image correlation technique using two synchronized industrial-grade cameras is extensively used for full-field 3D shape, displacement and deformation measurements. However, its use in resource-limited institutions and field-settings is inhibited by the need for relatively expensive, bulky and complicated experimental set-ups. To mitigate this problem, we established a cost-effective and ultra-portable smartphone-based stereo-digital image correlation system, which only uses a ubiquitous smartphone and an optical attachment. This optical attachment is composed of four planar mirrors and a 3D-printed mirror support, and can split the incoming scene into two sub-images, simulating a stereovision system using two virtual smartphones.
  • Design And Analysis Of Spoolable Reinforced Thermoplastic Pipes (Rtp) For On-Shore Oil And Gas Application

    A. Arafath, Abdul Rahim; Al-Ghamdi, Ali; Khandelwal, Ratnesh (2021-05-24) [Poster]
  • The Future Of Nonmetallic Composite Materials In Upstream Applications

    Badeghaish, Wael; Noui-Mehidi, Mohamed; Salazar, Oscar (2021-05-24) [Poster]