ORCID Profile
0000-0001-7374-7437
Current Organisation
Khalifa University of Science and Technology
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Publisher: Elsevier BV
Date: 12-2020
Publisher: IEEE
Date: 02-2018
Publisher: Elsevier BV
Date: 2022
Publisher: Elsevier BV
Date: 11-2018
Publisher: SAGE Publications
Date: 06-04-2023
DOI: 10.1177/00219983231168791
Abstract: The effective design of channels in dry tape preforms is crucial for achieving desired preform permeability for successful resin injection for composites manufacturing using Automated Fiber Placement (AFP) process. Achieving target gaps and their locations in the AFP layup is extremely challenging. This work investigates the correlation between the spatial variability of the preforms and the in-plane permeability using an X-ray Computed Tomography (XCT) based characterization framework. The tomographic images of two different dry carbon tape preforms with different tape widths were used to generate realistic and XCT based stochastic models to be used for numerical permeability predictions. The variability in the tape placement by the robotic head and its effect on preform permeability was also examined through stochastic geometric modeling of the laid preform. A benchmark transient permeability measurement set-up was utilized to obtain experimental in-plane preform permeability through 2D radial mold filling. The in-plane numerical permeability values showed significant scatter, with a coefficient of variance of 75%–130%, which deviated from the experimental measurements by approximately one order of magnitude. These findings strongly re-affirm that the experimental permeability measurement technique based on transient mold filling of dry fiber AFP preforms is complex however, the XCT based stochastic modeling technique is an effective way to estimate the permeability of dry fiber AFP preforms virtually.
Publisher: DEStech Publications, Inc.
Date: 15-10-2019
DOI: 10.12783/ASC34/31304
Publisher: Elsevier BV
Date: 11-2019
Publisher: Elsevier BV
Date: 09-2021
Publisher: Elsevier BV
Date: 06-2019
Publisher: DEStech Publications, Inc.
Date: 15-10-2019
DOI: 10.12783/ASC34/31305
Publisher: Elsevier BV
Date: 11-2019
Publisher: Wiley
Date: 16-03-2022
DOI: 10.1002/PC.26587
Abstract: In this study, an online process monitoring system based on rGO coated glass fabric sensors was developed to monitor different stages of the resin infusion process. The developed sensors were able to monitor reinforcement compaction response, resin flow, race tracking, and resin cure when using thermoset resin and a novel low viscosity thermoplastic resin (i.e., Elium®). The coated glass fabric patches and strips were embedded at different locations within the laminate. The electrical resistance changes occurring within the embedded sensors during different stages of the manufacturing process were continuously monitored. The relative drop in overall resistance of the sensors upon contact with the resin systems was different for epoxy resin and Elium® resin due to differences in their electrical conductivity. It was found that the coating quality, dimensions, and spatial position of the sensors within the laminate and the type of resin system affected the performance of the sensors.
Publisher: Elsevier BV
Date: 10-2019
Publisher: Wiley
Date: 15-12-2023
DOI: 10.1002/PC.27210
Abstract: In this study, two different type of glass and carbon fiber hybrid laminates were manufactured using a low‐viscosity thermoplastic resin that is, Elium®. A detailed microstructure visualization study was conducted using X‐ray computed tomography (XCT) analysis. The viscoelastic properties were examined through dynamic mechanical analysis. The mechanical performance was investigated through flexural and tensile tests along with a fractographic study using optical and scanning electron microscopy. The XCT analysis revealed a weak interface between the Elium® resin and the glass fabric, with glass fiber specimens exhibiting a void content of 1.24%, in contrast to the carbon fiber specimens which showed void content of only 0.28%. Therefore, adding glass fabric layers in the hybrid laminates increased the void content, which had a negative impact on the overall mechanical performance. The average flexural strength of the hybrid specimen having G 2 C 4 G 2 stacking sequence was observed to be 254% higher than pure GFRPC specimens. Similarly, the tensile strength and Young's modulus of the same hybrid specimen showed 155% and 380% increases, respectively, compared to the GFRPC specimens. This increase was primarily due to higher stiffness of the carbon fibers and their better fiber – matrix interface. Whereas the tensile strain of the hybrid specimen having G 3 C 2 G 3 stacking sequence was 37% higher than that of the CFRPC specimens. The SEM images highlighted fiber fracture and brittle failure modes in the carbon fiber specimens, in contrast to fiber pullout, interfacial failure, poor fiber‐matrix bonding and ductile failure modes in the glass fiber specimens.
Publisher: Elsevier BV
Date: 12-2020
Publisher: Elsevier BV
Date: 03-2021
Publisher: Elsevier BV
Date: 08-2017
Publisher: Elsevier BV
Date: 08-2022
Publisher: SAGE Publications
Date: 08-12-2022
DOI: 10.1177/08927057221145551
Abstract: In this study, carbon fiber/Elium ® composites are manufactured using the resin infusion manufacturing technique. Artificial cracks representing impact-induced delamination are incorporated during layup. The laminates are subsequently healed using several healing parameters. The bonding mechanisms are investigated through microscopic analyses and X-ray Computed Tomography (XCT). The mechanical performance of the healed composites is investigated through four-point bending tests. It is found that as the healing temperature is increased, the cracks are gradually healed by interdiffusion and macroscopic resin flow across each crack interface. The 3D models generated from XCT images show an increase in solid volume fraction from 48% to 70% at the optimum healing parameters. The flexural strength and flexural modulus of the undamaged composites subjected to optimized healing condition are significantly increased relative to the room temperature cured pristine s les. The residual flexural strength of the damaged s les healed at the optimum parameters is 96% of the reference condition. The SEM images confirm that delamination from the previously-healed crack interfaces is the most dominant failure mode in the healed s les, in contrast to fiber fracture and brittle failure in the undamaged reference composite s les. The results show that the damaged composite laminates can be effectively healed and repaired to as good as undamaged laminates using the interdiffusion mechanism.
Publisher: IOP Publishing
Date: 21-09-2018
Publisher: Elsevier BV
Date: 03-2019
Publisher: Springer Singapore
Date: 2020
Publisher: Wiley
Date: 11-2022
DOI: 10.1002/ENG2.12468
Abstract: Structural health monitoring (SHM) using self‐sensing cement‐based materials has been reported before, where nano‐fillers have been incorporated in cementitious matrices as functional sensing elements. A percolation threshold is always required in order for conductive nano‐fillers modified concrete to be useful for SHM. Nonetheless, the best pressure/strain sensitivity results achieved for any self‐sensing cementitious matrix are .01 MPa −1 . In this work, we introduce for the first‐time novel partially reduced graphene oxide based electronic textile (e‐textile) embedded in plain and as well as in polymer‐binder‐modified cementitious matrix for SHM applications. These e‐textile embedded cementitious composites are independent of any percolation threshold due to the interconnected fabric inside the host matrix. The piezo‐resistive response was measured by applying direct and cyclic compressive loads (ranging from 0.10 to 3.90 MPa). A pressure sensitivity of 1.50 MPa −1 and an ultra‐high gauge factor of 2000 was obtained for the system of the self‐sensing cementitious structure with embedded e‐textiles. The sensitivity of this new system with embedded e‐textile is an order of magnitude higher than the state‐of‐the‐art nanoparticle based self‐sensing cementitious composites. The composites showed mechanical stability and functional durability over long‐term cyclic compression tests of 1000 cycles. Additionally, a two time‐constant model was used to validate the experimental results on decay response of the e‐textile embedded composites.
Publisher: Elsevier BV
Date: 09-2020
Publisher: Elsevier BV
Date: 06-2022
Publisher: Elsevier BV
Date: 11-2017
Publisher: IEEE
Date: 03-2019
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 09-2021
Location: United Arab Emirates
Location: Pakistan
No related grants have been discovered for Muhammad Ali.