Research Outputs

Permanent URI for this communityhttps://hdl.handle.net/20.500.14288/2

Browse

Filters

2005 - 200912010 - 20194

Advanced Search

Filter by

Settings

Quartile: search.filters.quartile.Q2Subject: search.filters.subject.Composite materials

Search Results

Now showing 1 - 5 of 5
  • Placeholder
    PublicationMetadata only
    A novel mold design for one-continuous permeability measurement of fiber preforms
    (Sage Publications Ltd, 2015) N/A; N/A; Department of Mechanical Engineering; Yalçınkaya, Mehmet Akif; Sarıoğlu, Ayşen; Sözer, Murat; PhD Student; Master Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 110357
    One-continuous permeability measurement experiments allow measuring permeability of a fiber preform within a range of fiber volume fractions by conducting a single unsaturated (a.k.a. transient) flow experiment on a dry specimen at an initial thickness, and a set of saturated flow experiments on the wetted specimen by varying the thickness of the mold cavity. This approach allows quicker database construction and reduces the effect of inherent variation of fabric structure caused by inconsistent labor on permeability. In this study, the drawbacks of previous mold designs are eliminated by using appropriate sealing, gap thickness adjustment mechanism and features that allow straightforward and reliable manual operation. Experiments for three different fabric types are conducted and the results are discussed. It is mainly observed that the unsaturated permeability is higher than the saturated permeability.
  • Placeholder
    PublicationMetadata only
    Dynamic pressure control in vartm: rapid fabrication of laminates with high fiber volume fraction and improved dimensional uniformity
    (Wiley, 2019) Altan, M. Cengiz; Department of Mechanical Engineering; Department of Mechanical Engineering; Yalçınkaya, Mehmet Akif; Sözer, Murat; Master Student; Faculty Member; Department of Mechanical Engineering; College of Engineering; College of Engineering; N/A; 110357
    The compaction pressure on the fibrous preform is one of the most critical parameters in vacuum assisted resin transfer molding (VARTM), which significantly affects the preform permeability, mold filling time, and final thickness of the fabricated composite. In this study, the compaction pressure on the vacuum bag was controlled during and after the mold filling to achieve rapid impregnation and improve the fiber volume fraction of the laminate. It was shown that the dynamic pressure control (1) enabled the manipulation of the fabric permeability and faster distribution of the resin to decrease the mold filling time, (2) improved the dimensional uniformity of the laminate by reducing the thickness variation, and (3) increased the fiber volume fraction by further consolidating the preform and removing the excess resin. One of the most essential and prominent features of the process was shown to be the resin removal from the inlet by applying external pressure, which reduced the thickness variation in laminates from 15 to 1%. The mold filling time was reduced by 48% compared with conventional VARTM, while achieving a high fiber volume fraction up to 64% and a low void content of below 1%. POLYM. COMPOS., 40:2482-2494, 2019.
  • Placeholder
    PublicationMetadata only
    Effect of part thickness variation on the mold filling time in vacuum infusion process
    (Sage Publications Ltd, 2014) N/A; Department of Mechanical Engineering; Yalçınkaya, Mehmet Akif; Sözer, Murat; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 110357
    An experimental setup was used to fairly compare mold filling times in vacuum infusion and resin transfer molding, and a 9.5% shorter mold filling time in vacuum infusion was observed than in resin transfer molding. The setup was also used to conduct compaction and permeability characterization experiments, and the results were used in a simplified vacuum infusion model, which is more straightforward to solve than the conventional full and coupled models in the literature. Simulated filling time in vacuum infusion was 31% shorter than in resin transfer molding. The faster resin flow in vacuum infusion is explained by the fact that the thickness in the wetted upstream region increases with time, and thus the effective permeability in that region increases.
  • Placeholder
    PublicationMetadata only
    Effect of permeability characterization at different boundary and flow conditions on vacuum infusion process modeling
    (Sage Publications Ltd, 2017) N/A; N/A; Department of Mechanical Engineering; Yalçınkaya, Mehmet Akif; Çağlar, Barış; Sözer, Murat; PhD Student; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 110357
    Permeability characterization of a fabric preform is a key factor that affects the accuracy of process modeling of vacuum infusion. There are various flow types and boundary conditions (such as one-dimensional or radial flow under constant injection pressure or constant injection flow rate during unsaturated or saturated flow regimes) used in permeability measurement experiments in the literature. This study investigates the effect of using different flow and injection boundary conditions in permeability characterization on the results of coupled one-dimensional mold-filling and compaction model. The results of the model are compared with vacuum infusion mold-filling experiments. It is shown that using the permeability measured at constant injection pressure and unsaturated flow results in the closest fill time compared to the experiments for all three types of fabrics investigated in this study.
  • Placeholder
    PublicationMetadata only
    Influence of annealing on the performance of short glass fiber-reinforced polyphenylene sulfide (PPS) composites
    (Sage Publications Ltd, 2005) Arici, A; Sinmazcelik, T; Capan, L.; Department of Chemistry; Department of Chemistry; Yılgör, İskender; Yılgör, Emel; Faculty Member; Researcher; Department of Chemistry; College of Sciences; College of Sciences; 24181; N/A
    The influence of annealing on the morphology and the performance of randomly oriented short glass fiber-reinforced polyphenylene sulfide (PPS) composites have been investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMTA), impact tests, and scanning electron microscopy (SEM). Endotherms belonging to secondary crystals are seen 10-20 degreesC above the annealing temperatures. DMTA results showed that the annealed samples had higher glass transition temperatures and elastic moduli values when compared with the quenched samples. The effect of microstructure on elastic deformation, crack formation, and crack propagation are studied with instrumented impact tester.