Exploration of Voids, Acoustic Properties and Vibration Damping Ratio of Cyperus Pangorei Rottb Fiber and Ramie Fiber Reinforced with Epoxy Resin Hybrid Composites.

Noise pollution is a major threat to the health and well-being of the entire world; this issue forces researchers to find new sound absorption and insulating material. In this paper, the sound absorption coefficient and vibration damping factor of panels manufactured from Cyperus pangorei rottb and ramie fiber reinforced with epoxy resin are explored. Cyperus pangorei rottb grass fiber and ramie fiber are widely available natural fibers. Cyperus pangorei rottb grass fiber is used in mat manufacturing, whereas ramie is widely used as a fabric. Using both of these fibers, six variant panels using a vacuum resin infusion process (VRIP) were fabricated. The panels were named C, R, CR, RCR-Flat, RCR-Curved, and RCR-Perforated. All the panels were tested for the sound absorption coefficient using an impedance tube with a frequency ranging up to 6300 Hz. Modal analysis was carried out by using the impulse hammer excitation method. A micro X-ray computed tomography (CT) scan was used to study the voids present in the panels. The results were compared among the six variants. The results show that the RCR-curved panel had the highest sound-absorbing coefficient of 0.976 at a frequency range between 4500 Hz to 5000 Hz. These panels also showed better natural frequency and damping factors. The presence of internal voids in these panels enhances sound absorption properties. These panels can be used at higher frequencies.

Novel Technique for Design and Manufacture of Alternating Gradient Composite Structure of Aluminum Alloys Using Solid State Additive Manufacturing Technique.

This work analyzes a novel solid-state manufacturing approach of a friction stir additive manufacturing (FSAM) technique for fabricating multiple layers of alternating gradient composite structure using alternate layers of AA6061-T6 and AA7075-T6 aluminum alloys of 3 mm thickness. The evolution of the microstructure along the build direction and its impact on the tensile and microhardness properties were examined using optical microscopy, tensile tests, and Vickers microhardness tests. Nonuniform microstructures were detected along the build direction, and it was concluded that the most productive part of the construction was the nugget zone, which had fine equiaxed grains. It was identified that the grain sizes and precipitate sizes were affected by the varying thermal cycles created by the multiple passes of the tool. These events were identified as the primary reasons for the increase in strength and hardness of the FSAM build from the lower layer to the upper layer. In the final FSAM build the maximum hardness value was obtained as 182.3 HV and the ultimate tensile strength (UTS) was 420 MPa both of which were identified at the topmost layer. Moreover, the postmortem of the fractured samples revealed that the cause of failure was a combination of both ductile and brittle fractures. The findings of this study suggest that the FSAM approach may be used to fabricate large structures that are free of defects having expected mechanical characteristics and hence the newly fabricated composite can be used as a suitable substitute for the conventional AA6061 material applied in automobile components for its improved performance.

Performance Comparison of Advanced Ceramic Cladding Approaches via Solid-State and Traditional Welding Processes: A Review.

Ceramic coating has applications in enhancing the material's properties and can significantly improve the material's usability in varied temperatures and adverse operating conditions and widen its applicability scope. It can add to the various properties such as wear resistance, high-temperature degradation, thermal conductivity, material toughness, tensile strength, corrosion resistance, friction reduction, electric insulation, and the lifespan of the material. Various techniques have been suggested and implemented to achieve ceramic coating on a metal surface, each having their respective advantages and disadvantages. Hence, they can be distinguished for their applicability in different places. The bonding mechanism of metal particle systems has been researched to date, but there are still certain uncertainties regarding the ceramic particle system because of the dissimilarities in properties. The paper aims to profoundly investigate the various coating technologies available through welding processes and do a comparative study through numerical analysis and experimental results on the properties of coatings obtained from two broad categories of welding-solid-state and traditional/fusion processes. It was found that the solid-state processes in which the temperature remained well below the fusion temperatures overcame the mismatch in property and produced reliable coatings with enhanced mechanical properties.