Modern electronic devices need effective shielding from external Electromagnetic Interference (EMI) to function correctly. The Electromagnetic (EM) waves emerging from communication systems and medical devices must be isolated to safeguard humans from exposure. The mechanics of EMI shielding as well as several characterization methods are discussed in this paper. Existing trends and practices of designing, fabrication and use of polymer matrix composites for EMI shielding applications are covered. Several approaches and new solutions for fabricating composites either by modification of filler or matrix are discussed and prominent features of EMI shielding material are also discussed. Conducting polymers such as polyaniline, polypyrrole and polythiophene make them adept for EMI shielding applications. An assessment of the different factors affecting the performance of EMI shielding materials is also presented.

This work presents wear study on maraging steel developed by additive manufacturing using Direct Metal Laser Sintering, utilizing a laser beam of high-power density for melting and fusing the metallic powders. Short aging treatment was given to the specimen prior to the wear tests. The density and the hardness of the 3D printed maraging steel were found to be better than the homogenized-aged 18Ni1900 maraging steel. The wear resistance is an important aspect that influences the functionality of the components. The wear tests in dry condition were performed on maraging steel on pin/disc standard wear testing machine. The design of experiments was planned and executed based on response surface methodology. This technique is employed to investigate three influencing and controlling constraints namely speed, load, and distance of sliding. It has been observed that sliding speed and normal load significantly affects the wear of the specimen. The statistical optimization confirms that the normal load, sliding distance, and speed are significant for reducing the wear rate. The confirmation test was conducted with a 95% confidence interval using optimal parameters for validation of wear test results. A mathematical model was developed to estimate the wear rate. The experimental results were matched with the projected values. The wear test parameters for minimum and maximum wear rate have been determined.

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The present research work analyzed the effect of design modification with radial grooves on disc brake performance and its thermal behavior by using additive manufacturing based 3D printed material maraging steel. Temperature distribution across the disc surface was estimated with different boundary conditions such as rotor speed, braking pressure, and braking time. Design modification and number of radial grooves were decided based on existing dimensions. Radial grooves were incorporated on disc surface through Direct Metal Laser Sintering (DMLS) process to increase surface area for maximum heat dissipation and reduce the stresses induced during braking process. The radial grooves act as a cooling channels which provides an effective means of cooling the disc surface which is under severe condition of sudden fall and rise of temperatures during running conditions. ANSYS software is used for transient structural and thermal analysis to investigate the variations in temperatures profile across the disc with induced heat flux. FE based thermo-structural analysis was done to determine thermal strains induced in disc due to sudden temperature fluctuations. The maximum temperature and Von Mises stress in disc brake without grooves on disc surface were observed which can severely affect thermal fatigue and rupture brake disc surface. It was been observed by incorporating the radial grooves that the disc brake surface is thermally stable. Experimental results are in good agreement with FE thermal analysis. DMLS provides easy fabrication of disc brake with radial grooves and enhancement of disc brake performance at higher speeds and temperatures. Therefore, DMLS provides an effective means of implementing product development technology.

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Flax is a commercial crop grown in many parts of the world both for its seeds and for its fibers. The seed-based flax variety (linseed) is considered less for its fiber after the seed is extracted. In this study, linseed straw was utilized and processed to extract fiber and cellulose through optimization of retting time and a multi-step alkaline peroxide extraction process using the Taguchi design of experiment (DOE). Effects of retting duration on fiber properties as well as effects of solvent concentration, reaction temperature, and time on removal of non-cellulosic fiber components were studied using the gravimetric technique, Fourier transform infrared (FTIR) spectroscopy and thermal studies. Based on these findings, retting for 216 h at room temperature should offer adequate retting efficiency and fiber characteristics; 70% cellulose yield was extracted successfully from linseed straw fiber using 75% ethanol–toluene at 98 °C for 4 h, 6% NaOH at 75 °C for 30 min, and 6% H2O2 at 90 °C for 120 min.

In recent years, partial replacement of cement with bagasse ash has been given attention for construction application due to its pozzolanic characteristics. Sugarcane bagasse ash and fine bagasse particles are abundant byproducts of the sugar industries and are disposed of in landfills. Our study presents the effect of burning bagasse at different temperatures (300 °C and 600 °C) on the compressive strength and physical properties of bagasse ash-blended mortars. Experimental results have revealed that bagasse produced more amorphous silica with very low carbon contents when it was burned at 600 °C/2 h. The compressive strength of mortar was improved when 5% bagasse ash replaced ordinary portland cement (OPC) at early curing ages. The addition of 10% bagasse ash cement also increased the compressive strength of mortars at 14 and 28 days of curing. However, none of the bagasse ash-blended portland pozzolana cement (PPC) mortars have shown improvement on compressive strength with the addition of bagasse ash. Characterization of bagasse ash was done using XRD, DTA-TGA, SEM, and atomic absorption spectrometry. Moreover, durability of mortars was checked by measuring water absorption and apparent porosity for bagasse ash-blended mortars.

The current studies aim to measure the mechanical strength based on age, harvesting season and bamboo species in Ethiopia. The bamboo fibres are extracted using a roll milling machine, which was developed by the author. The age groups (1, 2 and 3 years), harvesting months (February and November), and bamboo species (Yushania alpina and Bambusa oldhamii) are the parameters of the current research studies. Prepregs and composites were produced from bamboo fibres and polypropylene. The mechanical properties of bamboo fibres and their composites in Ethiopia have not been investigated by researchers for the composite application so far. The tensile strength, Young’s modulus, and impact strength of injibara (Y. alpina) bamboo fibres reinforced PP composites from the ages of 1– 3 years old in November is 111 ± 9–125 ± 8 MPa, 15 ± 0.9–25 ± 0.72 GPa, and 47 ± 5 KJ/m2–57 ± 6 KJ/m2, whereas, in February, it is 86 ± 3.86–116 ± 10 MPa, 11 ± 0.71–23 ± 1.5 GPa, and 34 ± 4–52 ± 6 KJ/m2, respectively. Moreover, Kombolcha (B. oldhamii), bamboo fibres reinforced PP composites in November are 93 ± 7–111 ± 8 MPa, 7 ± 0.51–17 ± 2.56 GPa, and 39 ± 4–44 ± 5 KJ/m2, whereas, in February, it is 60 ± 5–104 ± 10 MPa, 12 ± 0.95–14 ± 0.92 GPa, and 26 ± 3 KJ/m2–38 ± 4 KJ/m2, respectively. Furthermore, Mekaneselam (Y. alpina) bamboo fibres reinforced PP composites in November are 99 ± 8–120 ± 11 MPa, 9 ± 0.82–16 ± 1.85 GPa, and 37 ± 4 KJ/m2–46 ± 5 KJ/m2, whereas, in February, it is 91 ± 8–110 ± 9 MPa, 8 ± 0.75–14 ± 1.86 GPa, and 34 ± 3 KJ/m2–40 ± 4 KJ/m2, respectively. At two years, November and Injibara bamboo have recorded the highest mechanical properties in the current research studies. Bamboo fiber strength in Ethiopia is comparable to the previous study of bamboo fibres and glass fibres used for composite materials in the automotive industry.