Flexural stability analysis of composite panels reinforced with stiffener integral woven preforms

3D weaving exhibits to be a guaranteeing innovation in delivering integrated near net shaped structures that might overcome the current issue of delamination and assembly cost. This paper highlights one such technique of producing preforms with integrally woven stiffener sections that can be used as a reinforcement material for composite panels. The woven performs were fabricated using high performance polyester yarns as a raw material and further consolidated to composite structures using epoxy resin. The flexural analysis of the composite panels developed from these performs revealed that the structures have better bending rigidity and structural integrity without any possibility of delamination prone failures. Investigations on fracture morphology were conducted to understand the composite failure mechanism and the structural deformation of the structures during loading. From the findings, it was evident that the polyester-epoxy material combination exhibited substantial residual strength and toughness properties.     

Modelling and simulation of heat transfer by convection in aerogel treated nonwovens

Simulation and numerical modeling are becoming increasingly popular due to the ability to seek solutions for a problem without undertaking real-life experiments. For the problems of heat transfer, these techniques to generate relevant data by incorporating different changes to the input parameters. Heat transfer property of textile materials is a major concern since it influences comfort properties of clothing. In this paper, numerical simulation was applied to evaluate the heat flux, temperature distributions, and convective heat transfer coefficients of the fibrous insulating materials treated with aerogel. The computational model simulated the insulation behavior of nonwoven fabrics without and with aerogel. Ansys and Comsol were used to model and simulate heat transfer. The simulation was performed assuming laminar flow and since the Mach number was < 0.3, the compressible flow model with Mach number < 0.3 was used. The results of simulation were correlated to experimental measurements for validation. Furthermore, aerogel-treated fabric samples showed better thermal performance. Using this model, the heat transfer properties of the nonwoven fabrics treated with aerogel can be optimized further.     

Airbags

In recent years, safety systems such as seat belts and airbags have been one of the fast-growing sectors within the automotive industry. Seat belts and airbags have made driving substantially safer since their introduction. Airbags are safety systems used to cushion the driver or passenger during a collision and reduce bodily injuries. The technology involved in the manufacturing and working of airbags is complex. Since the early stages of development, airbag technology has been undergoing continual evolution in terms of design, materials and performance. Airbags are typically made from woven fabric, which may be coated or uncoated but must be impermeable to gases and flame resistant. In terms of their operation, modern airbags are smart restraint systems, which can tailor the deployment of the airbag according to the crash severity, body size of the occupant and proximity of the occupant to the airbag system prior to deployment. The future of airbags is extremely promising because there are many diverse applications ranging from motorcycle helmets to aircraft seating. In this article, an outline is given of the historical development of airbags and their value in saving lives is illustrated by supporting statistical data. The essential parameters required for airbag yarn and fabric components are discussed in detail. In addition, the processes involved in the manufacture, assembly and testing of airbag systems are explained. The mechanisms and chemical reactions involved in the deployment of different types of airbags are also discussed, and recent developments in airbag design and their possible future applications are reported.     

Comparative analysis of mechanical properties of size films

The advent of very high speed shuttleless looms has increased the importance of sizing. Starch has been the most popular and economic size material. Synthetic binders are also being blended with starch to improve weaving loom efficiency. Some synthetic size materials have got restrictions in use mainly because of ecological reasons. In the recent years, many modifications have come up in the starch as a sizing agent. Different modifications give different properties, which can be suited for particular application. In the present study, a comparative analysis of different varieties of natural starch, modified starch and synthetic size materials have been carried out for their cohesion power, adhesion power, abrasion resistance and bending rigidity. Comparison is made between various varieties and also among different blends to see the effect of blending on different mechanical properties of size film. The effect of lubricant on properties of size film is also examined. In general, it is observed that paste characteristics and film properties of synthetic and modified starch are better than the natural starch.     

Study on a twin‐bed adsorption refrigeration system using R134a‐activated carbon pair

A low capacity twin‐bed adsorption refrigeration system has been built with R134a as a refrigerant and activated carbon as the adsorbent. Simple tube‐in‐tube heat exchangers have been fabricated and have been used as the adsorber beds. Activated carbon (granular type) has been filled in the annular space of the inner tube and outer tube. A plate heat exchanger has been used as the condenser and the temperature of cooling water has been maintained between 25°C and 30°C, also the evaporator has been custom designed as per requirements. A mathematical model has also been developed and the results obtained have been found to be comparable. While operating the system in the single‐bed mode a cooling power of 250.4 W has been obtained with a coefficient of performance (COP) of 0.38 with an average evaporator temperature of 18.4°C against a predicted value of 263.7 W with a COP of 0.41. While operating in the twin‐bed mode a cooling power of 281.3 W with a COP of 0.47 with an average evaporator temperature of 17.6°C has been obtained against a predicted value of 294.5 W with a COP of 0.52.     

Evaluation of Ni-Cr-P coatings electrodeposited on low carbon steel bipolar plates for polymer electrolyte membrane fuel cell

Polymer electrolyte membrane fuel cell (PEMFC) stacks suffer from the high cost and low volumetric energy of non-porous graphite bipolar plates. To resolve this problem, a bilayer coating consisting of Ni and Ni–Cr–P is deposited on AISI 1020 low-carbon steel using pulse electrodeposition. Ni/Ni–Cr–P-coated AISI 1020 is evaluated as a bipolar plate material for PEMFCs. Ni/Ni–Cr–P-coated substrates exhibit better corrosion resistance in both cathodic (air-purging) and anodic (H₂-purging) environment than the bare AISI 1020 substrate and lower interfacial contact resistance (ICR) than bare AISI 1020 and stainless steel. Further, it is expected to show better water management as the Ni/Ni–Cr–P coating is more hydrophobic than the bare substrate. Preliminary studies show that Ni/Ni–Cr–P-coated AISI 1020 plate can be a suitable candidate for replacing graphite as the bipolar plate of PEMFCs.     

Ethanol production from mahula (Madhuca latifolia L.) flowers with immobilized cells of Saccharomyces cerevisiae in Luffa cylindrica L. sponge discs

The dried spongy fruit of luffa (Luffa cylindrica L.), a cucurbitaceous crop available in abundance in tropical and sub-tropical countries has been found to be a promising material for immobilizing microbial cells. The aim of the present study was to examine the ethanol production from mahula flowers in submerged fermentation using whole cells of Saccharomyces cerevisiae immobilized in luffa sponge discs. The cells not only survived but also were physiologically active in three more cycles of fermentation without significant reduction (<5%) in ethanol production. After 96 h, there was 91.1% sugar conversion producing 223.2 g ethanol/kg flowers (1st cycle) which was 0.99%, 2.3% and 3.2% more than 2nd (221 g ethanol/kg flowers), 3rd (218 g ethanol/kg flowers) and 4th (216 g ethanol/kg flowers) cycle of fermentation, respectively. Furthermore, ethanol production by immobilized cells was 8.96% higher than the free cells.