A novel underground heating system for deicing applications

Due to the snow and ice on the roads in winter season, difficulties in transportation and accidents are unavoidable. Municipalities and residents put all their effort to clean up the streets and highways. Mechanical cleaning, salt and chemical applications, thermal heating are some common deicing and anti-icing methods currently used. Many of these methods have some disadvantages. While the salt and chemicals harm the concrete and steel reinforcement, thermal methods are quite expensive and difficult to install. Mechanical cleaning is labor extensive and costly. Environmental effects of using salt and chemical in long term cannot be neglected. Once all deicing techniques are reviewed, it is obvious that low-cost, efficient deicing technologies needed to be developed. In this study, for deicing and anti-icing purposes concrete was heated using carbon fiber electrical resistance technique. Heating panels were placed into the concrete and their heating performance was tested in different ambient temperatures. The effect of heat panel depth, carbon fiber form, power density and ambient temperature on the heating performance was studied. Once experimental study was completed, field application of the heating system was constructed and tested. It was concluded that carbon fiber heating system offers a viable solution for icing and snow accumulation problems

High Velocity Impact and Blast Loading of Composite Sandwich Panels with Novel Carbon and Glass Construction

This research investigates whether the layup order of the carbon-fibre/glass-fibre skins in hybrid composite sandwich panels has an effect on impact response. Composite sandwich panels with carbon-fibre/glass-fibre hybrid skins were subjected to impact at velocities of 75 ± 3 and 90 ± 3 m s−1. Measurements of the sandwich panels were made using high-speed 3D digital image correlation (DIC), and post-impact damage was assessed by sectioning the sandwich panels. It was concluded that the introduction of glass-fibre layers into carbon-fibre laminate skins reduces brittle failure compared to a sandwich panel with carbon-fibre reinforced polymer skins alone. Furthermore, if the impact surface is known, it would be beneficial to select an asymmetrical panel such as Hybrid-(GCFGC) utilising glass-fibre layers in compression and carbon-fibre layers in tension. This hybrid sandwich panel achieves a specific deflection of 0.322 mm kg−1 m2 and specific strain of 0.077% kg−1 m2 under an impact velocity of 75 ± 3 m s−1. However, if the impact surface is not known, selection of a panel with a symmetric yet more dispersed hybridisation would be effective. By distributing the different fibre layers more evenly within the skin, less surface and core damage is achieved. The distributed hybrid investigated in this research, Hybrid-(GCGFGCG), achieved a specific deflection of 0.394 mm kg−1 m2 and specific strain of 0.085% kg−1 m2 under an impact velocity of 75 ± 3 m s−1. Blast loading was performed on a large scale version of Hybrid-(GCFGC) and it exhibited a maximum deflection of 75 mm following a similar deflection profile to those observed for the impact experiments

Blast resilience of composite sandwich panels with hybrid glass-fibre and carbon-fibre skins

The development of composite materials through hybridisation is receiving a lot of interest; due to the multiple benefits, this may bring to many industries. These benefits include decreased brittle behaviour, which is an inherent weakness for composite materials, and the enhancement of mechanical properties due to the hybrid effect, such as tensile and flexural strength. The effect of implementing hybrid composites as skins on composite sandwich panels is not well understood under high strain rate loading, including blast loading. This paper investigates the blast resilience of two types of hybrid composite sandwich panel against a full-scale explosive charge. Two hybrid composite sandwich panels were mounted at a 15 m stand-off distance from a 100 kg nitromethane charge. The samples were designed to reveal whether the fabric layup order of the skins influences blast response. Deflection of the sandwich panels was recorded using high-speed 3D digital image correlation (DIC) during the blast. It was concluded that the combination of glass-fibre reinforced polymer (GFRP) and carbon-fibre reinforced polymer (CFRP) layers in hybrid laminate skins of sandwich panels decreases the normalised deflection compared to both GFRP and CFRP panels by up to 41 and 23%, respectively. The position of the glass-fibre and carbon-fibre layers does not appear to affect the sandwich panel deflection and strain. A finite element model has successfully been developed to predict the elastic response of a hybrid panel under air blast loading. The difference between the maximum central displacement of the experimental data and numerical simulation was ca. 5% for the hybrid panel evaluated

The influence of acrylate triblock copolymer embedded in matrix on composite structures’ responses to low-velocity impacts

In passive safety structures the use of composite materials has increased significantly recently due to their low specific mass and high energy absorption capacities. The purpose of this experimental study is to describe the macroscopic behaviors of different Kevlar woven composite materials with different kinds of matrix (pure and with acrylate based block copolymer additives: Nanostrength ) under lowvelocity impact. Tests were performed with a drop weight tower on square plates (100 100 mm2) clamped by means of a circular fixture. Images were recorded during impact by a high-speed video camera fixed underneath the plate. It was found that Kevlar epoxy composite material with Nanostrength M52N has the best resistance to perforation. The second purpose is to study the influence of physicochemical parameters (fibers ratio, percentage of M52N, micro-porosity) on the behavior of the selected composite material. Based on correlation between pictures, displacement, and loading histories, two criteria are defined to quantify the energy absorption capability of the composite material just before the fibers’ failure and after perforation of the plate. A high-fiber weight improves performance regarding criteria and also improves the efficiency of the block copolymer present in the epoxy matrix

Finite element analysis of functionally hybridized carbon/glass composite shafts

External torque on circular composite shafts produces linearly decreasing shear stresses along radial direction. The inner layers never stressed as much as outmost layer. Accommodating fiber stiffness of each layer based on these linearly decreasing stresses may be advantageous. To reduce the cost of carbon fiber-reinforced composite drive shaft, inner layers of shaft can be reinforced by hybrid fiber systems with less stiffness. To achieve that, while the top layer is still reinforced with carbon fiber, inner layers can be reinforced with the mixture of glass and carbon fiber. Without changing the fiber volume fractions, replacement of some carbon fiber with glass fiber will reduce the overall stiffness of fiber system. Mixture ratio or hybrid ratio can be calculated using linearly decreasing stress levels and the rule of mixture. These hybrid composite shafts can be manufactured by filament winding technique. During filament winding, composite shafts are wound layer by layer and filament type can be changed between the layers. The proper mixing ratio can be achieved by arranging the fiber count in each filament bundle. The relation between geometrical parameters and hybrid fiber volume fractions of composite shaft was derived. Finite element analysis on carbon fiber and functionally hybridized glass/carbon fiber shafts with same geometry was conducted. Stress, strain, and moment behavior of both shafts were compared. The possible advantages and disadvantages of hybridization were discussed. </jats:p

The bearing strength of pin loaded woven composites manufactured by vacuum assisted resin transfer moulding and hand lay-up techniques

AbstractThe bearing strength of pin loaded woven glass-fiber reinforced epoxy composites was investigated. To understand the effect of manufacturing methods on bearing strength of pin loaded composites, specimens manufactured using Vacuum Assisted Resin Transfer Moulding (VARTM) and Hand Lay-up methods were tested under tensile loading. In addition, the effect of geometrical parameters such as diameter of pin-hole (d), edge distance to pin hole diameter ratio (e/d) and, width to pin-hole diameter ratio (w/d) on the bearing strength of pin loaded composites were studied. It was observed that specimens manufactured using VARTM method sustained more load compared to the specimens manufactured using Hand Lay-up method. Geometrical parameters found to be very effective on failure modes, bearing strength and magnitude of sustained load

Safe Spaces For Women In Challenging Environments

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