Axial and Lateral Quasi-Static Crushing Behaviour of Segmented and Non-Segmented Composite Tubes

Considerable research interest has been directed towards the use of composite for crashworthiness applications, because they can be designed to provide impact energy absorption capabilities which are superior to those of metals when compared on weight basis. The use of composite circular tubes i n structural applications IS becoming more widespread throughout the auto motives, aircraft industry. This work examines the effect of segmentation on the crushing behaviour, energy absorption and failure mode of composite circular tubes. The segmented composite tube consists of more than one material, each with its own specific functions. Through out this study, segmented and non segmented composite tubes with different sequences were experimentally investigated under axial and lateral loading conditions. The effect of fibre reinforcement type and segments sequence on energy absorption and load carrying capacity were also presented and discussed. Load-displacement curves and deformation histories of typical specimens are presented and discussed. The results showed that non-segmented composite tubes were found to be very brittle (i.e. tissue mat glass fibre/epoxy tubes), and show very low initial failure crush load value of 1 .8 9kN, as well as low specific energy absorption value of O.065kJ/kg under axial crushing. Whereas, the carbon fabric fibre reinforced plastic (CFRP) tubes showed highest load-carrying capacity among the tested specimens with initial fai lure crush load value of I8.85kN as well as specific energy absorption value of I9 .27kJ/kg. On the other hand, segmented composite tubes including the tissue mat glass fibres were found to suffer from low energy absorption and the catastrophic failure mechanism initiated at the part made of tissue mat glass fibre/epoxy. Segmented Composite tubes from carbon fabric fibre and cotton fabric fibres exhibited good specific energy absorption value of 13.53 kj/kg as well as stable load-carrying capacity under axial loading. A change in segmentation sequence affects the crush loads significantly just for double fibre segmented composite tubes under lateral loading. The axial loaded segmented composite tubes have better load carrying capacity and energy absorption capability compared to the laterally loaded segmented composite tubes, and the failure modes were quite different

Design and processing of low alloy high carbon steels by powder metallurgy. P/M processing and liquid phase sintering of newly designed low-alloy high carbon steels based on Fe-0.85Mo-C-Si-Mn with high toughness and strength.

The work presented has the ultimate aim to increase dynamic mechanical properties by improvements in density and optimisation of microstructure of ultra high carbon PM steels by careful selection of processes, i.e. mixing, binding, alloying, heating profile and intelligent heat treatment. ThermoCalc modelling was employed to predict liquid phase amounts for two different powder grades, Astaloy 85Mo or Astaloy CrL with additive elements such as (0.4-0.6wt%)Si, (1.2-1.4wt%)C and (1-1.5wt%)Mn, in the sintering temperature range 1285-1300ºC and such powder mixes were pressed and liquid phase sintered. In high-C steels carbide networks form at the prior particle boundaries, leading to brittleness, unless the steel is heat-treated. To assist the breaking up of these continuous carbide networks, 0.4-0.6% silicon, in the form of silicon carbide, was added. The water gas shift reaction (C + H2O = CO + H2, start from ~500ºC) and Boudouard reaction (from ~500ºC complete ~930ºC) form CO gas in the early part of sintering and can lead to large porosity, which lowers mechanical properties. With the use of careful powder drying, low dew point atmospheres and optimisation of heating profiles, densities in excess of 7.70g/cm3 were attained. The brittle microstructure, containing carbide networks and free of cracks, is transformed by intelligent heat treatment to a tougher one of ferrite plus sub-micron spheroidised carbides. This gives the potential for production of components, which are both tough and suitable for sizing to improve dimensional tolerance. Yield strengths up to 410 MPa, fracture strengths up to 950 MPa and strains of up to 16 % were attained. Forging experiments were subsequently carried out for spheroidised specimens of Fe-0.85Mo+06Si+1.4C, for different strain rates of 10-3, 10-2, 10-1 and 1sec-1 and heated in argon to 700¿C, density ~7.8g/cm3 and 769 MPa yield strength were obtained.Libyan Education Ministry Offic

Assessment of Recycled Plastic Performance in The City of Zawia Libya

Plastic particles and other plastic pollutants exist in our environment and in the food chain and threaten human health. Inappropriate handling and disposal of plastic waste is a global problem and is still not resolved in many countries. When recycling companies need to deal with complex plastic, the problem becomes even more serious, which can prevent their recycling initiatives. The main purpose of this research is to determine whether recycled products can be used as post-consumer materials in various recycling ratios to produce new products without reducing quality. In the study, 0 percent, 20%, 50%, 70%, and 100 percent regrind ratios were used. Reduction, hardness, and solid density are the qualities studied. The results show that the properties did not change significantly

Assessment of Recycled Plastic Performance in The City of Zawia Libya

Plastic particles and other plastic pollutants exist in our environment and in the food chain and threaten human health. Inappropriate handling and disposal of plastic waste is a global problem and is still not resolved in many countries. When recycling companies need to deal with complex plastic, the problem becomes even more serious, which can prevent their recycling initiatives. The main purpose of this research is to determine whether recycled products can be used as post-consumer materials in various recycling ratios to produce new products without reducing quality. In the study, 0 percent, 20%, 50%, 70%, and 100 percent regrind ratios were used. Reduction, hardness, and solid density are the qualities studied. The results show that the properties did not change significantly

Thin-walled composite tubes using fillers subjected to quasistatic axial compression

It has been demonstrated that composites are lightweight, fatigue resistant and easily melded, a seemingly attractive alternative to metals. However, there has been no widespread switch from metals to composites in the automotive sector. This is because there are a number of technical issues relating to the use of composite materials that still need to be resolved including accurate material characterization, manufacturing and joining process. The total of 36 specimens have been fabricated using the fibre-glass and resin (epoxy) with a two different geometries (circular and corrugated) each one will be filled with five types of filler (Rice Husk, Wood Chips, Aluminium Chips, Coconut Fibre, Palm Oil Fibre) all these type will be compared with empty Tubes for circular and corrugated in order to comprehend the crashworthiness parameters (initial failure load, average load, maximum crushing load, load ratio, energy absorption, specific energy absorption, volumetric energy absorption, crushing force efficiency and crush strain relation) which are considered very sufficient parameters in the design of automotive industry parts. All the tests have been done using the "INSTRON Universal machine" which is computerized in order to simply give a high precision to the collection of the results, along with the use of quasi-static load to test and observe the behaviour of the fabricated specimens

Design and processing of low alloy high carbon steels by powder metallurgy : P/M processing and liquid phase sintering of newly designed low-alloy high carbon steels based on Fe-0.85Mo-C-Si-Mn with high toughness and strength

The work presented has the ultimate aim to increase dynamic mechanical properties by improvements in density and optimisation of microstructure of ultra high carbon PM steels by careful selection of processes, i.e. mixing, binding, alloying, heating profile and intelligent heat treatment. ThermoCalc modelling was employed to predict liquid phase amounts for two different powder grades, Astaloy 85Mo or Astaloy CrL with additive elements such as (0.4-0.6wt%)Si, (1.2-1.4wt%)C and (1-1.5wt%)Mn, in the sintering temperature range 1285-1300ºC and such powder mixes were pressed and liquid phase sintered. In high-C steels carbide networks form at the prior particle boundaries, leading to brittleness, unless the steel is heat-treated. To assist the breaking up of these continuous carbide networks, 0.4-0.6% silicon, in the form of silicon carbide, was added. The water gas shift reaction (C + H2O = CO + H2, start from ~500ºC) and Boudouard reaction (from ~500ºC complete ~930ºC) form CO gas in the early part of sintering and can lead to large porosity, which lowers mechanical properties. With the use of careful powder drying, low dew point atmospheres and optimisation of heating profiles, densities in excess of 7.70g/cm3 were attained. The brittle microstructure, containing carbide networks and free of cracks, is transformed by intelligent heat treatment to a tougher one of ferrite plus sub-micron spheroidised carbides. This gives the potential for production of components, which are both tough and suitable for sizing to improve dimensional tolerance. Yield strengths up to 410 MPa, fracture strengths up to 950 MPa and strains of up to 16 % were attained. Forging experiments were subsequently carried out for spheroidised specimens of Fe-0.85Mo+06Si+1.4C, for different strain rates of 10-3, 10-2, 10-1 and 1sec-1 and heated in argon to 700ºC, density ~7.8g/cm3 and 769 MPa yield strength were obtained.EThOS - Electronic Theses Online ServiceLibyan Education Ministry OfficeGBUnited Kingdo