Effect of Textile structure in the process parameters of thermoplastic bio-composite

Thermoplastic bio-composite have a higher potential of use based on the sustainability benefits. Natural fibres today are a popular choice for applications in bio- composite manufacturing. Hybrid yarns are a satisfactory solution to improve the fabrication of composites containing a thermoplastic matrix and plant-based fibres. Nevertheless, it is still difficult to produce bio-composites with superior mechanical properties, due to problematic impregnation and consolidation results during the production process. This paper investigates the processing parameters for the compression moulding of two different hemp/PLA textiles structure bio-composites (warp knitting and weaving structure). Finite element simulations are used to optimise the processing parameters (pressure, temperature, and time). The results demonstrated that the textile structure has a small effect on the time of production. Main while the pressure and temperature of processing parameters depend only on the type of matrix and the thickness of biocomposite has a big impact on the time of production

La fiabilité des arbres entaillés dans les machines agricoles : Applications sur les arbres clavetés

The fatigue resistance in service of shaft with key seat is an important parameter in the reliability of strongly sought structures such as the agricultural pieces. Evolution, in design, towards lighter structures and in use towards more and more austere requests in service, give the necessity of a better knowledge of the monotonous and cyclic behavior of shaft with key-seat. This thesis is devoted to study, at the same time, the effect of the geometry of key-seats and the influence of the cyclic loading mode (rotating bending and torsion). New database for fatigue behavior of specimens with key-seats of different geometry sizes under different loading modes (rotating bending and torsion) has receiving. Here also should be noted that the new grips system for biaxial machine test has improved tests performance near endurance limit conditions. Using the Finite Element method, the influence of the geometrical parameters and the type of key-seats on the stress concentration factor was determined. Analytical equations, for every type of key-seats ans loading mode, were proposed. The new ?volumetric approach? gives a good description of the fatigue failure, where the traditional approaches (hot spot) simplified are not appropriate to characterized especially in the case of shafts with key-seats. This new approach gives an effective stress in the volume of fatigue process zone, taking into account the relative stress gradient in this volume. This effective stress gives the estimation of life duration by returning this stress on Wöhler's curve of smooth specimens for the same of loading modeLa tenue en service des arbres clavetés est un paramètre important dans la fiabilité des structures fortement sollicitées tel le matériel agricole. L'évolution, en conception, vers des structures plus légères et en utilisant des sollicitations en service de plus en plus sévères, conduit à la nécessité d'une meilleure connaissance du comportement monotone ou cyclique des arbres clavetés. Cette thèse s'inscrit dans cette préoccupation et se propose d'étudier, à la fois, l'effet de la géométrie de la rainures de clavettes et l'influence du chargement appliqué aux arbres (flexion rotative ou torsion). Des calculs par éléments finis ont déterminé l'influence des paramètres géométriques et le type de rainure sur le facteur de concentration de contrainte. Des équations analytiques, pour chaque type de rainure et mode de chargement, ont été proposées. Des essais de fatigue sur des éprouvettes clavetées ont donné des informations sur l'influence des choix de la rainure et des paramètres géométries sur la durée de vie en fonction du mode de chargement. En notant que le nouveau système mécanique d'amarrage, pour la machine mufti-axiale, a permis de réaliser des essais de torsion près de la limite d'endurance, en assurant un bon alignement des éprouvettes. La nouvelle approche volumétrique donne de bonne estimation de la durée de vie, ou les approches traditionnelles (points chauds) simplifiées ne sont pas capables de la caractériser la rupture par fatigue, spécialement dans le cas des arbres clavetés. Cette nouvelle approche détermine l'amplitude de la contrainte effective dans le volume d'élaboration du processus en fatigue a partir de la loi de comportement cyclique en prenant en compte le gradient relatif des contraintes dans le volume. Cette contrainte effective permet d'estimer la durée de vie d'une éprouvette entaillée, en ramenant cette contrainte sur la courbe de Wohler des éprouvettes lisses pour un même mode de chargemen

La fiabilité des arbres entaillés dans les machines agricoles (Applications sur les arbres clavetés)

METZ-SCD (574632105) / SudocSudocFranceF

Towards sustainable textile sector: Fractionation and separation of cotton/ polyester fibers from blended textile waste

Textiles made of blended cotton/polyester fibers have a huge share of the markets nowadays. The desirable properties of these blends made them a popular choice for both producers and consumers. However, at the end of life, this blended textile waste is often being disposed of in landfills in many parts of the world, since the fibers are hard to be fractionated and/or separated from each other and sorted according to their type, which hinders their recyclability and re-introduction to the supply chain. A significant loss of resources and big environmental impacts are only few consequences of these practices. In this article, we highlight the state of the art of fractionation and separation of cotton/polyester blended textile waste and the methods used in literature, which could be classified into mechanical, chemical and biological approaches. Additionally, we critically discuss the challenges facing these processes and their scaling-up, providing insights on how to overcome these challenges and the new initiatives in this regard, in order to contribute to the circularity and sustainability of the textile sector

Effect of Textile structure in the process parameters of thermoplastic bio-composite

Thermoplastic bio-composite have a higher potential of use based on the sustainability benefits. Natural fibres today are a popular choice for applications in biocomposite manufacturing. Hybrid yarns are a satisfactory solution to improve the fabrication of composites containing a thermoplastic matrix and plant-based fibres. Nevertheless, it is still difficult to produce bio-composites with superior mechanical properties, due to problematic impregnation and consolidation results during the production process. This paper investigates the processing parameters for the compression moulding of two different hemp/PLA textiles structure bio-composites (warp knitting and weaving structure). Finite element simulations are used to optimise the processing parameters (pressure, temperature, and time). The results demonstrated that the textile structure has a small effect on the time of production. Main while the pressure and temperature of processing parameters depend only on the type of matrix and the thickness of biocomposite has a big impact on the time of production

Effects of Microwave Treatment in Immersed Conditions on the Mechanical Properties of Jute Yarn

The versatile bast fiber jute has environmental benefits compared to glass fibers. However, for jute to be used in a composite, the fiber properties need to be altered. This study aims to improve the mechanical properties of jute yarn to make it more suitable for technical applications as a composite. To alter its mechanical properties, jute yarn was immersed in water during microwave treatment. The time and power of the microwave settings differed between runs. Two states of the yarn were tested: fastened and un-fastened. Tensile testing was used at the yarn and fiber level, followed by Fourier-transform infrared spectroscopy (FTIR) and microscopy. The treatment result demonstrated the ability to increase the elongation of the jute yarn by 70%. The tenacity was also increased by 34% in the fastened state and 20% in the un-fastened state. FTIR showed that no change in the molecular structure occurred. The treatments resulted in a change of yarn thickness depending on the state of the yarn. The results indicate that microwave treatment can be used to make jute more suitable for technical applications depending on the microwave treatment parameters

Investigation of microwave treatment effects in the jute tenacity

The jute was subjected to microwave treatments in two different states: unfastened, andfastened. The effects in mechanical properties depend on the state during treatment. Theunfastened state increases the elongation of the jute yarn. For the fastened state, thetreatment increases the tenacity. The higher tenacity resulting from the treatment makes itpossible for jute yarn to be used in a broader range of applications

All-Cellulose Composites Properties from Pre- and Post-Consumer Denim Wastes: Comparative Study

This study reports the recycling of discarded denim textiles by the production of all-cellulose composites (ACCs). Discarded denim fabrics were shredded into fibers and then made into nonwoven fabrics by carding and needle punching. The produced nonwoven fabrics were converted to ACCs by one-step and two-step methods using an ionic liquid (IL), 1-butyl-3-methyl imidazolium acetate ([BMIM][Ac]). In this study, the effect of different ACC manufacturing methods, denim fabrics with different contents (a 100% cotton denim (CO) and a blend material (cotton, poly-ester and elastane (BCO)) and reusing of IL as a recycled cellulose solvent on the mechanical pro-perties of the formed ACCs were investigated. The ACCs were characterized according to their tensile and impact properties, as well as their void content. Microscopic analysis was carried out to study the morphology of a cross-section of the formed composites. The choice of the one-step method with recycled IL, pure IL or with a blend material (BCO) had no influence on the tensile properties. Instead, the result showed that the two-step method, with and without DMSO, will influence the E-modulus but not the tensile strength. Regarding the impact properties of the samples, the only factor likely to influence the impact energy was the one-step method with CO and BCO

Determination of Processing Parameters for Thermoplastic Biocomposites Based on Hybrid Yarns Using Finite Elements Simulation

This paper investigates the processing parameters for the compression molding of hemp/PLA hybrid yarn biocomposites and their effect on the final mechanical properties. Finite element simulations are used to develop and assess the processing parameters, pressure, temperature, and time. These parameters are then evaluated experimentally by producing the composites by two different methods, to compare the results of experimentally determined processing conditions to parameters determined by the simulation analysis. The assessment of mechanical properties is done with several experimental tests, showing small improvements for the composites produced with the simulation method. The application of the simulation analysis results in considerably reduced processing times, from the initial 10 min to only three minutes, thereby vastly improving the processing method. While the employed methods are not yet able to produce composites with greatly improved mechanical properties, this study can be seen as a constructive approach, which has the ability to lead to further improvements