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1

Development Of 3D Woven Fabric Based Pressure Switch

Shaker K., Nawab Y., Javaid M. U., Umair M., Maqsood M.

Autex Research Journal

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2015

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Vol. 15, no. 2

148--152

EN

This paper introduces a 3D woven fabric-based approach for the development of pressure switch. A fabric substrate, being elastic and extendable is very useful in addition to its high breaking strength and low cost. The developed resistive-type switch is based on the multilayer interlock 3D fabrics. In the top and bottom layers, certain number of conductive yarns are woven separated by cotton yarns in both transversal and thickness direction. Application of pressure makes the layers of conductive yarn to come in contact, resulting in a short circuit, which may be recorded using multi-meters. Removing the pressure cause the connection points to separate away and it depends on the weave design. Such switch can be used as an on/off switch for usage in security systems, can be sewn into carpets and wearable garments for a number of purposes.

2

Innowacyjna technologia przestrzennych dzianin kolumienkowych – struktura i właściwości

Pieklak K.

Zeszyty Naukowe. Włókiennictwo / Politechnika Łódzka

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2014

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z. 70

5--56

PL

W początkowej części pracy przedstawiono ogólne tendencje rozwoju w zakresie tekstyliów technicznych zarówno dzianych, tkanych jak i plecionych ze szczególnym uwzględnieniem wyrobów przestrzennych. Sformułowano istotne cechy budowy nowej generacji dzianin przestrzennych, w tym przestrzennych przeszywanych dzianin kolumienkowych, uwzględniających struktury o więcej niż dwóch warstwach zewnętrznych i przynajmniej jednej warstwie wewnętrznej. Na podstawie zdefiniowanej geometrii dzianin kolumienkowych 3D określono założenia do koncepcji budowy nowoczesnych osnowarek o więcej niż dwóch grzebieniach igłowych. W celu sprawdzenia poprawności postawionych założeń konstrukcyjnych zbudowano model użytkowy osnowarki czterogrzebieniowej, a następnie wytworzono na nim pierwsze struktury dzianych belek. Dla zdefiniowanych struktur dzianych opracowano model geometryczno - strukturalny bazujący na bryle w formie prostopadłościanu o podstawie kwadratowej. Ponadto opracowano algorytm projektowania strukturalno - technologicznego dzianin kolumienkowych 3D oraz zbudowano komputerowy program symulacji właściwości zarówno struktur dzianych jak i kompozytów, w którym wykonano badania symulacyjne właściwości belki przestrzennej. W środowisku programu ANSYS przeprowadzono także badania numeryczne wytrzymałości kompozytów przestrzennych. Dla rzeczywistych struktur belek kompozytów epoksydowo - szklanych wykonano badania empiryczne procesu zginania i ściskania z wykorzystaniem techniki termowizyjnej, w trakcie których prowadzono rejestrację wartości temperatury na powierzchni obciążanych kompozytów.

EN

In the beginning of the doctoral thesis was presented general trends in the development of technical textile s that contains both knitted fabrics, woven fabrics and plaited fabrics. The prepared analysis mainly based on the spatial textiles, that are mostly used in the composite systems. The paper contains four main sections. The first one includes the building and the technology of spatial warp - knitted fabrics and 3D stitch combined fabrics. These fabrics create solids that in cross - section have basic plane figures with an even number of sides, like squares, hexagons, or with an odd number of sides like triangles, pentagons. The cross - sections of the knitted fabrics may also have more sophisticated shapes such as T - bars, double - T bars, channel bars and others, whose form is similar to the commonly used structural beams. The spatial knitted fabrics can be produced from different types of threads. The chapter also describes the concept of building of the multi - needlebar machine with an even and odd number of needle bars. The basic mechanisms and machine components were characterized. The loop forming process for the three - and four - needlebar machines were determined. The prototype of the four - needlebar machines were designed and constructed. All mechanisms of the machines are operated manually. The first solid of the knitted structure with the square cross - section were manufactured on this machine. The new generation of the spatial warp - knitted fabrics and 3D stitch combined fabrics will be applied in the reinforcement of light and high - strength composites. The next chapter presents a geometric – structural model of the spatial warp - knitted fabrics based on the basic structure of the fabric in the form of a rectangular prism. The model of the 3D fabric is the s um of the parameters of the componential models: a model of the external layers and a model of the internal layers. An algorithm of the structural and technological design was developed. The algorithm contains the structure of the knitted fabric and based on its composite structure. The algorithm is built from four sections: the threads parameters, the basic parameters of the knitted fabrics, the structural and physical parameters of knitted fabrics and the parameters of the „knitted composites”. Nearly 450 mathematical relationships that describe the parameters of the fabric and the composite were formulated. These mathematical relationships were used to create a worksheet to simulate the geometric – structural parameters. The next chapter includes computer modeling of the mechanical properties of the „spatial knitted composites”. The simulations were performed in the ANSYS environment, based on the finite element method. The object of the research was a composite beam in the form of a thin - walled prism. The computational model was an "open model" based on the real values of the Young's modulus, that were measured on a testing machine, assuming that the model has anisotropic properties. The simulations were carried out in the three different systems of support, which means in the two - three - and four - point support system. In the calculations were changed: the internal layer geometry of the beam, the thickness of the external and the internal layers, the number and the distance between the perpendicular barriers, the construction of the barrier, the measured value of the Young's modulus and the value of the loading force. The total sum of the computational variants was 111. The last chapter includes an analysis of the strength properties of the spatial composites based on the infrared technique. The experimental research was carried out by three -, or four - point bending process and compression process of the composite beams. The composite beams were made from the fabrics from the glass fibers strengthened by an epoxy resin. The experiment was carried out on the measuring position equipped with two cameras: an infrared camera used for the registration of the thermal images and a digital camera. The recorded results of force and temperature on the surface of the composite were used to analyze changes of the exciting force and the temperature as a function of time. The building and the technology of the spatial warp - knitted fabrics and 3D stitch combined fabrics were awarded with a silver medal at the World Exhibition „Eureka Contest 2010”. They are also the object of one patent and three patent applications, six publications and a few oral presentations.

3

Investigation about the Manufacturing Technique of the Composite Corner Fitting Part

Wang P., Legrand X., Soulat D.

Autex Research Journal

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2014

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Vol. 14, no. 2

111--120

EN

Textile composite reinforcement forming has been employed in many aeronautic industries as a traditional composite manufacturing process. The double-curved shape manufacturing may be difficult and can lead to defects when the composite parts have high curvatures and large deformations. Compared with the textile composites forming, surface 3D weaving can demonstrate directly the geometry of final composite part without the stages involved in 2D product. The weaving in three directions is completely designed and warp and weft yarns are always perpendicular to the surfaces of the final 3D ply. These two manufacturing techniques are applied to produce an important piece of aircraft: the corner fitting. The 3D weaving results are compared with the experimental forming by a punch as same geometry as the corner fitting part. The conveniences and limits of each technique are investigated. The comparisons show particularly a perfect final 3D fabric with homogeneous fibre volume fraction performed by the surface 3D weaving technique.