To cite this version:P. Molnár, A. Ogale, R. Lahr, P. Mitschang. Influence of drapability by using stitching technology to reduce fabric deformation and shear during thermoforming. Composites Science and Technology, Elsevier, 2009, 67 (15-16), pp.3386. <10.1016/j.compscitech.2007.03.022>. I n f l u e n c e o f d r a p a b i l i t y b y u s i n g s t i t c h i n g t e c h n o l o g y t o r e d u c e f a b r i c d e f o r -m a t i o n a n d s h e a r d u r i n g t h e r m o f o r m i Accepted Manuscript ACCEPTED MANUSCRIPTInfluence of drapability by using stitching technology to reduce fabric deformation and shear during thermoforming Molnár, P., Ogale, A., Lahr, R., and Mitschang, P.Institut für Verbundwerkstoffe GmbH, Erwin-Schrödinger-Straße 58, 67663 Kaiserslautern, Germany AbstractForming of woven fabric into a complex shape involves shear deformation of the fabric elements (warp and weft). Various researchers investigated the shear deformation during the manufacturing of thermoplastic composites (TPC) based on the hemispherical geometry, where the highly deformed edges and corners are considered as a waste. In many applications the complete formed geometry including areas around the curvature has to be used. A new idea to influence the deformation behavior of woven fabric by incorporated seams at localized sections is presented in this paper. The study is based on the photographic analysis of dry sewn preforms and thermoplastic matrix (PA12) impregnated laminates, before and after the deformation. The seams applied at the highly deformable and predefined zones help to reduce fabric shearing or to transfer the shear forces into the unsheared areas during the thermoforming process. The intensity of reduction in the fabric shear depends on the type of the sewn geometry. The results obtained can be applied in the part design, the preform engineering, and the positioning of stitches.

Beams are structural elements commonly used in structure for construction designs. The use of wood as structural elements is very important because it is a material of renewable source, low density and satisfactory mechanical performance. When the wood surface is not properly treated, the structure can be destroyed not only by environmental conditions but also the attack of insects compro mising the design. This research aimed to evaluate the mechanical performance of the use of a particulate composite material (epo xy resin and structural Portland cement) as a way of reinforcing beams. The study of the mechanical performance of using this material in timber beams is essentially nu merical, based on the Finite Element Method, by using the static four points bending tests. The wood used in the simulation was the Eucalyptus grandis, and their mechanical properties were obtained fro m specialized literature in the area of timber structures. The results for d isplacements and stresses obtained fro m numerical analysis indicated that the co mposite material was able with successfully withstand the stresses caused by the loads, the same occurring with the wood, and the results of the hypothesis test for equivalence between meansrevelledtobeminor the influence ofPo isson's ratioon calculus of the displacements.

This research deals with theoretical and experimental studies of timber composite beams reinforced by cold formed steel sheets, submitted to bending. A combination of different materials aims to the exploitation the advantages of each material, of manner to have a viable set, in constructive, structural and economic issues. For the accomplish of the research were tested three timber beams with dimensions 40mm x 120mm x 1050mm, six timber reinforced beams in the superior surface with metallic profile with dimensions 50mm x 25mm x 2mm and six timber beams reinforced in inferior surfaces and in the superior surface with the same metallic profile. The spacing between the connectors was of 100mm, 200mm and 300mm. With the objective of supplying the necessary dimensioning, theoretical formularizations for these studies were presented to the determination of internal moment and the estimated deflection. For this, the timber mechanical properties, the steel and the connectors were determined. With the results of the characterization tests of the materials, the simple and composite beams were tested in bending, for reading of stresses and maximum vertical displacements of the rupture on the inferior and superior extremities. Such values were performed by means of electric strain gauges and dial gauges. Also, were determined: the tensions in the elements of the beams and presented the chart of stresses x displacements. It was observed that, in relation to the timber simple beam, it had average increase at the ultimate load, for beams with reinforced parts in the compressed surface, of 20%, and 49%, when placed stiffeners in compressed and tensioned surfaces. In deflection values, it had the average reduction of 15%, when used stiffeners in the superior surface and of 49% in the parts with stiffeners, in the surfaces were performed to compression and tension. The biggest reduction in deflections happened in beams with lesser spacing between connectors, indicating that the influence of the interaction is bigger in relation to displacements, to bending moment. In stress distribution chart in the cross sections it was adopted, in all cases, the triangular form for the timber and for the profile, it was adopted a rectangular form. It was obtained results that differ from the experimental values in 17% for simple beams, in 16% for parts hardened with profile in superior surface and 21% for the parts hardened with profile, in the surfaces upper and lower, indicating that the proposal formularization can be applied with safety. In the calculation of deflections of geometric properties of composite section, in elastic regime, were performed with the homogenized section. It was presented the equation for the determination of correction factor of the estimated deflection for the studied cases.

OSB panels were developed as a substitute for plywood. However, their properties in static bending, i.e. modulus of elasticity (MOE) and modulus of rupture (MOR) are often reduced. The aim of this study was to evaluate MOE and MOR of OSB manufactured with Pinus sp. and castor-oil based polyurethane resin, applying a wire mesh in order to improve those properties. Recommendations of normative document EN 310:1993 were obeyed. Results showed that mechanical properties considered are compatible with codes requirements and with values obtained by several authors in related literature. In static bending tests, the difference between parallel-to-grain MOE and MOR values of panels with and without wire mesh treatment was not significant. Statistical analysis reveals that the wire mesh pressing position does not affect MOE and MOR. However, these values are superior to those recommended, for OSB and plywood, by normative documents.

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