Papers by Keyword: Warp

Abstract: 6-inch 4H-SiC crystal ingot was successfully separated from a seed holder by the contraction enhancement of adhesive. The resin used as an adhesive with 10~30% in contraction ratio during the cooling was selected. The crack between seed holder and grown SiC crystal was observed to be formed after the cooling procedure and the crystal was easily separated from the seed holder without any machining process for the separation. The warp value and the rocking curve value of SiC crystal grown with modified adhesive was observed to be smaller than those of SiC crystal with conventional method.

Abstract: The modified hot-zone design, consisting of a new design and new materials for the backside of SiC seed holder was adopted for reducing stress in grown SiC crystal ingot and for reducing the warpage of 6-inch SiC wafer. Crucible lid on the backside of SiC seed holder was designed to be movable during the growth process. Based on the warp value and mapping measurement of FWHM (Full width at half maximum) value in X-ray rocking curve, the crystal quality of SiC crystals grown with new hot-zone design was observed to be better than conventional design.

Abstract: The impact of surface stress due to polish and grind processes on wafer bow was studied as a function of abrasive size. Results indicate that sub-surface damage from these processes can introduce significant surface stress. For polishing processes, this stress is proportional to mean abrasive size. The study also investigates stress as a function of depth below the wafer surface and finds that most stress is concentrated near the wafer surface.

Abstract: Coated fabrics have complex composite structure whose mechanical properties are considerably improved in relation with the initial basic material. They are obtained by applying a certain number of coatings to raw fabrics. In this paper the practical application of uniaxial testing of coated fabrics for determining its breaking properties and Poisson’s ratio is presented. Due to the anisotropy of woven and coated fabrics, Poisson's ratio changes over the fabric sample stretching. Experimental testing were carried out on two samples of plain weave cotton fabrics. The fabrics were tested before coating, and after one, two and three coatings. Samples are stretched with tensile force in the weft and warp direction, and based on different measured values of fabric stretching, warp and weft Poisson's ratio is calculated. The values of tensile force and relative extension of coated fabrics were measured, and breaking force values, elongation at break, contractions at break.

Abstract: Mechanical tests were performed at the Klokner Institute on samples of a textile glass reinforcement. These tests will be used for determining the modulus of elasticity of textile glass reinforcements and for assessing the maximal stress that the samples will withstand. Both of these quantities are required for further modeling of the structures and for designing elements made from textile reinforced concrete (TRC). The tests were carried out on a total of 10 samples made from a single piece of 2D net (produced by V. FRAAS, GmbH, Germany). The tests were carried out on AR-glass reinforcement (alkali - resistant glass) textile glass with 2400 TEX [g/km] fineness, which is often supplied with dimensions of 1 x 2 m. The first 5 samples were prepared in the direction of the warp (the direction of the load-bearing reinforcement), and the remaining 5 samples were prepared from the transverse direction (the direction of the weft). These samples were loaded by a constant force increasing up to collapse. Then the modulus of elasticity of the textile glass reinforcement and the stress at the strength limit were determined from the monitored data.

Abstract: Tension and elongation of warp is the key factors among various technical parameters in warp sizing process in textile production. Analysis of composition of tension & elongation in different zone on sizing machine.By means of mechanical device and electric sensor, as well as frequency conversion speed regulator controlled by PLC, the sizing warp tension &elongation has been regulated precisely. The principles and features of various sensors and their application on modern sizing machine regarding automation have been discussed in this paper.

Abstract: These paper aims to present an experimental study for determining the mechanical properties of woven fabrics used for airbags manufacturing. In order to realise the study, there were chosen two types of fabric, one that is coated with silicon and one that is uncoated. The experimental tests that were carried out were uniaxial tension tests for samples extracted on the warp and on the weft direction, the Bias test, a test specific for shear loads and the dome test, a test specific for biaxial loads. For the uniaxial tension test the force-displacement curve was obtained and the maximum values of the loads and the displacement. For the last two tests (bias test and dome test) there have been determined the maximum load, the displacement at maximum load, but also the local major strains obtained. All tests were carried out on a tensile and compression testing machine Instron 5587, while for measuring the main strains there has been used also the optical measuring system Aramis.

Abstract: The research on design of multi-bar Raschel lace is still little at present, but the research on design method of multi-bar Raschel lace is very urgent. So it becomes very important to make scientific classification of Raschel lace patterns and discuss the design method of multi-bar Raschel lace patterns. This study focuses on the basis of design skills of the lace pattern composition and structure, explores the typical design steps of Raschel lace patterns, analyzes the elements and application of lace fabric design, summarizes the common arrangement mode of lace fabric design and sums up the concrete problems and solving method of connection design. Then the scientific design idea of lace fabric can be proposed, which will provide useful references for the design of multi-bar Raschel lace patterns in domestic enterprises.

Abstract: Warping and distortion in plastic parts has been a serious problem in mold-injection.Traditional solution is to first produce a mold and then test the moldrepeatedly. By employing Moldflow, it can be easily to offer a precise analysisand prediction of warping in products. Meanwhile, the results can be used toadjust the designed structure and process conditions of the mold. Finally, themold and its products are optimized.

Abstract: In the modern manufacturing the 3D printing technology is the largest reform. The Selective Laser Sintering (SLS) occupies a special place in a hierarchical manufacturing technology. In the SLS process the shrinkage brought the ports size decreased and caused the warp. The fabrication parameters in SLS process played a major influence on the molding accuracy. With the sintering process of Polypropylene composite powder, the fabrication parameters were investigated. Through the gray relational analysis to manipulate the test date about the warp and molding accuracy, we could determine the impact of the most important factors molding accuracy. The result showed that about the warp and molding accuracy the most important parameter was the scan speed, followed by laser power.