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Sheet Metal (sheet + metal)
Selected AbstractsUltrasonically Welded Aluminium Foams/Sheet Metal , Joints,ADVANCED ENGINEERING MATERIALS, Issue 9 2006C. Born Abstract The ultrasonic welding technology enables to produce high-strength joints between sheet metal and aluminium foam sandwich (AFS) without melting of the metal or any damage of the foam structure. In the investigations the used welding processes and different factors influencing the weldability were varied. The achievable mechanical properties for ultrasonically welded metal joints, especially under monotonic and cyclic load, will be discussed. Additionally, results of microscopic investigations of the bonding zone and possible applications are presented. [source] Asbestos-related disease among sheet metal workers 1986,2004: Radiographic changes over time,,AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 7 2009FACOEM, Laura S. Welch MD Abstract Background In 1985, the Sheet Metal Workers International Association and the Sheet Metal and Air Conditioning National Association formed The Sheet Metal Occupational Health Institute Trust (SMOHIT) to examine the health hazards of the sheet metal industry. Between 1986 and 2004 18,211 individuals were examined. At the time of the first examination 9.6% of all participants (1,745) had findings consistent with parenchymal disease (ILO,>,1/0), and 21% (3,827) had pleural scarring. Methods 2181-Two thousand hundred eighty-one who had no radiographic evidence of pneumoconiosis on baseline examination underwent a second examination. Results By the second examination, 5.3% had developed parenchymal disease on chest radiograph; an additional 12.4% had developed pleural scarring without parenchymal disease. Factors that predicted new cases of pneumoconiosis on radiograph were the calendar year the worker entered the sheet metal trade, smoking, and shipyard work. Forty-seven percent of those smoking at the time of initial exam reported having quit smoking by the second examination. Conclusions Asbestosis is still occurring 50 years after first exposure. Exposed workers benefit from medical screening programs that incorporate smoking cessation. Am. J. Ind. Med. 52:519,525, 2009. © 2009 Wiley-Liss, Inc. [source] Tangible Heritage: Production of Astrolabes on a Laser EngraverCOMPUTER GRAPHICS FORUM, Issue 8 2008G. Zotti I.3.5 [Computer Graphics]: Computational geometry and object modelling , geometric algorithms, languages and systems; I.3.8 [Computer Graphics]: Applications Abstract The astrolabe, an analog computing device, used to be the iconic instrument of astronomers during the Middle Ages. It allowed a multitude of operations of practical astronomy which were otherwise cumbersome to perform in an epoch when mathematics had apparently almost been forgotten. Usually made from wood or sheet metal, a few hundred instruments, mostly from brass, survived until today and are valuable museum showpieces. This paper explains a procedural modelling approach for the construction of the classical kinds of astrolabes, which allows a wide variety of applications from plain explanatory illustrations to three-dimensional (3D) models, and even the production of working physical astrolabes usable for public or classroom demonstrations. [source] Ultrasonically Welded Aluminium Foams/Sheet Metal , Joints,ADVANCED ENGINEERING MATERIALS, Issue 9 2006C. Born Abstract The ultrasonic welding technology enables to produce high-strength joints between sheet metal and aluminium foam sandwich (AFS) without melting of the metal or any damage of the foam structure. In the investigations the used welding processes and different factors influencing the weldability were varied. The achievable mechanical properties for ultrasonically welded metal joints, especially under monotonic and cyclic load, will be discussed. Additionally, results of microscopic investigations of the bonding zone and possible applications are presented. [source] Adaptive through-thickness integration for accurate springback predictionINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2008I. A. Burchitz Abstract Accurate numerical prediction of springback in sheet metal forming is essential for the automotive industry. Numerous factors influence the accuracy of prediction of this complex phenomenon by using the finite element method. One of them is the numerical integration through the thickness of shell elements. It is known that the traditional numerical schemes are very inefficient in elastic,plastic analysis and even for simple problems they require up to 50 integration points for an accurate springback prediction. An adaptive through-thickness integration strategy can be a good alternative. The main characteristic feature of the strategy is that it defines abscissas and weights depending on the integrand's properties and, thus, can adapt itself to improve the accuracy of integration. A concept of an adaptive through-thickness integration strategy for shell elements is presented in this paper. Its potential is demonstrated using two examples. Calculations of a simple test,bending a beam under tension,show that for a similar set of material and process parameters the adaptive rule with seven integration points performs significantly better than the traditional trapezoidal rule with 50 points. Simulations of an unconstrained cylindrical bending problem demonstrate that the adaptive through-thickness integration strategy for shell elements can guarantee an accurate springback prediction at minimal costs. Copyright © 2007 John Wiley & Sons, Ltd. [source] A finite element model for thermomechanical analysis of sheet metal formingINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2004G. Bergman Abstract A thermal model based on explicit time integration is developed and implemented into the explicit finite element code DYNA3D to model simultaneous forming and quenching of thin-walled structures. A staggered approach is used for coupling the thermal and mechanical analysis, wherein each analysis is performed with different time step sizes. The implementation includes a thermal shell element with linear temperature approximation in the plane and quadratic in the thickness direction, and contact heat transfer. The material behaviour is described by a temperature-dependent elastic,plastic model with a non-linear isotropic hardening law. Transformation plasticity is included in the model. Examples are presented to validate and evaluate the proposed model. The model is evaluated by comparison with a one-sided forming and quenching experiment. Copyright © 2004 John Wiley & Sons, Ltd. [source] An improved, simple nest-box trapJOURNAL OF FIELD ORNITHOLOGY, Issue 1 2008Scott L. Friedman ABSTRACT The success of ornithological studies often hinges on a researcher's ability to capture individuals quickly and efficiently. Sometimes it is necessary to capture the same individual multiple times, as is the case in many metabolic, ecotoxicological, and immunocompetence studies. Several methods of capturing cavity-nesting birds at their nest boxes have been described. However, these methods proved inefficient when attempting to catch wary individuals that had already been captured previously. Here we describe a simple and inexpensive method for capturing cavity-nesting birds using a square plate of sheet metal (5.8 × 5.8 × 0.2 cm), a drinking straw, a piece of duct tape, and a monofilament line. This method has the advantages of allowing selective capture of one, but not both members of a pair and being nearly invisible to trap-shy birds. SINOPSIS El éxito de estudios ornitológicos está atado, muchas veces, a la habilidad del investigador para atrapar aves de forma rápida y eficiente. En ocasiones es necesario capturar el mismo individuo multiples veces, como es en el caso de estudios metabólicos, ecotoxicológicos o de inmunocompetencia. Se han descrito varios métodos para atrapar aves que anidan en cajas. Sin embargo, estos métodos han provado ser ineficientes cuando se intenta capturar aves que han sido alertadas por haberse capturado anteriormente. Describimos un método, simple y de bajo costo, para capturar aves que anidan en cajas, utilizando una plancha cuadrada de metal (5.8 × 5.8 × 0.2 cm), un sorbeto y un pedazo de cinta adhesiva plástica (duck tape) y un monofilamento. Este método tiene ventajas, y permite la captura selectiva de uno de los miembros de la pareja. El mismo es virtualmente invisible para las aves. [source] Non-linear dynamic contact of thin-walled structuresPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008Thomas Cichosz In many areas of mechanical engineering contact problems of thin,walled structures play a crucial role. Car crash tests and incremental sheet metal forming can be named as examples. But also in civil engineering, for instance when determining the moment,rotation characteristics of a bolted beam,column joint, contact occurs. Effective simulation of these and other contact problems, especially in three,dimensional non,linear implicit structural mechanic is still a challenging task. Modelling of those problems needs a robust method, which takes the thin,walled character and dynamic effects into account. We use a segment,to,segment approach for discretization of the contact and introduce Lagrange Multipliers, which physically represent the contact pressure. The geometric impenetrability condition is formulated in a weak, integral sense. Choosing dual shape functions for the interpolation of the Lagrange Multipliers, we obtain decoupled nodal constraint conditions. Combining this with an active set strategy, an elimination of the Lagrange multipliers is easily possible, so that the size of the resulting system of equations remains constant. Discretization in time is done with the implicit Generalized-, Method and the Generalized Energy,Momentum Method. Using the "Velocity,Update" Method, the total energy is conserved for frictionless contact. Various examples show the performance of the presented strategies. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Fabricating Design: A Revolution of ChoiceARCHITECTURAL DESIGN, Issue 4 2010Frank Barkow Abstract Berlin-based practice Barkow Leibinger has become synonymous with expertise in digital fabrication. For 12 years, the firm has been engaged in designing buildings for machine-tool company Trumpf in Stuttgart - a relationship that has given the firm remarkable insights into the laser cutting of sheet metal. Here, Frank Barkow describes the fruitful research that the studio has undertaken in laser cutting as well as two innovative projects that have resulted from it. He explains why a new technology like that of digital fabrication must be for architects by necessity ,a revolution of choice' - a speculation on where best to exploit new possibilities, albeit informed by research and experimentation. Copyright © 2010 John Wiley & Sons, Ltd. [source] Ultrasonic Metal Welding of Aluminium Sheets to Carbon Fibre Reinforced Thermoplastic Composites (Adv. Eng.ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009Mater. The Cover shows a hybrid joint for multi-material lightweight components realized by ultrasonic metal welding at the Institute of Materials Science and Engineering at the University of Kaiserslautern. Ultrasonic welding is one innovative technology for joining carbon fibre reinforced polymers (CFRP) with sheet metals like aluminium alloys or aluminium plated steels. The achievable mechanical properties of the ultrasonic welded joints were carried out by using statistical test methods. One example for the evaluation of the welding results is presented on the left hand side of the Cover. Additionally a scanning electron micrograph of the bonding zone of an aluminium/CFRP-joint is shown in the background. More details about the ultrasonic welding technique can be found in the article of F. Balle, G. Wagner and D. Eifler on page 35 of this issue. [source] Ultrasonic Metal Welding of Aluminium Sheets to Carbon Fibre Reinforced Thermoplastic Composites,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009Frank Balle The ultrasonic welding technology is an innovative method to produce hybrid joints for multi-material components. The investigations described in this paper were carried out using the ultrasonic metal welding technique for joining carbon fibre reinforced thermoplastic composites (CFRP) with sheet metals like aluminium alloys or aluminium-plated steels. The achievable mechanical properties as a function of the process parameters are presented. Additionally, microscopic investigations of the bonding zone are discussed. One important advantage of ultrasonic metal welding is the possibility to realise a direct contact between the load bearing fibres of the reinforced composite and the metallic surface without destroying the carbon fibres. [source] Machine Tools With Metal Foams,ADVANCED ENGINEERING MATERIALS, Issue 9 2006R. Neugebauer Abstract Machine tool construction calls for subassemblies with reduced weight while retaining excellent dynamic properties. Modern frame components do always meet required static stiffness but often display oscillation problems due to low component wall thicknesses. Breaking down solid steel structure into wide-area sandwich designs such as steel-aluminum foam-steel panels results in good static properties to be combined with excellent properties since these sandwiches have 30 to 40 times the flexural strength. This is due to their major geometrical moment of inertia in relation to adequate-mass steel sheet metals. In addition, the foam core dampens oscillations. Studies on foamed steel sections indicate that 2 to 3 times higher damping is likely in relation to unfoamed steel sections. These benefits were the motivation for the Chemnitz Metal Foam Center to accelerate development of extremely large-format sandwiches with dimensions of 1,500,×,1,000,mm2. [source] Inverse estimation of material properties for sheet metalsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 2 2004K. M. Zhao The main objective of this paper is to estimate the material properties for sheet metals subjected to loading and reverse loading by using an inverse method. Cyclic three-point bending tests are conducted. Bending moments are computed from the measured data, namely, punch stroke, punch load, bending strain and bending angle. Bending moments are also calculated based on the selected constitutive model. Normal anisotropy and non-linear isotropic/kinematic hardening are considered. Material parameters are estimated by minimizing the difference between these two bending moments. Modified Levenberg,Marquardt method is used in the optimization procedure. Stress,strain curves are generated with the material parameters found in this way. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||