P 383 - Extension of forming limits by vibration-superimposed deep-drawing process

P 384: Process for the rapid manufacture of deep-drawing and stretch-drawing tools from sheet metal lamellae for prototype and small-batch production (rapid tooling) The task of this research project was to develop a process for the rapid and cost-effective production of deep-drawing and stretch-drawing tools for sheet metal forming. The basic principle of the process is to construct the deep-drawing tool from sheet steel lamellae in a vertical arrangement. A particular advantage of laminating technology compared to other rapid tooling processes is the ability to realise even large tool geometries without significant additional time expenditure. Of particular importance is the prototype and small series production of large moulded sheet metal parts made of high-strength and higher-strength sheet steel. With regard to a short process chain, a continuous rapid tooling system should be developed from the design of the workpieces and tools on the CAD system through to the production and optimisation of prototype components. Various blank materials with and without elastomer intermediate layers were drawn using deep-drawing and stretch-drawing tools with simple and complex geometries, and the workpieces were analysed for surface quality and dimensional accuracy. The process-related stress on the intermediate layers was determined using accompanying numerical finite element simulation calculations. A self-developed clamping frame concept was used to hold the tool discs. In addition, a laminating programme was developed on the programming side and integrated into a commercial CAD system within the manufacturing process chain. The research work demonstrated the suitability of vertical laminating for the faster production of even complex sheet metal moulding tools for prototypes based on conventional deep-drawing and stretch-drawing processes as well as processes based on active media. In addition, suitable interlayer materials were identified on the basis of process-specific requirements, their reusability was demonstrated and the influence of the interlayer thickness in particular was determined on the basis of a stress analysis. The process concept developed enables small and medium-sized companies with a limited stock of semi-finished sheet metal products and a comparatively small machine park to keep up with the production of sample components and small series. STUDIENGESELLSCHAFT STAHLANWENDUNG e. V. Publication: 2001 Authors: Prof. Dr.-Ing. M. Kleiner, Dipl.-Ing. R. Krux

P 385 - The dependence of the beacon hardening effect on the change in shape - Development of extended design notes Authors: K. Siegert, S. Wagner, T. Müller Publication: 2005

P 387: Investigations into the process control of soft plasma welding on lap joints of high-alloy CrNi steels Flat slabs in composite construction have many economic and architectural advantages. By integrating the steel profile into the reinforced concrete ceiling, the overall construction height is reduced. A smooth lower edge of the ceiling can be left as a room closure and enables free architectural design. Cost-effectiveness is achieved through higher load-bearing capacity, i.e. larger spans and higher loads, than with conventional reinforced concrete flat ceilings. The high degree of steel construction prefabrication and the use of prefabricated concrete parts or composite profile sheets can considerably reduce the construction time. However, flat slabs in composite construction have a different load-bearing behaviour compared to composite beams with high structural steel chords, particularly due to the cracking of the reinforced concrete. Composite girders with the same slab behaviour behave more like pure reinforced concrete girders than like composite girders with an overpressed concrete chord. With this new type of construction, the usual neglect of the moment of inertia and the moment contribution of the reinforced concrete in composite construction is uneconomical and no longer applicable. The subject of the investigations is the determination of the load-bearing behaviour and the optimisation of the design of composite beams in hat form with the same slab. The main focus is on the realistic determination of the deformation, taking into account the partial composite effect. Experimental investigations with a total of nine test girders were carried out to verify the results derived by calculation. Six test beams were designed as single-span beams. Three test beams were tested in the negative moment range. A proposal for determining the deformations of flat slabs with hat profiles was derived on the basis of a calculation model that iteratively records the compliance in the composite joint and the material non-linearity of the reinforced concrete chord. With the new modified moments of inertia for the time t = 0 or t = _, more realistic deformations are determined compared to the very conservative regulations of the standard for this type of construction. In the usual area of application of flat slabs with hat profiles, reductions in the calculated deformations of up to 250 % result. By recording the reinforcement when determining the positive moment load-bearing capacity of the flat slab with hat profile, increases in load-bearing capacity of up to 35 % are possible in the usual area of application. For the negative moment range, the standard currently only permits a composite joint with full dowelling. Initial investigations show the influence of the partial bond effect on flat slabs with hat profiles under negative moment loads. The results of this study enable a more economical application of this new type of composite floor system. Structural engineers are provided with practical tools and decision criteria which, the authors hope, will lead to a wider acceptance of composite flat slabs in building construction. FORSCHUNGSVEREINIGUNG STAHLANWENDUNG e. V. Publication: 2002 Authors: Dr.-Ing. T. Böllinghaus, Dr.-Ing. Noack, Dipl.-Ing. T. Michael

P 389: Optimisation of the design of composite beams in hat form with the same slab thickness Flat slabs in composite construction have many economic and architectural advantages. By integrating the steel profile into the reinforced concrete slab, the overall building height is reduced. A smooth lower edge of the ceiling can be left as a room closure and allows a free architectural design. Cost-effectiveness is achieved through higher load-bearing capacity, i.e. larger spans and higher loads, than with conventional reinforced concrete flat ceilings. The high degree of steel construction prefabrication and the use of prefabricated concrete parts or composite profile sheets can considerably reduce the construction time. However, flat slabs in composite construction have a different load-bearing behaviour compared to composite beams with high structural steel chords, particularly due to the cracking of the reinforced concrete. Composite girders with the same slab behaviour behave more like pure reinforced concrete girders than like composite girders with an overpressed concrete chord. With this new type of construction, the usual neglect of the moment of inertia and the moment contribution of the reinforced concrete in composite construction is uneconomical and no longer applicable. The subject of the investigations is the determination of the load-bearing behaviour and the optimisation of the design of composite beams in hat form with the same slab. The main focus is on the realistic determination of the deformation, taking into account the partial composite effect. Experimental investigations with a total of nine test girders were carried out to verify the results derived by calculation. Six test beams were designed as single-span beams. Three test beams were tested in the negative moment range. A proposal for determining the deformations of flat slabs with hat profiles was derived on the basis of a calculation model that iteratively records the compliance in the composite joint and the material non-linearity of the reinforced concrete chord. With the new modified moments of inertia for the time t = 0 or t = _, more realistic deformations are determined in comparison to the very conservative regulations of the standard for this type of construction. In the usual area of application of flat slabs with hat profiles, reductions in the calculated deformations of up to 250 % result. By recording the reinforcement when determining the positive moment load-bearing capacity of the flat slab with hat profile, increases in load-bearing capacity of up to 35 % are possible in the usual area of application. For the negative moment range, the standard currently only permits a composite joint with full dowelling. Initial investigations show the influence of the partial bond effect on flat slabs with hat profiles under negative moment load. The results of this study enable a more economical application of this new type of composite floor system. Structural engineers are provided with practical tools and decision criteria which, the authors hope, will lead to a wider acceptance of composite flat slabs in building construction. FORSCHUNGSVEREINIGUNG STAHLANWENDUNG e. V. Publication: 2004 Authors: Prof. Dr.-Ing. U. Kuhlmann, Dipl.-Ing. J. Fries