P 1118 - Influences of steel and composite construction on the life cycle costs and marketability of multifunctional office and commercial buildings

P 1121 - Development of a method for the design of bonded joints in structures subject to vibration in agricultural machinery and plant engineering In constructions made of thicker steel sheets (approx. 3-8 mm) in agricultural machinery and plant engineering, adhesive bonding technology has so far only been used to a limited extent, although it is already an established joining method in other areas of application. Bonded joints are generally characterised by excellent behaviour under vibration load, which was also demonstrated on thicker steel sheets in a previous SME study by FOSTA e.V. in random sample tests. The main objectives of the project are - Experimental investigation of the strength behaviour of bonded joints made from thicker thicker sheets using higher-strength steels. Comparison of the strength behaviour of bonded and welded joints, - Development of a procedure for the design of bonded joints under cyclic loading as an cyclic loading as an alternative to welded joints. For this purpose, the joint and seam forms of welded construction details commonly used in agricultural machinery and plant engineering are analysed at the beginning and evaluated with regard to the feasibility of adhesive bonding solutions. A bracket connection is selected as a bonded sample component for subsequent investigations. At the beginning of the research project, the strength behaviour is examined in quasi-static, Wöhler and fatigue strength tests using the example of a lap joint suitable for adhesive bonding technology without and after exposure to media or corrosion. It is shown that bonded joints under quasi-static loading fall significantly short of the strength of the welded joints investigated. However, the strength of the bonded joints can be increased by using higher-strength adhesives. The potential of bonded joints lies in the high-cycle fatigue range. Due to the significantly lower notch effect, the fatigue behaviour above approx. 105 to 106 load cycles is much more favourable compared to welded joints. The influence of medial and corrosion effects must always be taken into account, i.e. seam seals are required in zones subject to greater stress in this respect. The high resistance to fatigue identified at the lap joint is also evident in the sample components analysed, provided the joint zones are sufficiently rigid. The lightweight construction potential of bonded high-strength steels is clearly demonstrated by the fact that a reduction in sheet thickness has a significantly lower impact on the service life compared to welded joints. To ensure handling strength in production, mechanical processes accessible from one and two sides (blind rivets, etc.) are analysed and evaluated. Finally, recommendations for the methodological procedure for the development of structural adhesive bonds for agricultural machinery and plant engineering are formulated from the project results. Based on the data obtained, a concept for determining the component S-N curve and the component fatigue strength using nominal shear stresses in accordance with the FKM guideline is presented. Publication: 2019 Authors: Prof. Dr.-Ing. G. Kötting, Prof. Dr.-Ing. G. Meschut

P 1114 - Feasibility and geometry prediction of sheet metal components with high and ultra-high strength steels Reducing manufacturing costs is a key factor in increasing the competitiveness of manufacturing companies. In this context, clinching offers great potential, as this process makes it possible to produce functional surfaces in just one production step and without post-processing. Push-through forming is defined in DIN 8587 as a shear forming process in which one workpiece part is displaced relative to another with a rectilinear tool movement. The plastic deformation is achieved, analogous to fine blanking or shearing shear cutting with a small cutting gap, plastic deformation is mainly caused by a state of shear stress. The tool technology and tool kinematics of the processes are also similar. This leads to the conclusion that piercing largely corresponds to a cutting process without cutting through the workpiece. In order to reduce the weight of components and to be able to dispense with a tempering process, sheet metal made of high-strength and ultra-high-strength steel is increasingly being used. However, there is hardly any experience in the design and development of these grades. In order to ensure the safety of the process in the early development phase the process is simulated using the finite element method. This poses particular challenges in terms of material modelling. It is known from shear cutting that the temperature in the shear zone can rise to over 300 °C. Furthermore, degrees of deformation and strain rates are to be expected that cannot be modelled using conventional experiments such as the tensile test. In order to reduce the experimental effort, a methodology is presented and validated in this research project in order to nevertheless enable an efficient prediction of the geometry and feasibility of a sheet metal component with through-set. For this purpose, the interleaving line is broken down into recurring mould elements. The characteristic shape of these interspersions is determined experimentally for four different sheet metal materials. materials. Subsequent material modelling based on a simple test procedure is used as the starting point for determining the correction model. This is followed by an adjustment of this model in order to minimise the deviation between simulation and experiment. By interpolating between the mould elements, it is possible to adapt the material model locally for complex interspersion geometries. This makes it possible to assess the feasibility and geometry of interspersions made of high-strength and ultra-high-strength steels at an early stage of development. Authors: Prof. Dr.-Ing. W. Volk, J.-M. Stahl M.Sc. Publication: March 2020

P 1123 - Hollow section truss structures with bonded strut connections Foundation structures for offshore wind turbines are often designed as jacket truss structures for water depths of more than 20 metres. Until now, the individual hollow profiles of these truss structures have been joined by welding. Due to the spatial intersection of the pipe profiles at the junctions and the resulting complex weld seam geometries, as well as the large open areas required for final assembly, this represents a major manufacturing effort. An innovative hybrid connection of the struts to the corner posts of these supporting structures is the focus of this research project. The concept combines the joining methods of bonding, welding and bolting by forming nodal partial shells at the ends of the struts. These individual partial shells are formed in such a way that they enclose the corner strut and are completed to form a complete shell during assembly. After the individual partial shells have been bolted together, the remaining gap between the gusset ring shell and the corner post tube wall is joined using adhesive technology. This work step takes place in the manufacturing plant and therefore under defined ambient conditions. This design has the advantage that permanently acting static loads (such as dead weight) are almost completely dissipated by the continuous corner stems. Furthermore, the lack of welded connections on the corner posts results in an increase in local fatigue strength. In addition, the hybrid connection enables prefabrication of the struts and the modular design of the jacket. First, the requirements and boundary conditions of the jacket support structure are analysed and defined in the research project. In close cooperation with companies from the offshore wind energy sector, the stresses from wind, wave impact and turbine operation are determined. Real climate data measured on research platforms in the North Sea is also analysed and the requirements for the adhesive bond are derived from this. Due to the dimensional tolerances of the bonded parts, thick-film bonds of up to 25 mm are required. Extensive numerical investigations are used to analyse the stress on the bonded joint and steel structure. Numerical models of the entire jacket support structure are created for this purpose. A global framework model is combined with volume models in the area of the bonded connections in order to determine the local stress of the bond. It is shown that both highly rigid and elastic adhesives can be used due to the design of the connections. In the next step, suitable, commercially available 2-component adhesives are selected on the basis of the boundary conditions and requirements. These are characterised experimentally. Based on the results, two adhesives are then prioritised in coordination: a highly rigid 2-component polyurethane adhesive and an elastic 2-component adhesive based on EP-PU hybrid. Publication date: January 2021 Authors: Dr.-Ing. M. Albiez, J. Damm, M.Sc., Prof. Dr.-Ing. T. Ummenhofer, Dipl.-Wirt.-Ing. S. Myslicki, Dr. T. Vallée, H. Ehard, M. Eng., Prof. Dr.-Ing. Ch. Schuler

P 1112 - Statistical validation of small batches in steel processing The research project "Statistically safeguarding small series in steel processing" focussed on the development of a concept for the introduction of statistical process control (SPC) in small series production. The focus was on the steel processing value chain. The particular potential of the concept includes a sustainable increase in product quality and a reduction in scrap and quality costs. The basic approach for the concept development was the development of a similarity model for the expert-based grouping of small series on the basis of similar quality characteristics and processes with the help of a suitable classification and coding system. By analysing entire small series groups within the framework of statistical process control, it is possible to increase the number of available samples and thus also the statistical reliability. The latter can be quantified using a developed risk model. The quantified certainties provide a basis for describing similarities between small batch groups and their small batches. In addition, a similarity measure can be derived that can be used to evaluate the small series groups formed. The implemented KleiSta software demonstrator makes it possible to visualise the group samples in the context of adapted interactive quality control charts and calculates the statistical certainties for various quality statements as well as the similarity measures. The Fraunhofer Institute for Production Technology IPT developed the concept and the KleiSta software demonstrator as the executing research centre and project coordinator during the project period from 1 September 2015 to 31 August 2017 in close cooperation with a project support committee consisting of the following 14 manufacturing companies (small, medium-sized and large companies) and with the Forschungsvereinigung Stahlanwendung e.V. (FOSTA): - 3win Maschinenbau GmbH - ArcelorMittal Ruhrort GmbH - ASK GmbH - Bittner Werkzeugbau GmbH - EZM Edelstahlzieherei Mark GmbH - Innolite GmbH - Krott & Heuter GmbH - Leistritz Turbomaschinen Technik GmbH - Lemken GmbH & Co KG - Ortlinghaus-Werke GmbH - Phiesel GmbH - Rolls-Royce Germany Ltd & Co KG - Saarstahl AG - Ziehwerk Plettenberg GmbH & Co KG I n the course of the research project, regular committee meetings and topic-specific workshops provided a platform for the participating companies to define individual requirements for the concept and the KleiSta software demonstrator as well as suitable small series products and processes for the application of statistical process control. Individual meetings were also held to identify and compile available data that could be used for initial sample analyses and subsequent validation. Further information on the project can be found on the website www.kleista.de. Publication: 2018 Authors: K. Kostyszyn