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Neueste Publikationen

[ 1 ] Schwennen, J.; Sessner, V. & Fleischer, J. (2016), „A New Approach on Integrating Joining Inserts for Composite Sandwich Structures with Foam Cores“. Procedia CIRP, Hrsg. Rikard Söderberg, S. 310-315.
Abstract:
Due to their high potential in lightweight designs composite sandwich structures with foam cores are gaining in importance in the automotive industry. To carry localized loads, sandwich structures require load introduction elements. In current solutions applied in the aerospace industry the inserts are embedded after the sandwich panels have been manufactured. This is very time consuming and therefore too expensive for automotive industry. In this paper, two new approaches are investigated experimentally, where the inserts get integrated during the preforming process or during the foam core manufacturing. With these manufacturing methods the performance and failure behavior of various insert geometries and different foam core densities will be determined by static pull out tests.

[ 2 ] Muth, M.; Schwennen, J.; Bernath, A.; Seuffert, J.; Weidenmann, K. A.; Fleischer, J. & Henning, F. (2018), „Numerical and experimental investigation of manufacturing and performance of metal inserts embedded in CFRP“, Production Engineering, S. 141-152.
Abstract:
Due to their outstanding specific mechanical properties, carbon fibre reinforced plastics (CFRP) exhibit a high application potential for lightweight structures. With respect to multi-material design and to avoid drilling of structural CFRP parts to join them to other components, embedded metal elements, so called inserts, can be used. The inserts consist of a shaft and a baseplate which is embedded between the fibre layers. So far, only punctiform inserts have been subject to research. One feasible geometry are linear inserts which have not been studied yet. In this work, the performance of two different types of linear inserts will be investigated. The shapes are based on a punctiform insert which is made out of a threaded shaft welded onto a baseplate whose performance under different types of loading has been investigated before. The first type of linear inserts has the same cross-section as the reference punctiform insert but is of a linear form. The second type is a quasi-linear insert which consists of a baseplate with the same dimensions as the first linear inserts and three threaded shafts welded onto it. All samples are manufactured by resin transfer moulding (RTM). Depending on the geometry of the insert and the preforming concept it is potentially possible to maintain the fibre continuity. For the inserts with a continuous shaft and in the proximity of the insert, it is necessary to cut fibres of the top layers which are aligned perpendicular to the shaft. For the quasi-linear insert, it is possible to maintain the fibre continuity as the fibres are guided around the circular shafts. Additional to mechanical tests that are carried out, mould-filling and curing simulations are performed for different inserts to analyse the influence of the process parameters onto the part quality. In the main series of tests, the specimens are characterized regarding their failure behaviour and load bearing capacity under quasi-static loads. The results of the experiments show that, compared to the punctiform reference insert, the linear load introduction elements exhibit higher load bearing capacity. However, the linear load introduction elements are inferior regarding specific load bearing capacity and furthermore increase process complexity during preforming and production.

[ 3 ] Gebhardt, J.; Schwennen, J.; Lorenz, F. & Fleischer, J. (2018), „Structure optimisation of metallic load introduction elements embedded in CFRP“, Production Engineering, S. 131-140.
Abstract:
The combination of construction parts made of fibre-reinforced plastics (FRP) and metal holds great lightweight design potential but places high demands on the necessary joining technologies. Metallic load introduction elements that are embedded in the manufacturing process of FRP components are a promising joining technology. In order to fully exploit the potential of this technology, approaches to increase the load bearing capacity of inserts, particularly under pull-out loads, have been missing. The aim is therefore to derive a method for the simulative structural optimisation of embedded inserts. The load bearing capacity increases under pull-out loads through smoothing of failure-critical stress peaks using the optimisation of the thickness distribution of the insert’s base plate. The increase of the load bearing capacity of the optimised insert geometry is confirmed through experimental validation.

[ 4 ] Bürgin, J.; Belkadi, F.; Hupays, C.; Gupta, R. K.; Bitte, F.; Lanza, G. & Bernard, A. (2018), „A modular-based approach for Just-In-Time Specification of customer orders in the aircraft manufacturing industry“, CIRP Journal of Manufacturing Science and Technology, Band 21, S. 61-74.
Abstract:
The demand for flexibility in the configuration of highly customized capital goods such as aircrafts is rising. Customers request specifying product options later than required by the currently defined order fulfilment process of the OEM. However, late changes of previously configured products can cause disturbances in global production networks. In this paper, a modular-based approach is presented, allowing customers to specify options just-intime depending on the respective lead times following an Engineer/Order-to-order (EOTO) strategy. The concept of Just-In-Time Specification with its respective phases of order specification and steps of production planning is described and applied to the aircraft manufacturing industry.

[ 5 ] Stricker, N.; Echsler Minguillon, F. & Lanza, G. (2017), „Selecting key performance indicators for production with a linear programming approach“, International Journal of Production Research, S. 5537-5549. https://doi.org/10.1080/00207543.2017.1287444
Abstract:
Modern production systems are prone to disruptions due to shorter product life cycles, growing variant diversity and progressively distributed production. At the same time, reduced time and capacity buffers diminish mitigation opportunities, requiring better tools for production control. Performance measurement with key performance indicators (KPIs) is a widely used instrument to detect changes in production system performance in order to coordinate appropriate countermeasures. The main challenge in planning KPI systems consists in determining relevant KPIs. On the one hand, enough KPIs must be selected for a sufficiently high information content. On the other hand, the cognitive abilities of users are not to be overstrained by selecting too many KPIs. This tradeoff is addressed in a proposed selection process using an integer linear programme for objective KPI selection. In order to achieve this goal, crucial facets of the information content requirement are formalised mathematically. The developed method is validated using a practical application example, showing the influence of model parameter selection on optimisation results. The formalisation of the information content is shown to be a novel and promising approach.

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