Mehrskalen-Modellierung von Reibungsbehaftetem Kontakt für Komplexe Problemstellungen im Ingenieurwesen

Fördergeber Deutscher Akademischer Austauschdienst (DAAD)
Ministero dell'Istruzione dell'Università e della Ricera (MIUR)
Zeitraum 2018-2020
Partner MUSAM Lab, IMT School for Advanced Studies Lucca, Italien (Prof. Paggi)
Kurzbeschreibung The aim of this project is to develop an efficient two-scale numerical scheme integrating implicit finite element computations at the macro-scale and the boundary element method at the micro-scale for the accurate solution of frictional contact problems with microscopic interface roughness. The whole range of sliding regimes, from the full stick to the full slip and also full sliding, will be handled, as well as any complex loading path. The problem of frictional contact is relevant in many research areas of engineering and physics. In mechanical engineering, it is important in configurations such as bolted joints, wheel-rail contact, bearings, brakes or wheel-asphalt contact. It is also of interest for the interaction between soil and pile foundations in civil and geotechnical engineering applications. In biomechanics, the relative motion in hip-joint prostheses leading to wear is also ruled by friction. In all of such fundamental problems, the interface between bodies in contact is not flat and its roughness presents multiscale features that influence the deformation and the stress states in the material.
Kontakt am IMCS Prof. Dr.-Ing. Alexander Popp

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Experimentelle Charakterisierung und Numerische Simulation des Automated Fiber Placement (AFP)-Prozesses für Faserverbundkunststoffe

Fördergeber Deutsche Forschungsgemeinschaft (DFG), PO 1883/3-1
Zeitraum 2017-2020

Partner

Lehrstuhl für Carbon Composites, TU München (Prof. Drechsler)
Lehrstuhl für Numerische Mechanik, TU München (Prof. Wall)
Kurzbeschreibung The efficient, high-quality and reproducible production of thermoplastic fiber-reinforced plastic components requires automated manufacturing processes. Due to its load-path oriented deposition of fibers to near-net-shape components, automated fiber placement (AFP) has particularly great potential. With proper temperature control during thermoplastic AFP (TP-AFP) in-situ consolidation is possible, i.e. a consolidation in place of the process without downstream thermosetting. However, the understanding of the process is still far from reaching the level of maturity necessary for a broad industrial application of TP-AFP. For example, it is still difficult today to define suitable process windows for the most important key parameters such as laser power, velocity and compaction pressure so that a consistently high quality of components is assured. In particular, the prediction of residual stresses and distortion is only solved insufficiently and process calibration is often based on a trial-and-error method. The reasons for this discrepancy between low prediction accuracy and high industrial demands can likewise be ascribed to possibilities of experimental characterization and modeling and simulation that are not yet maxed out. Therefore, the aim of this project is to improve process understanding in the area of TP-AFP fundamentally through novel experimental studies and methods of numerical simulation.
Kontakt am IMCS Prof. Dr.-Ing. Alexander Popp

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Bottom-Up-Modellierung von Stents und Stentgrafts für die Endovaskuläre Aortenreparatur (EVAR) von Aneurysmen

Fördergeber   Daimler und Benz Stiftung
Zeitraum   2016-2018
Partner   Institute of Industrial Science, The University of Tokyo, Japan (Prof. Oshima)
Kurzbeschreibung   Arterial stent placement has become a very important and successful intervention in vascular surgery. One of the most common scenarios includes so-called self-expandable stent grafts composed of a special fabric graft and a metal stent mesh. Stent grafts are used in endovascular aortic repair (EVAR) to support weak localized bulges (aneurysms) in an artery being at risk of rupture, most commonly for abdominal aortic aneurysms (AAA). Over the last decade, an enormous thrust of research regarding the computational analysis of biomedical engineering problems in general, and regarding vascular mechanics and AAA in particular has taken place. While significant progress has been made, the computational analysis of AAA stent grafts using finite element methods (FEM) is still not predictive enough to give specific advice to vascular surgeons on how to optimally place the device during EVAR. Possible risks, which are still far from being fully understood, include a movement of stents away from the desired location (migration), leaking of blood around stent grafts (endoleakage) and damage of the arterial wall caused by the stent itself. The main objective of this project is the development, implementation and validation of new innovative FEM simulation tools for AAA stent grafts based on a bottom-up modeling approach. All relevant micro-geometrical and mechanical features of the complex stent graft designs will be included into the new models, thus allowing for a significantly increased accuracy of stent expansion and placement simulations.
Kontakt am IMCS   Prof. Dr.-Ing. Alexander Popp

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