Universität Stuttgart

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Publication Type: search.filters.UBSTyp.KonferenzbeitragAuthor: search.filters.author.Hoßfeld, Max

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Now showing 1 - 4 of 4
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    A new approach to modelling friction stir welding using the CEL method
    (2013) Hoßfeld, Max; Roos, Eberhard
    Although friction stir welding (FSW) has made its way to industrial application particularly in the last years, the FSW process, its influences and their strong interactions among themselves are still not thoroughly understood. This lack of understanding mainly arises from the adverse observability of the actual process with phenomena like material flow and deposition, large material deformations and thermomechanical interactions determining the mechanical properties of the weld. To close this gap an appropriate numerical model validated by experiments may be helpful. But because of the issues mentioned above most numerical techniques are not capable of modelling the FSW process. Therefore in this study a Coupled Eulerian-Lagrangian (CEL) approach is used for modelling the whole FSW process. A coupled thermomechanical 3D FE model is developed with the CEL formulation given in the FE code ABAQUS® V6.12. Results for temperature fields, weld formation and the possibility of void formation are shown and validated.
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    A fully coupled thermomechanical 3D model for all phases of friction stir welding
    (2016) Hoßfeld, Max
    Although friction stir welding (FSW) has made its way to industrial application particularly in the last years, the FSW process, its influences and their strong interactions among themselves are still not thoroughly understood. The lack of understanding mainly arises from the adverse observability of the actual process with phenomena like material ow and deposition, large material deformations plus their complex thermo-mechanical interactions determining the weld formation and its mechanical properties. A validated numerical process model may be helpful for closing this gap as well as for an isolated assessment of individual influences and phenomena. Hereby such a model will be a valuable assistance for process and especially tool development. In this study a Coupled Eulerian-Lagrangian (CEL) approach with Abaqus V6.14 is used for modeling the whole FSW process within one continuous model. The resolution reached allows not only simulating the joining of two sheets into one and real tooling geometries but also burr and internal void formation. Results for temperature fields, surface and weld formation as well as process forces are shown and validated.
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    Challenges and state of the art in industrial FSW - pushing the limits by high speed welding of complex 3D contours
    (2018) Hoßfeld, Max; Hofferbert, Dave
    Over the last 25 years, Friction Stir Welding (FSW) has been gradually moving from research over first applications into mass production. Today, requirements for consistently high-quality welds occur in parallel with a demand for high throughput as well as production flexibility. This paper gives an insight to the state of the art of industrial FSW mass production, current trends, challenges and market demands as well as the potential of high speed complex contour welding on modern multi-axis FSW machinery with respect to process parameters, material properties, machinery requirements and control algorithms, and methods. The design strategy of complex 3D contours as a chance to maximize efficiency is introduced; challenges of its implementation with respect to the state of the art in FSW are described. This includes the importance of advanced force control methods, fixture design, clamping forces and methodology for sustaining high-quality welds as well as the management of distortions and residual stresses by thermal management and optimization of process parameters. Examples of successful weld performance are described. Steps to be taken that result in high-quality welds, as well as situations to be avoided, are discussed. The publication was written based on results of the DFG project RO 651/16-1 that was carried out at the University of Stuttgart.
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    High speed friction stir welding of thick copper plates
    (2015) Hoßfeld, Max
    When welding large copper parts, the process is strongly limited by the high thermal conductivity and capacity as well as the high temperature strength of copper. These slow down the welding process and require a large heat input. By this the process forces are high and probe failure is a severe issue. Typical welding speeds of thick copper plates today are around 50 to 150 mm/min under laboratory like conditions, requiring a spindle torque up to 1000 Nm, excluding usual multipurpose FSW-machines from this application. This study shows the process and tool development including the verification of a robust tool design. The process is carried out on a multipurpose machine reaching welding speeds up to 500 mm/min in 20 mm rolled Cu-OF. A significant reduction of the process forces, especially traverse force and spindle moment is reached. Due to the relatively low heat input good mechanical properties could be achieved. Tool design, parameters, microstructure, hardness profiles and tensile properties are shown.