Development and Application-oriented Validation of a Reliable Smoothed Particle Hydrodynamics Discretization for Solids to describe Friction Stir Welding

• Applicants: Professor Dr.-Ing. Peter Eberhard; Professor Dr. Siegfried Schmauder, Ph.D.
• Subject Area: Mechanics
• Term: from 2017 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 388107621

• Final Report Year: 2023

Final Report Abstract

The goal of the project was the extensive improvement of the basic SPH formulation for solids and, thereby, the development of a fairly new kind of versatile, non-standard reliable simulation technique suitable for a wide range of applications. As the FSW process shares many of its characteristics with plenty of other industrial applications, it provides an adequate basis for an application-related validation of the developed discretization method. The objective of the present project was therefore to extend SPH simulation algorithms for the FSW scenario and to model this particular process as precisely and effectively as possible. In the first part of the project, a physically-based material model for natural hardening aluminum alloys, suited for the simulation of friction stir welding was developed, calibrated and implemented into the SPH simulations. This model was extended in the second part of the project to include effects of precipitation hardening. The model was calibrated with hot compression tests of an AA 6016 T4 aluminum alloy. The SPH framework was severely improved and adopted for the needs of FSW modelling. To provide stable results in the presence of large deformations, the hourglass control scheme was implemented in the SPH environment. Extensive research was done with regard to friction modelling. Due to complexity and controversial mechanisms involved, it proved to be a challenge for numerical simulation. However, the implementation improvement of the friction modelling was still achieved in course of the project. The bonding occurring during friction stir welding was also investigated. First existing bonding criteria were researched and appropriate model for the FSW method was selected. This criterion, along with additional features, was implemented into SPH framework. The methodology and implementation were successfully validated with a simple example and then extended to the simulation of FSW. It provided with additional knowledge about the process. The model has a potential for the FSW process design optimization, while predicting the weld quality. Friction stir welding with tools with shortened pins were conducted in order to get welds with lack of penetration. The results were compared with friction stir welding finite element simulations. It was shown that the plastic strain with a proper limit value can be used to predict where bonding takes place in the welds. The performed experimental and numerical studies helped in gaining better understanding of the FSW process. Despite few challenges, several novel approaches were successfully developed, implemented and used. That resulted in an expansion of the tool, which assists not only in improvement and optimization of FSW, but also of other industrial applications of complex nature. Additionally, this provides an extensive base for further research. Several publications were created during this project which also make the results available to the public and several doctoral theses, written during this project duration, contain many additional details.

Publications

• Adaptive Anpassung des Anstellwinkels beim Rührreibschweißen zur Berücksichtigung von Bauteiltoleranzen und Dickenänderungen, DE 10 2018 113 638.2, 2018
  Werz, M.; Weihe, S. & Panzer, F.
  
• Development of a model to investigate the interaction between process and machine tool and the resulting dynamics of friction stir welding. Mathematical Modelling of Weld Phenomena, Vol. 12, pp. 585-613.
  Panzer, F.; Werz M. & Weihe, S.
  
• Experimental investigation of the friction stir welding dynamics of 6000 series aluminum alloys. Production Engineering, 12(5), 667-677.
  Panzer, Florian; Werz, Martin & Weihe, Stefan
  
• Gegenhalter, Vorrichtung und Verfahren zum Rührreibschweißen, DE 10 2018 111 496.6, 2018
  Werz, M.; Weihe, S. & Panzer, F.
  
• Friction stir welded and deep drawn multi-material tailor welded blanks. Materials Testing, 61(7), 643-651.
  Panzer, Florian; Schneider, Matthias; Werz, Martin & Weihe, Stefan
  
• Tracking of material orientation in updated Lagrangian SPH. Computational Particle Mechanics, 6(3), 449-460.
  Shishova, Elizaveta; Spreng, Fabian; Hamann, Dominik & Eberhard, Peter
  
• A physically based material model for the simulation of friction stir welding. Materials Testing, 62(6), 603-611.
  Panzer, Florian; Shishova, Elizaveta; Werz, Martin; Weihe, Stefan; Eberhard, Peter & Schmauder, Siegfried
  
• An advanced study on discretization-error-based adaptivity in Smoothed Particle Hydrodynamics. Computers & Fluids, 198, 104388.
  Spreng, Fabian; Vacondio, Renato; Eberhard, Peter & Williams, John R.
  
• Experimental and numerical research on friction stir welding of aluminum and aluminum-steel joints to improve their mechanical properties. Dissertation, 2020
  Werz, M.
  
• Gegenhalter, Vorrichtung und Verfahren zum Rührreibschweißen, DE 10 2020 108 356.4, 2020
  Werz, M.; Weihe, S. & Panzer, F.
  
• Reversible inter-particle bonding in SPH for improved simulation of friction stir welding. Computational Particle Mechanics, 10(3), 555-564.
  Shishova, Elizaveta; Panzer, Florian; Werz, Martin & Eberhard, Peter