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The rotary friction welding (RFW) is a robust, precise, productive and economical joining process that is used in many areas of mechanical engineering to produce lightweight structures consisting of combinations of ferrous and non-ferrous materials, for instance aluminium alloy and steel. Crucial for the design of such lightweight structures is the knowledge about the bonding strength. The bonding strength is the result of the bond formation depending on the present transient kinematic, kinetic and thermal states during the welding process being directly determined by the welding process parameters. Despite several years of empirical research, no reliable numerical modelling approach exists for the RFW process to analyse the bonding strength based on these transient state variables. For this reason, an improvement of the bond formation and therefore an increase in the bonding strength can only be tested experimentally. The main motivation of this paper is to develop an appropriate modelling approach for the estimation of the bonding strength for friction welded lightweight structures manufactured of an aluminium alloy and a structural steel. Therefore, a couple of aluminium alloy and steel welding experiments with different process parameters were performed and subsequently analysed concerning to the resulting bonding strength. Moreover, all the welding experiments were simulated in regard to the corresponding welding process in order to determine the present kinematic, kinetic and thermal state variables, like the strain rate, the stress and the temperature. Thus, a model for the characterization of the bond formation can be developed, which allows a correlation between the bond formation and the resulting bond strength based on the chosen welding process parameters. Finally, the model will be examined and discussed in terms of its plausibility and applicability. • Process simulation of friction welded lightweight structures made of aluminium alloy and structural steel. • Estimation of the transient kinematic, kinetic and thermal state variables in the welding contact zone. • Detailed derivation of a numerical modelling approach to analyse the bonding strength based on the state variables. • Experimental validation. [ABSTRACT FROM AUTHOR]

The rotary friction welding (RFW) is nowadays an industrial well-established and common welding technique since it allows the combination of a wide range of ferrous and non-ferrous materials, for instance, aluminium alloy and steel in order to create a lightweight structure. Therein, the major challenge is, due to the diverging physical properties, to determine suitable and stable parameters for the welding process. In this context, there is a great industrial demand for appropriate simulation tools to capture the relevant physical phenomena within the welding process and thereby to identity the optimal welding parameters. Various holistic models have been constituted to simulate the RFW process. Whereby, the major differences concern the methods of modelling the material and frictional behaviour. In a recent work, a straightforward material model based on a Carreau fluid formulation together with a shear strength confined Coulomb friction model has been adopted. The main motivation of this paper is to validate the capability and the precision of this proposed modelling approach as well as to represent some modelling aspects in a more tangible way. For that purpose the RFW process of a couple of aluminium to steel welded joints with different process parameters were simulated. Subsequently, a validation of the simulated and measured process variables was done concerning the comparison of the flash formation, the final shortening, the transient shortening rate and temperature evolution. • Representation of an approach for modelling the rotary friction welding process. • Detailed derivation of the used finite element model. • Explanation concerning to the friction and contact modelling. • Description of the applied meshing and remeshing procedure. • Comparison of experimental and simulation results. [ABSTRACT FROM AUTHOR]