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Die Universität Paderborn im Februar 2023 Bildinformationen anzeigen

Die Universität Paderborn im Februar 2023

Foto: Universität Paderborn, Hannah Brauckhoff

M. Sc. Fabian Kappe

M. Sc. Fabian Kappe

Werkstoff- und Fügetechnik

Wissenschaftlicher Mitarbeiter - Mechanische Fügetechnik

+49 5251 60-5328
Pohlweg 47-49
33098 Paderborn

Sonderforschungsbereich Transregio 285

Mitglied - Wissenschaftlicher Mitarbeiter - Teilprojekt C02

+49 5251 60 5328

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Increasing flexibility of self-piercing riveting by reducing tool–geometry combinations using cluster analysis in the application of multi-material design

F. Kappe, L. Schadow, M. Bobbert, G. Meschut, Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications (2022)


Determining the properties of multi‑range semi‑tubular self‑piercing riveted joints

F. Kappe, S. Wituschek, M. Bobbert, G. Meschut, Production Engineering (2022)


Mechanical Properties and Joinability of AlSi9 Alloy Manufactured by Twin‐Roll Casting

M. Neuser, F. Kappe, J. Ostermeier, J.T. Krüger, M. Bobbert, G. Meschut, M. Schaper, O. Grydin, Advanced Engineering Materials (2022), 24(10), 2200874

AlSi casting alloys combine excellent castability with high strength. Hence, this group of alloys is often used in the automotive sector. The challenge for this application is the brittle character of these alloys which leads to cracks during joint formation when mechanical joining technologies are used. A rise in ductility can be achieved by a considerable increase in the solidification rate which results in grain refinement. High solidification rates can be realized in twin–roll casting (TRC) by water-cooled rolls. Therefore, a hypoeutectic EN AC–AlSi9 (for European Norm - aluminum cast product) is manufactured by the TRC process and analyzed. Subsequently, joining investigations are performed on castings in as-cast and heat-treated condition using the self-piercing riveting process considering the joint formation and the load-bearing capacity. Due to the fine microstructure, the crack initiation can be avoided during joining, while maintaining the joining parameters, especially by specimens in heat treatment conditions. Furthermore, due to the extremely fine microstructure, the load-bearing capacity of the joint can be significantly increased in terms of the maximum load-bearing force and the energy absorbed.

Joining of multi-material structures using a versatile self-piercing riveting process

F. Kappe, S. Wituschek, M. Bobbert, M. Lechner, G. Meschut, Production Engineering (2022)

<jats:title>Abstract</jats:title><jats:p>Due to the increasing use of multi-material constructions and the resulting material incompatibilities, mechanical joining technologies are gaining in importance. The reasons for this are the variety of joining possibilities as well as high load-bearing capacities. However, the currently rigid tooling systems cannot react to changing boundary conditions, such as changed sheet thicknesses or strength. For this reason, a large number of specialised joining processes have been developed to expand the range of applications. Using a versatile self-piercing riveting process, multi-material structures are joined in this paper. In this process, a modified tool actuator technology is combined with multi-range capable auxiliary joining parts. The multi-range capability of the rivets is achieved by forming the rivet head onto the respective thickness of the joining part combination without creating a tooling set-up effort. The joints are investigated both experimentally on the basis of joint formation and load-bearing capacity tests as well as by means of numerical simulation. It turned out that all the joints examined could be manufactured according to the defined standards. The load-bearing capacities of the joints are comparable to those of conventionally joined joints. In some cases the joint fails prematurely, which is why lower energy absorptions are obtained. However, the maximum forces achieved are higher than those of conventional joints. Especially in the case of high-strength materials arranged on the die side, the interlock formation is low. In addition, the use of die-sided sheets requires a large deformation of the rivet head protrusion, which leads to an increase in stress and, as a result, to damage if the rivet head. However, a negative influence on the joint load-bearing capacity could be excluded.</jats:p>

Numerical Investigation of the Influence of a Movable Die Base on Joint Formation in Semi-tubular Self-piercing Riveting

F. Kappe, S. Wituschek, V. de Pascalis, M. Bobbert, M. Lechner, G. Meschut, in: Materials Design and Applications IV, Springer International Publishing, 2022

Due to economic and ecological requirements and the associated trend towards lightweight construction, mechanical joining technologies like self-piercing riveting are gaining in importance. In addition, the increase in lightweight multi-material joints has led to the development of many different mechanical joining technologies which can only be applied to join a small number of material combinations. This leads to low process efficiency, and in the case of self-piercing riveting, to a large number of required tool changes. Another approach focuses on reacting to changing boundary conditions as well as the creation of customised joints by using adaptive tools, versatile auxiliary joining parts or modified process kinematics. Therefore, this study investigates the influence of increased die-sided kinematics on joint formation in self-piercing riveting process. The aim is to achieve an improvement of the joint properties by superimposing the punch feed. Furthermore, it is intended to reduce required tool changes due to the improved joint design. The investigations were carried out by means of a 2D-axisymmetric numerical simulation model using the LS-Dyna simulation software. After the validation of the process model, the die was extended to include driven die elements. Using the model, different kinematics as well as their effects on the joint formation and the internal stress concentration could be analysed. In principle, the increased actuator technology enabled an increase of the interlock formation for both pure aluminium and multi-material joints consisting of steel and aluminium. However, the resulting process forces were higher during the process phases of punching and spreading.

Review on mechanical joining by plastic deformation

G. Meschut, M. Merklein, A. Brosius, D. Drummer, L. Fratini, U. Füssel, M. Gude, W. Homberg, P. Martins, M. Bobbert, M. Lechner, R. Kupfer, B. Gröger, D. Han, J. Kalich, F. Kappe, T. Kleffel, D. Köhler, C. Kuball, J. Popp, D. Römisch, J. Troschitz, C. Wischer, S. Wituschek, M. Wolf, Journal of Advanced Joining Processes (2022), 5, 100113

Mechanical joining technologies are increasingly used in multi-material lightweight constructions and offer opportunities to create versatile joining processes due to their low heat input, robustness to metallurgical incompatibilities and various process variants. They can be categorised into technologies which require an auxiliary joining element, or do not require an auxiliary joining element. A typical example for a mechanical joining process with auxiliary joining element is self-piercing riveting. A wide range of processes exist which are not requiring an auxiliary joining element. This allows both point-shaped (e.g., by clinching) and line-shaped (e.g., friction stir welding) joints to be produced. In order to achieve versatile processes, challenges exist in particular in the creation of intervention possibilities in the process and the understanding and handling of materials that are difficult to join, such as fiber reinforced plastics (FRP) or high-strength metals. In addition, predictive capability is required, which in particular requires accurate process simulation. Finally, the processes must be measured non-destructively in order to generate control variables in the process or to investigate the cause-effect relationship. This paper covers the state of the art in scientific research concerning mechanical joining and discusses future challenges on the way to versatile mechanical joining processes.


Investigation of the influence of varying tumbling strategies on a tumbling self-piercing riveting process

S. Wituschek, F. Kappe, M. Lechner, Production Engineering (2021)


Joining suitability of cast aluminium for self-piercing riveting

M. Neuser, F. Kappe, M. Busch, O. Grydin, M. Bobbert, M. Schaper, G. Meschut, T. Hausotte, IOP Conference Series: Materials Science and Engineering (2021), 012005


Influence of various procedures for the determination of flow curves on the predictive accuracy of numerical simulations for mechanical joining processes

M. Böhnke, F. Kappe, M. Bobbert, G. Meschut, Materials Testing (2021), 63(6), pp. 493-500

The predictive quality of numerical simulations for mechanical joining processes depends on the implemented material model, especially regarding the plasticity of the joining parts. Therefore, experimental material characterization processes are conducted to determine the material properties of sheet metal and generate flow curves. In this regard, there are a number of procedures which are accompanied by varying experimental efforts. This paper presents various methods of determining flow curves for HCT590X as well as EN AW-6014, including varying specimen geometries and diverse hardening laws for extrapolation procedures. The flow curves thus generated are compared considering the variety of plastic strains occurring in mechanical joining processes. The material data generated are implemented in simulation models for the joining technologies, clinching and self-piercing riveting. The influence of the varied methods on the predictive accuracy of the simulation model is analysed. The evaluation of the differing flow curves is achieved by comparing the geometric formation of the joints and the required joining forces of the processes with experimentally investigated joints.

Influence of rivet length on joint formation on self-piercing riveting process considering further process parameters

F. Kappe, C.R. Bielak, V. Sartisson, M. Bobbert, G. Meschut, in: ESAFORM 2021, University of Liege, 2021

Driven by the CO2-emission law by the European government and the increasing costs for raw materials as well as energy, the automotive industry is increasingly using multi-material constructions. This leads to a continuous increase in the use of mechanical joining techniques and especially the self-piercing riveting is of particular importance. The reason for this is the wide range of joining possibilities as well as the high load-bearing capacities of the joints. To be able to react to changing boundary conditions, like material thickness or strength variation of the sheets, research work is crucial with regard to the increase of versatility. In this paper, a numerical study of the influences on the selfpiercing riveting process is presented. For this purpose, the influence of different process parameters such as rivet length and die depth on various quality-relevant characteristics were investigated. With the help of the design of experiment, significant influences were determined and interactions between the individual parameters are shown.

New Approach for Versatile Self Piercing Riveting: Joining System and Auxiliary Part

F. Kappe, M. Bobbert, G. Meschut, Key Engineering Materials (2021), 883, pp. 3-10

The increasing use of multi-material constructions lead to a continuous increase in the use of mechanical joining techniques due to the wide range of joining possibilities as well as the high load-bearing capacities of the joints. Nevertheless, the currently rigid tool systems are not able to react to changing boundary conditions, like changing the material-geometry-combination. Therefore research work is crucial with regard to versatile joining systems. In this paper, a new approach for a versatile self-piercing riveting process considering the joining system as well as the auxiliary joining part is presented.


Investigation of influencing parameters on the joint formation of the self-piercing riveting process

F. Kappe, S. Wituschek, M. Lechner, M. Bobbert, G. Meschut, M. Merklein, 2020

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