Research and development focuses

Current projects | Completed projects

With a combination of different metallic materials in form of firmly bonded material compounds of steel and aluminium or titanium and aluminium it is possible to produce customized designs with improved properties. Both the weld geometry and the local material behaviour are influenced by process parameters during welding. A coupling of process, structure and structural simulation, in consideration of local material conditions and developing seam geometry for evaluating the quasi-static strength of laser beam welded hybrid compounds can reduce the number of expensive experiments and thus increase the efficiency of hybrid structures and their potential of lightweight construction.

• Efficient method to calculate the weld geometry in a process simulation
• Models and material data to describe the material behaviour
• Structural model of welding process to determine the local material conditions after welding

Contact: Dipl.-Ing. Annika Barr

The combination of different metallic materials enables the generation of specifically improved properties for structural lightweight components. By joining of such materials the properties can be improved at global as well local level, which leads to attractive solutions for advanced lightweight designs. Whereas Titanium alloys show particular high mechanical strength and good corrosion resistance, Aluminium alloys provide a considerable lower density and consequently potential for weight savings, which is of great interest especially for the aircraft and automobile sector. By co-extrusion in contrast to conventional joining processes, e. g. welding, no impairments in material microstructures result in form of heat affected zones, porosity or grain growth. Therefore co- extrusion exhibits an attractive solution for combining Aluminium with Titanium based alloys. Hence, regarding the critical bonding zones the metallurgical interrellations during co-extrusion are largely unexplored. The aim of the project is to deepen the knowledge of the metallurgical interrelations based on three technical relevant material combinations and to demonstrate the limits of the co-extrusion process.

• Metallurgical investigations of the bonding zone in consideration of both the initial state of the material components and the thermomechanical relations resulting from the extrusion process
• Investigations and evaluation of the influence of precoatings on the adhesion

Contact: Dipl.-Ing. (FH) Barbara Striewe

Combinations of Fibre-Reinforced Plastics (FRP) and metals find more and more their way in development and constructions for lightweight applications, to adapt the properties of component to the local requirements. Currently the join of these components is realized by adhesive or mechanical bonding. In particular in view of weight optimized, integral structures with increased mechanical properties innovative construction- respectively bonding design are preferable or even necessitates.

The development of integral designs for high stressed and reliable Aluminium-FRP-intersection structures in lightweight design are main topics of the DFG-Researchgroup (FOR 1224). Therefore the aspects design, dimensioning, manufacturing and mechanical properties will be investigated basically. For corresponding bonding concepts the ability for lightweight designs, reliability and manufacturing will be proven within the project.

• Design of Aluminum-FRP-bondings
• Dimensioning and manufacturing of the bondings
• Verification and analysis of the failure for tensile strength
• Transfer to industrial manufacturing processes

Contact: Dr.-Ing. Kai Schimanski

Thermoforming is suitable for the production of lightweight structures out of textile reinforced thermoplastics and offers a high potential for the application in large-scale series due to short cycle times and the use of semi-finished products (boards of multilayer textile reinforced thermoplastics). Although lightweight products manufactured by this technology expect to provide benefits against conventional fabricated products the technique is currently only distributed in some niches. Reasons for these reservations of this technology are deficits in process control, which prevent an economical enforcement versus conventional technologies up to now.

The aim within this project is to overcome these deficits and consequently increase the attractivity of the thermoforming technology for the manufacturing of light weight components in the automotive and the aerospace industry. Necessary technological developments of the project lead to the realisation of an efficient and safe thermoforming process. During the project among other aspects a fast, powerful method for the numerical simulation of thermo-mechanical forming process shall be developed. Procedures outside and inside the continuous fibre reinforced thermoplastic sheet will be considered. Outside influences include the tempering of the tool, pressure and the adhesion – slide properties between work piece and tool, which are influenced by the release agent. Inside influences are crystallisation of the thermoplastic matrix during cooling and the draping of the reinforcement textiles in the desired form. By the application of the simulation the tool can be designed with an iterative method. The following primary goals shall be realized through this project:        

• Specific temperature control for the forming process, consisting of contract-free temperature measurement and temperature controlled form tools 
• Control of thermal and frictionally induced interactions between component and tool by adjusted release agent systems 
• Simulation tool for the design, analysis, optimisation of the thermoforming processes and for the design of distortion compensation tool

Contact: Dr.-Ing. Kai Schimanski

During heat treatment of age hardenable aluminium alloys the resulting mechanical properties are particularly influenced by the quenching process. To achieve the required strength, a high quenching rate after solution annealing is necessary, predominantly realised by using aqueous quenching media. Those can lead to a non-uniform cooling of the components and thereby to distortion which may result in costly post processes after heat treatment. As an advanced quenching method gas quenching enables more uniform quenching characteristics. However, applied to quench sensitive aluminium alloys or components with larger cross sections the attainable quenching intensity of gas quenching is insufficient in order to achieve the required strength.

Spray cooling in flexible nozzle fields combines the advantages of a high quenching intensity and uniform quenching characteristics and leads to both high strength and less distortion. By the use of two-phase sprays water/air it is possible to adapt the mechanical properties to component load profile by adjusting the quenching intensity to the component geometry. The variation of the phase mixture (from 100 % air to 100 % water) enables a partial age hardening of highly stressed component areas. Furthermore a homogeneous distribution of quenching intensity could be realised in order to avoid distortion. 

• Engineering of flexible nozzle fields for quenching of components based on simulation of flow field by CFD 
• Adaptation of mechanical properties on component load profile by partial distribution of quenching intensity
• Minimization of distortion by local variation of quenching intensity allowing for component geometry and local component load

Contact: Dipl.-Ing. Andrea Rose

Nowadays, aluminum alloys are exceedingly used for modern constructional elements. Because of low density, aluminum alloys are up to standard of lightweight materials, without additional treatment, however, surface layer aluminum alloys are restrictedly applicable as high-performance material. Electron beam multi-processes provide a promising opportunity for generation of wear-resistant layers on aluminum structures.

• Wear and corrosion resistance of aluminum structures
• Reduction of the manufacturing expense by multi-process technologies
• Flexible processing by different technological processes at different effect places with only one electron beam

Contact: Dipl.-Ing. Andrea Rose

After heat treatment of aluminium basis materials, distortions can occur in significant dimensions, just like in chipping processes. The investigation of the distortion behaviour is provided by a system orientated process analysis that has been developed in the research field of SFB 570 “Distortion Engineering” and which has proven to be a very promising technique in view of strategies for distortion control. On the basis of the system oriented approach, process chains in the industrial environment of aluminium basis materials are analyzed concerning their distortion potentials in this venture. Thus essential comprehension of distortion mechanisms can be aquired. The aim of this project is to develop practice orientated distortion compensation strategies to realize the reduction of material inventory, chipping effort and to ensure higher process reliability.

• Analysis of parameters on the distortion during chipping and heat treatment of structure components based on Aluminium basis alloys
• Determination of the interactions between chipping and heat treatment
• Development of strategies for distortion compensation techniques with special consideration of industrial process chains

Contact: Dipl.-Ing. Ole Karsten

The continuing miniaturization of mechanical products e.g. in the automotive sector requires a development of process chains which enables the manufacturing of micro components in high quantities. The aim of the project as a part of the Collaborative Research Centre 747 “Micro Cold Forming” are both the adjustment of cold forming attributes of the semi-finished micro components and the adjustment of the final usage properties due to heat treatment. The research programme is focused on a wide range of components made of materials like hardenable aluminium alloys, austenitic steels and ferritic-perlitic steel grades. Depending on the type of material, it is intended to investigate several heat treatment technologies. For the hardening of micro components made of steel, a novel facility for heat treatment while "falling"  through a furnace, has been developed.  

• Development of process chains for the manufacturing of micro components in high quantities
• Development of new technologies for heat treatment (e.g. in "free fall") and integration into the process chain
• Investigation of the influence of heat treatment parameters on the component properties

Contact: Dipl.-Ing. Roland von Bargen