Prof. Dr.-Ing. Frank Balle

Walter and Ingeborg Herrmann Chair for Engineering of Functional Materials

Frank Balle researches and develops sustainable, multi-functional materials concepts as well as their characterization and process technologies.


Vision: Renewable materials systems with nearly infinite life

The road to technical metabolism

Imagine there were almost no waste, just as in nature there are only nutrients. In other words, imagine technical metabolism. On the way to this optimal goal, the initial selection of materials and available processing technologies play a decisive role.

After an engineering system reaches its end of life, the performing capacity of the system components are tested using a material-specific evaluation method. Safe reuse, or alternatively, optimal recovery of all components is the goal. Key technologies for effecting closed material life cycles are joining, separation and repair procedures for functional materials. The materials-science motto is thus: after use is before use!

The INATECH group led by Frank Balle follows this vision with the following approaches to research and education:

  • Hybrid materials systems: next-generation material composites and joints

    Lighter and more efficient structures that are simultaneously more functional and cost neutral to manufacture cannot feasibly be realized using monolithic materials concepts. Hybrid materials systems on the other hand open the way to new, customized solutions. A hybrid materials system is the result of the skillful combination of different materials or even classes of material by means of new manufacturing processes for composite materials or material compounds using a material-specific joining procedure.

  • Ultra + X: Pioneer applications of power ultrasonics

    The pivotal “Ultra + X” research project covers all areas that use power ultrasonics for characterizing or producing mostly hybrid materials systems. Frequency oscillations of up to 20,000 Hz are used to join very different materials, particularly light metals (Al, Ti, steels) with polymerized fiber-composite materials (CFK, GFK), and also glass and ceramics. A long-term goal is the further development of power ultrasonics towards a sustainable technology that can join, separate and repair “at the push of a button”; in other words, technical metabolism. Moreover, the technology used for the patented, quick calculation of the shelf-life of fiber-composite materials, is also employed to deeply examine application-relevant issues on the robustness and durability of materials systems.

  • Multi + X: Multifunctional materials concepts and multi-material systems of the future

    In addition to the production of hybrid lightweight structures, intrinsically produced composite materials are currently the focus of a fundamental examination. One focal point of this examination is the evaluation of the mechanically functional properties of composite materials such as C-Fiber and metal-fiber-strengthened plastics (CFK, MCFK) with a view to shelf-life/durability and digital damage monitoring. The foundations of transmitting welded joins at laboratory scale to component-like structures (multi-spot joints) are also being researched.


The central focus of the research is hybrid materials engineering: the joining of materials as well as researching composite materials for sustainable engineering applications

Ultra + X: Development and application of power ultrasonics for engineering applications

Solid state joining of dissimilar materials e.g. Al, Ti, steels with fiber-composite materials (CFK, GFK) as well as glasses or ceramics; end-of-life estimation and longevity of fiber-composite materials.

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Multi + X: Multifunctional materials concepts and multi-material systems

Fundamental study of intrinsically produced composite materials with a focus on the mechanical-functional properties of composite materials (CFK, MCFK) and sustainable processes of hybrid structures.

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Hybrid materials engineering: composite materials and hybrid joints

Produce lighter and more efficient structures while also improving functionality and keeping production costs neutral: no longer feasible using monolithic materials concepts. New production procedures and the skillful combination of dissimilar materials open the way to innovative concepts.

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Current research areas at the Walter and Ingeborg Herrmann Chair for “Engineering of Functional Materials” (EFM):

Aging resistant metal/CFRP joints for aerospace applications (USS transfer)

Accelerated lifetime determination of fiber composites by ultrasonic fatigue (VHCFK)

Activation and introduction of relevant defects in hybrid material systems by power ultrasonics (SCHARF)

Sustainable tool concepts and condition monitoring for robust ultrasonic welding processes (NaSoKo)

Damage-tolerant, electrically conductive and monitorable fiber composites for aircraft applications (MCFK)

Ultrasonic joining of multi-material structures for automotive applications (Multi-Spot)


Frank Balle is Professor of Engineering of Functional Materials at the Engineering Faculty of the Albert-Ludwigs-University Freiburg. After his diploma program with its emphasis on materials engineering and design, Frank Balle pioneers the combination of light metals and carbon fiber-composite materials using power ultrasonics. After the PhD to Dr.-Ing. of Engineering, he founded a group with the help of the German Research Foundation (DFG) to study ultrasonic joining of multi-material structures. After two post-doctoral visits at the Oak Ridge National Laboratory (USA) and establishing his own group at the chair for Materials Science and Engineering at the University of Kaiserslautern, he took on the leadership and development of the new researc field “Hybrid Materials Engineering” as a junior professor. In 2018, he received several calls to university professorships, responding finally to the appointment from the Universtiy of Freiburg at INATECH and founded the new chair for “Engineering of Functional Materials”.

At INATECH, Prof. Balle researches the engineering of hybrid, often multifunctional materials systems. To this end, sustainable, ultrasonic-based procedures for joining different engineering materials as well as the rapid estimation of the durability of composite materials are being developed. The strongly application-oriented research projects are carried out with fundamental examinations of the microstructure, the bonding and damage mechanisms as well as the corresponding properties of selected engineering materials. In addition to established lightweight metals, such as aluminum and titanium alloys, polymer fiber-composite materials in particular, e.g. CFRP and GFRP, are currently being researched. Skillful combinations of new multifunctional concepts for fuselage and chassis applications in the aviation and automotive industries are two current examples. Based on the research vision on renewable materials systems, Frank Balle’s group is also engaged in new concepts concerning the repair, debonding and recycling on demand of hybrid materials.

You can find further information at his chair’s internet site.


Prof. Dr.-Ing. Frank Balle
Tel.: +49 761 203-54200

Walter and Ingeborg Herrmann Chair for Engineering of Functional Materials

University of Freiburg
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Emmy Noether Street 2
79110 Freiburg, Germany

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Christine Höher
Tel.: +49 761 203-54226

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