Project: Application of detonation forming in fuel cells manufacturing

Manufacturing processes in industry are subject to various challenges. The manufactured parts are not only to be produced without defects, but the process itself should also not be expensive and require a short period of time.
The Institute of General Mechanics, headed by JARA-ENERGY member Prof. Bernd Markert, is investigating a promising process for forming processes such as those occurring in the automotive industry. As part of the "Gas Detonation: Numerical Modelling of the Gas Detonation Process" project, the scientists are investigating gas detonation forming (GDF), which promises a very short production time. Specifically, the experts are investigating the application of the process in the production of fuel cells.

Gas detonation forming (GDF) is a high-speed forming method, which has the potential to form complex geometries, including sharp angles and undercuts, in a very short process time. The produced parts can be stiff and have good strength-to-weight ratio, therefore, these products are widely used for automobiles, domestic appliances, aircraft and drink cans. Scientists at IAM, investigate the GDF of DC04 steel cups. The deformed geometry of the cup and thickness distributions is compared with the experimentally obtained values. Moreover, the fractured specimen in the experiments is studied using adapted damage parameters for the numerical simulations. Figure 1 shows schematic representation experimental setup of the GDF and formed cups in experiment and in numerical simulations.

_{Figure 1: Schematic representation of the experimental setup of the GDF (left). Detonation formed cup in experiment and predicted by numerical simulations (right).}

The experimental investigations of GDF have shown the ability to produce sharp corner at the bottom of formed cups without observable wrinkles on the flange or skirt. Also, the proposed computational model is able to predict experimental results accurately [1,2].

_{Figure 2: Sample flow plate in fuel cells that can be produced with GDF, especially shape of the gas channels.}

Nowadays, the outer graphite layers of fuel cells (gas channels), which transports oxygen and hydrogen, are built of metals to reduce the costs. Conventional contact based forming methods, such as deep drawing or incremental forming, cannot ensure an intact surface. Therefore, our aim is to use GDF technique to build these metallic parts. We intend to create theses complex shaped structures by controlling the plastic deformation of the specimen and employing different options such as fixed die design and flexible tooling. The important advantage of using this method is that it is a contact-free forming process. Thus, especially in fuel cells, this technique can be useful to maintain the coating of the plates.

To this end, this research project will address the following fundamental questions:

• What are the optimal parameters of GDF process such as pressure and tube dimensions?
• Which design and amount of tooling is required to make the gas channels shape?
• How are the mechanical properties of the products compared to conventional techniques?

[1] SP Patil, M Popli, V Jenkouk, B Markert. Numerical modelling of the gas detonation process of sheet metal forming. Journal of Physics: Conference Series. Vol. 734, No. 3, 2016.
[2] V Jenkouk, SP Patil, B Markert. Joining of tubes by gas detonation forming. Journal of Physics: Conference Series. Vol. 734, No. 3, 2016.