Forming by Locally Varying Vaporizing Actuators

Funding: German Research Foundation (DFG)
Project: 391967465
Contact: Marlon Hahn M. Sc.

Discharging a capacitor bank over an Al foil leads to the foil’s rapid vaporization (called vaporizing actuator) so that the resulting pressure – depending on the actuator placement – can be used for a locally flexible sheet metal forming operation.

Aiming at a predictive process design, a two-step approach for the establishment of a multi-physical modeling exists. The electrical energy deposition until the so-called burst point was already investigated numerically as well as analytically. The burst energy density corresponds to a certain impulse pressure, by which the strain rate-dependent forming is modeled in the second step. Regarding a spatially complete simulation, a meshless method is considered for the expanding foil actuator. Yet, in a simplified code the sheet blank has first been expressed as a “plastically connected mass chain” (chain model in figure), loaded by a pre-defined impulse over the vaporization region of the actuator. Measurements employing Photon Doppler Velocimetry (PDV) validate the inertia-caused dynamics of the forming history (see figure).

Exemplary comparison between experiment and simplified forming model