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A novel excitation method for pyroshock simulation

Houshmand, Behnam; Lacher, Alexander; Juengel, Níkolas; Prasol, Lukas; Wagner, Utz von; Uhlmann, Eckart

Pyroshocks are structural responses to transient excitation caused by the essential use of pyrotechnic devices in aerospace applications. In order to avoid damage in aerospace structures due to pyroshocks, tests are performed on earth prior to launching space modules. In these tests, explosive loads are often replaced by alternative excitation methods such as hammer pendulums or shakers simulating on earth the impact taking place in space. However, there does not yet exist an adequate excitation method satisfying all requirements of a fast, reliable, predictable and repeatable test setup. Whereas hammers are poorely controllable in terms of generating desired shock spectra, shakers show limitations in terms of the bandwidths of up to 10 kHz which are prescribed in the test specifications. The authors present a novel contactless and non-destructive excitation method for pyroshock test devices based on a mechatronic coupling by applying Lorentz forces to the carrying structure. For generating the corresponding magnetic field, the capacitor of a Resistor-Inductor-Capacitor RLC resonator circuit is initially charged and then discharged leading to high currents in the coil which is placed close to the carrying structure. Latter is then inducing a counter current in the aluminum structure which reacts with high multidirectional Lorentz forces. Any adjustments are done by tuning the properties of the circuit such as initial charge, capacitance and inductance. By connecting several different coils, frequency modulation and by splitting the currents more complex signals can be generated matching the natural frequencies of the structure. Almost all disadvantages of common excitation methods are eliminated by the proposed mechanism.
Published in: Journal of vibration and control, 10.1177/1077546315573904, Sage Publications
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  • This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.