Mitigation of pyrotechnic shock on sensitive equipment
Customer: Confidential Country: France Application: Defense and Aerospace
Pyrotechnic shocks caused, for instance, by weapon fire, the launch of a missile or the separation of the nose cone from a spacecraft launcher generate extremely energetic vibration waves which propagate very rapidly through the structures nearby.
Sensitive equipment may be severely damaged, compromising its proper functioning and the whole system viability.
Metravib has developed systems to mitigate such shock waves to an acceptable level for the equipment.
The challenge was to design devices to protect equipment (with important life span) from pyrotechnic shocks without increasing vibration levels during their operational use.
In other words, such devices have to be rigid enough not to induce low suspension modes that could couple with corresponding modes of the surrounding structures while being flexible enough to efficiently mitigate the shock energy.
The imposed environmental constraints were strict (space compliance) which made the research of adequate materials difficult. Moreover, the mass and bulk modulus of the solution had to be minimized.
To define, then produce the relevant pyrotechnic shock attenuation solution, Metravib has developed its own elastomeric materials from existing materials in order to meet the different environmental requirements.
Theoretical calculations were carried out in order to roughly design the elastomer part, checking that the proposed dimensions would ensure the targeted flexibility and meet the stiffness constraints in all directions.
This first theoretical dimensioning was further validated thanks to finite element computations. In parallel, Metravib used its own Dynamic Mechanical Analysis (DMA) machines to characterize the elastomeric part intended for the attenuators.
Then, Metravib realized mock-ups and prototypes:
Manufacturing of elastomer rings
Manufacturing of mechanical interfaces
Integration, testing and validation of the corresponding prototypes