Fast Thermomechanics

Fast thermodynamic phenomena

After a nuclear explosion, the quasi-instantaneous energy deposition generated by the photons arriving on a structure induced very significant thermomechanical constraints. In order to assess the vulnerability of mechanical systems with respect to such a situation, the following aspects are addressed:

• Thermal Shock – constraint wave propagation
• Impulse
• Structural and thermostructural response

Dedicated software including engineering and computation codes (based on analytical and Monte-Carlo methods) are used by NUCLETUDES to address all these topics as well as the amount of deposited energy. NUCLETUDES’ specific know-how lies in its ability to design behavioural models adapted to very brief energy deposition scenarios (lasting a few tens of nanoseconds) for different types of materials.

NUCLETUDES’ competence also includes the validation of these models through dedicated tests using in particular its STAEL facility (see test facilities page). One may note that such tests need to precisely define the experimental protocol.

Materials behaviour in case of thermal shock

The potential consequences of a thermal shock on a material range from a constraint to damage and rupture.
The assessment of the behaviour of a material facing a thermal shock is done using 1D, 2D or 3D hydrodynamic codes combined with specific models customized to the studied materials and systems.

  Examples

Mesomechanical model of a 3D composite material:                                   

Behavioural study of a thin fiber-based material:

Impulse

The impulse study corresponds to the accelerations of objects facing a materials phase change.

Structural and thermostructural response

Structural and thermostructural response corresponds to the long-term behaviour of ths sub-systems and systems taking into account:

• Constraints - deformations
• Heat transfer
• Vibrations modes

Vibration mode of a cone-shaped object:

Thermal Shock – constraint wave propagation