Structural dynamics

EPX implements specific models able to analyze various mechanical situations, such as shocks, impacts, explosions, wave propagations and their consequences on structures…

Spatial discretization for structures is mainly achieved through finite elements, but some meshless models, such as SPH particles, or discrete models are also available.

Impacts

The safety of industrial facilities imposes a detailed analysis of accidents due to impact to impacts of projectiles. These accidents can be classified into two main categories regarding the materials involved.

1.      Only strains (potentially large) occur.

For instance, due to a handling accident, the fall of a heavy object can damage structures located on its trajectory. It implies the verification of the acceptable amplitude of the consecutive strains and the demonstration that, even slightly damaged, the impacted structures can still fulfill their role for the safety of the installation.

2.     Penetration or fragmentation occur.

For instance, a hard object perforates a concrete well, ejecting fragments and potentially leading to the complete ruin of the structure. In some cases, meshless or discrete approaches are best suited to deal with this kind of phenomena.

Speficic constitutive laws

EPX implements various, generally non-linear, constitutive laws for structures. They may be categorized as follows.

• Metallic structures: for example, Von Mises laws (perfect, with isotropic or kinematic hardening, with dependancy to the strain rate…), Johnson-Cook law ; damage variables may be associated to any of these laws.
• Non-metallic structures: several laws deal with the behavior of concrete under extreme loading, some exotic laws handle brittle behavior, for instance for ice or glass.
• Structures under high pressure: these laws are the hydrodynamic type.

Exemples

Crash of a perforated cylinder

Bird impact on rotor blades (meshless SPH approach for the projectile)