EXPLICIT DYNAMICS

HIGHEST dynamics, analyzed by us.

The dynamic behavior of structures is usually described by implicit solvers. However, if the time to be simulated becomes so short that the propagation of the sound and shockwaves within the structure has to be considered, we use LS-DYNA as an explicit FEM solver within the FEM. Not only can these highly dynamic behaviors be studied, but also failure criteria such as tearing structures can be detected.

Collisions and grounding are usually the highest loads that can occur for ships and offshore structures. In the automotive industry, the combination of numerical simulations with crash tests is common.

In maritime structures, these crash tests are not performed due to size and cost. The explicit solution within the FEM offers the possibility to simulate collisions between ships as well as with fixed structures such as bridges and offshore installations on the computer.

Occurring cracks and plastic deformations can be simulated by special failure criteria and absorbed energy can be evaluated. Thus, the potentially occurring damage can be described in detail. Conclusions on escaping oil or diesel as well as the potential of penetrating water can be assessed. Also statements about the stability of the entire structure can be made.

For naval military vessels such as submarines, the impact of explosions from mines, torpedoes or depth charges is particularly high. As an expert in dynamic calculation with FEM, we support shipyards and their supply industry with individual shock calculations.

We offer many years of experience in the evaluation of rigidly connected, but also elastically mounted aggregates, foundations and furnishings under shock load.

In the case of complex structures or platforms, which are elastically mounted, not only the stress but also plastic strain within the structure in the time domain is evaluated by a dynamic calculation. In addition, statements about the deflection, the residual acceleration as well as the necessary shock clearance and spectral evaluations in the frequency domain are possible.

If aggregates are installed in a submarine or a military surface vessel, they must survive the shock of an underwater explosion either unscathed or without any harm to the crew. In order to reduce the acceleration in case of shock, it is recommended to store the unit elastically.

When choosing the damping elements, various aspects such as the natural frequency, deflection, residual acceleration and relative displacement must be taken into account.

We assist you in selecting suitable damper elements and analyze the interaction with the aggregate. This is done by self-developed and proven analytical tools. The proof of the elastically mounted structure is then carried out by a transient calculation by means of FEM.

Structures adjacent to the ship structure are hit directly by the shockwave. In addition, the pressure wave is reflected by the hull and hits the structure, which is to be examined, again. We investigate these effects as well as the vibrational behavior of the structure in water by explicit solution methods within the FEM.

We model the geometry, the surrounding medium and the surrounding structure. The latter can be idealized as a boundary condition. The explosive charge is modeled and the pressure spread by the fluid in the time domain is calculated.

Knowing in advance what works afterwards.

 

Schock simulation with FEM
Crash simulation with LS Dyna and FEM
COllision simulation with LS Dyna and FEM

REFERENCES

A selection of our references:

  • Finite element analysis of a methanol reformer of a submarine for different trims, heelings, shock excitations for all spatial directions as well as thermal analysis of the reformer tubes
  • Feasability study, FE calculation and topology optimization of a hammer adapter for ramming of large monopiles
  • Several collision calculations for an inland waterway tanker (MoveIt project/EU) including variations of the main frame, bulbous bow and plate thickness variations of the double hull
  • Several shock calculations for components on board of different submarines
  • Dynamic simulation of single and double elastic mounteed platforms 
  • Several shock calculations for components on board of a frigate
  • Design and dimensioning of an elastic foundation for shockproof devices on a corvette

 

 

S.M.I.L.E. - FEM

GmbH

Winkel 2
D-24226 Kiel / Heikendorf
fon: +49 431 - 210 80 20
fax: +49 431 - 210 80 28


e-mail: info@smile-fem.de