OFFSHORE WIND ENERGY

HOLISTIC FEM calculations for the offshore industry.

Wave load

The main loads on offshore structures are due to the sea state. It acts on the one hand as an extreme single load in the form of strong storms, but also as a continuous operating load in the form of non-stop waves. Since fixed offshore structures, unlike ships, cannot be docked for inspection work and maintenance under offshore conditions is difficult and expensive, a close look at the damage is essential.

We calculate the wave loads acting on your fixed offshore structures like jackets, tripods, and monopoles by solving the Morrison equation. Thus we quickly receive the loads acting on the structure.

In case of floating structures and gravity base foundations, we determine the hydrodynamic loads by simulating the sea state using the potential solver ANSYS AQWA. Hereby we receive not only a motion simulation of your floating structure but also the resulting loads acting on the structure.

Ice load

Ice loads have a significant impact on the strength calculation, if offshore structures are located in arctic conditions. On the one hand, the load resulting from drifting ice on the foundation needs to be considered. On the other hand, there is the deposition of ice due to humidity and water spray on the structure itself. This increases the impact surface for wind and wave loads as well as the net mass. Especially adfreezing on the wings of wind turbines leads to particularly strong vibrations and high loads on the blades.

Collisions

There is always a risk of collision between offshore structures and ships. The collision of offshore suppliers at the designated boat landing is usually idealized by a static strength calculation of the structure.

In case of a collision with a drifting ship, we perform a FEM simulation with the explicit solver LsDyna. The impact of the collision on both structures can be simulated with a very high level of detail.

Vibrations and underwater noise

We carry out vibration analyzes of offshore structures for you. We consider the elasticity of the soil embeddedness as well as the influence of the surrounding water. Particularly important is the avoidance of resonance when excited by the sea or an imbalance of the rotors.

When installing offshore structures, there is a strong emission of underwater noise. Especially the ramming of foundations is a major cause of this noise emission. An excerpt of our research in this field can be found in our publications. We carry out ramming simulations, analyze the noise radiation into the surrounding water and evaluate noise protection concepts for your offshore application.

Offshore foundations

We do all the common FEM calculations for your offshore foundations, whether we evaluate an initial concept, create computational evidence for classification societies, or assist with certification. Above all, through design-accompanying calculations, the development work of innovative structures can be accelerated and made more efficient.

We perform strength analyzes as well as fatigue calculations of large jacket structures by idealizing them as line bodies. Details like the pile sleeve connections or pipe joints are modeled as a detailed submodel.

For floating offshore structures, we analyze the seakeeping behavior, taking the bracing and anchoring into account. In addition, we carry out strength calculations taking into account the special conditions of such systems.

Soil interaction of offshore foundations

The ground connection is always considered to be challenging in offshore foundations. States of the art are still rammed pile foundations. We model the interaction of the piles, as well as the foundation in the case of a gravity foundation, with the surrounding soil, since the stiffness of the connection has a high influence on the strength and stability of the entire foundation.

Offshore platforms

We perform strength calculations, fatigue analyzes and vibration analyzes of offshore platforms. We consider the global properties such as strength, stiffness and vibration behavior of the holistic structure. The coupling with the foundation is also considered. Details can be evaluated efficiently with the FEM, too. Thus, foundations of aggregates or the connection to the foundation can be simulated.

Offshore supply vessels, jack up barges and installation vessels

Floating offshore structures such as construction vessels and supply vessels are subject to special loads. We assist in the design of these structures through applied FEM calculations. Of particular importance is the assessment of highly loaded and specialized detail constructions such as crane and winch foundations or jacketing systems.

In jack-up barges and construction vessels, we not only assess the strength of the construction for static loads, we also evaluate the dynamic behavior and stability according to DIN ISO 19905.

When installing offshore installations, nature conservation must always be observed. This also applies to the reduction of underwater noise in the case of pile driving of piled foundations. Technical implementations to achieve this goal are, for example, the cofferdam, the bubble curtain or hydro sounddamper. Also a variation in the geometry of pile, anvil and hammer are possible.

We support you in finding the right noise protection concept for your project using numerical simulations. We also recommend the literature published by us on this topic.

Many components for offshore use are characterized by their size and weight. This makes transportation to the operation site difficult. In addition, the components have been designed for operation and rarely for transportation.

As a qualified engineering office we support you in designing the transport of your individual cargo. We determine the loads acting on the cargo, substructure and the surrounding structure and check their strength by means of an FEM calculation based on current regulations or individual boundary conditions. In addition, we check the forces occurring in the cargo securing and lashing provided.

Lifting operations are subject to strict conditions under offshore conditions. We not only check the strength of the hoist and the cranes, we also evaluate the strength of the cargo to be lifted.

Offshore lifting operation with FEM
Offshore foundation
Offshore wind energy

REFERENCES

A selection of our references:

  • Strength calculation of the lifting operation of the entire tansformer platform block including rigging configuration and traverses
  • Strength analysis, modal analysis, certification assistance and generation of theoretical models of bubble propagation for a small bubble curtain (SBC)
  • Strength analysis, modal analysis, CFD calculation, technical drawings and design brief for an offshore wind energy converter as a guyed foundation
  • FEM calculation of strength, fatigue strength, collision (ship impact) and lifting process of a met mast
  • Several strength calculations for the offshore accomodation platform DanTysk (subcontractor; landing platform, grout connection, mudmats, pile sleeves, connection bridge to transformer platform, collision (ship impact), pile catcher, pile sway, tank deck, topsite equipment, stabbing, several bolt calculations)
  • FE strength analysis (ULS) of the HELWIN Alpha cable tower foundation
  • FE fatigue strength analysis (FLS) of HELWIN Alpha cable tower
  • FE strength analysis (ULS) of ship impact of HELWIN Alpha cable tower
  • FE strength analysis of the skidding process of the SYLWIN Alpha baseframe between 2 offshore transportation barges
  • FE strength analysis of the offshore barge transportation of the SYLWIN Alpha baseframe
  • FE strength analysis of the submerging process of an offshore barge (baseframe SYLWIN Alpha)

 

 

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