AquaSim utilize several building blocks – or structural elements – to render the nature of structures. These facilitate for the modeling of simple as well as complex structures and operations. If you have further questions to the capabilities of the software, please contact our team for more information. We will gladly guide you in the decision process.

## Nodes

Nodes are a computational resource in 3D space that describes the endpoints of the structural elements. Each node has six degrees of freedom and may be assigned custom properties to help the user to solve the problem investigated.

## Point loads

Loads and momentums may be assigned to individual- or groups of nodes inn all – or selected – degrees of freedom. Useful for simple weight supplement or more complex interactions.

## Impulse loads

Impulse loads are useful for analysis of operational conditions such as collisions, falling objects and other accident limit state situations. The impulse load changes the momentum of the object over a very short period of time.

## Springs

Several spring types are available, ranging from basic conservative springs where a spring stiffness is defined, to more complex features where nonlinear data is applied. Buoy spring for simple and effective modelling of small and large volume buoys. Adding a spring stiffness and maximum allowed force in the node. Other features for springs:

- Normal spring: conservative spring where stiffness is applied to the translatory or rotational degrees of freedom in the node.
- Initial spring: for initial damping of translations or rotations. Well suited for systems with large initial deflections.
- Displaced spring: for restricting movement of a node to a predefined amount.
- Dampner spring for damping effects in translation and rotation.
- Offloaded spring: for systems with large initial stiffness which gradually decrease.

## Shape

Add shapes to nodes for more visual appearance of you model. AquaSim has a rich library for buoy shapes, springs, floaters, possibilities for customization and adding new shapes. The shapes have no physical properties and do not contribute to response in the analyze model.

## RAO

RAO (Response Amplitude Operator) are statistics used for determining the probable behavior of an object at sea. Add first order RAO for displacement or for second order slow drift effects to nodes. Useful for imposing prescribed motion pattern of objects.

## Prescribed

Prescribed displacement and rotation of nodes for analyzing simple movements of objects or more complex in combination with RAO.

## Structural elements

Your final model will consist of a discrete number of structural elements. Individually, or by groups, assigned mechanical and physical properties.

- Hinge: for hinged systems such as quays, wave damper systems, steel floating collars.
- Winch systems: for equipment winching analysis. Possibilities for winching in, out and define velocity of the winch system.
- Line break: time-dependent break of line suitable for analysis of accidental limit state. E.g., mooring analysis, powerlines, suspended bridges.
- Valve: for regulation of fluid flow into- or out of compartments.

## Truss

Truss is a structural element capable of withstanding tensile and compressive loads. The user may apply mechanical properties such as Elastic modulus, mass density, cross section area, drag loads, damping, pretension etc. The truss component does not have bending- or torsional resistance, making it suitable for ropes and chains. Apply physical properties as prescribed displacement/rotations, line-break, winch systems, nonlinear behavior, or bar dampner to the truss system. Applicable for, but not limited to:

- Mooring components
- Powerlines
- Wires in suspended systems as bridges, buildings,
- Security systems for landslide / avalanche / highways
- Cables

## Beam

Beams are applied for rendering structures with a cross section. These elements are capable of withstand axial, torsional, and bending stiffness. The stiffness of the beam is given by the cross section and the mechanical properties. Meaning the opportunities for material choices are many. Applicable for, but not limited to:

- Truss constructions
- Floating collars, barges, buoys, pontoons
- Building components
- Wind turbines
- Pipes
- Hoses
- Offshore floating and static units
- Subsea equipment and installations
- FPSO

## Membrane

Membranes are panels of three, four or six nodes. In the classical form it is applied to describe flexible nets and fabrics. In each panel, twines are defined to describe the net, where input is the twine diameter and mask width. In addition, bending stiffness can be applied for semi-flexible fabrics and stiff shell elements. The membrane deforms under the influence of the applied loads, making it unique in the FEM-software industry. Applicable for, but not limited to:

- Fish farm nets
- Lice skirts
- Tarps
- Canvas
- Closed and semi-closed compartments
- Vessels
- Complex sections and beams

## Environmental loads

The possibilities to describe environmental loads in AquaSim are extensive and includes winds, waves, current, bathymetry and topography.

- Wind can be applied as constant or time dependent, including wind gusts and spectrum. User defined spectra or NORSOK.
- Waves can be applied as sinusoidal regular waves or irregular from wave spectra. JONSWAP, Pierson-Moskowitz, ITTC or user defined. Short crested, long crested, symmetric direction distribution and random wave periods.
- Currents may be constant in the water column or varying both in time and space.
- Three-dimensional seabed from loaded data sources or flat with linear elastic behavior.
- Three-dimensional topography from loaded data sources for rendering landscape.

## Fatigue analysis

AquaSim calculates stresses, stress distribution and stress ranges useful as input in fatigue analysis.

## Buckling

AquaSim allows you to check the buckling properties of your design. This is seamlessly integrated in the analysis process, allowing you to run directly from your AquaSim model. Buckling analysis provides essential information about deformation of structural components under loads. This is particularly important for slender structures where critical bucking may occur for stress levels well below those vital for failure. Buckling analysis may be conducted both with- and without environmental loads.

## Eigenperiod (natural frequency)

AquaSim provide you with the necessary tool to investigate natural frequencies of your design. Uncover and determine the natural frequencies in your structure, with- and without environmental loads, which will contribute to cost-effective design development. Gain insight into the structures’ oscillation characteristics to help you in the decision-making process.