50. Wave energy capture device 2

The identification tag for this tutorial is PDS-ABK. Pregenerated input files for this tutorial are found in the folder named PDS-ABK in the provided tutorial input files.

50.1. Tutorial overview

This tutorial covers:

Using multiple ABA connections in a chain sequence
The revolute ABA joint

Fig. 50.1 Wave energy converter

50.2. Initializing the WEC system RigidBody DObjects

Create a new project.
Create three RigidBody DObjects and call them base0, paddle0, and paddle1.

Note

The wave energy converter will be comprised of a submerged frame and two buoyant paddles attached with revolute pin joints.
It is assumed the submerged frame is flooded and therefore has no buoyancy.

Add a RigidBodyCylinder feature called paddlePipe to the library, set the $Diameter to 1 m, $Length to 3.5 m
Add a RigidBodyCylinder feature called longPipe to the library, set the $Diameter to 1 m, $Length to 12 m, and $BuoyancyFroudeKrylov to 0.
Add a RigidBodyCylinder feature called shortPipe to the library, set the $Diameter to 1 m, $Length to 4 m, and $BuoyancyFroudeKrylov to 0.
Set mass moments of inertia of base0 arbitrarily to 1e5 kg*m² and the mass to 2e4 kg.
Set mass moments of inertia of paddle0 and paddle1 arbitrarily to 1e3 kg*m² and the mass to 1e3 kg.

50.3. Adding cylinders to base0

Add the longPipe and shortPipe cylinders to base0. Assume the rigid body frame is located in the middle of one of the short pipes as indicated in Fig. 50.2.
The base0 input file show look like the following:

// Mass properties
$Ix 1e5
$Iy 1e5
$Iz 1e5
$Ixy 0
$Ixz 0
$Iyz 0
$DefineInertiaAboutCG 1
$CGPosition -6 0 0
$Mass 2e4

// Numerical
$Kinematic 0

$Cylinder shortPipe 0 0 0 90 0 0
$Cylinder shortPipe -12 0 0 90 0 0
$Cylinder longPipe -6 2 0 0 90 0
$Cylinder longPipe -6 -2 0 0 90 0

Fig. 50.2 Base layout

50.4. Adding cylinders to paddle0 and paddle1

Note

By design, the rigid body frame will be set at the bottom of the paddles on the rotation axis.

Add the paddlePipe cylinder to paddle0 and paddle1. The input files for both paddles should look like following:

// Mass properties
$Ix 1e3
$Iy 1e3
$Iz 1e3
$Ixy 0
$Ixz 0
$Iyz 0
$DefineInertiaAboutCG 1
$CGPosition -2 0 0
$Mass 1e3

// Numerical
$Kinematic 0

$Cylinder paddlePipe 0 0 0 90 0 0
$Cylinder paddlePipe 0 0 -1 90 0 0
$Cylinder paddlePipe 0 0 -2 90 0 0
$Cylinder paddlePipe 0 0 -3 90 0 0
$Cylinder paddlePipe 0 0 -4 90 0 0

50.5. Creating ABA connections

Create an ABA connection and make base0 master of paddle0.
Create a second ABA connection and make base0 master of paddle1.
Change the connection information for both connections to set the $Joint property as type 1. This creates a revolute joint.
Set the $FollowerJointAxis property to 1 for both connections. This sets the revolute axis to the y-axis for the follower RigidBody.
Create a RigidBodyABAConnectionJoint feature called paddleConnection.
In the connection section, change the connection joint reference type property from the default $PrismaticJointLinear to $RevoluteJointAngular and reference the RigidBodyABAConnectionJoint feature created.

Note

The paddles are located 1/3 and 2/3 along the span of the base0 hull.

For paddle0, specify the $MasterConnectionLocation property to have the offset (-4,0,0) m with no rotation and the $FollowerConnectionLocation property to have the offset (0,0,0) m with no rotation.
For paddle1, specify the $MasterConnectionLocation property to have the offset (-8,0,0) m with no rotation and the $FollowerConnectionLocation property to have the offset (0,0,0) m with no rotation.
Set the state for base0 to be a location of (0,0,3) m with no velocity or rotation.
Set the state for paddle0 and paddle1 to have an ABA state with one degree of freedom and a velocity of 0 deg/s and a angle of 0 degrees.

50.6. Running the simulation and visualizing in PostPDS

Set Airy waves with height of 3 m and a period of 7 seconds.
Set the water depth to 50 m.
Run the simulation for 60 seconds.
Visualize the results in PostPDS.