**3.2 Ship model making**

ANSYS modeling can be done in two ways, namely direct generation and solid modeling. In direct creation, element creation is done directly by defining the nodes required for an element. This method is best used if only a small number of elements are planned. But for complex shipbuilding with a large number of elements, this method was impractical. Whereas in solid modeling, the definition of the model is from the points (keypoint) serving a line. From these lines an area can be made and then the area can be formed by volume.

**Figure 1.** *Ship scheme. Source: (Model Fast Patrol Boat (FPB) 42m).*

To make a ship model by means of solid modeling, the first thing to do is redrawing it. In this case, the drawing data obtained from AutoCAD is redrawn in ANSYS. This is done because it is difficult to make repairs if the drawing from AutoCAD is imported directly into ANSYS. In addition, this redrawing is done to avoid the possibility that there are parts that cannot be read in ANSYS during the model import process. Redrawing begins by entering the keypoint coordinates obtained from the AutoCAD drawing. The first keypoint coordinates entered are the lines plan coordinates followed by the accommodation deck coordinates. The keypoint formed is connected to a line. Then from these lines an area is made. So that the area formed consists of keypoints and lines. The area used for plate and line modeling is used for the modeling of the reinforcements (ivory and supports).

From the line plan drawing (station) from AutoCAD which is then converted into a line plan (ivory), the coordinates of the points that form the body plan curve can be obtained. The coordinates of these points are entered into ANSYS as a keypoint. Furthermore, the keypoints are connected into a curve to form an ivory curve (transom to ivory 84). These curves are then linked into areas. The area formed consists of keypoints and lines. Henceforth, the area formed is used for plate modeling and the curved lines forming the area are used as an enforcer (ivory).

After the hull area is formed, it is continued with the construction of the superstructure. Furthermore, from the geometric model formed, an element known as meshing is created. Before the meshing process is carried out, the element size must first be planned. In addition, it must also be determined the type of element and material properties to be used.

#### *3.2.1 Selection and determination of elements*

The elements contained in ANSYS can be categorized into 2D (2 dimensional) and or 3D (3 dimensional) element types. ANSYS elements consist of point elements, line elements, area elements, and solid elements. Several LINE elements in ANSYS can be selected according to your needs and analysis to be carried out.

For the modeling of the supports, supports, flanges, ivory, deck beams and other profiles used Beam 189\_Quadratic Finite Strain Beam. Beam 189 is an element

#### *Finite Element Method for Ship Composite-Based on Aluminum DOI: http://dx.doi.org/10.5772/intechopen.94973*

suitable for use in slender structure analysis to slightly thick structures of beams. This element is based on Timoshenko's beam theory [10]. The deformation effect of shear forces is also included. Beam 189 is a quadratic (3-Node) beam element in 3-D space. Beam 189 has six degrees of freedom, consisting of three translations and three rotations. This element is good for linear, large rotational or nonlinear strain applications.

Beam 189 is used for modeling ivory, beam, reinforcement, support, large ivory, flange and pillar because it has the ability to be a beam. In addition, the quadratic form gives more accurate results than the linear form.
