3d Modeling Fea CATIA v5

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3D modeling and structural analysis in CATIA V5r17


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Introduction

3D modeling

3D computer graphics (in contrast to 2D computer graphics) are graphics that use a

three-dimensional representation of geometric data (often Cartesian) that is stored in the

computer for the purposes of performing calculations and rendering 2D images. Such images

may be stored for viewing later or displayed in real-time

3D computer graphics rely on many of the same algorithms as 2D computer vector graphics in

the wire-frame model and 2D computer raster graphics in the final rendered display. In

computer graphics software, the distinction between 2D and 3D is occasionally blurred; 2D

applications may use 3D techniques to achieve effects such as lighting, and 3D may use 2D

rendering techniques.

3D computer graphics are often referred to as 3D models. Apart from the rendered graphic, the

model is contained within the graphical data file. However, there are differences. A 3D model is

the mathematical representation of any three-dimensional object. A model is not technically a

graphic until it is displayed. Due to 3D printing, 3D models are not confined to virtual space. A

model can be displayed visually as a two-dimensional image through a process called 3D

rendering, or used in non-graphical computer simulations and calculations.

In 3D computer graphics, 3D modeling (also known as meshing) is the process of developing a

mathematical representation of any three-dimensional surface of object (either inanimate or

living) via specialized software. The product is called a 3D model. It can be displayed as a two-

dimensional image through a process called 3D rendering or used in a computer simulation of

physical phenomena. The model can also be physically created using 3D printing devices.

Models

3D models represent a 3D object using a collection of points in 3D space, connected by

various geometric entities such as triangles, lines, curved surfaces, etc. Being a collection of

data (points and other information), 3D models can be created by hand, algorithmically

(procedural modeling), or scanned.

3D models are widely used anywhere in 3D graphics. Actually, their use predates the

widespread use of 3D graphics on personal computers. Many computer games used pre-

rendered images of 3D models as sprites before computers could render them in real-time.

http://en.wikipedia.org/wiki/3D_computer_graphicshttp://en.wikipedia.org/wiki/Three-dimensional_spacehttp://en.wikipedia.org/wiki/3d_computer_graphics_softwarehttp://en.wikipedia.org/wiki/3D_renderinghttp://en.wikipedia.org/wiki/3D_renderinghttp://en.wikipedia.org/wiki/3D_renderinghttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Simulationhttp://en.wikipedia.org/wiki/3D_printinghttp://en.wikipedia.org/wiki/3D_printinghttp://en.wikipedia.org/wiki/Simulationhttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/3D_renderinghttp://en.wikipedia.org/wiki/3d_computer_graphics_softwarehttp://en.wikipedia.org/wiki/Three-dimensional_spacehttp://en.wikipedia.org/wiki/3D_computer_graphics


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Today, 3D models are used in a wide variety of fields. The medical industry uses detailed

models of organs. The movie industry uses them as characters and objects for animated and

real-life motion pictures. The video game industry uses them as assets for computer and video

games. The science sector uses them as highly detailed models of chemical compounds. The

architecture industry uses them to demonstrate proposed buildings and landscapes throughSoftware Architectural Models. The engineering community uses them as designs of new

devices, vehicles and structures as well as a host of other uses. In recent decades the earth

science community has started to construct 3D geological models as a standard practice.

Representation

Almost all 3D models can be divided into two categories.

Solid - These models define the volume of the object they represent (like a rock). These

are more realistic, but more difficult to build. Solid models are mostly used for nonvisual

simulations such as medical and engineering simulations, for CAD and specialized visual

applications such as ray tracing and constructive solid geometry

Shell/boundary - these models represent the surface, e.g. the boundary of the object,

not its volume (like an infinitesimally thin eggshell). These are easier to work with than solid

models. Almost all visual models used in games and film are shell models.

Because the appearance of an object depends largely on the exterior of the object, boundary

representations are common in computer graphics. Two dimensional surfaces are a good

analogy for the objects used in graphics, though quite often these objects are non-manifold.

Since surfaces are not finite, a discrete digital approximation is required: polygonal meshes (and

to a lesser extent subdivision surfaces) are by far the most common representation, although

point-based representations have been gaining some popularity in recent years. Level sets are a

useful representation for deforming surfaces which undergo many topological changes such as

fluids.

The process of transforming representations of objects, such as the middle point coordinate of

a sphere and a point on its circumference into a polygon representation of a sphere, is calledtessellation. This step is used in polygon-based rendering, where objects are broken down from

abstract representations ("primitives") such as spheres, cones etc., to so-called meshes, which

are nets of interconnected triangles. Meshes of triangles (instead of e.g. squares) are popular as

they have proven to be easy to render using scanline rendering. Polygon representations are

not used in all rendering techniques, and in these cases the tessellation step is not included in

the transition from abstract representation to rendered scene.


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CATIA

CATIA (Computer Aided Three-dimensional Interactive Application)is a multi-platform

CAD/CAM/CAE commercial software suite developed by the French company Dassault

Systemes. It is written in the C++ programming language.

CATIA competes in the CAD/CAM/CAE market with Siemens NX, Creo Elements/Pro, Autodesk

Inventor, and many others who are less known.

History

CATIA started as an in-house development in 1977 by French aircraft manufacturer

Avions Marcel Dassault, at that time customer of the CAD/CAM CAD software to develop

Dassault's Mirage fighter jet, then was adopted in the aerospace, automotive, shipbuilding, and

other industries.

Initially named CATI (Conception Assistée Tridimensionnelle Interactive — French for

Interactive Aided Three-dimensional Design ) — it was renamed CATIA in 1981, when Dassault

created a subsidiary to develop and sell the software, and signed a non-exclusive distribution

agreement with IBM.

In 1984, the Boeing Company chose CATIA as its main 3D CAD tool, becoming its largest

customer.

In 1988, CATIA version 3 was ported from mainframe computers to UNIX.

In 1990, General Dynamics Electric Boat Corp chose CATIA as its main 3D CAD tool, to design

the U.S. Navy's Virginia class submarine.

In 1992, CADAM was purchased from IBM and the next year CATIA CADAM V4 was published. In

1996, it was ported from one to four Unix operating systems, including IBM AIX, Silicon

Graphics IRIX, Sun Microsystems SunOS and Hewlett-Packard HP-UX.

In 1998, an entirely rewritten version of CATIA, CATIA V5 was released, with support for UNIX,

Windows NT and Windows XP since 2001.

In 2008, Dassault announced and released CATIA V6. While the server can run on Microsoft

Windows, Linux or AIX, client support for any operating system other than Microsoft Windows

is dropped.


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Scope of Application

Commonly referred to as a 3D Product Lifecycle Management software suite, CATIA supports

multiple stages of product development (CAx), from conceptualization, design (CAD),

manufacturing (CAM), and engineering (CAE). CATIA facilitates collaborative engineering across

disciplines, including surfacing & shape design, mechanical engineering, equipment and

systems engineering.

Surfacing & Shape Design

CATIA provides a suite of surfacing, reverse engineering, and visualization solutions to create,

modify, and validate complex innovative shapes. From subdivision, styling, and Class A surfaces

to mechanical functional surfaces.

Mechanical Engineering

CATIA enables the creation of 3D parts, from 3D sketches, sheetmetal, composites, molded,

forged or tooling parts up to the definition of mechanical assemblies. It provides tools to

complete product definition, including functional tolerances, as well as kinematics definition.

Equipment Design

CATIA facilitates the design of electronic, electrical as well as distributed systems such as fluid

and HVAC systems, all the way to the production of documentation for manufacturing.

Systems Engineering

CATIA offers a solution to model complex and intelligent products through the systems

engineering approach. It covers the requirements definition, the systems architecture, the

behavior modeling and the virtual product or embedded software generation. CATIA can be

customized via application programming interfaces (API). CATIA V5 & V6 can be adapted using

Visual Basic and C++ programming languages via CAA (Component Application Architecture); a

component object model (COM)-like interface.

Although later versions of CATIA V4 implemented NURBS, V4 principally used piecewise

polynomial surfaces. CATIA V4 uses a non-manifold solid engine.

Catia V5 features a parametric solid/surface-based package which uses NURBS as the core

surface representation and has several workbenches that provide KBE support.

V5 can work with other applications, including Enovia, Smarteam, and various CAE Analysis

applications.


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In later chapters will be given detailed description of 3D part design, sketch,and generative

structure analysis. For structure analysis of console here will be used finite element analysis

(FEA), with linear finite elements.

Structural analysis is the determination of the effects of loads on physical structures and

their components. Structures subject to this type of analysis include all that must withstand

loads, such as buildings, bridges, vehicles, machinery, furniture, attire, soil strata, prostheses

and biological tissue. Structural analysis incorporates the fields of applied mechanics, materials

science and applied mathematics to compute a structure's deformations, internal forces,

stresses, support reactions, accelerations, and stability. The results of the analysis are used to

verify a structure's fitness for use, often saving physical tests. Structural analysis is thus a key

part of the engineering design of structures.

A structure refers to a body or system of connected parts used to support a load. Important

examples related to Civil Engineering include buildings, bridges, and towers; and in other

branches of engineering, ship and aircraft frames, tanks, pressure vessels, mechanical systems,

and electrical supporting structures are important. In order to design a structure, one must

serve a specified function for public use, the engineer must account for its safety, aesthetics,

and serviceability, while taking into consideration economic and environmental constraints.

Other branches of engineering work on a wide variety of nonbuilding structures.

Classification of structures

It is important for a structural engineer to recognize the various types of elements composing a

structure and to be able to classify structures as to their form and function. Some of the

structural elements are tie rods, rod, bar, angle, channel, beams, and columns. Combination of

structural elements and the materials from which they are composed is referred to as a

structural system. Each system is constructed of one or more basic types of structures such as

trusses, cables and arches, frames, and surface structures.


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Finite elements analysis

The finite element method (FEM) is a numerical method that can be used for the accurate

solution of complex engineering problems. The method was first developed in 1956 for theanalysis of aircraft structural problems. Thereafter, within a decade, the potentialities of the

method for the solution of different types of applied science and engineering problems were

recognized. Over the years, the finite element technique has been so well established that

today it is considered to be one of the best methods for solving a wide variety of practical

problems efficiently. In fact, the method has become one of the active research areas for

applied mathematicians. One of the main reasons for the popularity of the method in different

fields of engineering is that once a general computer program is written, it can be used for the

solution of any problem simply by changing the input data.

The analysis of the coupled system of Finite element is obtained by discretization of the

continuum, thus allowing the numerical simulation of output of the continuum to the given

input impulses. The physical properties that are included in the model are obtained in discrete

form,that is as points that arise from discretization. These points are called nodal points or

simply nodes.

In the FEM, the structural system is modeled by a set of appropriate finite elements

interconnected at points called nodes. Elements may have physical properties such as

thickness, coefficient of thermal expansion, density, Young's modulus, shear modulus and

Poisson's ratio.

Based on the discretization of physical problems, interpolation and by introducing interpolation

functions with the introduction of natural (local) coordinate system, the establishment of the

equilibrium equations for elements and the overall structure, leads to the matrix of elements

and systems. The detailed description of these matrixes , along with mathematical calculus is

not part of this work.


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Modeling in Catia v5r17

Part Design

When program starts this how it looks. In the top left corner of the screen we see Start button

and by clicking it a dropdown menu appears. There we select Mechanical DesignPart Design

.

The sreen now looks like this.


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With click on ,,+,, we expand the Part1(Part1) and then by double clicking on Part1 we enter the

Part Design enviorment.

Next screen looks like this.

In the center are planes (xy,xz,yz) which will be used for drawing the skech of console. On theright are features for creating and modyfaing 3D part. But first we enter the skech enviorment

by clicking on plane (yzin this case) and then on Sketch (white icon on the right,below mouse

pointer) or double clicking on the plane. Next window will appear.


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On the right side are (in order top to down)

1. Constraints defined in Constraints Box – it can be used for constraining,dimesioning

and positionig geometry.

2. Constraint – it can be used for dimensiong lines, or diameters, or distances from

selected object.

3. Fix Together – it can be used to fix two or more objects

4. Edit Multi-Constraint – it can be used for editing dimesions,positions,...

5. Profile – it can be used for drawing continious lines, arcs, or circles

6.

Rectangle – it can be used for drawing rectangles, sqares, hexagons, paralelograms,...

7. Circle – it can be used for drawing circles using several methods (example tri-point circle

, where user specifies 3 points of circle, first point is begining , the second presents its

second boundary, and the third is the end of circle)

8.

Spline – it can be used for drawing line who look like they are drawn with free hand

9. Elipse - it can be used for drawing elipses using several methods

10. Line- it can be used for drawing lines using several methods (i.e. bitangent bitween two

circles)

11. Axis – it is used for drawing axis

12.

Point - it can be used for drawing point on a selected space(using several methods),

which can be used in Kinematics analysis

13. Corner - it is used to round corners

14. Chamfer - it is used to slice corners

15.

Trim - it can be used to delete parts of a object

16. Mirror - it can be used for copying elements like a mirror


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17. Project 3D elements - it can be used for projecting edges of already created objects.

I have chosen to draw my sketch by using rectangle, and this is how it looks.

Now we will use Constraint to dimesion this sketch.

Now we leave sketch enviorment by clicking the Exit workbench buttton.


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Now we click on the Pad button to create 3D solid.

In the field Lentgh we enter the lentgh of beam which is in this case 100 mm. The element

looks like this.

Next step is to click on one of the surfaces of solid and then on Apply Material to aplly a

material on model, which is steel in this case. We select tab Metal than we search for Steel

and then we click on Steel, then on apply button and finaly on OK button.


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Model now looks like this. And now we are ready to proceed on Structural analysis.


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Structural analysis

We click on Start Analysis and Simulation Generative Structural Analysis to enter the

enviorment for structural analysis.

In the next window that will appear we choose Static Analysis and then we click on OK

button.


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Catia has automaticly created a finite element mesh using linear elements. In order to see

the mesh we select Specification tree(on the left upper side). We click on Nodes and

elements with right click and a dropdown meny will appear. Here we select Visualise Mesh.


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On next window we click OK.

Now it looks like this.

We can change mesh size and sag by double clicking on Green Teatraedar in the center of

the part.

Window like this one will open.


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Since this is a school example nothing will be changed. Next step is to create and set

constraints. But first we must deactivate mesh.

After that we select will change view of 3D part by selecting Shading with material.


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Next step is to select one surface whis will represent the fixed end. Then we click on Clamp

to limit its degree of freedom (DOF). Because its fixed this has 0 degrees of fredom.


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On next window we click OK.

Next step is to set load, which is in this case pressure. The surface where the pressure will

be applied is selected and the we click on icon Pressure.


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Now we define the intesity of pressure(100000 Nm2 in this case) with the direction(the

direction of the tip of red arrows ) and then click OK to confirm and apply. Then we need to

activate mesh.

Next step is to run the solver by clicking on icon Compute.

After you have selected what do you want to compute click OK.


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And then again click OK to run the solver.

Next step is to click on icon Von Mises stress to see distribution of loads.

Model with the distribution of loads


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We can check the displacements as well by clicking the Displacement icon.

By double clocking on the arrows a window will open where we can change the way

displacement is shown.


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If we choose Average iso it will look like this. After that we click on OK to close the window.


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References:

1. The finite element method in engineering, Singertsu S. Rao, Elsevier Science &

Technology Books, Miami,20042. http://en.wikipedia.org/wiki/Finite_element_method

3. http://en.wikipedia.org/wiki/Structural_analysis

4. http://en.wikipedia.org/wiki/3D_modeling

5. http://en.wikipedia.org/wiki/3D_computer_graphics

6. http://en.wikipedia.org/wiki/CATIA
http://en.wikipedia.org/wiki/Finite_element_methodhttp://en.wikipedia.org/wiki/Finite_element_methodhttp://en.wikipedia.org/wiki/Structural_analysishttp://en.wikipedia.org/wiki/Structural_analysishttp://en.wikipedia.org/wiki/3D_modelinghttp://en.wikipedia.org/wiki/3D_modelinghttp://en.wikipedia.org/wiki/3D_computer_graphicshttp://en.wikipedia.org/wiki/3D_computer_graphicshttp://en.wikipedia.org/wiki/CATIAhttp://en.wikipedia.org/wiki/CATIAhttp://en.wikipedia.org/wiki/CATIAhttp://en.wikipedia.org/wiki/3D_computer_graphicshttp://en.wikipedia.org/wiki/3D_modelinghttp://en.wikipedia.org/wiki/Structural_analysishttp://en.wikipedia.org/wiki/Finite_element_method

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3d Modeling Fea CATIA v5