CIM SEMINAR

8/7/2019 CIM SEMINAR

http://slidepdf.com/reader/full/cim-seminar 1/46

B y:

SI DDHA R T H KA SHY A P

MT 10 C DM0 0 2

CAD DATA EXCHANGE

AND CAD STANDARDS



ISSUES

In the product development process, dataexchange and sharing has now risen to the top of theagenda.

Different subcontractors, many of whom are oftengeographically diverse.

The CAD interoperability issue - using one CADsystem in-house, yet needing to deliver designs to, or

receive designs from, another system, poses achallenge to industries.





DATA TRANSFER

The format of design data depends on its origin.

Transferring data must embrace the complete productdescription stored in its database.

The various data are GEOMETRIC DATA ,METADATA , DESIGN INTENT DATA andAPPLICATION DATA

Data also depend on different stages of the productlifecycle.



CAD KERNALS

CAD data formats are governed by the (solid)modeling kernels that the CAD systems are built upon.

A collection of classes and components comprised of

mathematical functions that perform specific modelingtasks.

Ø SOLID MODELING

Ø

CELLULER MODELINGØ FREEFORM SHEET/SURFACE MODELING



Cont..

Kernel contains functions such as

Ø Creation and editing.

Ø Feature modeling support.

Ø Advanced surfacing, thickening and hollowing,

Ø blending and filleting and sheet modelling.

Ø graphical and rendering support

(hidden-line, wire-frame and drafting).



WORKING OF CAD KERNEL

The CAD graphic user interface (GUI) interfaces withthe kernel’s functions through so-called applicationuser interface.

Take Parasolid® modelling kernel as an example,which provides 3D digital representation capabilitiesfor NX™, Solid Edge.





Over the years, various kernels have been developedand adopted by different CAD systems (Table1).

Some are proprietary; others use popular ones

through licensing,e.g. ACIS® by Spatial Technology Corporation, and Parasolid® by UGS.





DATA TRANSLATION

Dualk er ne

lCAD

s

Dual kernel CAD system

Dir ec

tdatat

Direct data translators

Commo

n

Common/neutral translators



DUAL KERNEL CAD SYSTEM

It is a unique technique which puts together twodifferent CAD kernels in one system.

BENEFIT :-

- A bility to work on models developed under eitherkernel

- Combining data from either kernel into a singlemodel.

PROBLEM :-

- Difficult to build

- Multiple kernel types in market



Cont..

IronCAD®

Ø It is the first dual kernel system which is twincombination of ACIS® and Parasolid®.

Ø Uses both kernels simultaneously, switching back and forth when needed.

Ø The nanosecond switch is usually invisible to theuser.

CAXA™ is a product design and collaborative datamanagement system. Combination of the same two.



DIRECT DATA TRANSLATORS

Translates the modeling data stored in a productdatabase directly from one CAD system format toan-other in one step.

There exists a neutral database.The neutral database must be general, governed by theminimum required definitions

Independent of any vendor format.





Cont..

CADporter from Elysium™

Ø A CAD file reader.

Ø This product can read several different formats of CAD files from various vendors.

Ø It is a two-way transfer between the CAD systems.

Ø A CAD system can import a Pro/E® part andrewrite it to another format such as Catia® orAutoCAD® DWG format.





NEUTRAL TRANSLATORS

Converts a proprietary CAD data format into a neutraldata format and vice versa, and this neutral data ismade available to the users.

This neutral data format may be of an international orindustry accepted data format or a proprietary dataformat.

There are a few popular industry standards such as,

DXF PDES

XML



DXF

DXF is the AutoCAD's CAD data file format,developed by Autodesk®.

Enables data interoperability between AutoCAD®

and other programs.Originally introduced in December 1982 as part of AutoCAD® 1.0.

It is primarily a 2D based data format.

The DXF format is a tagged data representation of all the information contained in an AutoCAD®drawing file.



Organization of DXF file

HEADER section – General information about thedrawing. Each parameter has a variable name and anassociated value.

CLASSES section – Holds the information forapplication defined classes whose instances appear inthe BLOCKS, ENTITIES, and OBJECTS sections of the

database.



TABLES section – This section contains definitionsof named items. It contains the following tabulateddata:

ü Application ID (APPID)

ü Block Record (BLOCK_RECORD)

ü Dimension Style (DIMSTYPE)

ü

Layer (LAYER)ü Linetype (LTYPE)

ü Text style (STYLE)

ü User Coordinate System (UCS)



BLOCKS section – Contains Block Definition entitiesdescribing the entities comprising each Block in thedrawing.

ENTITIES section – Contains the drawing entities,including any Block References.

OBJECTS section – Contains the data that apply tonon-graphical objects, used by AutoLISP™ and

ObjectARX® applications.THUMBNAILIMAGE section – Contains thepreview image for the DXF file.

END OF FILE



IGES

Originated in the late 1970’s.

Treats the product definition as a file of entities. Eachentity is represented in an application-independent

format.To and from which the native representation of aspecific CAD/CAM system can be mapped.

Entities

Ø Geometric.

Ø Non-geometric.



NATIVE MODEL



Cont..

Geometry entities define a physical shape

Points--curves--surfaces--solids--relations.

Non-geometry entities serve to provide:

1) A viewing perspective in which a planar drawingmay be composed

2) Annotation and dimensioning appropriate to the

drawing.3) Specific attributes or characteristics for individual

or groups of entities.



IG

ES

● STA R

T

● GLOBAL

● DIRECTORY ENTRY

● PARAMETER DATA

● TERMINATE



Cont..

Transfer both 2D and 3D finite elements.

LACKS A MEANS OF TRANSFERRING SOLIDOBJECTS.

Entities can be added but they are not standardized to be acceptable across all CAD systems.



PDES

Product Data Exchange Specification.

PDES was designed to completely define a product forall applications over its expected life cycle.

PDES is designed to be informationally complete forall downstream applications and to be directly interpretable by these applications.



Cont..

The main types of data which are used in PDES todescribe a product include,

1) Administrative and Control data

2) Geometry such as points, curves and surfaces

3) Topology such as vertices, loops and faces

4) Tolerances

5) Form Features

6) Attributes such as surface finish

7) Material Properties

8) Part Assemblies



Cont..

Click to edit Master text stylesSecond level● Third level●

Fourth level● Fifth level

DESCRIPTION OF A HOLE



Cont..

Where,

FLSn -- Face Logical Structure n

SLSn -- Surface Logical Structure n

CLSn -- Curve Logical Structure n

TSDn -- Three Space Direction n

Pn -- Point n

LLSn -- Loop Logical Structure n

ELSn -- Edge Logical Structure n

VTXn -- Vertex n





STEP

ISO 10303 is an ISO standard for the computer-interpretable representation and exchange of product manufacturing information.

Its official title is: Automation systems and integration Product data representationand exchange.

It is known informally as "STEP"

(Standard For The Exchange Of Product ModelData)



DATA EXCHANGE● Define data form.● Hold a copy.● Transitory data.

DATA SHARING● Same copy access.● Operation at same time.

DATA ARCHIVING● Data as per standard kept for future use



COMPONENTS OF STEPARCHITECTURE



1. Description methods:-

Specifying the data constructs of STEP.

EXPRESS (ISO 10303-11, 1994)

Ø It is the data specification language.

Ø Defined structural constraints and algorithmicrules.

Ø Graphical notations EXPRESS(G)

DEFINITION SYMBOL

SUPPLEMENTRY TEXT



2. Implementation methods:-

Standard implementation techniques for theinformation structures specified by the only STEP dataspecifications intended for implementation, applicationprotocols.

This series includes

Ø The physical file exchange structure (ISO 10303-21, 1994),

Ø The standard data access interface (ISO 10303-22, 1998),

Ø Language bindings (ISO 10303-23).



3.Conformance testing:-

CONFORMANCE TESTING

METHODOLOGY & FRAMEWORK ● Testing of implementations of various STEP parts.● Testing methods are standardized in the ISO 10303-30

series of parts.

ABSTRACTTEST SUITS● Set of abstract test cases● Enable the development of good processors● Encourage trouble-free exchange.● specifies input data to be provided to the implementation

under test.

D ifi i



INTEGRATED RESOURCES

APPLICATION PROTOCOL

APPLICATION INTERPRETED CONSTRUCTS

4. Data specifications:-





CASE STUDY FOR STEP: BOEING 777







COMAPRISON

Click to edit Master text stylesSecond level● Third level● Fourth level●

Fifth level

C S



REFERENCES

Integrating Advanced Computer-Aided Design,Manufacturing, and Numerical Control:Principles and Implementations by XUN XU.

Barequet, G. (1997). Using geometric hashing to repairCAD objects. IEEE Computational Science &Engineering, 4(4), 22-28

Barequet, G., & Duncan, C. A. (1998). RSVP: A

geometric toolkit for controlled repair of solid models.IEEE Transactions on Visualization And ComputerGraphics, 4(2), 162-177

Bloor, S., & Owen, J. (2003). Product Data Exchange.

UK: Taylor & Francis.



THANK YOU

Documents

CIM SEMINAR