An Analyst s View: STEP-Enabled CAD-CAE Integration Stephen Gordon NASA s STEP for Aerospace Workshop JPL, Pasade

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Computer aided design CAE Integration DomainsPurpose, Scope, and Scale of AnalysisCAD-Centric versus CAE-Centric ProcessesCategories of Integration (What is genuinely

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´╗┐An Analyst's View: STEP-Enabled CAD-CAE Integration Stephen Gordon NASA's STEP for Aerospace Workshop JPL, Pasadena, CA January 17, 2001

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Outline of Topics CAD-CAE Integration Domains Purpose, Scope, and Scale of Analysis CAD-Centric versus CAE-Centric Processes Categories of Integration (What is really 'Consistent'?) De-Featuring Geometry (Content, Amount of Detail) Geometry 'Sexual orientation Changing' Needs and Tools "Reproduction Specific Geometry" versus Computer aided design Geometry Collaboration (Inter-and Intra-Company) ISO STEP 10303 is not just about Data Exchange AP209 is an Enabler for CAD-CAE Integration AP209 = CAD + CAE + FEM + FEA + PDM (Mnemonic) Backup Slides

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CAE Functionality Computer-Aided Engineering (CAE) is comprised of many changed and differing capacities, contingent on one's association and it's structure. My emphasis will be on the trade and sharing of outline and building information (to a great extent geometry and material data) for use in computational examination devices, particularly limited component technique codes. My motivation today is to characterize where I see, as an investigator, the potential and developing use for ISO STEP AP209. There is no endeavor to slight numerous other imperative (non-diagnostic) building capacities in the CAD-CAE area identified with the general outline, endorsement, and life-cycle of the items we make.

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CAD and CAE Integration The way to comprehension CAD-CAE Integration, is identified with the scale, degree and reason for the required designing investigation - e.g. Limited Element Analysis (FEA). It is not just identified with the presence of caught CAD geometry, a discernment unwittingly left amid item display 'walk-throughs'. The nearer the scale, extension and motivation behind a building investigation is to the sort and detail of the current CAD item display geometry, the more prominent the probability that a firmly coupled , mechanized , or even consistent incorporated CAD-CAE process can be actualized.

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Scope, Purpose, and Scale Small-scale, single part enhancement "Gadgets & Gadgets" Large-scale recreation, e.g. vehicle crash-value These may both utilize a similar programming, yet with fundamentally extraordinary models!

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Large-Scale Simulation, Full Vehicle Models Part of the CAE Domain Such investigations and recreations likely incorporate multi-material science and media-structure connection

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CAD and CAE Integration When the scale, degree and reason for a designing examination are not reliable with the sort and detail of the current CAD item show geometry, a PC helped "man-on top of it" or semi-robotized process might be more doable and suitable than a completely mechanized process. (Still a place for building judgment.) We have found that the time and cost to change, re-work, and de-highlight CAD geometry can in some cases be more prominent than that for making examination models from promptly produced "admired" geometry. (Not a famous view in this day and age!) The more conceptual, romanticized geometry utilized for examination is additionally alluded to as "Reproduction Specific" or "FEA-Specific Geometry".

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Analysis Model Creation (e.g. FEA) Geometry is not generally the same! Change Type or "Sex" Derived Idealized Geometry Engr. Butt-centric. Display (FEM) Captured CAD Geometry Simplify Idealize De-Feature Pave Mesh Discretize A mechanical architect, a basic designer, and a channeling specialist may each require distinctive types of geometry catch.

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Geometry Representation 1D Line (Curve) Same Object ... 2D Surface (Shell) Multiple/Different Forms of Geometry Capture 3D Solid (Volume)

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Exploded View - Same Geometry, Different Data Capture 1D Line (Curve) 2D Surface (Shell) 3D Solid (Volume) "Sex Changing"

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Integrated CAD-CAE Process The benefit of building examination and improvement right on time ('in advance') in the outline procedure is presently promptly acknowledged and is for the most part unassailable. Sadly, there is regularly the observation (in some cases from MCAD seller buildup) that designing investigation is an absolutely consistent process inside CAD. This view can be an injury to numerous divisions of business, where strong item models have turned into the CAD approach of decision, however the wrong geometry for investigation. Luckily, articles in the writing have as of late mirrored some of these distinctive perspectives on conveying examination.

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Recent Articles Show Enlightened Views "Three-Dimensional CAD Design and Analyzing with Shell Elements - A Soluble Contradiction?", by M. W. Zehn, H. M. Baumgarten, & P. Wehner, NAFEMS seventh Int'l. Conf., Newport, RI, April 1999 "Don't Change the Model Till the Simulation Finishes", by Paul Kurowski, Machine Design , August 19, 1999 "New kid on the block Mistakes - Over Reliance on CAD Geometry", by Vince Adams, NAFEMS Benchmark , October 1999 "Normal Misconceptions About FEA", by Vince Adams, ANSYS Solutions , Fall 2000 "Eight Tips for Improving Integration Between CAD and CFD", by Scott Gilmore, Desktop Engineering , May 2000

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"Don't Change the Model Till the Simulation Finishes" by Paul Kurowski Machine Design August 19, 1999 When investigation geometry is not the same as outline geometry! "Reenactment particular geometry"or "FEA-particular geometry"

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CAD-CAE Integration Whether CAD-CAE applications can be firmly coordinated and robotized relies on: The scale, extension, and motivation behind the CAE examination. The nature and sort (request, or "sexual orientation") of the caught CAD geometry. The measure of detail required for the CAE application. Today's bottleneck in CAD-CAE joining is not robotized work (framework) era, it lies with effective formation of suitable reproduction particular geometry.

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The First "Issue" - Geometry Type when all is said in done, the most robotized CAD-to-CAE procedures are for MCAE "same sexual orientation" geometry classes, eg. gadgets and devices, or 3D volumes loaded with 3D versatility tet or hex strong components; or funneling examination utilizing 1D geometry. In the structures teach, our ship product offerings frequently include huge scale, streamlined geometry and examination models, e.g. expansive gatherings of hardened 2D plate/shell surfaces and system structures. Nonetheless, venture CAD item demonstrate geometry catch is on a very basic level 3D strong displaying supplemented with 1D "structures" substances. Thin-walled structure is all the more precisely and productively examined as plates and shells.

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Same "Sex" Geometry Creating Engineering Analysis Models Geometry Type Analysis Model Type 1D Lines, Curves 2D Surfaces 2D 'Cut" Surfaces (or Sections) 3D Volumes Beams, Trusses Axisymmetric Shells Stiffened Plates & Shells Plates & Shells Plane Stress/Strain Elasticity Axisymmetric Solids ("Quasi-3D") 3D Solid Elasticity

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CAD-Centric Approaches Creating Engineering Analysis Models Captured CAD Geometry Idealized Geometry Analysis Model Type (Eg. FEM) CAD Structures (1D) 1D Lines, Curves 2D Surfaces 2D 'Cut" Surfaces (or Sections) 3D Volumes Beams, Trusses Axisymmetric Shells Stiffened Plates & Shells Plates & Shells Plane Stress/Strain Elasticity Axisymmetric Solids ("Quasi-3D") 3D Solid Elasticity CAD Surfaces (2D) CAD Solids (3D) Can be "Consistent" 'Sexual orientation Changing' Required

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CAD-Centric Process with a 3D Solid Product Model Creating Engineering Analysis Models Captured CAD Geometry Idealized Geometry Analysis Model Type (Eg. FEM) 1D Lines, Curves 2D Surfaces 2D 'Cut" Surfaces (or Sections) 3D Volumes Beams, Trusses Axisymmetric Shells Stiffened Plates & Shells Plates & Shells Plane Stress/Strain Elasticity Axisymmetric Solids ("Quasi-3D") 3D Solid Elasticity Requires "Sex Changing" 3D Solid Product Model

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The Second "Issue" - Model Content and Amount of Detail when all is said in done, the caught CAD geometry contains a lot of detail, important for making drawings and for assembling support, yet an excessive amount of detail for most admired FEA models. Along these lines, the glorification part of FEA requires streamlining the geometry, evacuating undesirable subtle elements which are not similar with the size of the admired FEA demonstrate. Illustrations incorporate expelling little openings, including or evacuating filets, notwithstanding dispensing with entire bits which might be glorified as an unbending mass, or may not be in the examination by any means! This procedure of disentanglement is now and then alluded to as "stifling the points of interest" or "de-including" the geometry. For welded structure including highlights (weld filets) to the CAD item model might be required for itemized push examination.

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Welded Thin-Walled Structure with a 3D Solid Product Model Portion of establishment for flexible mounts and stun snubbers Weld material is clarified (e.g.weld images), yet not unequivocally caught as filets in the item display (as it would be for a machined part) Joint Surface Index JXXX Typical de-highlighting may incorporate taking out the little gaps however keeping the bigger ones. While, an including change could add weld filets to maintain a strategic distance from stress focuses or singularities at sharp corners.

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Categories of CAD-CAE Integration Category I - The CAD Geometry and the Simulation-Specific Geometry are the same (indistinguishable). This is the genuinely "consistent" case; there is no adjustment in detail, no de-highlighting, and no geometry sexual orientation evolving required. Experts and creators utilize the same (or copy duplicates of the same) geometry. Class II - Existing (accessible) CAD geometry has the wrong substance; it is excessively point by point as well as of the wrong sort to bolster the scale, degree, and motivation behind the required or most suitable kind of investigation. Changes are required to include elements or expel superfluous detail from, and additionally alter the sexual orientation of, the CAD geometry to make Simulation-Specific Geometry amiable to a