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Published byWesley Cockfield Modified about 1 year ago

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By Mritunjay Kumar

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Course Content a)Surface modeling overview b)Surface modeling process c)Basic Surface modeling functions d)Case study for Basic functions e)Advance Surface modeling Functions f)Case study for Advanced functions g)Create complex surfaces using proper techniques h)Case study for surfacing techniques i)Repair imported data by IDD function j)Case study for IDD functions k)Create Surfaces from Scan data l)Case study for scan modeling a)Surface modeling overview b)Surface modeling process c)Basic Surface modeling functions d)Case study for Basic functions e)Advance Surface modeling Functions f)Case study for Advanced functions g)Create complex surfaces using proper techniques h)Case study for surfacing techniques i)Repair imported data by IDD function j)Case study for IDD functions k)Create Surfaces from Scan data l)Case study for scan modeling

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a) Surface modeling overview Introduction of surfaces and shapes Nurbs/Bezier Curves and surfaces

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A surface is a two-dimensional, topological manifold. The most familiar examples are those that arise as the boundaries of solid objects in ordinary three-dimensional Euclidean space R 3 — for example, Shapes like Sphere, cylinder and flat surfaces are coming together and form free form surface and those are complex quilts in pro/e language Surface modelling is different technique to create complex shapes which are not possible by solid modelling tools and sometimes we need to create different uneven shapes to fulfil design requirement and there are different kind of shapes are creating one surface quilt Introduction of Surfaces Reference:

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Simple shapes can be described by basic geometry objects such as a Set of two or more points Line, Curve, Plane, Square, Circle, Cube or Sphere. Concave or Convex type Most shapes occurring in the physical world are complex and those are two types Non rigid and Rigid. Reference: Introduction of Shapes

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Surfaces and shapes Reference:

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Surfaces and Shapes Rim part after deformation Reference: Rim part before deformation Example of a rim part global modification. The constraint is on the upper boundary (G0+G1+G2 fixed). The handle is the lower curve (translated). Example of a rim part global modification. The constraint is on the upper boundary (G0+G1+G2 fixed). The handle is the lower curve (translated). Tangent and Curvature continuity between two surfaces are playing important role into surface modeling to achieve require shapes

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Nurbs: Non-uniform rational basis spline (NURBS) is a mathematical model commonly used in computer graphics for generating and representing curves and surfaces. It offers great flexibility and precision for handling both analytic (surfaces defined by common mathematical formulae) and modeled shapes Bezier: Bezier surfaces are a species of mathematical spline used in computer graphics, computer-aided design, and finite element modeling. Bezier surface is defined by a set of control points. Similar to interpolation in many respects, a key difference is that the surface does not, in general, pass through the central control points; rather, it is "stretched" toward them as though each were an attractive force. Nurbs and Bezier Reference:

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Difference between Nurbs and Bezier Single Nurbs surface Nurbs surface divided into subsets called Bezier Nurbs Surface Complex area possible by single surface Less flexibility as patches are connected Control points are always connected directly to the curve/surface NURBS evolve into two parametric directions, called s and t or u and v. Nurbs Surface Complex area possible by single surface Less flexibility as patches are connected Control points are always connected directly to the curve/surface NURBS evolve into two parametric directions, called s and t or u and v. Bezier Surface Complex area possible by patch subsets More flexibility for individual patches Control points are not connected to each other Bezier evolve into only one parametric direction, usually called S or u Bezier Surface Complex area possible by patch subsets More flexibility for individual patches Control points are not connected to each other Bezier evolve into only one parametric direction, usually called S or u Reference:

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Difference between Nurbs and Bezier Bezier Surfaces Nurbs Surfaces Bezier Surfaces Reference:

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Surface modeling process Difference between surface and solid modeling b) Surface modeling process

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Create datum features in model which represents main skeleton Plan feature sequences based on shell or closed type part Create surface patches using curves and sketch entity Complex shapes can be achieved by Boundary blend and other functions Define draft to all surfaces w.r.t die direction Merge all surfaces to each other and create single quilt Create rounds on edges at last before thickening part Add holes and cutout features on thicken or solid part Assign material and other parameters to part Surface modeling process steps

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User's 2D concept sketch 3D template model After aligning the template with the sketch user draws directly on the sketch. Final shape obtained after modifying the template and adding new feature edges Final solid model after surface creation and Modification Overview of Surface modeling process Surface modeling process for 2D sketch Reference:

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Template alignment User draws an approximate bounding box on the sketch and marks its eight corners User draws an approximate bounding box on the sketch and marks its eight corners Default conjuration of the template is an orthographic side view the corners of the template bounding box would exactly match the red dots marked by the user Reference: Back

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Modification of a 2D curve Original curve and the modifier strokes. New shape of the target curve. The original curve is shown dashed for reference. Reference: Back

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Initial Surface Model Initial boundary loop consisting of four curves Initial boundary loop consisting of four curves Preliminary triangulation using a vertex created at the centroid Preliminary triangulation using a vertex created at the centroid Final result after face splitting and mesh smoothing using V- spring method Final result after face splitting and mesh smoothing using V- spring method Edge swapping Reference: Back

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Surface modification Initial surface model Modification of seat base by manipulating control point structure Concavity applied to surface keeping the boundary vertices fixed Concavity applied to surface keeping the boundary vertices fixed Reference: Back

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Input Sketch Initial Template Design in progress Final Template Surface Model Triangular mesh near the headlight Example of Surface modeling process Reference:

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Surfaces and solids are the underlying math that defines the geometry of the forms you create. There are three ways to define 3D geometry: solids, surfaces and wireframes. Wireframes don’t play much of a role in CAD, but primarily in digital content creation (DCC) and gaming. The easiest way to understand the difference between surface and solids modeling is to think of a water balloon; the water in the balloon would be solids modeling, while the latex skin would be surface modeling. Reference: Surface and solid modeling

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Difference between surface and solid modeling Solid Modeling Surface Modeling Solid modeling is defining an object with geometric mass Surface modeling is defining an object’s exterior with an infinitesimally thin skin Solids modeling programs usually create models by creating a base solid and adding or subtracting from it with subsequent features Skin is created by lofts, sweeps, and NURBS curves - i.e. sculptured surfaces with lots of curvature Features such as extrudes, extrude cuts, revolves, radii, chamfers, etc. Examples of solids modeling programs are Solidworks, CATIA, and ProEngineer Reference: The surfaces are either defined by poles or guide curves. A surface is considered a solid only when it is completely enclosed. It is used to make technical surfaces (e.g. air plane wing) or aesthetic surfaces (e.g. car’s hood). It was originally developed for machine design, and is used heavily for engineering with large part assemblies, digital testing and rapid prototyping It was developed for the aerospace and automotive industries in the late 70s. Rhinoceros 3D and Alias Studio Tools are examples of a surface modeling programs

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Basic surface modeling functions Editing, Merging functions c) Basic Surface modeling functions

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Basic surface modeling functions Creating Extrude surfaces Select sketching Plane Create sketch and assign depth Change mode from solid to surface

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Creating Revolve surfaces Select sketching Plane Create sketch then define rotation axis and angle Change mode from solid to surface Basic surface modeling functions

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Creating Fill surfaces Select sketching Plane Create a sketch Select existing sketch or create a new Basic surface modeling functions

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Creating Sweep surfaces Create a sketch Select mode from solid to surface Pause for sketch menu to create trajectory Create trajectory and define start point Select on icon to start sketch Basic surface modeling functions

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Creating Blend surfaces Select mode (Sketch or Selected) Insert section 1 Insert section 2 and define offset value Section 1 Section 2 You can define normal condition with Plane at both side sections Basic surface modeling functions

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Surface editing and Merging functions Surface mode Surface trim by extrude Surface trim by thicken Trimming surface by extrude option

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Surface editing and Merging functions Extending surfaces Select surface edges Click here to extend surface Different options to extend surface

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Surface editing and Merging functions Trimming and merging operations Input Output Open trimming_merging.prt Different options will be performed during training

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Case study will perform during training session using basic surface modeling functions. d) Case study for basic functions

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Create datum curve using different functions Advanced surface modeling functions e) Advanced surface modeling functions

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Creating curve through points Datum curve functions Different techniques will perform during training session Select datum point feature from model tree Spline curve passing through all points

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Creating blend curve Datum curve functions Differed techniques will perform during training session Select end point 2 Select end point 1 Tangent condition at end point 1 Tangent condition at end point 2

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Advanced Surface Modeling Functions Creating Surfaces by Swept blend Click here Insert section 2 Section 1 Section 2 Select Trajectory Menu for trajectory, Sections and edge continuity

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Creating Surfaces by Boundary blend Advanced Surface Modeling Functions Input Output 2 nd direction Select Curve 1 Select Curve 2 1 st direction Selection for 1 st direction Define tangent continuity

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Creating Sweep surfaces with multiple trajectories Advanced surface modeling functions Output Input Origin Chain 1 Chain 2 Chain 3 Click here to select multiple trajectory Trajectory selection menu Enter sketch mode

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Creating Surfaces by N sided blend Advanced Surface Modeling Functions Open N-sided_patch.prt Input Output Click on N-sided surf Select all edges together then click on Done

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Creating surface by Graph feature Advanced Surface Modeling Functions Open part graph_sweep.prt Create graph feature Select trajectory Sketch a geometry Define relation in sketcher mode Sketch should contain coordinate system Create sweep surface

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Using trajpar with sweep surface features Advanced Surface Modeling Functions Open trajpar.prt Create sketch Select trajectory to create sweep feature Sketch circle Enter relations SD3 denotes circle diameter 120 is mean diameter Magnitude is 10 Trajpar varies from 0 to 1 35 Cycles

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Input Output Reference: Exercise will performed during training session f) Case study for advanced functions

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Working with 3D curves and Surfaces Geometry Analysis functions g) Create complex surfaces using proper techniques

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Creating offset curve Datum curve functions Select edge Offset by variable Variable dimension value 160 Variable dimension value 380 Differed techniques will perform during training session

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Input Output Working with 3D curves and surfaces Refer next slide to proceed further

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Create a new part in Creo Import case_study2.igs A A E E D D C C B B Name assign to surfaces for identification Click on Surfaces > Surface free form to create untrimmed surface Click on Surface A to create untrimmed surface Repeat same process for surface B Next level activities to be perform during training session

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Working with Draft and B-side design Input Output Activity will perform during training session

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Geometry analysis functions Curvature using sections Curvature section tool can analyze curvature along sections for selected surfaces. reference, System creates a series of porcupine

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Geometry analysis functions Offset Surface or Curve Offset surface analysis can create a surface mesh at an adjustable offset value from the selected surfaces. This is useful to check overlapping of the surface mesh reveals locations which could cause problems when thickening part

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Geometry analysis functions Analyze draft angle Select surfaces or solid geometry Select pulling direction Enter draft angle If draft value is 3 then flanges may have different color

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Create 3D surfaces and thicken part h) Case study for surfacing techniques Input Output

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Surface modeling by master model technique Input Output The Master Model technique is a style of surface modeling with top- down-design methodology. Master modeling technique is used to design products that use multiple interlocking body components to form an enclosure with an overall styled shape.

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Redefining & Deleting Imported Geometry Heal & Collapse Geometry i) Repair imported data by IDD function

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Import data doctor(IDD) tool can repair imported geometry. Gaps between surfaces and tangent continuity defined by IDD. Following are the common errors which can be found in imported geometry Bad surfaces (concave domain or boundaries with parallel) Bad two-sided edges Bad wireframe curves Poorly tessellated edges Short one-sided edges (warning) Bad vertices (warning) Unsatisfied wireframe Unsatisfied tangency Gaps not added to wireframe Non tangent edges Small surfaces Import data doctor tool overview

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Imported geometry process flow Import iges or other type surface data in Creo If any open gaps and errors found then repair it by Import data doctor Study surface model and plan next activity Create free form surface using Surface free form option Create sketch, points or curves to start surface modeling operations Create surfaces by extrude, sweep or boundary blend option Trim/cut surfaces by extrude, trim or extend option Merge overlapping surfaces by Merge Intersect option Solidify or thicken surface to get final model

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Input Output Surfaces is not tangent continuous Open area need to fill j) Case study for IDD functions

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Create a new part in Creo Click to enter for IDD editing environment Training session activity

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Create 3D surfaces from Scan data Trace sketch from JPEG or Tiff k) Create surfaces from scan data

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Create 3D model from scan data Import scan data file in Creo or Wildfire Check part location w.r.t top level assembly If not placed properly then move it to correct location Verify scan quality and study part shape and boundary Create datum planes and X-sec passing through scan data Create datum curve by X-sec option Create sketch and 3D curves using X- sec curve and Scan data Create surfaces from curves and build features Check deviation between scan and surface data

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Trace sketch from JPEG or Tiff images Input Output Reference:

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Create a new part in Creo Click to add images Select plane to place Image Select Image Deodrant1.jpg and Repeat same activity to import Deodrant2.jpg Select Image Deodrant1.jpg and Repeat same activity to import Deodrant2.jpg Use different functions from Images menu to adjust its position Activity will perform during training session

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Create a new part in Creo Import faceted data casestudy_l.stl Activity performed during training session l) Perform scan modeling exercise

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Thank You

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