Solid modelling
From Wikipedia, the free encyclopedia.

Solid modeling studies unambiguous representations, models, of solid objects suitable for computer processing. It is also known as volume modeling.

Primary uses of solid modeling are for CAD, computer graphics and animation, Rapid prototyping, medical testing, and visualization of scientific research.

Basic Concepts

• Sweeping
  • An object is specified in terms of volumes "swept out" by moving of a primitive along a simple curve. These volumes either add to the object ("extrusion") or remove material ("cutter path").
  • Also known as sketcher based modeling.
  • Analogous to various manufacturing techniques; extrusion, milling, lathe operations...
• Boundary representation
  • A solid object is represented by surfaces of its boundary.
  • Also knowing as 'surfacing'.
  • Analogous to various manufacturing techniques; Injection moulding, casting, forging, thermoforming...
• Parameterized primitive instancing.
  • An object is specified by the reference to the library of parameterized primitives
  • e.g.- a bolt is modeled for a library, this model is used for all bolt sizes by modifying a set of its parameters
• Spatial occupancy
  • The whole space is subdivided into regular cells, and the object is specified by the set of cells it occupies.
  • Models described this way lend themselves to Finite difference analysis
• Decomposition
  • Similar to "spatial occupancy", but the cells are neither regular, nor "prefabricated".
  • Models described this way lend themselves to FEA.
• Constructive solid geometry.
  • e.g. - The '.stl' file format for stereolithography and other rapid prototyping methods

Solid modeling CAD

Solid modelers have become commonplace in engineering departments in the last five years due to increased performance of pc's and competitive pricing of the software. They are the work horse of machine designers.

These software packages combine the basic concepts listed above into a virtural reality to design and analyze machines in.

Solid Modeling software packages do the following (at a minimum);

• model solid parts
• model assemblies of parts
• maintain libraries of parts and assemblies
• calculate mass properties of parts and assemblies
• reflect the 'bill of material' required to build the product
• create technical drawings from the solid models
• aid visualization with shading, rotating, hidden line removal, etc...

Most modern software packages also have additional capabilities;

• Bi-directional parametric associatively (modification of any feature is reflected in all information relying on that feature; drawings, mass properties, assemblies, etc... and contra wise)
• kinematic, interference and clearance checking of assemblies
• specialized add-in modules (FEA, sheet metal, surfacing, hose/cable routing, electrical component packaging...)
• management of controlled documents and revision levels
• inclusion of programming code in a model to control and relate desired attributes of the model
• automated programming of CNC machines
• Photo realistic rendering
• Import/Export routines to exchange data with other software packages

Medical solid modeling

Modern computed axial tomography and magnetic resonance imaging scanners can construct solid models of interior body features.

Uses of medical solid modeling

• Visualization
• Visualization of specific body tissues (just blood vessels and tumor, for example)
• Creating solid model data for rapid prototyping (to aid surgeons preparing for difficult surgeries, for example)
• Combining medical solid models with CAD solid modeling (design of individually tailored hip replacement parts, for example)

Related articles

• Computer graphics
• Computational geometry

External links

Some commercial Solid Modelers

• Pro/E
• Catia
• Unigraphics
• Solid Edge
• Solid Works
• ParaLogix

The original article can be found at: http://en.wikipedia.org/wiki/Solid_modelling.
All text is available under the terms of the GNU Free Documentation License.