StCAD

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StCAD

Developer:	Aik-Siong Koh,PhD
OS:	32-bit MS Windows (NT/2000/XP), All POSIX (Linux/BSD/UNIX-like OSes)
Use:	3D Modeling, Scientific Engineering,Motion Simulation,Multi Body Dynamics,CAD,Open Source,Smalltalk
License:	GPL or LGPL
Website:	www.askoh.com [1]

Free software Portal

StCAD is a basic 3D CAD framework in Smalltalk (VisualWorks 7.x) which has been used to develop freeCAD and CADSM. It extends the GF/ST 2D drawing framework into 3D. It also include 'StGeo' which is the 3D geometric domain, 'StMath' which provides the mathematical support for 3D CAD and motion simulation computations, and 'StDoc' which is a simple word processor. 'StMath' is also suitable for engineering, scientific and business computing. The parcels are open source using GNU Lesser General Public License. Users can use these parcels with other private software to create 3D applications like motion simulation, finite element analysis(FEA), CAD, scientific visualization, etc.

[edit] What StCAD can do ?

StCAD allows users to create and manipulate assemblies, which are collections of 3D parts. The parts are 3D solids, which can be connected by joints, constraints, contacts, actuators, springs, dampers or forces. The parts and connections define the structure or mechanism that the assembly is meant to represent. Animation is possible, if the user can provide time series of position and orientation data for the parts.

Users can also obtain output data in the form of plots and tables. XY plots can be zoomed and set to equal scales. Data series available include linear and angular displacements, velocities, accelerations and other user generated data.

StCAD has been used to create a freeware called freeCAD and a shareware CADSMwhich is a 3D CAD with Motion Simulation. The parcel 'StMbD' has been included to provide a functional demonstration, but its source code is hidden.

[edit] What are the features of StCAD?

StCAD is capable of full 3D pan, zoom, tilt and rotate. Available solids are extrusions of rectangles, circles, ellipses and polygons. The solids can be positioned and oriented exactly in space, as are markers on the solids. Exact specification of linear and angular velocities of solids in space are also possible. Mass and inertia properties can be user specified or automatically computed based on uniform density. Available joints are spherical (ball), revolute (pin), translational (slider), cylindrical, planar, fixed, universal, point in line, point in plane, parallel, perpendicular, no rotation, constant velocity, rack pinion, screw. The curve-curve contact allows liftoffs and collisions based on coefficient of restitution. Available actuators are rotary and translational. Their motions are user prescribed functions of time. Forces and torques are user prescribed functions of time, displacements and velocities in all three components or along connecting markers. Example formulas for spring, damper, bushing, beam, aerodynamic, inverse square law and other forces and torques are given. Available functions are sqrt, exp, ln, lg, sin, cos, tan, arctan, arctan2, spline, spectral density. Users can specify constant gravity of arbitrary magnitude and direction.

Users need to provide the domain to simulate the behavior of the system. Simulation progress can be animated and stopped any time. After simulation, the computed solution can be used for animation or frame by frame analysis. Full 3D pan, zoom, tilt and rotate is available during simulation and animation. Users can also obtain output data in the form of plots and tables. XY plots can be zoomed and set to equal scales. Individual parts can be saved into files and reinserted into any assembly repeatedly. Assemblies can be saved in binary or tab delimited text format with textual notes and simulation data for later reload. The text format allows pre and post processing of assemblies by other programs, especially spreadsheet programs. Other specific text formats are for MOSES, PDMS Review and POV-Ray. 'StCAD' runs on Windows, Macintosh PC, Linux PC and other Unix's. Assembly data are unchanged across platforms.