Page Last Updated And Links Checked: 28 June 2003 Page Last Updated And Links Checked: 28 June 2003 Strand7 Introduction
Strand7 is a good, Australian (and Australian owned) finite element analysis (FEA) package. It had it's origins in Sydney University. It is marketed in Europe (outside the UK) as "Straus7". This is serious software and both the commercial and educational prices are very reasonable.
Of particular interest to me in Version 2.1.0 (released in March 02) is the 'AutoMesher' which permits importing of CAD models to become the FEA model. In fact I first got into AutoCad Mechanical and Mechanical Desktop because of the FEA facility offered (which I appreciate is limited).
You can download a restricted version, install it, and then download the help files and install them into the help folder. This trial version has one advanced option not available, you cannot build as big a model, and you can't save your answers (but you can print them!) so it's an excellent way to check out what Strand7 can do.
In addition to the reasonable lab price, Strand7 is attractive from an educator's point of view because the ease of use of the Windows interface which is reasonably quick for for the students to learn. Also the student can also download the resticted version and have it at home to use, outside of lab hours, to do assignments for the FEA course and later subjects where a printed FEA output (and the student's interpretation of course) is a contributing part of the assessment.
What Is Finite Element Analysis (FEA) And Why Do I Need It.
To me it's about pride. The most cutting remark people can make about your drawing is that it is a "pretty picture" and they could say this for two reasons:
1. The drawing has to be precise so that the code itself can be used as part of the manufacturing process if required. Alternatively there must be sufficient information on the drawing itself for the builder/manufacturer to be able to refer to it to purchase materials, make tooling and then make or build the item. You can't tell experienced people how to suck eggs and they will probably fill in a lot of gaps, but if they toss the drawing back at you saying that what you have drawn is impossible to make or there is not enough information provided to permit it it be made, then all you have is a pretty picture.
2. If all goes well with 1. above the next worry is that what is made from your drawings actually works. It has to do the job it was designed to do and if it does not, then your drawing has turned out to be just a pretty picture. This is where a computer based FEA tool is potentially so useful because you can validate or improve aspects of your design while its still on the drawing board.
The major steps designers go through is creating reatively low cost mathmatical and drawing models then increasingly costly, non-working or working scale models and then very expensive prototypes. The earlier you identify a problem and correct it or decide on a change of direction the more cost efficient the whole process becomes.
As soon as your preliminary number crunching permits a drawing proposal to start to take shape you can use FEA to apply loads and service conditons to your drawing model as if it where an real manufactured prototype. It is mathamatical and drawing modelling using the power of computers. If components are overstessed or deflect too much under load then the design can be altered or alternative materials used. Finally the allowable loads, operating speeds or life of the component can be specified. This is what I mean by pride, when you hand your drawing over to the the next guy in the chain everyone knows it's not just a pretty picture.
Strand Websites
www.strand.aust.com/strand7
G+D Computing's Strand7 FEA (Finite Element Analysis) System. 32 bit Windows based.
Info from UK dealer site, Imagineering below, says 'Ver 2.1.0 with AutoMesher released 13 Mar 02' (Sydney site needs updating!).
You can download St7Demo.zip (5.1MB unzips to 11MB), the limited demonstration version of Strand7. It may be used to generate any size model, but the solver will accept only models with at most 20 beams, 100 plates and 100 bricks. The nonlinear solvers are not available and data cannot be saved.
After downloading the zip, extract the files and run SETUP.EXE. After installing the software, browse the "../Mesh" folder as this contains a few sample models, ready to solve and post-process. If you wish to install the Strand7 Help Files (recommended), download St7Help.zip (6.5MB unzips to 14MB), extract the files and place them in the "../Help" folder of the Strand7 Demo.
You can read through the Web Notes (see the side navigation links) for examples of how Strand7 can be used. They are like mini-tutorials and you can download little working modules of the examples and run them. Modelling shock loads, which in the past could only be done by a practical test, facinates me.
G+D Computing provide excellent training at all levels for professionals. ** However if you're in Sydney, Australia and you are a student, retired, or trying to make youself more employable, email me and I'll direct you to some low cost community college type training in computer classroom group of about 12 participants. Similar courses are available for AutoCad and Mechanical Desktop.
www.iuk.co.uk Imagineering. UK dealer.
Converting A CAD Model To An FEA Model
There are three main tools (and a number of associated ones) to convert CAD models into FEA models introduced in Ver 2.1.0 are:-
1. Clean Geometry. Prepares the CAD model for use in FEA. Include removing unwanted geometric detail or unintended discontinuities.
2. Surface Automeshing. Generates Tri3, Quad4, Tri6 or Quad8 surface elements (2D finite elements termed 'plates').
3. Solids Automeshing. Generates Tet4 or Tet10 elements (3D finite elements termed 'bricks').
The CAD package has to be able to export the model in either ACIS (.sat) or IGES (.igs) format. You can do this with AutoCad, Mechanical Desktop or Rhino 3D and (presumably) Inventor. Here Rhino 3D can function in it's file translation role that many use it for by importing a model in that packages native format and then exporting it in the required ACIS or IGS format.
The exported CAD file can be imported into a new Strand7 model file being opened or imported into a existing model file curently open.
The steps to import the CAD model into a new Strand7 model file are:-
File > New
Global > Units > Nmm (..or the units specified in the CAD file if it is from the USA or Burma)
File > Import
Files of Type (..select ACIS (.sat) or IGES (.igs) as approriate)
OK
(..browse for, and select the file)
(..accept the default import setting options for the time being)
Save the new Strand7 file (..note that the Strand7 model name has changed from the default Meshxx to the imported file name)
(..further note that if you subsequently import another model into the same Strand7 file the name will not change)
Sites of Interest to Strand7 Users
www.mech.uq.edu.au/subjects/e4309/index/lecture_notes/overview.htm ## 400 Not Found 27Apr03 to 28Jun03 ##
Uni of Queensland
Mech 3300 Finite Element and Fracture/Fatigue Lecture Notes. Strand7 is used for the practical work on the course but these html lecture notes are aimed at providing the necessary overview to be able to intelligently use a commercial finite element package.
Strand7 Tutorials
Tutorials are available within the downloaded Strand7 Demo
G+D Computing's Strand7 website has a number of tutorials.
The UK dealer, Imagineering'sSupport Page has four interesting sample loadings and output to peruse.
If you know of any Strand7 tutorials that would be useful to others please contact me. Thank you.
Miscellaneous Facts
STRAND7 consists of approximately 250,000 lines of Delphi (Object Pascal), 60,000 lines of FORTRAN90 and 10,000 lines of C++. A considerable amount of work was spent in the initial design of the data structures, file handling and graphics engine. This has resulted in a very tight and efficient package. STRAND7 runs as a single window application, similar to other software products such as MS-Excel, etc., and uses the Multiple-Document-Interface (MDI) paradigm. This allows STRAND7 to work on multiple models at one time, with the possibility to exchange data between models in a graphical manner, much like standard Cut-Paste operations in other applications. Unlike STRAND6, there is no Main Menu as such, and all functions including pre-processing, solving and post-processing are accessed from the one STRAND7 window. G+D Computing Pty Ltd - (Added: 26-Mar-2002 to www.seismolinks.com/Cool ..the links page of an earthquake and seismology website)
Warning: I use Strand7 and the (limited) FEA facility within Mechanical Desktop and AutoCad Mechanical. The listings below are the source of definitive information about these companies and their products. My notes and observations are only about what interests me or otherwise draws my attention.
Stuctural Research & Analysis Corp (SRAC)
Privately owned. Brought by Dassult who also also brought SolidWorks (and the kernal company that supplied the kernal for Inventer which precipitated AutoDesk getting their own Kernal and using it for IV5.3)
www.cosmosm.com Cosmos
Maze of products but appears to be principally:-
COSMOS/DesignStar:- Offers versions which provide associativity with specific modellers such as MDT, Solidworks, Solid Edge, Pro/ENG and Inventor for example. Changes made in one program are automatically updated in the other, so that the analysis tools available in COSMOS/DesignSTAR can be throughout all stages of the design process.
COSMOS/Works (as in SolidWorks):- I guess same as COSMOS/DesignStar but very specifically tunned to SolidWorks. Don't know. Maybe something that runs inside SolidWorks?
ALGOR
www.algor.com Algor
Offers:
FEA
Mechanical Event Simulation
FEA in CAD
Piping Design and Analysis
'Distance Education': I suspect this means web-casts and CD based videos.
ANSYS
www.ansys.com Ansys
Eight products. Interesting start point is ANSYS/ED for US$300 (less for students/academics). It can beupgraded to higher-level ANSYS applications.
MSC Software -Nastran
www.mscsoftware.com MSC Software. For Nastran.
Offers include:
MSC.Dytran: General purpose, 3D simulation of high-speed response of solids, structures, and fluids.
MSC.Linux: All the components to build computer clusters, specifically Beowulf clusters.
MSC.Marc: General purpose finite element program for advanced engineering simulation. Since 1971.
MSC.Nastran: MSC.Nastran is the 'premium computer aided engineering (CAE) tool that major manufacturers worldwide rely on'.
MSC.Patran: simulation of mechanical products.
MSC.VisualNastran: FEA using Windows graphical interface.
MSC.ADAMS: Family of functional virtual prototyping applications, allowing complete system performance simulation.
Plus a dozens more ..eg MSC.Fatigue and MSC.InteractivePhysics (for teaching!)for example. It seems MSC.FEA is Nastran and Pastran together and it appears visualNastran contains Marc, Nastran and Patran.
Goes on and on. Something I saw suggested Marc was originally a company or product they bought out.
Contact: Aussie John wpsmoke@yahoo.co.uk