Strand 7 – the CAD-Reviews independent review

Comprehensive analysis for complex structures

Strand 7 review screenshot

Strand 7 from G+D Computing

G+D Computing of Sydney have released Strand 7, a Windows native version of their respected 3D finite element analysis package.

Offering extensive modelling and analysis tools, it has established users in construction, automotive, materials handling, aeronautical, biomedical engineering and naval architecture applications.

Building on the ease of use of earlier versions, multiple models can now be opened simultaneously and data can be copied between them or into other applications using the Windows clipboard.

Models can be dynamically rotated in wireframe or shaded mode.

The automatic edge detection and extraction function generates a wireframe that is representative of the structure, but contains a relatively small number of lines.

File locations can be set so that model data can be stored on a file server while temporary work files can be on a faster local PC drive.

Strand7 is fully units-aware so that physical units such as metres and kilograms can be combined with feet and pounds.

Although data can be imported from CAD modellers in DXF, ACIS or STL format, the preferred method is to construct an optimised model directly within Strand 7.

The number of nodes, elements or equations in a model is not limited although any practical limitation on model complexity is likely to be hardware related.

The maximum number of load cases of 32,768 is likely to be more than is ever required.

Standard elements include beam, truss, spring damper, plate shell, 3D membrane, tetrahedral, wedge and pyramid plus links and contact constraints.

To aid modelling and experimentation, the undo and redo facility is unlimited even after the model is saved.

Sub-modelling allows subsequent meshing at a scale appropriate to the local detail without having to re-solve the entire model.

In addition the supplied library of customisable standard beam sections, custom sections can also be defined.

The section calculator generates a true torsion constant for all sections and renders them into the graphical editor.

Plate element thickness can also be rendered to improve visualisation and to highlight any errors.

Verification tools such as aspect ratio contours on plates and volume contours on bricks help find elongated or collapsed elements.

Once the model is created it can be used with all modules and analyses and subsequently be edited to iterate the design towards the required goals.

The range of materials includes both linear and non-linear models encompassing isotropic, orthotropic, anisotropic, soil and rubber with a library of properties for common engineering materials.

Both symmetric and unsymmetric laminated composites can be analysed using dedicated pre processing, solver and post processing modules.

The laminate engineering properties and the characteristic matrices are defined through the Compose Laminate module of the property input dialog and the orientation of each ply can be defined using the graphical Laminate Pre-processor.

The comprehensive suite of solvers available in Strand 7 includes static linear, non-linear and bucking, dynamic natural frequency, harmonic response and spectral response, linear and non-linear transient dynamic and steady state and transient heat transfer.

Although the majority of engineering structures can be considered to behave lineally and the assumptions made for linear solutions are valid, when the effects of geometry changes can no longer be neglected Strand 7 is also able to handle geometric non-linear behaviour.

A simple example is pressing a curved shell against a flat rigid surface in which case the contact area will expand as the external load increases.

Special contact elements are used to model such situations and the static or transient non-linear solvers are used to generate accurate results.

Strand 7 also offers extensive reporting and result visualisation tools including tabulated outputs and graphical plots.

Any quantity that has been calculated such as stresses, strains, forces and moments can be displayed on a coloured contour plot of the entire model or on cutting planes.

Stresses can also be plotted as vectors to indicate direction in addition to magnitude.

By selecting two points in the model an XY graph can be generated for any result parameters to be displayed in a separate window or superimposed onto the model.

Result data can be filtered by group or property or by selecting entities on the model using the Peek tool.

A print preview gives control over page formatting for spreadsheet data output.

A built in animator enables contour plots to be animated to show result variation with deflection.

These can be saved out as Strand animation files .SAF or as a series of bitmaps.

A freely distributable viewer can be used to make Strand files accessible to the full engineering team.

The Viewer does not allow any editing or saving of the model and printing functions are disabled.

Strand is a comprehensive analysis tool aimed at complex structural exercises as opposed to the current crop of design centric tools that link directly with CAD modellers but typically offer a subset of functionality.

Although data can be transferred from CAD models it is not associative and probably not the best approach until the full auto-mesher is available later this year.

This is not to detract from Stand 7’s real strengths however.

For many exercises the generation of a model optimised for the analysis is the best approach and allows design iteration before commencing design detailing or documentation.

For such a complex tool, Strand 7 is very approachable, the comprehensive range of tools minimising the need to compromise on the appropriate technique or level of result visualisation.

With the first level of functionality available for £1,950 including maintenance and support from Imagineering, Strand 7 also offers excellent value for money.