Mechanical Technology July 2015

⎪ Computer-aided engineering ⎪

Once complete, the part performance is verified before the resulting geometry is smoothed using Evolve, the free-form design software from solidThinking, or the geometry can be exported into a CAD package for refinement and integration. Evolve makes use of NURBS (non- uniform rational basis splines) – com- monly used in computer graphics for generating and representing curves and surfaces. “NURBS allows for flexibility and are widely used in free-form design and clay modelling tools,” he explains. Underpinning solidThinking’s optimi- sation capability is Altair’s OptiStruct ® structural optimisation technology which is available under HyperWorks licens- ing for more advanced simulation and analysis, if required. On the manufacturing side, additional options allow part topology optimisation that suits the preferred manufacturing method. “We are particularly strong on 3D printing or additive manufacturing. Designs can be exported for pre-3D print processing to several packages developed by the major 3D printer manu- facturers, for example 3-maticSTL from Materialise,” Smith continues, adding, “3D part printing allows a high degree of complexity and flexibility in terms part geometry”. But manufacturing shape controls for processes such as casting, moulding or stamping are also embedded into the op- timisation constraints. If being extruded, for example, solidThinking generates constant cross-section topologies based

on the extrusion direction. In spite of the power of the solidThink- ing Inspire, “the software is very easy to learn” and it is compatible with existing CAD tools, such as Creo Parametric. “Typical training for a design engineer can be done in a single day,” Smith assures. Niche successes include: the sup- porting struts for satellites, a simple basic design that is then lightweighted to optimise dynamic performance; the hinges on aircraft doors, which resulted in a 64% weight saving; and advanced bicycle frames. “Not only is Inspire successful in the aerospace industry, but also automotive manufacturers, such as Daimler AG, are officially certifying solidThinking Inspire for company wide use,” Smith reports. With the Daimler certification, all design engineers within the car and truck development departments of the company may now use solidThinking Inspire within their projects, giving them an opportunity to create efficient struc- tures with minimum weight. This works for components, assemblies, and entire systems. Design engineers may also use solidThinking Inspire to apply a required stiffness on a component where needed, helping to avoid undesired vibrations and contributing to overall vehicle comfort and quality. Standalone licences of solidThinking products are available through the lo- cal channel partners or as tools within Altair’s HyperWorks suite of simulation software. 

While developers will typically start with CAD, then go to engineering analysis based on the 3D CAD model and then onto manufacturing, we advise a process change involving these three questions being addressed in advance of CAD. On the material side, composites, aluminium or titanium are typically used as substitute options in lightweighting ex- ercises. Any change in material, however, must come with an associated change in the topology of the new component. “The cornerstone of solidThinking Inspire involves automatic topology optimisation,” Smith says, opening the software to display how solidThinking works. “At its starting point, a part is sketched using primitive solids (cubes, cylinders, etc.), or an existing part can be imported and de-featured to define the design space. Then the fasteners, joints and boundary contact points are defined, before the required materials and external structural loads are assigned.” Once the basic shape, engineering materials and specifications have been assigned, solidThinking begins to gener- ate an ideal shape. “Embedded in the analysis tools are bio-mimicry philoso- phies. Bones grow stronger along load- paths where they need to. In the same way, the geometry of a part can have ribs, struts or thickening added where it is needed and removed where it is not needed. The topology of the part can, therefore be quickly and automatically established before doing any detailed design,” he reiterates.

Mechanical Technology — July 2015

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