Al Dean continues his look at the Inventor 2008 release, moving on from general design and drawing tools to task- and application-specific updates to Inventor Series and Inventor Professional.

Inventor 2008 supports the insertion and routing of ribbon cables with full control over the shape of the cable, including the ability to define multiple twists and folds.

In March we focussed on all of the general updates in Inventor 2008 - those that pertain to users of the core Inventor Series. This month we’re going to delve a little deeper in to the world of task-specific tools with both Inventor Series and Inventor Professional – including sheet metal, welded frame design, Design Accelerators and simulation to name but a few – so let’s get cracking, starting with Sheet metal.

Sheet metal is something that all vendors have concentrated on over the past few years – some with more success than others. Inventor has seen a lot of work in this regard in the last few revs and 2008 is no different. It sees the tools for working with folded forms advance beyond just the standard form creation tools and more into the realms of production preparation.

First of all there’s been a lot of work done to make the system more usable. For example, the terminology used is each operation is more analogous to the production environment, rather than cryptic modelling operations. Also, folded and unfolded forms of the same part are viewable in two windows, so you can switch between the two easily as needs be – as opposed the existing method of being able to have just one displayed at a time.

But let’s deal with the core sheet metal modelling updates first. There are new tools available for the creation of flanges in a more intelligent manner. If you’re creating a series of flanges around the base of a sheet you can now select each edge and have the system create all the flanges within the same feature – making edits a lot more efficient as you’re not manually creating each feature. If you’re running a flange around an edge, the system will wrap all of those edges and close the corners (with user controlled mitring) automatically. Alongside this, the manufacturing related updates are most impressive – and as always with sheet metal, this boils down to punching.

Users now have the ability to create standardised Punch tools which are stored within a library and have separate IDs (for easier manufacturing set-up). These can also contain a base sketch which is used to represent each punched form in the flattened sheet, with a layout sketch inserted in the flat pattern (and downstream drawings) – making documentation and production planning easier. Also related to this, the system allows you to create views of the flat pattern and automatically extract bend and punch information for documenting how the product is manufactured and produced. Finally on the documentation side, within drawings you can now add intelligently linked bend and punch tables which relate to the features you extract and display bend IDs, angles, depths, and co-ordinates which are essential for punch machine programming.

Enhancements to the dynamic simulation in Inventor 2008 support analysis of the stress on parts at different points, or time steps, in the simulation cycle.

Skeletal modelling

Another area that’s seen some intelligence added is the handling of skeletal modelling workflows. It’s always been possible to create a top-down driven assembly model, where the basic form of parts within an assembly are controlled by a single, high-level master sketch (as is common in machinery or mechanism design), but when you updated that sketch (however minutely) all the parts had to be updated and regenerated. From Inventor 2008 onwards the system handles updates on only those parts which have changed.

Welded Frame Design

Relating to skeletal modelling, the Welded Frame Design tools have also seen some work and these allow you to create frame layouts based on any geometry. Previously, you had to either use a block model, from which edges were used as the basis for the framework, or a 3D wireframe model using 3D curves. You can now work in a more flexible manner, so edges, wireframe entities, or references from existing geometry can all be used to construct the basic frame form. Also in frame design updates, you can now merge sections around profiles meaning that curved forms are created in a single feature, rather than the split up sections you’d typically get before – which makes BOMs more accurate. Also, end treatment conditions are now stored as part of the browser tree, making edits more efficient and you can now edit profiles of your beam sections. Previously, you’d have to delete and re-enter sections that drive the framework and rebuild them. Now, sections can be changed on the fly and the junction conditions are maintained. This makes design changes (such as swap extrusion suppliers, materials, section types) much more efficient.

In Inventor 2008, integration of the dynamic simulation and stress analysis environments is enhanced to provide more control over which loads are included in the FEA (finite element analysis).

Design Accelerators

One of the leading concepts that Autodesk has been promoting with the last few releases is Functional Modelling – the idea that you define the function, performance and operational requirements of your product, then have the system create the actual geometry, parts and assemblies. While this is always going to be a work in progress, this release sees some tidying up of the tools Autodesk acquired from MechSoft a couple of years ago and some work to extend their usefulness.

Firstly, the UI for all of the Design Accelerators has been updated so that it’s consistent with how Inventor works, meaning that the user can get to grips with these advanced tools in a much shorter space of time (as there’s little in the way of an additional learning curve). Also, the way these things work has changed, so that all of your design of gears, cams, belts etc is conducted in context, allow you to take references from existing geometry, position components, then use the built-in wealth of intelligence to define the parameters, then build the actual geometry.

A good example is the improvement of the shaft generator. Essentially, you create the basic shape (such as different shaft features, keyways, sections, etc), then use the intelligent calculation tools to finalise them based on required mechanical properties. A report is generated which documents the decisions you’ve made, the inputs and outputs. Once done, the system builds the model and now even constrains the relevant parts or features. Essentially, you’re letting the system do the modelling, while you consider the function. With this new way of working, rework or duplication of effort is reduced to a minimum – you have already told the system where the shaft interfaces with other parts, so why have to repeat that to constrain it in place? A much more sensible way to work, I’m sure you’ll agree. The only downside is that the system doesn’t store these which is a real shame as it would assist with documentation management. You can store it in Vault though, if you’re working within a managed environment.

Another good example is the chain and belt creation tools. You define the gears/belts, chains/belts according to design intent (using references from your model), input the drive characteristics and have the system perform strength calculations. You can restrict the chain or belt to specific lengths so you’re building in standardisation of parts. Everything is previewed in full 3D so you can dynamically experiment with the function of the drive. Once you’re happy with it, the system creates a report (same limitations apply), builds the 3D forms (including full chain description which is essential for mass property calcs and even creates the constrained model not only in terms of position, but also for the inter gear/pulley relationships – so you can drive the mechanism and see the effects.

Integrated simulation & analysis

Autodesk has been building more analysis and simulation into Inventor for the past few releases – partly in partnership with Ansys, but also with the motion simulation tools it acquired from Solid Dynamics last year (which made their first appearance in the R11 release). This release sees this extended and expanded in several key areas. Firstly, you can now conduct thin wall analysis on sheet metal parts using the Stress Analysis tool. This uses a single brick element to represent uniform thickness materials. On the motion simulation side, work has been done to compress the workflow by providing automatic joint definition when you want to simulate an assembly’s motion. Assembly constraints are automatically converted into simulation joints, but of course, you can edit them should needs be (assembly constraints sometimes don’t lend themselves or are inappropriate for motion studies). Also on the motion front, you can export multiple time steps from your motion run for analysis using the stress tools. By defining the time steps required, the system will transfer that information. You then add any additional load and restraint conditions.

When ready, you can have the system automatically solve each time step or choose to do them individually. As the system automatically creates the results plots, you can choose to display two results sets alongside each other and synchronise their display manipulation, so that you can perform in-depth inspection of each time step – the same tools can be used to compare different studies. Interestingly, you have a new option to have the system rotate the environment, rather than the part, which for moving or rotating parts makes the whole process more efficient as both sets can be presented in the same synchronised orientation.

Also in the motion realm, you can now apply an imposed motion on a part within a mechanism. At the beginning of the design process this allows you to define the required motion of a part over time (using graph or imported data) then use that to define the geometry of the part that drives that motion. You can then use a persistent tracing technique which takes a point within that model and traces its movement through space. The result is a spline which represents the motion of that point which can then be referenced to a sketch in another part. While this sounds rather complex, when you consider the ability to have the system automatically create a cam profile, which has been defined from the very start to provide a specific motion, the power is pretty obvious and not just related to cam definition either.

Finally for analysis and simulation, you can now perform a geometry abstraction process which automatically removes small features or blends which aren’t required or are non-critical to the analysis process. The feature suppression process for FEA isn’t automatic. The idea here is that you can elect to suppress a feature just for the FEA analysis; it will still show up in the model and any drawings you’ve created. In the FEA environment you now have a dedicated features folder that shows all model elements and their current status with respect to analysis only.

Ribbon cable design

Elsewhere within the Inventor Professional offering, there has been work done on increasing the types of cable design and routing that can be carried out. For this release, this sees heavy concentration of the design of ribbon cables, as are common in many high-tech products. The workflow is pretty similar to that of more standard cabling processes. You start by defining the connectors on your model. If set-up correctly, these will contain pin IDs, so you’re building in design intent from the start. Once you have two, the system places a basic ribbon that runs from one connector to the other. Of course, unless you’re lucky, this isn’t going to represent how you want to run the cable through your product, so the system includes a number of tools that allow you to constrain it into position, run it through features and create folds (both single and double) - something you can only do with ribbons. One interesting area is how the system handles running a cable through a slot. You define where you want the ribbon to run through, and then use a graphical handle to twist the cable in to the correct position so that it runs through without interference.

Once your cable is in place and routed as you require, the system can create the unfolded form in a drawing sheet, you can add a representation of the connectors at each end and add manufacturing/production information automatically, such as pin IDs, folding details and such.

In conclusion

OK, over the past two months, we’ve looked at all the new updates and enhancements to Inventor 2008, both within the core Inventor Series and the Inventor Professional variant – but what do I make of it? The answer is I’m impressed. If you look at the updates to how Inventor and AutoCAD interact (in the March back issue) you can see that while Autodesk isn’t quite ready to forget the Inventor Series bundling, they’re thinking about how the dual system workflow can be improved. There’s an argument that much of it is to keep people on maintenance and I’m sure that’s the case, but there is a good justification for maintaining both Inventor and AutoCAD within your organisation – not all processes require 3D, but what should happen is that you can share information intelligently and associatively between the two.

The modelling tools within Inventor are gaining more maturity, both in terms of capability and pure geometry handling, but also how they operate within an industrial workflow. The updates that allow easier handling and reuse of third party imported data mean that you can now solve many of those types of problems - on your terms. If you need to import a 3D STEP file and use that to build from, you can do so and do it intelligently as there are now tools to support that. If you just need to import it for reference and display purposes, then there’s now no need to go through the often tortuous process of preparing data just for light work.

If I had to single out one highlight of Inventor 2008, it would have to be Functional Design. Now, this is a pretty widely used term and one that’s applied to all manner of products, concepts and technology, but within the Autodesk context, it makes sense. The Design Accelerators in particular take the concept of developing a product in 3D using the engineering requirements as the driving factor to heart.

When I think back to when Inventor was initially announced, I remember thinking – that’s a cool name for a product. And I look at the system now and I’m starting to think that it’s finally living up to that name. Inventor is gaining competitive advantage through the use of intelligent technology that allows you to invent as you would, from engineering and design principles, rather than cryptic modelling operations and for that reason alone – I like it a lot.

For part one of this article, click here