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solidThinking Inspire in the Design Process

By Francis Sebastian, November 26, 2013

Inspire is software tuned for design exploration during preliminary stages of the development of a product. It enables designers to study topological options using dimensional, loading, support, and material properties. It does this without the hassle of complicated set-ups and the expertise normally required for FEA (finite element analysis) studies (see figure 1).

Figure 1: A 3D-printed aircraft door hinge (at bottom) is transformed after using Altair’s OptiStruct optimization tool. Source: Altair

Inspire is stand-alone software from solidThinking. It has a basic solid-geometry creation toolset and an optimization platform based on OptiStruct, an optimization platform from the parent Altair. In this article, I am going to look at how Inspire fits into the proverbial toolbelt for engineers, architects, and product designers (see figure 2).

Figure 2: Inspire expanding the design exploration phase to include later stages (indicated by red dotted lines) and reduce the number of design iterations

Inspiring the Design Process

Fluidity is not a term used generously in the design process when describing the contribution of MCAD software, and there are good reasons for this: the steep learning curve of traditional MCAD software, its cost, and the difficulty of such software to communicate with proprietary data formats (i.e., translation errors).

In an age when pinch-to-zoom and voice interaction blurs human-to-machine interaction, the user interface of most design software is still firmly limited by dialog boxes and software frameworks developed and used by a previous generation of software frameworks. It is no wonder many designers prefer to perform their initial studies on paper. Although it is hard to supplant the immediacy of pencil-on-paper for formal explorations, subsequent iterations occur mostly in software for easier repetition and communication.

Inspire enhances the design process in three ways: (a) through the user interface, (b) by its ability to work with generic and industry-standard data formats, and (c) with its fast, powerful optimization process. Let's take a look at each of these.

Simplifying the User Interface

The toughest challenge when working with a UI (user interface) in engineering design software is to find the location of all its tools. I often find myself drowning in icons, sub-menus, and the ribbon's split buttons. Most software developers design this kind of UI, unfortunately, and the result is a long learning curve and lost productivity.

The hidden cost here is that of translation. Designers like to use paper, and sometimes even easy-to-use software for quickly exploring forms and ideas. As a designer myself, my first instinct is to confirm the design's viability as quickly as possible on paper, or the software of my choice. Ultimately, I need to record the designs in a more widely used format for analysis, be it spatial, structural, or thermal.

The point here is that every change in format requires translation and the accompanying loss of data. One of the ways that Inspire eases translation costs is by shortening the learning curve. It does this by making it easy to move models in and out of the software, and by making it easy to create geometry within the application. It's not necessarily innovative, but solidThinking had the idea of creating an interface with just four menus, along with tools that are hierarchically bunched together on an uncluttered screen. For users more familiar with traditional MCAD applications, this is simply mind-blowing (see figure 3).

Figure 3: The simple UI of Inspire; the inset shows how tools are grouped around a common theme, and are visible only on mouse hover

The only other interface where I have seen such thoughtful design is in games, navigation software, and Web and phone apps. Rather than using the UI as a technical layer between the designer and the idea, Inspire's interface is an extension of the designer's thought framework.

Software Interoperability

With MCAD applications increasingly converging in terms of features and target industries, interoperability is a term widely abused by marketing. Software makers realize that in their fragmented market, everyone has to play nice. The caveats relating to functional inadequacies of interoperability are, however, usually hidden or - worse still - discovered at an inopportune stage of design development.

From this perspective, Inspire is very straight-forward: it accepts 3D solid objects created in the popular industry-standard formats, because it needs only the 3D volume of the model. This is called its "Design Space," within which we can perform formal explorations. To explore formal variations, for example, I trace the parts I want to optimize, and then add material descriptors, loads, and constraints.

Note that Inspire is available in both PC Windows and Mac OS X versions, making it less of a headache when it comes to managing IT ecosystems.

Inspire and 3D printing

3D printing is not a recent development, but now is quickly becoming a staple within the design process. Inspire requires solids as input for its optimization; coincidentally, 3D printing also prefers solids (or water-tight surfaces). In this sense, models generated in Inspire are almost always print-ready.

(3D printing is usually not as simple as hitting the Print button. Limitations in the strength of the print medium, such as powder or plastic, determine the smallest load-bearing component that can be printed without the object crumbling under its own weight. The problem with models not made of 3D solids, such as those made from 3D surfaces, is that these models tend to have miniscule gaps that increase the likelihood of print failure.)

Inspire's Role of Topological Optimization in Form-seeking

Aside from material characteristics, the geometry of the engineered form determines many of its functional characteristics, such as cost, type of manufacturing processes, and the operational life of the finished product. While most forms seem intuitive or deductive, complex interaction of forces and constraints are hard to deduce with certainty.

Topological optimization is the defining feature of Inspire. The optimization can be performed using two basic criteria: maximum strength and minimum mass. When these two criteria are combined with more sophisticated constraints, such as material thickness, natural frequencies, gravity, forces and constraints, then it becomes possible to develop an extended range of forms and solutions that previously were too time consuming to attain.

Many of the publicity images made with Inspire show morpho-genic (biologically-inspired) outcomes.

Without such an exploration in the initial phase, designers would otherwise have to wait until later in the product development cycle (such as during analysis) to find out whether the designed form is best suited its purpose.

Figures 4 and 5 show the first two versions of a humble wall shelf bracket I designed. I designed the bracket with of different materials, one aluminum and the other common ABS plastic. The support is constrained by two pins connected to a backplate, which is then attached to a wall.

Figure 4: Optimization a aluminum shelf bracket with a 200 lb load and 1in-lbft torque

Figure 5: Same bracket take on different shape if made with ABS plastic

Figure 6 shows the result after the load is doubled on the bracket, but with a uniformly distributed support provided by the backplate.

Figure 6: Bracket with a uniformly distributed back support, and without the two pin supports

Caveats

Like many software tools, Inspire is based on a mature technology yet has room for improvement. For instance, topological optimization is most successful with isotropic materials, ones that have the same properties throughout. This is not really a limitation of the software, but of the technique itself, because materials are defined by Inspire in terms only of their Young's modulus, Poisson ratio, density, and yield stress. This uniformity works fine for many plastics and metals, but not for brittle, reinforced, or directional materials, and so those materials are not particularly suitable for optimization.

The default library provided with Inspire consists of a variety of steel, aluminum, titanium, and plastics. Orthotropic materials (such as wood) and reinforced one (such as composites and concrete) require analysis methods that are unavailable within Inspire.

Secondly, Inspire cannot create complex forms based on splines or NURB surfaces. It works only with 3D solids. While performing tests using 3D solids generated with a 3rd party CAD program and exported to the *.stl file format, I found that Inspire can easily import the geometry, but I have to trace the 3D form using Inspire's solid-creation tools to perform optimization.

Results shown have non-smooth surfaces which may be a result of limiting the number of iterations done by the program. The assumption is that enough iterations would result in a smooth surface in the examples used but iterations were limited in this review in the interest of time.

Resulting shapes may be non-intuitive or unconventional. While Inspire may create be a breakthrough design that was never before considered, I suggest a healthy skepticism would be in order. Rather than accept the results as unassailable, it wouldn't hurt to get a sanity check, such as a rough calculation, a nod from an experienced analyst.

SolidThinking has a sister product called Evolve, which is designed for building complex forms. Inspire can open models generated by Evolve, perform optimizations, and then return the models.

Inspired Mass Customization

So what is the significance to a software tool like Inspire? Firstly, innovative forms are no longer the exclusive domain of organizations with resources to invest in fancy technology. We are in the midst of a democratization of access to technology. With the advent of 3D printing and just-in-time manufacturing, designs now require near-instant prototyping (or pseudo-manufacturing) or at the very least very short manufacturing cycles.

Another paradigm shift affecting a large number of industries is the seeming number of infinite customization options. In an age where the stroke of the genius is quickly replaced by the ability to pick a winning mutation from all the permutations generated by intelligent tools, software packages like Inspire no longer are optional accessories; they are powerful weapons for achieving much needed advantages over the competition.

Conclusion

solidThinking's Inspire is a tool designed to be part of a tool set, rather than a standalone product for engineering design or analysis. With its easy to use interface, Inspire is perfectly suited to the new generation of design engineer (or even artist) that would like quick results with a minimum of training. It suggests alternative shapes that may not have been considered in a traditional design process. It facilitates 3D printing, a technology that will let us create products we never knew could exist. From this perspective, solidThinking Inspire is the right tool when introduced at the best possible time.

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About the Author

  Francis Sebastian is an architect by training. He teaches, supports and provide implementation services for the AEC industry in the New York tri-state area and writes for his para-analytics blog. More....

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