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Engineering calculation software: making the most of predictive engineering

17 February 2011

The ability to make accurate predictions puts any professional head and shoulders above the rest. This is true, whether you forecast the weather or trends in stock markets. And for the design engineers and product developers who regularly use CAD in the course of their daily work, accurate prediction can also be a key differentiator. Numerous CAD tools exist to predict the outcome of a product design exercise before it moves through physical prototyping and manufacturing and into the hands of the customer, including software for structural analysis, mechanical dynamics, and virtual prototyping. Even the reuse of existing CAD models can be a valuable predictive resource.

The better the designer can predict the fit, feel, function, cost and reliability of the finished product, the better the chances of delivering a competitive product on time and within budget. Of course, design engineers and product developers know this; what they may not realise, however, is that the often overlooked process of automating engineering calculations can be every bit as important as using analysis tools, virtual prototypes, and other predictive resources.

CAD software has evolved to make the fundamental mathematics of product design transparent to design engineers. However, CAD design also requires frequent ad hoc calculations for everything from performing unit conversions to testing probability models. These vital calculations are, in some cases, still performed manually, particularly when the development process is simple and straightforward. But when was your last project simple and straightforward? Tough market competition, fast-moving supply chains, and customer expectations all demand a fast-track approach. Development cycles may be squeezed from months to weeks and budgets inevitably tightened. Performing engineering calculations manually – or even using spreadsheets – just doesn’t cut the mustard these days!

Automating the process of performing ad hoc calculations has become essential – and not just for the sake of speed. It also enables the specific intent of the original designer to be documented automatically, and in a form that’s both traceable, testable and, most importantly, reusable.

Take the following example. A designer tasked with creating a new shock absorber calls up the current-generation product model from the CAD library. Thanks to engineering calculation software, the new designer sees the detailed assumptions and decisions of the original designer. These might show, for instance, that the shock absorber was originally intended for a certain-sized axle, and then later changed to fit a different-sized axle. Knowing this, the designer can determine where the new model might be affected by any compromises (for example, in axle clearance or vibration threshold) that the original designer had to make.

Armed with powerful engineering calculation software, product development professionals are able to predict the form, fit and function of their designs modelled in 3D CAD. This information helps the new designer save considerable time and minimise cost by reusing the early generation design, while at the same time maintaining product quality.

Automating the capture of engineering calculations helps in other ways, too. For instance, a designer can undertake a preliminary analysis requiring calculations that would be too difficult or time-consuming to do manually and thus predict the behaviour of a component or material before it is submitted for a fuller analysis. From this, the designer can tighten the assumptions that will be passed to the analysis software, saving the time and cost of unnecessary testing.

Engineering calculations are proving to be useful, and often necessary, at all points along the design cycle, from concept planning, where early sizing or early validation, can save valuable time, through requirements definition to design modelling and eventual manufacture.

Engineering calculation software can be very useful for pre- and post-processing support of industry standard finite element analysis (FEA) and other tools. As a pre-processor, engineering calculation software helps with basic sizing and testing of top-level assumptions, and thus can sharpen the focus of the problem that’s presented to the analysis application. This insight enables the engineer to avoid wasting time on a misdirected analysis project. A full FEA simulation can take several hours, so it’s beneficial to make the analysis as meaningful as possible.

As a tool for post-processing, engineering calculation software helps the designer to ‘sanity-check’ the analysis results by running simplified tests that will deliver numbers in the same range as the FEA outputs. For instance, to sanity-check our shock absorber example’s stress test, the designer can use engineering calculation software to place a virtual box around the component, and then put a load on the box. True, engineering calculation software can’t perform the same deformation testing as the FEA tool, but it does deliver results via the applied box that should be within range of the FEA tests.

Before turning the model over to manufacturing, the designer can use engineering calculation software to check that the product will meet manufacturing specifications. These could range from tolerance requirements to safety and/or Six Sigma parameters. Again, the software won’t perform extensive testing, but in a matter of seconds it can answer simple conditional statements like: ‘does the model meet this safety requirement?’ Chances are, the model will pass these simple tests, but if it raises a flag, the designer – and the entire organisation – will be far better off than if the model had been passed directly to manufacturing, where solving even a small problem can quickly become very costly and likely jeopardise delivery schedules.

Take a look at the stories presented here in our special newsletter, in which we focus on PTC’s engineering calculation software, Mathcad. This application has become very popular with product development organisations of all sizes and industries, as it combines robust functions with a novel, easy-to-use whiteboard interface, as well as featuring the power of natural-maths notation.

Les Hunt

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