CAE Not the Best Means of Solving Brake NVH Issues

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The Brake Academy recently posted the following article questioning the use of CAE – computer-aided engineering — as the primary means of determining the basis of brake NVH issues.

Brake NVH simulation and modelling. Does their use lead to lazy thinking?

A response to blog “Got Brake NVH Problems?” by Dr. Mo Esgandari:

On an educational visit to India, I was talking to a well-known company about upskilling of staff. The main concern expressed by the chief engineer was the company could readily employ young engineers who could “drive” the CAE systems but that they did not understand the background theory. That understanding was regarded as necessary so the company could “tune” the models to meet the company needs.

I often wonder whether we need to rename CAE as CDE – Computer Dependent Engineering. We have forgotten that the “A” means “aided” and as a result there is now a tendency to use computational techniques, rather than think about the task in hand. Worse still, there is a tendency for young engineers to believe the results. When did the philosophy “use appropriate technology” be discarded from the toolbox of our engineers?

As an educationalist (with a strong interest in the education of engineers to meet the demands of the 21st century), and a practicing design engineer, my biggest “initial” concern with computer aided design/drawing was that the student engineer ceased to think how detail parts were made. They were more impressed with colors, shadowing, and the ability to view a component in 3D. Up to that point the engineer could look at a drawing and visualize its 3D shape by reading the 2D drawing – that was part of their training.

One of the necessities not mentioned in the article was that all CAE models need to be verified. With aerodynamic analysis (CFD) the car (or a scaled model) is placed on a 6-point balance machine and subjected to a variety of wind conditions. The laminar flow lines may be replicated using smoke trails and as a result separation readily observed. Even the wind effects around wing mirrors are analyzed and the computational model optimized to actual events.

Similarly, FEA has the advantage of access to endless historical experiments and material data that may even indicate the magnitude of stress raisers. Standards have been produced to advise the radii at the root of keyways and gear teeth to minimize such concentrations of stress. That element of detail design is now lost in the ether of CAE. Theories of elastic failure cease to be understood and if questioned many engineers are unaware what a “Mises” stress means.

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As such, the models are used in these activities with some degree of confidence and are readily validated and optimized. The packages provide valuable results which are readily accepted – and in general, without question. It is not clear whether “an analysis in order of magnitude” accompanies the use of FEA – indeed it is easier to accept the results without challenge.

To view the entire post, click HERE.

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