Remapping the world of design

Written by: Tom Shelley | Published:

Designing, simulating and mapping the results of tests into the same CAD model in the same environment is now a reality. Tom Shelley reports



You can now design a machine in all its aspects, model it, simulate it, design the test rig and then map the test results onto the original model to compare predictions with reality. How? By combining the world’s leading instrumentation design and test software with some of the world’s leading 3D modelling and simulation software.

NI LabView and SolidWorks have been combined into a pre-release tool kit that allows the mechanical, electrical and control software to be designed at the same time together to achieve a desired result. And LabView test data can be mapped onto SolidWorks’ geometry to compare them with CosmosWorks predictions, using NI Insight.

All aspects of design, simulate and test can now be conducted in a common environment. And while the tools are still at an early stage in development, they are far enough advanced to be used to accelerate and improve product development enormously.

At the recent SolidWorks World event, National Instruments product manager Nipun Mathur explained how the initiative came into being. “One big trend is that purely mechanical systems are transitioning to electromechanical. We therefore need an holistic approach to designing machines that combine mechanical and electrical elements, control and embedded software.”

The result is the NI LabView-SolidWorks Mechatronics Toolkit (Alpha version 01). Using this, it is possible, for example, to design a pair of motion slides, and use SolidWorks and CosmosMotion to design the mechanics and detect possible collisions when the mechanics are driven through a motion profile developed using LabView and the NI Motion Assistant.

There is still much work to do. For instance, there is at present no simple way to simulate limit switches. Mathur explained that the user can, however, work round this. “In SolidWorks, you know exactly where you are. You can then read the position you have reached in LabView and trigger the switch.”

Despite its early stage of development, the software is already being used to design serious products. Mathur briefly described an electrical connector tinning machine, designed to be deployed without the need to build a physical prototype. “You must not have any vibration or fast movement that might lead to short circuits [through metal bridging the pins]”, he warned. Meanwhile, the toolkit, he added, can also help with motor sizing selection, using SolidWorks to establish motor torque and speeds. He then briefly described the development of a digital photo kiosk, designed by Boston Engineering, in which the challenge was to establish precise web tensioning by controlling motor speed, despite vibrations caused by the cutter head. Although they did not use the toolkit as such, they employed the same approach as is embodied within it, with the result that the final product can print photographs - “10 times faster than the competition”, according to Mathur.

If the final product is an aircraft wing or mass-produced car, however, there’s no way it is going to be possible to produce this without building a prototype, or prototypes, and testing them to the nth degree. Swapnil Padhye, another product marketing engineer with National Instruments, explained that at present, people usually design and simulate in 3D, and produce test results as 2D traces and tables. He offered examples of typical outputs from conventional systems, with complicated tables of results and masses of squiggly lines, followed by an account of how a manufacturer of laptop computers in Austin, Texas, tackled the problem of improving drop testing with regard to the survival of computer hard drives. Test results were mapped back onto the original 3D model in order to improve the positioning of eight vibration and shock sensors.

The results of experiments on heat transfer measurements were also shown. In this case, a rectangular aluminium plate was fitted up with thermocouples on its underside and two heat sources full of boiling water were placed on the upper side. CosmosWorks was used to analyse the expected transient thermal response and then Ni Insight to bring the simulated measured data into the same environment - so they could be colour mapped onto the same SolidWorks 3D model and viewed as they changed with time. There was, as might be expected, fairly good agreement between the two, but they were not entirely the same. Padhye then revealed that the same techniques had already been applied to a real-world problem involving the control of the temperature of a spectrometer inside a vacuum chamber on what looked like one of the large research accelerators in Germany, which involved simulating temperature and correlating test results from some 400 individual thermocouples.

Of even more practical importance was an experiment that involved modelling and testing an aluminium physical model of part of an aircraft wing, equipped with 15 channels of strain gauges. The wing was designed and modelled in SolidWorks and clamped at one end, representing the fuselage, and subjected to mechanical loading at the other. The model was meshed and simulated using CosmosWorks, and the strain gauge test results and the LabView test data colour-mapped back onto the Cosmos mesh using Insight. Again, the two sets of results were extremely close, but not totally identical. In fact, the differences could be discerned at a glance.

The same techniques have also been trialled in - and no doubt are already being applied to - vibration analyses. SolidWorks has so far issued two White Papers on this topic: ‘Incorporating Mechatronics into Your Design Process’ and ‘Integrating 3D Mechanical Design and Analysis with Physical Testing’, which suggests that the technology is already all done and dusted. Documentation from National Instruments is more cautious, though, concerning the Mechatronics Toolkit, observing: “This is an alpha pre-release version of the toolkit, intended for lead users who are interested in evaluating the technology. This version has known issues and limitations….If you encounter an issue or bug, please report it by emailing Mechatronics@ni.com with detailed information on the problem and instructions on how to reproduce the issue.”

None of that should deter those who feel inclined to ‘have a go’, although the likelihood is that they will run into problems along the way and have to find workarounds. Still, the benefits are likely to greatly outweigh the effort, even if the pain in new software is always there.

Pointers

* By using a new toolkit that brings LabView and SolidWorks together to work with each other, it is possible to design mechanical and control elements of machines at the same time

* The software is at an early stage, but has already been used successfully in real-world applications

* It is also possible to colour-map test results back onto SolidWorks models for more rapid evaluation and in order to be able to compare them with the results of software simulation



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