Systematic Lightweight Construction Via Drag-and-Drop
Lightweight construction is one of the most important requirements in automotive development. But how much weight is saved by lightweight construction depends largely on the experience and intuition of the developers and designers. If this employee leaves, part of the know-how goes with him. To prevent this, CSI is developing methods to systematically address weight reduction.
Building lighter vehicles is one of the most important ways to save energy and protect the environment. However, lightweight construction can also be a tricky matter: It is possible that a door developer saves 1 kg in weight on his work package — but the entire vehicle will not become any lighter, but heavier instead. This is due to the fact that the modified door impairs stability. In other areas of the body lightweight construction requires reinforcements that weigh much more than was saved on the door in the first place. In reality, such a result will hardly ever go into series production, because such aberrations will be noticed in time. But if the findings of Tobias Lüdeke, an engineer at CSI Entwicklungsstechnik GmbH's PhD thesis, can be put into practice, the development should no longer lead to such dead ends. One could even look for lightweight construction approaches that reinforce each other and also take costs into account.
Developers Consider Lightweight Construction Too Late
In 2010, the mechatronics engineer at Saarland University began his doctoral thesis. In addition to his work as a research assistant at the Chair of Design Engineering of Prof. Dr. -Ing. Michael Vielhaber, he researched current development processes in order to improve them through his new systematics. One of the first findings: developers usually only deal with lightweight construction when a physical or virtual prototype is available. This is clearly too late, says Lüdeke,"because the developers have the greatest opportunities to influence weight, costs and other aspects at the very beginning of development, when the product is designed on the basis of the requirements, i. e. long before prototypes exist".
The problem: During this early phase, there is hardly any information available on the effects modified products will have on the weight and, for example, the costs. That is why Lüdeke designed a systematic approach with many formulas which allow us to calculate the impact of a modified design on different properties of the final product. Lüdeke has proven that the formulas work. However, they have so far only provided a rough indication: Does the design change make the product lighter or heavier? Further research and development is needed to provide more precise information.
The second part of Lüdeke's dissertation, which he completed with the colloquium in June, is much closer to implementation. Therein he examined the "secondary weight savings". A well-known example: It is possible to design the engine ten kilograms lighter, which results in further secondary savings because the motor suspension has to be less robust and even the brakes may be a little smaller. “I have developed a system model for this purpose which records such secondary effects on the basis of mathematical formulas," explains Lüdeke. Further development of the system would ultimately make it possible to calculate the influences of the measures on costs and recycling, for example, at the design stage, when modifications can still be easily implemented.
Easy and Fast On-Screen Configuration
In the meantime, the innovation team of the CSI, in which Tobias Lüdeke has also been working since May 2015, is pushing the topic of systematic lightweight construction in a joint research work with Prof. Vielhaber. This project also involves the consideration of many parameters by means of practical investigations. With the help of the experienced CSI staff, the formulas are to be adapted to real development work. “I cannot give any figures, but I'm pretty sure that this is still a good way to reduce weight," says Lüdeke. He cites studies which assume that additional secondary savings of about 0.5 to 1.0 kg per kg of primary savings are possible. Making this potential available would be an important contribution. But Lüdeke's vision goes even further. “Ideally, I could imagine that a kind of vehicle configurator would be created on the basis of my approach and the data and findings of the manufacturers. Of course, this would not be intended for end customers who, in a traditional sense, design their dream vehicle. It could rather be used during the early stages of the product development process and could represent a real milestone for development efforts."
Specifically, this would mean that the configuration or modification of features (e. g. dimensions, wheelbase) and properties (such as vehicle class, type of drive technology, target market) can be carried out quickly and easily on the screen by drag-and-drop. In this way, it would be possible to make rough statements on weight, center of gravity, costs, consumption, range and many other characteristics in a very short time — not only before the first physical but even before the first virtual prototype.
This article was first published by blechnet.
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