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注意：点击图片源中的链接以及整个博客 演化轻型结构工程（ELiSE）是一种系统化的设计优化方法，使用来自自然界的轻型多功能结构实现重量减轻50％并缩短开发时间。由基督教哈姆博士在LED 阿尔弗雷德-韦格纳研究所，亥姆霍兹中心极地与海洋研究所（AWI，不来梅，德国），埃莉斯包括一组已完成项目在各种各样的公司的仿生学专家和设计工程师汽车，航空航天，航海和工业市场。
ELiSE针对广泛的应用优化了仿生设计，包括 Bionic Design and Biomimicry
The Bionic Partition Project combined generative design and additive manufacturing to demonstrate a bionic design for the A320 passenger-to-galley partition with the potential to cut weight and production steps by 50% and to increase material usage (buy-to-fly ratio) to 95%. In the video below, Airbus says it will start to look for more cabin parts to adapt and demonstrate. Not Just Topology Optimization What Hamm is talking about is hierarchical structures, a common solution found in nature, where the multi-scale organization — from the nano to macro level, (see below) — of ordinary building blocks produces extraordinary properties. “Look at nacre, for example,” says Hamm, “which consists mainly of a very brittle material, calcium carbonate. But due to its hierarchical structure, it is tough. However, it is always used in nature in flat structures, not complex shapes. But what we are working on are very complex geometries as well as complex nanostructures.” He advises to look at the work of Markus J. Buehler at MIT.
Narrowing Natural Models to Diatoms
Another key benefit to diatoms is their production process. Hamm says they can build whatever forms they want to, whereas a tree is much more limited in the forms lignin and cellulose can create. He explains, “The diatoms’ structures precipitate within vesicles which are bordered by flexible membranes, whose geometries are manipulated by the cytoskeleton, so crazy forms can be developed.”
How Does ELiSE Work? Hamm explains, “If you have very little design freedom — [i.e. if the constraints prohibit much exploration of alternatives] — then that affects the scope of the approach.” It is also important to understand the design drivers. For example, is it more important to achieve lightweight or to use a cheaper material? “It is also crucial to detail all of the load cases,” Hamm adds. “You have to know what all of the technical challenges are. These are often not as well-known as they should be.”
The team then makes a road map for the customer, outlining scope, budget and schedule options. Once the customer finalizes those details, the ELiSE team begins its screening process, looking at models in nature. “We create preliminary designs as starting points,” says Hamm, “and either optimize them in parallel or take one with the highest potential and provide a range of optimized variations. But we also validate along the way. We establish a benchmark of what the state of the art is so that we can evaluate our development.” He notes that design optimization is a large topic in itself. “We create parametric models based on the natural geometry that can change easily and allow beta offspring. We pick the best and it creates offspring. So it’s a bit like evolution. But you need a starting point and this is what we do well.” The steps involved in the ELiSE process are illustrated in the B pillar example above.
“The idea is that optimization is not climbing one hill,” says Hamm, “but is instead like a mountain range with many peaks and you don’t really know where you are.” It makes sense to climb one peak to get a view. “You have so many parameters you can vary,” he adds. “It’s good to use very different approaches to the same problem in order to develop a landscape of the optimization options, and thus, be able to identify which offers the best overall solution. Hamm notes that ELiSE has been standardized in cooperation with the Association of German Engineers (VDI, Düsseldorf) as a biomimetic process to generate lightweight solutions. Ideas Like Load-adapted Honeycomb
Hamm says ELiSE can be used to design a load-adapted honeycomb structure with optimal diameter sizes and wall thicknesses, improving stiffness and cutting weight by 20-50% compared to classical structures. The irregularity of the cells also affects the structure’s vibration properties. Another project, “ELiSE AuST — Automation and standardization of the bionic ELiSE process”, was part of the research project BIO-OPT, which looked at automation, validation, benchmarking and standardization of bionic optimization processes. Funded by the German Federal Ministry for Economic Affairs and Energy (BMWi), ELiSE AuST led to exciting results with regard to development of bionic stiffening structures. One of the main objectives was to develop generic algorithms for the automated, load-dependent and adaptive dimensioning of surface stiffening structures in lightweight designs. This helps automate the design process, making it less time-consuming. As part of this work, a design case was explored where a surface uniformly stiffened with a constant-height honeycomb was compared to a bionic design where the honeycomb varied in height and diameter, according to mechanical loading. The bionic design reduced weight from 621 g to 497 g without violating displacement and maximum thickness constraints.
Composite Applications
In the bionic automotive side bumper project, the biological archetypes chosen for concept development featured sophisticated crash behaviors. The five most efficient concepts were determined by comparing their energy absorption capacity from explicit crash simulations. The best performing concept for the internal structure of the side bumper was determined and used to develop a composite material for the structure.
A thermoplastic matrix reinforced with carbon fibers was used to create adaptive, load optimized honeycombs. Due to the high energy absorption of the bionic concept, the occupant protection performance remains unchanged, even with a very low weight construction. ELiSE is also seen as an enabler for new structural paradigms geared toward additive manufacturing, including the bionic bike design it has developed — reportedly the lightest aluminum folding bike in the world.
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