Lightweight Design

How to Integrate Bionics in Lightweight Design?

| Author / Editor: Prof. Dr. Heike Beismann* / Alexander Stark

For the development of a bionic product, VDI Guideline 2221 can be taken as the basis for a seven-step methodological procedure. Bionics is also relevant for die casters, especially in lightweight design.

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The vein structure of the maidenhair fern can serve as a biological model for the uniform flow of coolant through molds. The solution is provided by the geometric Frac-Therm algorithm.
( Source: Beismann/Grunewald; ©Kanea - )

The VDI Guideline 2221 (Methodology for Developing and Designing Technical Systems and Products) deals with generally applicable, industry-independent fundamentals of methodological development and design and defines those work sections and work results which, due to their general logic and expediency, can serve as guidelines for a procedure in practice. Since the core development of a bionic product is also a development process, VDI 2221 can be taken as a basis and starting point of a methodical procedure for the development of bionic products. This applies all the more, since the VDI 2221 only provides industry-independent data.

The development process of VDI 2221 comprises seven work steps specifying the necessary tasks and the results of these tasks.

1. Clarify and Specify the Task

Starting from a technology pull-process, the job arises from technology. In the first work stage of a development order, the job has to be clarified and specified. The process results in a list of requirements, which can also be compiled as a specification sheet depending on the nature of the job. In order to fulfil this task, various analysis and target setting methods can be applied, but also costs and economic efficiency calculation procedures contribute to this.

During this stage of the development process, the first step is to define purely technical requirements. Nevertheless, bionics and biology can already play an important role in this phase. For larger bionic projects in particular, it makes sense to put together an interdisciplinary project team right from the start. The first methodological challenge is to capture the thoughts of others in an interdisciplinary team. Workshops with different creativity techniques can help to develop a common understanding.

2. Determination of Functions and Structures

This work section deals with the determination of the overall function and the sub-functions to be fulfilled. Functional structures are defined as the result of the task, for which the VDI guideline lists some methods from the area of analysis and target setting methods — in particular functional structuring.

The interdisciplinary integration of experts from bionics and biology in the project team also facilitates the exchange between different disciplines. Especially when determining functional structures, it is important to be able to recognize and assign possible structure-function correlations at an early stage, as they play an important role in biology. Even if it is important to achieve a purely technical description of the required functions at first, in a bionic project the developed functions can be put into a biological context. The first analogies of the functions between biological and technical systems can be identified.

3. Identify Solution Principles

In work section three of VDI 2221, solution principles for all functions are identified. One or more basic solutions are expected as the result of the work. The basic solution describes a solution for a delimited construction task, while solution principles do not necessarily have a direct connection to a certain construction task.

A number of methods for the development of ideas are available for the search for solution principles. These range from creativity techniques and morphological boxes to the use of existing solutions in construction catalogs. The aim is to develop further solution variants. Evaluation procedures and decision techniques must then be used to select the most promising solution principles from the principles found.

For the defined functions of the functional structure, solution principles can also be found in nature. The basis for the transferability of biological systems to technical systems is based on the fact that the same physical laws and constants apply to both systems. In this section, biology plays a decisive role in a bionic project. For a conventional project in which only the search space is to be expanded, the search for biological models and functions must be included. In this phase, a conventional development process can be extended by a bionic approach.

In particular, the applicability of bionic optimization methods to a specific task can be tested here. Already established bionic optimization methods such as structural optimizations, evolutionary algorithms or the geometric algorithm Frac Therm have the potential to generate solution proposals in manageable time frames. At this point in the development process, one must verify whether the methods can deliver the desired solution principles and which expertise must be obtained for it.

4. Structuring into Feasible Modules

In work section four, the basic solution to be pursued further is divided into realizable modules before the labor-intensive implementation takes place. The result of the work is a modular structure, which already shows the feasible solution including the connection (interfaces) of the different modules. Here, too, methods for function structuring, but also creativity techniques and cost and profitability calculation methods can be applied.

Whereas in the previous section fundamental solutions were derived from the biological structure-function correlations, experts from biology and engineering now have to work closely together to divide the modules into manageable parts. Only then, can they develop exactly fitting modules. To this end, it is necessary to achieve a reasonable degree of abstraction. This means that the biological solution principle is simplified without making it arbitrary or, in the other extreme, simply creating a copy of a biological model.

5. Design of the Modules

The crucial modules are specified in work section fve. Preliminary designs are created for the individual modules. In this work section, engineering know-how is particularly important.

In a bionic project, however, close coordination with experts from the field of can ensure that the preliminary designs are not developed isolated from the biological solution principles and thus lose a great deal of innovation potential. In this work phase, simulations take center stage, while solution-finding methods play a subordinate role. For this purpose, profitability calculations are becoming more important in this section.

6. Design of the Complete Product

In work section six, the previously individually available modules are complemented and connected with each other. The result is an overall draft which contains all the essential specifications. Especially, engineering skills are outlined here. The methods from the previous section are also used in this one. This section requires less expertise from biology than the previous ones.

7. Elaborate Usage Data

The complete design is realized in work section seven. This results in the product documentation and usage data. Here, too, the methods from the previous work sections can be applied. The input from biology can be further reduced.

*Prof. Dr. Heike Beismann, Department of Biology and Bionics, Westfälische Hochschule Bocholt

This article was first published by Konstruktionspraxis

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