Inspiring ideas for lightweight construction

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HASCO Hasenclever GmbH + Co KG

Renishaw plc

DIPROFIL Diamantprodukter AB

Fraunhofer-Institut für Produktionstechnologie IPT

Verein Deutscher Werkzeug- maschinenfabriken e. V. (VDW)

The entire design is modified to suit the new material

Because materials cannot be simply replaced on a one-for-one basis, the design needs to be modified to suit the new material concerned. Finite-element simulation has proved its practical worth in this context. “At the computer, we take a detailed look at the specific points in the design that are the most yielding, in order to determine the causes involved,” explains Filippos Tzanetos. “We then attempt to replace some of the existing components by their equivalents in aluminium or CFRP, or to improve the dynamic behaviour at certain critical points by means of reinforcements or ribs.”

R&D

Retrofit for Industry 4.0: Application for existing machines

Working with CFRP is a particular challenge for design engineers, since the material behaves anisotropically: “anisotropy” is a term describing the direction-dependence of a property or an operation. This means that in the case of fibre-reinforced materials the mechanical strength or rigidity will depend on the direction of the fibres. A CFRP component, however, behaves differently in a simulation to its behaviour in reality. Filippos Tzanetos lays out the details for specialists: “The meaningfulness of the simulation is estimated using the uncertainty propagation defined in DIN ISO 21748:2014-05. The uncertainty of the model’s parameters exerts a certain influence on the uncertainty of the model’s output variables. This is calculated using the Monte Carlo simulation method.”

In projects of this kind, the Fraunhofer Institute is often assisted by other institutes or spin-offs, but in this case the scientists found the support they needed in-house. “In our institute, we have a department for fibre-reinforced-composite and laser-system technologies”, reports Filippos Tzanetos. “This department has over the course of many years accumulated a lot of can-do competences in the field of dimensioning machine tool components made of fibre-reinforced plastics (FRPs), and provides us with proactive support in the shape of simulation expertise for fibre-reinforced component dimensioning.”

Gallery

Success assured by synergised competences

Support of this kind is indispensable for solving questions encountered when it comes to using FRP components in plant and machinery construction, since these materials, by virtue of their anisotropic properties, are not often used here. “Up to now, there has been a notable reluctance to use FRPs because in contrast to conventional materials there is no recourse available to existing design and dimensioning standards and therefore it’s not that easy to predict an FRP component’s dynamic behaviour in conjunction with the rest of the machine’s structure,” explains the Aachen-based scientist. “Mistakes are made, for example, when a component is dimensioned in terms of its mechanical strength in just one axis direction, while ignoring the mechanical strength in the other axis directions. But if we use simulation tools to fine-tune the interrelationship between the FRP component and the machine tool’s own dynamics, nothing can go wrong. So to solve the problem, the requisite competences are brought together in our company within this project.”

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