Optimizing durable dynamic structures

lightweight construction, structural durability, structural dynamics

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The demands placed on components and structures in relation to vibration behavior are increasing in all areas of mechanical and plant engineering, as well as the mobility industry. At the same time, products must be optimized in terms of lightweight construction, while still ensuring sufficient service life. The optimization of structural dynamics on the one hand and the evaluation of service life on the other are usually considered separately from one-another. As part of the DuraDyn research project, Fraunhofer LBF is developing a methodology for the holistic, numerical optimization of lightweight structures, taking structural dynamics and service life into account, from which medium-sized companies in particular will be able to benefit.

DuraDyn research project

One face to the customer principle

Fraunhofer LBF is valued by its clients as a trusted partner in the areas of vibration technology and structural durability, as well as a strategic partner in lightweight construction and sustainability. To develop sustainable products and leverage the potential of lightweight construction, both the structural dynamics and the structural durability of structures have to be considered and optimized. The Institute has longstanding expertise and established tools for both issues, but they are usually applied separately. Since structural optimization and service life assessment are technically and operationally coupled to each other and linked in terms of personnel – especially for medium-sized companies – a tool is now being developed as part of the DuraDyn project, which will enable attractive offers for the holistic optimization of products. This allows us to implement a “one face to the customer principle”, as desired by the customer.

Creating added value by combining numerical methods

The aim here is to develop a numerical method to simultaneously optimize the structural dynamics and service life of components and systems using a calculation process. For this purpose, the parametric model reduction is extended to include the observation of modal stresses at critical points. These modal stresses are incorporated into the methods for evaluating fatigue strength to develop a method for the simplified evaluation of welded joints. The detail of welded joints was deliberately chosen, due to the fact that a local evaluation on the basis of maximum strains and strain gradients is vital in this context, but cannot be determined using dynamic models. The methods for optimizing dynamic systems are then extended to the evaluation of service life, so that, for example, the required minimum service life can be specified as an additional boundary condition for the optimization. The validation and demonstration of the methodology uses industry-related application scenarios, in which structures, in particular those related to agricultural engineering, are looked at.