Reliable component design through realistic stress simulations and innovative design concepts

reliability design, additive manufacturing, lightweight construction

Additive manufacturing offers unprecedented opportunities for the sustainable lightweight design of components. At the same time, it presents those responsible for components with major challenges when it comes to reliably exploiting the strength potential of additively manufactured components. The process-related material properties as well as the impact of defects differ significantly from conventional manufacturing processes. The AM FATIGUE LABS are creating new types of application safety by developing dedicated design concepts and investigation methods for additively manufactured components.

In the AM FATIGUE LABS, realistic simulations are developed that show reliable design characteristics for the design of additively manufactured components. They also ensure design validation by taking the influence of all relevant process parameters into account. Specially-developed load simulators increase the precision and reproducibility of the measurements. This insight into the cyclic material and component behavior would be almost impossible using classical testing methods.

To also be able to exploit the advantages of additive manufacturing for safety-relevant components, in terms of lightweight construction, many challenges have to be met in the alternating field of component geometry, manufacturing, operational stresses and environmental influences.

The locally inhomogeneous microstructure as a function of build direction, powder application direction and exposure strategy differs significantly from the microstructure in classical manufacturing processes.

Local phenomena drive component fatigue

The realization that component fatigue is driven by local phenomena is becoming increasingly important, especially for additively manufactured components. The new levels of freedom in component development require a new design concept to be able to leverage the potential of this manufacturing technology for cyclically stressed, safety-relevant components as well. On the one hand, the manufacturing process induces geometric defects in the form of pores, inclusions or rough surfaces; on the other hand, the very limited local heating leads to the formation of significant property gradients. Here, factors including the direction of construction and the design of the required support structures also play a significant role in the formation of the material microstructure, thereby affecting the local properties, including the defect distribution.

Optical strain measurement produces new insights

In the AM FATIGUE LABS, the Fraunhofer LBF team uses a range of optical strain sensors whose measurement signals have the required real-time capability. In this way, strain control is made possible, for example, in component areas that are relevant for failure. At the same time, the researchers derive information about the local damage mechanism from the synchronous-load measurement of local strain fields. This information can be used for component optimization. What is more, it can also be used to increase material utilization by taking defect-oriented material behavior into account in early design phases.

»The derivation of dedicated design concepts and investigation methods will create a level of application safety for additively manufactured components that cannot be achieved with currently available codes, all of which are based on classical manufacturing technologies.«

Dr. Rainer Wagener

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Area Of Expertise Reliability Design