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Laser Additive Manufacturing (LAM) enables economical production of complex lightweight structures as well as patient individual implants. Due to these possibilities the additive manufacturing technology gains increasing importance in the aircraft and the medical industry. Yet these industries obtain high quality standards and demand predictability of material properties for static and dynamic load cases. However, especially fatigue and crack propagation properties are not sufficiently determined. Therefore this paper presents an analysis and simulation of crack propagation behavior considering Laser Additive Manufacturing specific defects, such as porosity and surface roughness. For the mechanical characterization of laser additive manufactured titanium alloy Ti-6Al-4V, crack propagation rates are experimentally determined and used for an analytical modeling and simulation of fatigue. Using experimental results from HCF tests and simulated data, the fatigue and crack resistance performance is analyzed considering material specific defects and surface roughness. The accumulated results enable the reliable prediction of the defects influence on fatigue life of laser additive manufactured titanium components.

Today, laser additive manufacturing (LAM) is used in more and more industrial applications. Due to a new freedom in design it offers a high potential for weight saving in lightweight applications, e.g., in the aerospace industry. However, most design engineers are used to design parts for conventional manufacturing methods, such as milling and casting, and often only have limited experience in designing products for additive manufacturing. The absence of comprehensive design guidelines is therefore limiting the further usage and distribution of LAM. In this paper, experimental investigations on the influence of part position and orientation on the dimension accuracy and surface quality are presented. Typical basic shapes used in lightweight design have been identified and built in LAM. Thin walls, bars, and bore holes with varying diameters were built in different orientations to determine the process limits. From the results of the experiments, comprehensive design guidelines for lightweight structures were derived in a catalog according to DIN 2222 and are presented in detail. For each structure a favorable and an unfavorable example is shown, the underlying process restrictions are mentioned and further recommendations are given.

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