Jan Papuga is employed as a researcher at the Czech Technical University in Prague, Faculty of Mechanical Engineering and also as fatigue analyst in Evektor company. His work is focused above all on multiaxial fatigue, fatigue of notched components and general fatigue estimation procedures. More of his outputs can be found on www.pragtic.com
Abstract Keynote (143)These days, some multiaxial fatigue solution is commonly embedded in most publicly available fatigue solvers. The lecture discusses the known facts within the domain of multiaxial fatigue estimation, and the level they are experimentally proven to be validated. The individual steps of the analysis are analyzed. These are: load path deconstruction to individual cycles, their analysis and segmentation to amplitude and mean components of stresses/strains, their merging into the damage parameters and the characteristic features of various types of damage parameters. These are only some of the prerequisites to a statement of the damage level induced by the evaluated loading, and to an adequate assessment of the remaining useful life, requesting the usage of the damage accumulation method validated in the domain of multiaxial loading. The lecture discusses the scope of validation these prerequisites were subjected to, so that the second step – remaining life calculation or even its extension - could be taken responsibly enough. Though engineering could be called the craft of mastering multitude of incalculable factors, the lecture is concluded by a call for a corrective collaborative action that could improve the status quo and shed more light on the quality of the calculation process.
Abstract (108)The paper presents experimental results and results of different fatigue strength assessment methods carried out on hollow specimens from AlSi10Mg with a specific design featuring an internal cavity and a cylindrical outer surface. The selected test geometry combines the design freedom of additive manufacturing with the suitability for surface temperature / thermographic measurements. Compared to classic cylindrical hollow specimens, increasing the inner diameter of the active part lessens the stress gradient in the torsion loading case, while keeping the outer dimensions still acceptably small for layer-by-layer or Laser Powder Bed Fusion technology. The surface in the tested section was left as-built, while the heat treatment recommended by the AM machine manufacturer was applied. Four loading cases were tested in the high cycle fatigue area under load-controlled configuration – push-pull, torsion, and combined loading of in-phase and out-of-phase tension-torsion. All loading cases featured fully reversed loading cycles. The results show that these specimens reach substantially higher lifetimes (or fatigue strengths) if the coacting load channels are out of phase compared to the case, in which the same stress amplitudes are applied in phase. The fatigue strength estimation performed using several multiaxial fatigue strength criteria shows that only some of the methods follow the same behavior.
|Room 6||Thursday 30th November||11:45-12:15||Jan Papuga|
S01-4 Additive Manufacturing
108 - Multiaxial fatigue analysis of additively manufactured hollow specimens from AlSi10Mg
|Room 6||Thursday 30th November||16:15-17:00||Jan Papuga|
143 - Responsible Fatigue Design of Components under Multiaxial Loading