Ein "virtuellen Labors" für Ni/PU Hybridschäume: stochastische mikromechanische Identifikation und effektive numerische Simulationen
Mechanische Eigenschaften von metallischen Werkstoffen und ihre mikrostrukturellen Ursachen
Zusammenfassung der Projektergebnisse
Thanks to their porous nature, open-cell metal foams (OCMFs) have a unique combination of properties: a low weight, a high energy absorption during impact, excellent heat conductivity, excellent catalyst properties, and more. Although additive manufacturing can more precisely generate metallic mesostructures with less uncertainty, OCMFs are orders of magnitude cheaper. Nevertheless, the stochastic nature of their mesostructures and the lack of predictive computations to include OCMFs’ uncertainties hinders their wide-spread use in manufacturing and industry. The aim of the DFG-FNR project Open-Cell Metal Foams was a virtual lab for open-cell metal foams that can predict macroscopic mechanical responses and their variations, based on the mesoscopic and microscopic distributions of the geometrical and mechanical parameters. A discrete mesostructural model will act as the virtual lab. It will account for variations of the strut connectivity, variations of the strut dimensions and variations of the strut material parameters. The model developments and the experimental identification of the stochastic geometrical and material parameters were performed for Ni/PU hybrid foams, which are substantially cheaper than alternative open-cell hybrid metal foams. The project involved two co-PIs: Prof. Dr.-Ing. Dr. Anne Jung at Saarland University (UdS) and Dr Lars Beex at the University of Luxembourg (UL). The proposed work was subdivided over the two teams as follows: (A) The UdS team (Reis, Jung) focused on the experimental tasks: improving the robustness of the manufacturing process of the hybrid Ni/PU OMCF, the construction of a new two-point bending setup for single struts, including digital-image-correlation measurements (to measure full deformation and strain fields during mechanical tests), and a cheap and fast measurement technique to identify the geometry of single struts as well as inverse parameter identification. (B) The UL team (Rappel, Tomar, Chen, Beex) focused on the computational tasks: the finite element simulations, the beam finite element simulations, the constitutive models, but mostly on the probabilistic modelling and the probabilistic frameworks to identify the mechanical parameters and random fields’ parameters. The main inventions in the projects were on the experimental side the development of three-point and two-point bending tests for the micromechanical identification of material parameters from individual foam struts. Therefore, in addition a high-precise and accurate method for measuring local strain fields on the single struts was developed using digital imaging. Noise in force and strain field were determined and analysed. From the experimental results, stochastic material parameters were determined to apply to a 3D beam model acting as virtual lab using Bayesian inference to predict mesoscopic material properties of small foam parts from micromechanical strut properties.
Projektbezogene Publikationen (Auswahl)
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Improving DIC Accuracy in Experimental Setups. Advanced Engineering Materials, 21(7).
Reis, Martin; Adorna, Marcel; Jiroušek, Ondřej & Jung, Anne
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Noise reduction for DIC measurements. PAMM, 19(1).
Reis, Martin; Diebels, Stefan & Jung, Anne
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DIC Measurements on Single Struts of Ni/PU Hybrid Foams—Damage Behaviour During Three-Point Bending. Advanced Structured Materials, 423-430. Springer International Publishing.
Reis, Martin; Diebels, Stefan & Jung, Anne
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Micromechanical Characterisation of Ni/PU Hybrid Foams. Materials, 13(17), 3746.
Reis, Martin; König, Kristian; Diebels, Stefan & Jung, Anne
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Application of Ultraviolet (UV) Radiation and Fluorescence for DIC Measurements - Quality Improvement. Optics and Lasers in Engineering, 158, 107140.
König, Kristian; Reis, Martin; Vielhaber, Michael & Jung, Anne
