@article{KubaschinskiGottwaltTetzlaffetal.2023, author = {Kubaschinski, Paul and Gottwalt, Albin and Tetzlaff, Ulrich and Altenbach, Holm and Waltz, Manuela}, title = {Modelling and simulation of the hardness profile and its effect on the stress-strain behaviour of punched electrical steel sheets}, volume = {54}, journal = {Materials Science \& Engineering Technology}, number = {4}, publisher = {Wiley}, address = {Weinheim}, issn = {0933-5137}, doi = {https://doi.org/10.1002/mawe.202200283}, pages = {512 -- 526}, year = {2023}, abstract = {The shear cutting of electrical steel sheets has a significant influence on the magnetic and mechanical material properties. Due to plastic deformation and strain hardening in the area of the punched edge, the electrical steel sheets exhibit a characteristic hardness profile. This study deals with the modelling of the resulting hardness profile by means of finite-element simulations. Elastic-plastic material properties are obtained from spherical nanoindentation testing as a function of the local hardness. In particular, representative stress-strain values are determined by applying Tabor's concept of indentation stress-strain curves. The choice of the appropriate stress- and strain-constraint factors is discussed with respect to the nanoindentation test setup used. Following this, the representative stress-strain values are analytically described to determine true stress-strain curves for the local assignment of different material models depending on the hardness. The implementation of the modelling approach in a finite-element simulation is presented for a punched electrical steel sheet specimen under monotonic loading. The simulation results are basically in good agreement with experimental data and confirm the expected influence on the mechanical material behaviour due to the shear cutting process.}, language = {en} } @article{HandwerkerKesslerMarzbanietal.2021, author = {Handwerker, Michael and Kessler, J{\"o}rg and Marzbani, Hormoz and Tetzlaff, Ulrich}, title = {Annealing of chopped and continuous fibre reinforced polyamide 6 produced by fused filament fabrication}, volume = {2021}, pages = {109119}, journal = {Composites Part B: Engineering}, number = {223}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1879-1069}, doi = {https://doi.org/10.1016/j.compositesb.2021.109119}, year = {2021}, language = {en} } @article{ThambiTetzlaffSchiessletal.2020, author = {Thambi, Joel Luther and Tetzlaff, Ulrich and Schiessl, Andreas and Lang, Klaus-Dieter and Waltz, Manuela}, title = {Evaluation of the relationship between stress and lifetime of Pb-free solder joints subjected to vibration load using a generalized local stress approach}, volume = {2020}, pages = {113560}, journal = {Microelectronics Reliability}, number = {106}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0026-2714}, doi = {https://doi.org/10.1016/j.microrel.2019.113560}, year = {2020}, language = {en} } @article{TetzlaffGerberAmelangetal.2019, author = {Tetzlaff, Ulrich and Gerber, Alexander and Amelang, Rudolf and Lemos, Georges}, title = {Investigation of the Creep Resistance of a Spray-Compacted Si-Particle Reinforced Al-Based MMC (Dispal® S270)}, volume = {2019}, journal = {Key Engineering Materials}, number = {809}, publisher = {Trans Tech Publications}, address = {Baech}, issn = {1662-9795}, doi = {https://doi.org/10.4028/www.scientific.net/KEM.809.87}, pages = {87 -- 93}, year = {2019}, language = {en} } @article{KubaschinskiGottwaltTetzlaffetal.2022, author = {Kubaschinski, Paul and Gottwalt, Albin and Tetzlaff, Ulrich and Altenbach, Holm and Waltz, Manuela}, title = {Calibration of a combined isotropic-kinematic hardening material model for the simulation of thin electrical steel sheets subjected to cyclic loading}, volume = {53}, journal = {Materials Science \& Engineering Technology}, number = {4}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1521-4052}, doi = {https://doi.org/10.1002/mawe.202100341}, pages = {422 -- 439}, year = {2022}, abstract = {The combined isotropic-kinematic hardening model enables the description of the cyclic transient elastic-plastic material behaviour of steel. However, the determination of the material model parameters and understanding of their influence on the material response can be a challenging task. This study deals with the individual steps of the material model calibration for the simulation of thin electrical steel sheets under cyclic loading. Specific recommendations are made for the determination of kinematic and isotropic hardening material parameters. In particular, the isotropic hardening evolution is described by Voce's exponential law and a simple multilinear approach. Based on the multilinear approach, which allows for different slopes in the evolution of the yield surface size, an alternative calibration of the isotropic hardening component is proposed. As a result, the presence of the yield plateau in the first half cycle can be accurately captured, while convergence issues in the material model definition for numerical simulations can be avoided. The comparison of simulated load cycles with experimental cyclic tests shows a good agreement, which indicates the suitability of the proposed material model calibration for electrical steel.}, language = {en} } @article{KiehlScheidGrafetal.2023, author = {Kiehl, Maximilian and Scheid, Adriano and Graf, Karin and Ernst, Benedikt and Tetzlaff, Ulrich}, title = {Coaxial laser cladding of cobalt-base alloy Stellite™ 6 on gray cast iron/investigations on friction, wear versus commercial brake pad, and corrosion characteristics}, volume = {237}, journal = {Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering}, number = {14}, publisher = {Sage}, address = {London}, issn = {2041-2991}, doi = {https://doi.org/10.1177/09544070221145512}, pages = {3285 -- 3303}, year = {2023}, language = {en} } @article{ErnstKeimTetzlaff2022, author = {Ernst, Benedikt and Keim, Simon and Tetzlaff, Ulrich}, title = {On the anisotropic indentation modulus and anisotropic creep behavior of β-Sn characterized by nanoindentation methods}, volume = {2022}, pages = {143392}, journal = {Materials Science and Engineering: A}, number = {848}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-4936}, doi = {https://doi.org/10.1016/j.msea.2022.143392}, year = {2022}, language = {en} } @article{HandwerkerKesslerMarzbanietal.2022, author = {Handwerker, Michael and Kessler, J{\"o}rg and Marzbani, Hormoz and Tetzlaff, Ulrich}, title = {Pressure and heat treatment of continuous fibre reinforced thermoplastics produced by fused filament fabrication}, volume = {8}, journal = {Progress in Additive Manufacturing}, number = {2}, publisher = {Springer}, address = {Cham}, issn = {2363-9520}, doi = {https://doi.org/10.1007/s40964-022-00315-5}, pages = {99 -- 116}, year = {2022}, abstract = {Fused filament fabrication allows for the additive manufacturing of complex geometries without requiring moulds. However, due to large air voids and poor layer adhesion, the mechanical properties of parts manufactured using fused filament fabrication lag behind those of parts manufactured using conventional techniques. A previous study found that the tensile strength and Young's modulus of such parts could be increased by a heat-treatment process. However, large air voids were still present after annealing. This study, therefore, investigates the influence of a post-pressure-treatment process on the mechanical performance and the air void ratio of continuous glass fibre-reinforced polyamide 6 in the directions perpendicular to the fibres. Without the treatment, Young's modulus on the plane parallel to the printing bed is eight times higher than Young's modulus perpendicular to it. Annealing at 1 MPa homogenises the material and leads to a significant increase of both the tensile strength (55 MPa) and Young's modulus (5 GPa). Increasing the pressure to 3 MPa only slightly increases the mechanical performance, whereas a further increase to 6 MPa causes no significant changes.}, language = {en} } @article{LemosFredelPyczaketal.2022, author = {Lemos, Georges and Fredel, M{\´a}rcio Celso and Pyczak, Florian and Tetzlaff, Ulrich}, title = {Creep resistance improvement of a polycrystalline Ni-based superalloy via TiC particles reinforcement}, volume = {2022}, pages = {143821}, journal = {Materials Science and Engineering: A}, number = {854}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-4936}, doi = {https://doi.org/10.1016/j.msea.2022.143821}, year = {2022}, language = {en} } @article{VolpatoTetzlaffFredel2022, author = {Volpato, Guilherme and Tetzlaff, Ulrich and Fredel, M{\´a}rcio Celso}, title = {A comprehensive literature review on laser powder bed fusion of Inconel superalloys}, volume = {2022}, pages = {102871}, journal = {Additive Manufacturing}, number = {55}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2214-7810}, doi = {https://doi.org/10.1016/j.addma.2022.102871}, year = {2022}, language = {en} } @article{ErnstKubaschinskiSchiessletal.2024, author = {Ernst, Benedikt and Kubaschinski, Paul and Schiessl, Andreas and Waltz, Manuela and H{\"o}ppel, Heinz Werner and Tetzlaff, Ulrich}, title = {Comparison of the Young's modulus of the lead free solder alloy Sn-Ag3.8-Cu0.7 determined by hot tensile tests, ultrasonic measurements and 𝛽-Sn single crystal calculations}, volume = {2024}, pages = {147354}, journal = {Materials Science and Engineering: A}, number = {916}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-4936}, doi = {https://doi.org/10.1016/j.msea.2024.147354}, year = {2024}, abstract = {Sn-based solders are known for their tendency to form coarse grained microstructures. In combination with the high elastic anisotropy of 𝛽-Sn, the overall elastic properties and their interpretation require a careful discussion of the structure-property-relationship as elastic constants are often important input parameters for creep or fatigue models. This study therefore investigates the influence of microstructure and testing method on the Young's modulus E for the widespread lead free solder alloy Sn-Ag3.8-Cu0.7 (SAC387) using bulk specimens. Due to its already high homologous temperature at room temperature (Thom ≈ 0.6 = T/Tm for Tm being the melting temperature), hot tensile tests generally bear the risk of superimposed creep deformation. Mechanical testing becomes even more challenging, since yield strengths are usually low for these alloys. Consequently, in addition to the hot tensile tests executed for the engineering strain rate 𝜖̇𝑒 = 1 ⋅ 10-3 s-1, two supplemental methods are used to determine the Young's modulus comprising of the dynamic resonance frequency measurement and the calculation of the Young's modulus based on single crystal compliance data of the majority phase 𝛽-Sn.Young's moduli yielded from dynamic resonance frequency measurement and calculations based on single crystal compliance data showed comparable results of (E35 ◦C ≈ 55 GPa, E80 ◦C ≈ 51 GPa and E125 ◦C ≈ 48 GPa). Hot tensile tests showed similar data with the largest deviation at 80 ◦C, where E80 ◦C ≈ 53 GPa was determined. These absolute values and their temperature dependence can be attributed to the microstructure of the cast specimens which show a general preferred orientation of 𝛽-Sn grains close to <110> after analysis via electron backscattered diffraction (EBSD). A comparison with literature data revealed significant differences in the Young's moduli which are likely to be attributed to differences in the preferred orientation of 𝛽-Sn grains.}, language = {en} } @article{GottwaltKubaschinskiWaltzetal.2023, author = {Gottwalt, Albin and Kubaschinski, Paul and Waltz, Manuela and Tetzlaff, Ulrich}, title = {Influence of the cutting method on the fatigue life and crack initiation of non-oriented electrical steel sheets}, volume = {2024}, pages = {108073}, journal = {International Journal of Fatigue}, number = {180}, publisher = {Elsevier}, address = {Oxford}, issn = {1879-3452}, doi = {https://doi.org/10.1016/j.ijfatigue.2023.108073}, year = {2023}, abstract = {The fatigue behavior of thin electrical steel sheets under cyclic loading is investigated in dependence on the edge surface. Therefore, four different edge conditions are compared, whereas the edge is either laser cut, shear cut, wire cut, or polished. Strain- and stress-controlled fatigue tests are performed to determine S-N curves in the low cycle regime as well as in the high cycle regime. Microstructural data is collected by non-contacting (optical) Profilometry, Nanoindentation, X-Ray Diffraction, and Electron Backscatter Diffraction to understand the differences in fatigue life by considering surface roughness, residual stresses, hardness, and microstructure. Shear cut specimens achieve the lowest fatigue life, while the other edge conditions reach relatively similar values in the LCF regime. Crack initiation is mainly intergranular in the case of defect-free edges. This tendency has a considerable influence on the observed fatigue behavior.}, language = {en} } @article{GottwaltKubaschinskiWaltzetal.2023, author = {Gottwalt, Albin and Kubaschinski, Paul and Waltz, Manuela and V{\"o}lkl, Rainer and Glatzel, Uwe and Tetzlaff, Ulrich}, title = {Cyclic deformation behavior of non-oriented electrical steel sheets}, volume = {2023}, pages = {145684}, journal = {Materials Science and Engineering: A}, number = {886}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0921-5093}, doi = {https://doi.org/10.1016/j.msea.2023.145684}, year = {2023}, language = {en} } @article{ViewegerDielSchweigeretal.2024, author = {Vieweger, Daniel and Diel, Sergej and Schweiger, Hans-Georg and Tetzlaff, Ulrich}, title = {Mechanical Properties of Raw Filaments and Printed Specimens: Effects of Fiber Reinforcements and Process Parameters}, volume = {16}, pages = {1576}, journal = {Polymers}, number = {11}, publisher = {MDPI}, address = {Basel}, issn = {2073-4360}, doi = {https://doi.org/10.3390/polym16111576}, year = {2024}, abstract = {Fused Deposition Modeling (FDM) is a well-established manufacturing method for producing both prototype and functional components. This study investigates the mechanical properties of FDM components by material and process-related influencing variables. Tensile tests were conducted on seven different materials in their raw filament form, two of which were fiber-reinforced, to analyze their material-related influence. To cover a wide range from standard to advanced materials relevant for load-carrying components as well as their respective variations, polylactic acid (PLA), 30\% wood-fiber-reinforced PLA, acrylonitrile butadiene styrene (ABS), polycarbonate (PC), a blend of ABS and PC, Nylon, and 30\% glass-fiber-reinforced Nylon were selected. The process-related influencing variables were studied using the following process parameters: layer thickness, nozzle diameter, build orientation, nozzle temperature, infill density and pattern, and raster angle. The first test series revealed that the addition of wood fibers significantly worsened the mechanical behavior of PLA due to the lack of fiber bonding to the matrix and significant pore formation. The polymer blend of ABS and PC only showed improvements in stiffness. Significant strength and stiffness improvements were found by embedding glass fibers in Nylon, despite partially poor fiber-matrix bonding. The materials with the best properties were selected for the process parameter analysis. When examining the impact of layer thickness on part strength, a clear correlation was evident. Smaller layer thicknesses resulted in higher strength, while stiffness did not appear to be affected. Conversely, larger nozzle diameters and lower nozzle temperatures only positively impacted stiffness, with little effect on strength. The part orientation did alter the fracture behavior of the test specimens. Although an on-edge orientation resulted in higher stiffness, it failed at lower stresses. Higher infill densities and infill patterns aligned with the load direction led to the best mechanical results. The raster angle had a significant impact on the behavior of the printed bodies. An alternating raster angle resulted in lower strengths and stiffness compared to a unidirectional raster angle. However, it also caused significant stretching due to the rotation of the beads.}, language = {en} } @article{GottwaltKubaschinskiWaltzetal.2024, author = {Gottwalt, Albin and Kubaschinski, Paul and Waltz, Manuela and Tetzlaff, Ulrich}, title = {Influence of Subsequent Heat Treatment on Fatigue Behavior of Shear-Cut Electrical Steel Sheets}, volume = {3}, journal = {Alloys}, number = {4}, publisher = {MDPI}, address = {Basel}, issn = {2674-063X}, doi = {https://doi.org/10.3390/alloys3040017}, pages = {281 -- 294}, year = {2024}, abstract = {The fatigue behavior of a fully processed, non-oriented electrical steel sheet is investigated in dependence on shear-cutting parameters and a subsequent heat treatment. For this, stress-controlled fatigue tests are performed before and after annealing at 700 °C for a total of six different shear-cutting settings. For all parameters, the fatigue strength of shear-cut sheets is improved by the heat treatment. This is due to reduction in a large part of the strain hardening region as well as the reduction in tensile residual stresses. Both were introduced during shear cutting and act detrimental to the fatigue strength. However, the intensity of this improvement depends on the shear-cutting parameters. This is related to the corresponding edge surfaces characteristically being formed during shear cutting. Specimens cut with a worn cutting tool show a more pronounced increase in fatigue life. In contrast, specimens produced with a sharp-edged cutting tool and high cutting clearance hardly benefit from the heat treatment. This appears to be caused by differences in surface topography, in particular coarse topographical damage in the form of grain breakouts. If these occur during shear cutting, the crack formation is not significantly delayed by additional annealing.}, language = {en} } @article{deSouzaPintoPereiraGutjahrPereiraetal.2023, author = {de Souza Pinto Pereira, Adriano and Gutjahr, Jhonattan and Pereira, Milton and Tetzlaff, Ulrich and Fredel, M{\´a}rcio Celso}, title = {Processability of thin-powdered Inconel X750 and TiC metal matrix composite by laser-directed energy deposition}, volume = {35}, pages = {042040}, journal = {Journal of Laser Applications}, number = {4}, publisher = {LIA}, address = {Orlando}, issn = {1042-346X}, doi = {https://doi.org/10.2351/7.0001134}, year = {2023}, language = {en} } @inproceedings{MohdKreinerSchmidetal.2024, author = {Mohd, Zubair Akhtar and Kreiner, Christian and Schmid, Maximilian and Zippelius, Andreas and Tetzlaff, Ulrich and Elger, Gordon}, title = {Fully Connected Neural Network (FCNN) Based Validation Framework for FEA Post Processing to Improve SAC Solder Reliability Analysis}, booktitle = {2024 IEEE 10th Electronics System-Integration Technology Conference (ESTC), Proceedings}, publisher = {IEEE}, address = {Piscataway}, isbn = {979-8-3503-9036-0}, doi = {https://doi.org/10.1109/ESTC60143.2024.10712023}, year = {2024}, language = {en} } @article{GuldenGramstatStichetal.2018, author = {Gulden, Florian and Gramstat, Sebastian and Stich, Anton and Hoppel, Heinz Werner and Tetzlaff, Ulrich}, title = {Properties and Limitation of an Oxide Coated Aluminum Brake Rotor}, pages = {2018-01-1877}, journal = {SAE Technical Paper}, publisher = {SAE}, address = {Warrendale}, issn = {0148-7191}, doi = {https://doi.org/10.4271/2018-01-1877}, year = {2018}, language = {en} } @article{VolpatodeSouzaPintoPereiraNeumeieretal.2025, author = {Volpato, Guilherme and de Souza Pinto Pereira, Adriano and Neumeier, Steffen and Hotza, Dachamir and G{\"o}ken, Mathias and Tetzlaff, Ulrich and Fredel, M{\´a}rcio Celso}, title = {Influence of a Standard Heat Treatment on the Microstructure and Properties of Inconel X-750 Produced by Laser Powder Bed Fusion}, volume = {27}, pages = {2500306}, journal = {Advanced Engineering Materials}, number = {24}, publisher = {Wiley}, address = {Weinheim}, issn = {1527-2648}, doi = {https://doi.org/10.1002/adem.202500306}, year = {2025}, abstract = {The production of nickel-base superalloys through powder bed fusion using a laser beam (PBF-LB) offers a promising method for reducing the cost of aeronautical components, especially those with complex geometries. However, when these materials are processed using PBF-LB, the standard heat treatments developed for conventional manufacturing routes do not consistently yield predictable microstructures or mechanical properties. Thus, this study analyzes how PBF-LB affects the microstructure and mechanical behavior of Inconel alloy X-750 when compared to a hot-rolled counterpart after undergoing a standard precipitation-hardening heat treatment (solution annealing, stabilization, and precipitation). Microstructure is examined using analytical electron microscopy and high-energy X-ray diffraction, while mechanical behavior is assessed through microhardness. Significant differences between both manufacturing routes are detected, so that PBF-LB processing led to an increase in grain size, anisotropy, fraction of low-angle grain boundaries, mean angle of misorientation, and dislocation density. Moreover, PBF-LB promoted the formation of γ′-Ni3(Al,Ti) and η-Ni3Ti phases during solution annealing and stabilization, respectively. Notably, the formation of γ′ contributes to an anomalous microhardness increase observed between these steps. These findings suggest that PBF-LB may inhibit recrystallization and facilitate precipitation during heat treatment, thereby affecting the performance of components produced using this technology.}, language = {en} }