@article{41488,
abstract = {{The additive manufacturing (AM) of innovative lattice structures with unique mechanical properties has received widespread attention due to the capability of AM processes to fabricate freeform and intricate structures. The most common way to characterize the additively manufactured lattice structures is via the uniaxial compression test. However, although there are many applications for which lattice structures are designed for bending (e.g., sandwich panels cores and some medical implants), limited attention has been paid toward investigating the flexural behavior of metallic AM lattice structures with tunable internal architectures. The purpose of this study was to experimentally investigate the flexural behavior of AM Ti-6Al-4V lattice structures with graded density and hybrid Poisson’s ratio (PR). Four configurations of lattice structure beams with positive, negative, hybrid PR, and a novel hybrid PR with graded density were manufactured via the laser powder bed fusion (LPBF) AM process and tested under four-point bending. The manufacturability, microstructure, micro-hardness, and flexural properties of the lattices were evaluated. During the bending tests, different failure mechanisms were observed, which were highly dependent on the type of lattice geometry. The best response in terms of absorbed energy was obtained for the functionally graded hybrid PR (FGHPR) structure. Both the FGHPR and hybrid PR (HPR) structured showed a 78.7% and 62.9% increase in the absorbed energy, respectively, compared to the positive PR (PPR) structure. This highlights the great potential for FGHPR lattices to be used in protective devices, load-bearing medical implants, and energy-absorbing applications.}},
author = {{Abdelaal, Osama and Hengsbach, Florian and Schaper, Mirko and Hoyer, Kay-Peter}},
issn = {{1996-1944}},
journal = {{Materials}},
keywords = {{General Materials Science}},
number = {{12}},
publisher = {{MDPI AG}},
title = {{{LPBF Manufactured Functionally Graded Lattice Structures Obtained by Graded Density and Hybrid Poisson’s Ratio}}},
doi = {{10.3390/ma15124072}},
volume = {{15}},
year = {{2022}},
}
@article{41490,
author = {{Hein, Maxwell and Lopes Dias, Nelson Filipe and Kokalj, David and Stangier, Dominic and Hoyer, Kay-Peter and Tillmann, Wolfgang and Schaper, Mirko}},
issn = {{0142-1123}},
journal = {{International Journal of Fatigue}},
keywords = {{Industrial and Manufacturing Engineering, Mechanical Engineering, Mechanics of Materials, General Materials Science, Modeling and Simulation}},
publisher = {{Elsevier BV}},
title = {{{On the influence of physical vapor deposited thin coatings on the low-cycle fatigue behavior of additively processed Ti-6Al-7Nb alloy}}},
doi = {{10.1016/j.ijfatigue.2022.107235}},
volume = {{166}},
year = {{2022}},
}
@article{33338,
author = {{Hein, Maxwell}},
journal = {{Crystals}},
publisher = {{MDPI}},
title = {{{Influence of Physical Vapor Deposition on High-Cycle Fatigue Performance of Additively Manufactured Ti-6Al-7Nb Alloy}}},
doi = {{10.3390/cryst12091190}},
year = {{2022}},
}
@article{33340,
author = {{Hein, Maxwell and Lopes Dias, Nelson Filipe and Pramanik, Sudipta and Stangier, Dominic and Hoyer, Kay-Peter and Tillmann, Wolfgang and Schaper, Mirko}},
journal = {{Materials}},
title = {{{Heat Treatments of Metastable β Titanium Alloy Ti-24Nb-4Zr-8Sn Processed by Laser Powder Bed Fusion}}},
year = {{2022}},
}
@article{36332,
abstract = {{AlSi casting alloys combine excellent castability with high strength. Hence, this group of alloys is often used in the automotive sector. The challenge for this application is the brittle character of these alloys which leads to cracks during joint formation when mechanical joining technologies are used. A rise in ductility can be achieved by a considerable increase in the solidification rate which results in grain refinement. High solidification rates can be realized in twin–roll casting (TRC) by water-cooled rolls. Therefore, a hypoeutectic EN AC–AlSi9 (for European Norm - aluminum cast product) is manufactured by the TRC process and analyzed. Subsequently, joining investigations are performed on castings in as-cast and heat-treated condition using the self-piercing riveting process considering the joint formation and the load-bearing capacity. Due to the fine microstructure, the crack initiation can be avoided during joining, while maintaining the joining parameters, especially by specimens in heat treatment conditions. Furthermore, due to the extremely fine microstructure, the load-bearing capacity of the joint can be significantly increased in terms of the maximum load-bearing force and the energy absorbed.}},
author = {{Neuser, Moritz and Kappe, Fabian and Ostermeier, Jakob and Krüger, Jan Tobias and Bobbert, Mathias and Meschut, Gerson and Schaper, Mirko and Grydin, Olexandr}},
issn = {{1438-1656}},
journal = {{Advanced Engineering Materials}},
keywords = {{Condensed Matter Physics, General Materials Science}},
number = {{10}},
publisher = {{Wiley}},
title = {{{Mechanical Properties and Joinability of AlSi9 Alloy Manufactured by Twin‐Roll Casting}}},
doi = {{10.1002/adem.202200874}},
volume = {{24}},
year = {{2022}},
}
@article{34069,
author = {{Schramm, Britta and Martin, Sven and Steinfelder, Christian and Bielak, Christian Roman and Brosius, Alexander and Meschut, Gerson and Tröster, Thomas and Wallmersperger, Thomas and Mergheim, Julia}},
issn = {{2666-3309}},
journal = {{Journal of Advanced Joining Processes}},
keywords = {{Mechanical Engineering, Mechanics of Materials, Engineering (miscellaneous), Chemical Engineering (miscellaneous)}},
publisher = {{Elsevier BV}},
title = {{{A Review on the Modeling of the Clinching Process Chain - Part I: Design Phase}}},
doi = {{10.1016/j.jajp.2022.100133}},
volume = {{6}},
year = {{2022}},
}
@article{34068,
author = {{Schramm, Britta and Friedlein, Johannes and Gröger, Benjamin and Bielak, Christian Roman and Bobbert, Mathias and Gude, Maik and Meschut, Gerson and Wallmersperger, Thomas and Mergheim, Julia}},
issn = {{2666-3309}},
journal = {{Journal of Advanced Joining Processes}},
keywords = {{Mechanical Engineering, Mechanics of Materials, Engineering (miscellaneous), Chemical Engineering (miscellaneous)}},
publisher = {{Elsevier BV}},
title = {{{A Review on the Modeling of the Clinching Process Chain - Part II: Joining Process}}},
doi = {{10.1016/j.jajp.2022.100134}},
year = {{2022}},
}
@article{34070,
author = {{Schramm, Britta and Harzheim, Sven and Weiß, Deborah and Joy, Tintu David and Hofmann, Martin and Mergheim, Julia and Wallmersperger, Thomas}},
issn = {{2666-3309}},
journal = {{Journal of Advanced Joining Processes}},
keywords = {{Mechanical Engineering, Mechanics of Materials, Engineering (miscellaneous), Chemical Engineering (miscellaneous)}},
publisher = {{Elsevier BV}},
title = {{{A Review on the Modeling of the Clinching Process Chain - Part III: Operational Phase}}},
doi = {{10.1016/j.jajp.2022.100135}},
year = {{2022}},
}
@article{31238,
author = {{Kupfer, Robert and Köhler, Daniel and Römisch, David and Wituschek, Simon and Ewenz, Lars and Kalich, Jan and Weiß, Deborah and Sadeghian, Behdad and Busch, Matthias and Krüger, Jan Tobias and Neuser, Moritz and Grydin, Olexandr and Böhnke, Max and Bielak, Christian-Roman and Troschitz, Juliane}},
issn = {{2666-3309}},
journal = {{Journal of Advanced Joining Processes}},
keywords = {{Mechanical Engineering, Mechanics of Materials, Engineering (miscellaneous), Chemical Engineering (miscellaneous)}},
publisher = {{Elsevier BV}},
title = {{{Clinching of Aluminum Materials – Methods for the Continuous Characterization of Process, Microstructure and Properties}}},
doi = {{10.1016/j.jajp.2022.100108}},
year = {{2022}},
}
@inbook{29771,
author = {{Grydin, Olexandr and Mortensen, Dag and Neuser, Moritz and Lindholm, Dag and Fjaer, Hallvard G. and Schaper, Mirko}},
booktitle = {{Light Metals 2022}},
isbn = {{9783030925284}},
issn = {{2367-1181}},
publisher = {{Springer International Publishing}},
title = {{{Numerical and Experimental Investigation of Heat Transfer in the Solidification-Deformation Zone During Twin-Roll Casting of Aluminum Strips}}},
doi = {{10.1007/978-3-030-92529-1_96}},
year = {{2022}},
}
@inproceedings{25047,
author = {{Křivská, B and Šlapáková, M and Králík, R and Bajtošová, L and Cieslar, M and Grydin, Olexandr and Stolbchenko, M and Schaper, Mirko}},
booktitle = {{IOP Conference Series: Materials Science and Engineering}},
issn = {{1757-899X}},
title = {{{Resistivity and Formation of Intermetallic Layer in Aluminum-Steel Clad Strip}}},
doi = {{10.1088/1757-899x/1178/1/012035}},
volume = {{1178}},
year = {{2021}},
}
@article{28017,
abstract = {{Processing aluminum alloys employing powder bed fusion of metals (PBF-LB/M) is becoming more attractive for the industry, especially if lightweight applications are needed. Unfortunately, high-strength aluminum alloys such as AA7075 are prone to hot cracking during PBF-LB/M, as well as welding. Both a large solidification range promoted by the alloying elements zinc and copper and a high thermal gradient accompanied with the manufacturing process conditions lead to or favor hot cracking. In the present study, a simple method for modifying the powder surface with titanium carbide nanoparticles (NPs) as a nucleating agent is aimed. The effect on the microstructure with different amounts of the nucleating agent is shown. For the aluminum alloy 7075 with 2.5 ma% titanium carbide nanoparticles, manufactured via PBF-LB/M, crack-free samples with a refined microstructure having no discernible melt pool boundaries and columnar grains are observed. After using a two-step ageing heat treatment, ultimate tensile strengths up to 465 MPa and an 8.9% elongation at break are achieved. Furthermore, it is demonstrated that not all nanoparticles used remain in the melt pool during PBF-LB/M.}},
author = {{Heiland, Steffen and Milkereit, Benjamin and Hoyer, Kay-Peter and Zhuravlev, Evgeny and Keßler, Olaf and Schaper, Mirko}},
journal = {{Materials}},
keywords = {{grain refinement, crack reduction, laser beam melting, aluminum alloy, titanium carbide, nanoparticle, PBF-LB/M}},
title = {{{Requirements for Processing High-Strength AlZnMgCu Alloys with PBF-LB/M to Achieve Crack-Free and Dense Parts}}},
doi = {{https://doi.org/10.3390/ma14237190}},
year = {{2021}},
}
@inproceedings{28440,
author = {{Triebus, Marcel and Reitz, Alexander and Grydin, Olexandr and Grenz, Julian and Schneidt, Andreas and Erhardt, Rüdiger and Tröster, Thomas and Schaper, Mirko}},
booktitle = {{13th European LS-DYNA Conference 2021}},
location = {{Ulm}},
title = {{{Forming Simulation of Tailored Press Hardened Parts}}},
year = {{2021}},
}
@inproceedings{24426,
author = {{Urbanek, Stefan and Pauline, Frey and Magerkohl, Sebastian and Zimmer, Detmar and Tasche, Lennart and Schaper, Mirko and Ponick, Bernd}},
keywords = {{Elektromotor, Elektromaschine, Additive Fertigung, AF, AM, Additive Manufacturing, DMRC, KAt}},
location = {{Connecticut, USA}},
title = {{{Design and Experimental Investigation of an Additively Manufactured PMSM Rotor}}},
doi = {{10.1109/IEMDC47953.2021.9449566}},
year = {{2021}},
}
@article{24589,
abstract = {{Additive manufacturing, e.g. by laser powder bed fusion (LPBF), is very attractive for lightweight constructions, as complex and stress-optimised structures integrating multiple functions can be produced within one process. Unfortunately, high strength AlZnMgCu alloys tend to hot cracking during LPBF
and thus have not so far been applicable. In this work the melting and solidification behaviour of
AlZnMgCu alloy powder variants with particle surface inoculation was analysed by Differential Fast
Scanning Calorimetry. The aim is to establish a method that makes it possible to assess powder modifications in terms of their suitability for LPBF on a laboratory scale requiring only small amounts of powder.
Therefore, solidification undercooling is evaluated at cooling rates relevant for LPBF. A method for the
temperature correction and normalisation of the DFSC results is proposed. Two ways of powder modification were tested for the powder particles surface inoculation by titanium carbide (TiC) nanoparticles:
via wet-chemical deposition and via mechanical mixing.
A low undercooling from DFSC correlates with a low number of cracks of LPBF-manufactured cubes. It
appears that a reduced undercooling combined with reduced solidification onset scatter indicates the
possibility of crack-free LPBF of alloys that otherwise tend to hot cracking.}},
author = {{Zhuravlev, Evgeny and Milkereit, Benjamin and Yang, Bin and Heiland, Steffen and Vieth, Pascal and Voigt, Markus and Schaper, Mirko and Grundmeier, Guido and Schick, Christoph and Kessler, Olaf}},
issn = {{0264-1275}},
journal = {{Materials & Design}},
keywords = {{Aluminium alloy 7075, Differential fast scanning calorimetry, Solidification, Undercooling, Additive manufacturing}},
title = {{{Assessment of AlZnMgCu alloy powder modification for crack-free laser powder bed fusion by differential fast scanning calorimetry}}},
doi = {{10.1016/j.matdes.2021.109677}},
year = {{2021}},
}
@article{26191,
author = {{Voswinkel, Dietrich and Sapli, Hüseyin and Kloidt, Dennis and Heggemann, Thomas and Homberg, Werner and Grydin, Olexandr and Schaper, Mirko}},
issn = {{1757-8981}},
journal = {{IOP Conference Series: Materials Science and Engineering}},
title = {{{Improving the Accuracy of Deep Drawn Fiber-Metal Laminate Parts by Preliminary Surface Treatment}}},
doi = {{10.1088/1757-899x/1190/1/012028}},
year = {{2021}},
}
@phdthesis{26900,
abstract = {{Mit Hilfe der additiven Fertigung, insbesondere dem pulverbettbasierten selektiven Laserstrahl-schmelzen (LBM), können hochkomplexe Strukturen endkonturnah hergestellt werden. Die große Designfreiheit ermöglicht, zelluläre Leichtbaustrukturen zu erzeugen, deren mikrostrukturellen und mechanischen Eigenschaften direkt vom generativen Fertigungsverfahren abhängen. Insbesondere im Bereich des Leichtbaus bieten zelluläre Strukturen neue Ansätze zur Verminderung des Energieverbrauchs. Um dieses Potential vollständig ausschöpfen zu können, müssen die Effekte, die zum Versagen der Bauteile mit integrierten Gitterstrukturen führen, quantitativ beschrieben und verstanden werden. Dies ist Voraussetzung für eine sichere Auslegung. Dazu werden im Rahmen der vorliegenden Arbeit die charakteristischen Eigenschaften dieser Strukturen sowie die Einflussgrößen im Aufbauprozess näher beleuchtet.
Im Rahmen dieser Dissertation werden numerische und experimentelle Untersuchungen von zwei unterschiedlichen Gitterstrukturtypen aus den Werkstoffen 316L und TiAl6V4 vorgestellt. Beide Werkstoffe werden unter monotoner, einachsiger Belastung getestet. Die parallel dazu durchgeführte digitale Bildkorrelation (DIC) ermöglicht gleichzeitig die detaillierte Analyse der lokalen Dehnungsverteilung während der Verformung. Mikrostrukturelle Eigenschaften und die resultierenden Gittercharakteristika werden mit Hilfe von rasterelektronenmikroskopischen Analysemethoden untersucht. Zudem erfolgt die Entwicklung eines Finite-Elemente- Modells, mit der Anforderung eines möglichst geringen Rechenaufwandes. Ein abschließender Vergleich der realen Dehnungsverteilung mit der FE- Analyse verifiziert das Modell.}},
author = {{Sieger, Alexander}},
isbn = {{ 978-3-8440-7924-1}},
keywords = {{Additive Fertigung, TiAl6V4, 316L, Gitterstrukturen, L-PBF}},
pages = {{136}},
title = {{{Mikrostrukturausprägung additiv gefertigter Gitterstrukturen}}},
volume = {{23}},
year = {{2021}},
}
@inproceedings{29812,
abstract = {{Aluminum-steel clad composites are used as structural elements in car bodies and chases as well as in the chemical industry due to a combination of high strength of steel, low density of Al and high corrosion resistance of both materials. An important parameter influencing mechanical properties of the composite is the microstructure of the bonding region between Al and steel layer. During manufacturing of the final product, clad sheets can be subjected to elevated temperatures which enhance diffusion between the metals. As a result, a brittle intermetallic phase, deteriorating the bond strength between steel and aluminum, forms at the interface. This paper focuses on study of the interfacial microstructure in a twin-roll cast Al-steel clad strip and its evolution during in-situ annealing in transmission electron microscope. Due to isochronal annealing above 500 °C, Al5Fe2 phase forms at the interface. Nucleation centers formed at the beginning of heating experiment expand and form continuous layer. The kinetics of the growth follows the parabolic law typical for diffusion-controlled phase transformations.}},
author = {{Křivská, Barbora and Šlapáková, Michaela and Minárik, Peter and Fekete, Klaudia and Králík, Rostislav and Stolbchenko, Mykhailo and Schaper, Mirko and Grydin, Olexandr}},
booktitle = {{APPLIED PHYSICS OF CONDENSED MATTER (APCOM 2021)}},
issn = {{0094-243X}},
location = {{Online}},
publisher = {{AIP Publishing}},
title = {{{In-situ TEM observation of intermetallic phase growth in Al-steel clad sheet}}},
doi = {{10.1063/5.0067491}},
year = {{2021}},
}
@article{24535,
abstract = {{Implementing the concept of mixed construction in modern automotive engineering requires the joining of sheet metal or extruded profiles with cast components made from different materials. As weight reduction is desired, these cast components are usually made from high-strength aluminium alloys of the Al-Si (Mn, Mg) system, which have limited weldability. The mechanical joinability of the cast components depends on their ductility, which is influenced by the microstructure. High-strength cast aluminium alloys have relatively low ductility, which leads to cracking of the joints. This limits the range of applications for cast aluminium alloys. In this study, an aluminium alloy of the Al-Si system AlSi9 is used to investigate relationships between solidification conditions during the sand casting process, microstructure, mechanical properties, and joinability. The demonstrator is a stepped plate with a minimum thickness of 2.0 mm and a maximum thickness of 4.0 mm, whereas the thickness difference between neighbour steps amounts to 0.5 mm. During casting trials, the solidification rates for different plate steps were measured. The microscopic investigations reveal a correlation between solidification rates and microstructure parameters such as secondary dendrite arm spacing. Furthermore, mechanical properties and the mechanical joinability are investigated.}},
author = {{Neuser, Moritz and Grydin, Olexandr and Andreiev, Anatolii and Schaper, Mirko}},
issn = {{2075-4701}},
journal = {{Metals}},
title = {{{Effect of Solidification Rates at Sand Casting on the Mechanical Joinability of a Cast Aluminium Alloy}}},
doi = {{10.3390/met11081304}},
year = {{2021}},
}
@article{24537,
author = {{Neuser, Moritz and Kappe, Fabian and Busch, M and Grydin, Olexandr and Bobbert, Mathias and Schaper, Mirko and Meschut, Gerson and Hausotte, T}},
issn = {{1757-8981}},
journal = {{IOP Conference Series: Materials Science and Engineering}},
title = {{{Joining suitability of cast aluminium for self-piercing riveting}}},
doi = {{10.1088/1757-899x/1157/1/012005}},
year = {{2021}},
}