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Aufsatz
Constant Temperature Approach for the Assessment of Injection Molding Parameter Influence on the Fatigue Behavior of Short Glass Fiber Reinforced Polyamide 6
(2021-05-13)
Short glass fiber reinforced plastics (SGFRP) offer superior mechanical properties compared to polymers, while still also enabling almost unlimited geometric variations of components at large-scale production. PA6-GF30 represents one of the most used SGFRP for series components, but the impact of injection molding process parameters on the fatigue properties is still insufficiently investigated. In this study, various injection molding parameter configurations were investigated on PA6-GF30. To take the significant ...
Aufsatz
Thermal Properties of Plasticized Cellulose Acetate and Its β-Relaxation Phenomenon
(2021-04-21)
Cellulose acetate (CA), an organic ester, is a biobased polymer which exhibits good mechanical properties (e.g., high Young’s modulus and tensile strength). In recent decades, there has been significant work done to verify the thermal and thermomechanical behaviors of raw and plasticized cellulose acetate. In this study, the thermomechanical properties of plasticized cellulose acetate—especially its β-relaxation and activation energy—were investigated. The general thermal behavior was analyzed and compared with ...
Aufsatz
On the low-cycle fatigue behavior of thermo-mechanically processed high-strength aluminum alloys
(2021)
In the present work low-cycle fatigue experiments were carried out on thermo-mechanically processed AA6082 and AA7075 sheets to evaluate mechanical properties under cyclic loading. Different cooling rates imposed by use of tempered forming tools after solutionizing and subsequent aging treatment led to the formation of precipitates with differing sizes and morphologies. Specimens thermo-mechanically processed in tools with temperatures of 24 °C and 200 °C showed superior mechanical properties under both monotonic and ...
Konferenzveröffentlichung
On the Challenges toward Realization of Functionally Graded Structures by Electron Beam Melting—Fe-Base Shape Memory Alloy and Stainless Steel
(ASTM International, 2020-09-22)
In the present study, an iron-manganese-aluminum-nickel (Fe-Mn-Al-Ni) shape memory alloy was processed on an austenitic steel (AISI 304) build platform by electron beam melting in order to study the feasibility of realizing functionally graded structures consisting of two different materials (i.e., a functional and a structural material). Compression specimens consisting of the processed shape memory alloy and the austenitic build platform in equal parts were investigated. The microstructure was analyzed in the ...
Aufsatz
Process Influences in the Combined Compacting and Back-Injection Process to Produce Back-Injected Self-Reinforced Composites (SRCs) – Analysis via Multiple Regression Modelling
(2021-11-21)
A new process to produce back-injected self-reinforced composites (SRCs) is presented. In contrast to other investigations on back-injection of SRCs, a process is presented which allows compacting and back injection of SRCs in one step where the SRCs are partly consolidated only via melt pressure inside the cavity. The mechanical properties of SRCs depend to a large extent on the process parameters of temperature and pressure during manufacture. These parameters are not yet known for back-injected areas. Sensors ...
Aufsatz
Joining of Contact Pins and Conductive Compounds via Injection Molding – Influence of the Flow Situation on the Electrical Contact Resistance
(2020-04-09)
While a lot of research can be found in the field of bulk resistance of carbon filled polymers, comparatively few papers focus on contact resistance between compound and metal contacts. Due to that small number of researches that deal with contact resistances, studies of the influence of injection molding conditions and parameters on the contact resistance are also very rare. In contradiction to that, these influences on bulk resistance have been studied. The objective of this work was to investigate the electrical ...
Dissertation
Bewertung von Eigenspannungen nach dem Laserstrahlhärten von komplex geformten Komponenten und additiv gefertigten Bauteilen
(2021)
Die Laserstrahlbearbeitung hat sich im Laufe der letzten Jahre zu einem wichtigen Forschungsschwerpunkt in industrieller und akademischer Hinsicht entwickelt. Neben der Erschließung neuer Anwendungsgebiete durch den Vorteil einer hohen Bearbeitungsflexibilität überzeugt die laserbasierte Materialbearbeitung vor allem durch einen lokal beeinflussbaren Energieeintrag. Jedoch sind derzeit mit zunehmender geometrischer Komplexität und Bauteilgröße nur begrenzte Tiefenwirkungen der gewünschten Druckeigenspannungen ...
Aufsatz
Effect of Crystallographic Orientation and Grain Boundaries on Martensitic Transformation and Superelastic Response of Oligocrystalline Fe–Mn–Al–Ni Shape Memory Alloys
(2021-07-26)
In situ tensile tests employing digital image correlation were conducted to study the martensitic transformation of oligocrystalline Fe–Mn–Al–Ni shape memory alloys in depth. The influence of different grain orientations, i.e., near-〈001〉 and near-〈101〉, as well as the influence of different grain boundary misorientations are in focus of the present work. The results reveal that the reversibility of the martensite strongly depends on the type of martensitic evolving, i.e., twinned or detwinned. Furthermore, it is ...
Aufsatz
Shape Memory Effect and Superelasticity of [001]-Oriented FeNiCoAlNb Single Crystals Aged under and without Stress
(2021-06-10)
The two-step ageing of Fe-28Ni-17Co-11.5Al-2.5Nb (at.%) single crystals under and without stress, leads to the precipitation of the γ′- and β-phase particles. Research has shown that γ–α′ thermoelastic martensitic transformation (MT), with shape memory effect (SME) and superelasticity (SE), develops in the [001]-oriented crystals under tension. SE was observed within the range from the temperature of the start of MT upon cooling Mₛ, to the temperature of the end of the reverse MT upon heating Af, and at temperatures ...
Aufsatz
Influence of the Miniaturisation Effect on the Effective Stiffness of Lattice Structures in Additive Manufacturing
(2020-10-29)
Thin-walled and cellular structures are characterised by superior lightweight potential due to their advantageous stiffness to weight ratio. They find particular interest in the field of additive manufacturing due to robust and reproducible manufacturability. However, the mechanical performance of such structures strongly depends on the manufacturing process and resultant geometrical imperfections such as porosity, deviations in strut thickness or surface roughness, for which an understanding of their influence is ...