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Aufsatz
Effects of blending poly(lactic acid) and thermoplastic polyester polyurethanes on the mechanical and adhesive properties in two-component injection molding
(2022-09-16)
One possible way to increase the use of bioplastics and thus contribute to a more resource-efficient and sustainable economy is to broaden the application range of such bioplastics. Poly(lactic acid) (PLA) is a promising and commercially available bio-based and biologically degradable polymer, which exhibits a high strength and stiffness but is very brittle. Blending with other polymers can lead to an enhancement of the ductility of the PLA. The goal of this work was to show that blending of PLA with a bio-based ...
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
Influence of ethylene oxide and gamma irradiation sterilization processes on the degradation behaviour of poly(lactic acid) (PLA) in the course of artificially accelerated aging
(2024-02-10)
To promote the application of bio-based materials in the field of medical technology, it is essential to conduct additional research, focusing on their long-term performance after sterilization. For this purpose, the study examines the aging behaviour of three poly(lactic-acid) (PLA) materials, sterilized with either ethylene oxide or gamma irradiation, over a two years aging period, in accordance with ASTM F1980-21. During these investigations, a direct correlation between moisture absorption and degradation progression ...
Aufsatz
Mechanical Characterization and Simulation of Wood Textile Composites (WTC) supported by Digital Image Correlation (DIC)
(2023-05-30)
Wood Textile Composites (WTC) based on willow wood fabrics and polypropylene were produced using a hot compacting process in order to open up new and innovative areas of applications for wood. Due to their attractive and variable design, the WTCs are to be used in areas with a high visual impact, for example as a facade element. In tensile and 3-point bending tests, it was shown that the mechanical properties of WTC are strongly dependent on the heterogeneous structure of the composite. Both strength and elongation ...
Aufsatz
Energy Resolved Residual Stress Analysis with Laboratory X-Ray Sources
(2017-04-17)
It is well known that existing residual stress fields play an important role for strength and lifetime of components. Consequently there is a great interest in the availability of fast, reliable and possibly nondestructive methods for their determination. In this context, X-ray diffraction methods play an important role in technical practice as well as in scientific research. They are based on the determination of lattice strains from which residual stresses are determined applying Hooke's law with appropriate elastic ...
Aufsatz
Pathways toward the Use of Non-Destructive Micromagnetic Analysis for Porosity Assessment and Process Parameter Optimization in Additive Manufacturing of 42CrMo4 (AISI 4140)
(2024-02-20)
Laser-based powder bed fusion of metals (PBF-LB/M) is a widely applied additive manufacturing technique. Thus, PBF-LB/M represents a potential candidate for the processing of quenched and tempered (Q&T) steels such as 42CrMo4 (AISI 4140), as these steels are often considered as the material of choice for complex components, e.g., in the toolmaking industry. However, due to the presence of process-induced defects, achieving a high quality of the resulting parts remains challenging in PBF-LB/M. Therefore, an extensive ...
Aufsatz
Modification of self-reinforced composites (SRCs) via film stacking process
(2022-02-25)
This work presents the mechanical behavior of self-reinforced composites (SRCs) manufactured and modified via film stacking. For modification, interleaved films made of polypropylene (PP), a thermoplastic elastomer and a polyolefin engage were combined in different ways to induce the elastic modifier into the matrix material. The content of modifier was also varied in two ways. First, the films were produced out of a single material and second out of a compound. So, the same content of modifier was implemented in two ...
Aufsatz
Bend Straightening of a Carbonitrided Gear Shaft – Consequences on Residual Stresses and Retained Austenite near the Surface
(2017-06-20)
Carbonitriding of shafts in drive technology is strongly connected with distortion. Bend straightening is an important process step in order to eliminate distortion without removing the hardened surface layer. As shown in several investigations, even for simple part geometries, bending induced stresses and plastic deformations have a strong impact not only on the residual stress state but also on the microstructure after straightening. As gear shafts become increasingly filigree and complex in their geometry, the ...
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 ...
Aufsatz
Parameter identification for constitutive models of innovative textile composite materials using digital image correlation
(2019-11-18)
This contribution focuses on an innovative composite material consisting of textile layers made from continuous wooden fibers embedded in a thermoplastic matrix. A finite element simulation of potential use‐cases is planned to support the development process and to study the suitability of the material in an architectural context. The simulation is based on a constitutive model assuming homogenous orthotropic elastic behavior and will be expanded to include multiscale modeling in future research. The material parameters ...