@misc{YellurSeidlitzKukeetal., author = {Yellur, Manoja Rao and Seidlitz, Holger and Kuke, Felix and Wartig, Kevin and Tsombanis, Nikolas}, title = {A low velocity impact study on press formed thermoplastic honeycomb sandwich panels}, series = {Composite Structures}, volume = {225}, journal = {Composite Structures}, issn = {0263-8223}, doi = {10.1016/j.compstruct.2019.111061}, pages = {111061}, abstract = {At present plywood structures are used in the loading area of utility structures. Low velocity impact studies on these structures showed cracks on its lower surface. Hence, in the current study low-velocity impact of a lighter honeycomb sandwich structure is investigated to satisfy the needs of the utility vehicle segment. To meet this objective, facing sheets are manufactured using the polypropylene matrix and glass fibers. Polypropylene honeycombs are used in the study. Depending on the experimental boundary conditions, a cross-ply laminate set up is used for the facing sheets. An impact energy of 100 J is chosen in the study. This energy caused visible failure on the plywood sample. Hence a lighter sandwich construction which can resist 100 J impact is implemented in this study. Influence of top and bottom facing sheet thicknesses on the amount of damage inflicted on its surfaces are studied. Experimental histories of absorbed energy and contact force are recorded. A finite element analysis is performed using LS-DYNA and numerical results are compared with the experimental responses. A honeycomb sandwich panel [0/90/90/0/Core/0/90/90/0] meeting the objective of the study is seen as an optimum replacement for the existing plywood structures.}, language = {en} } @inproceedings{SeidlitzKukeTsombanis, author = {Seidlitz, Holger and Kuke, Felix and Tsombanis, Nikolas}, title = {Advanced joining technology for the production of highly stressable lightweight structures, with fiber-reinforced plastics and metal}, series = {3rd International MERGE Technologies Conference (IMTC), Chemnitz, 2017}, volume = {1}, booktitle = {3rd International MERGE Technologies Conference (IMTC), Chemnitz, 2017}, number = {2}, doi = {10.21935/tls.v1i2.76}, pages = {54 -- 67}, abstract = {Organic sheets made of fiber-reinforced thermoplastics can make a crucial contribution to increase the lightweight potential of a technical design. They show high specific strength- and stiffness properties as well as good damping characteristics, while being able to show a higher energy absorption capacity than comparable metal constructions. In addition, organic sheets provide good recycling capabilities. Nowadays, multi-material designs are an established way in the automotive industry to combine the benefits of metal and fiber-reinforced plastics (FRP). Currently used technologies for the joining of organic sheets and metals in large-scale production are mechanical joining and adhesive technologies. Both require large overlapping areas to achieve the desired joint strength and stiffness of the technical design. Additionally, mechanical joining is usually combined with "fiber-destroying" pre-drilling and punching processes. This will disturb the force flux at the joint zone by causing unwanted fiber- and inter-fiber failure and inducing critical notch stresses. Therefore, the multi-material design with fiber-reinforced thermoplastics and metals needs optimized joining techniques that don't interrupt the force flux, so that higher loads can be induced and the full benefit of the FRP material can be used. This article focuses on the characterization of a new joining technology, based on the Cold Metal Transfer (CMT) welding process, that allows to join organic sheets and metals in a load path optimized design. This is achieved by realigning the fibers around the joint zone by the integration of a thin metal pin. The alignment of the fibers will be similar to load paths of fibers inside structures found in nature. A tree with a knothole is always going to align its fibers in principle stress direction. As a result of the bionic fiber design, high joining strengths can be achieved. The increase of the joint strength compared to blind riveting was performed and proven with stainless steel and orthotropic reinforced composites in tensile shear-tests, based on the DIN EN ISO 14273.}, language = {en} } @inproceedings{SeidlitzKukeTsombanis, author = {Seidlitz, Holger and Kuke, Felix and Tsombanis, Nikolas}, title = {Leichtbautechnologien und Mischbauweisen mit Faser-Kunststoff-Verbunden}, series = {Innovationsforum des Regionalen Wachstumskerns Westlausitz, Cottbus, 2016}, booktitle = {Innovationsforum des Regionalen Wachstumskerns Westlausitz, Cottbus, 2016}, pages = {19}, language = {de} } @misc{SanthanakrishnanBalakrishnanSeidlitzWartigetal., author = {Santhanakrishnan Balakrishnan, Venkateswaran and Seidlitz, Holger and Wartig, Kevin and Tsombanis, Nikolas}, title = {Influence of processing parameters on the impact behaviour of glass/polyamide-6 composite}, series = {Composites Part B: Engineering}, volume = {159}, journal = {Composites Part B: Engineering}, issn = {1359-8368}, doi = {10.1016/j.compositesb.2018.09.064}, pages = {292 -- 299}, abstract = {This study aims to investigate the low-velocity impact response and post-impact flexural behaviour of glass/polyamide-6 (G/PA-6) composite. G/PA-6 composites with a layup configuration of [02,902]s were prepared via press-forming technique. Composite samples were developed using four different processing conditions, by modifying compression pressure and heating temperature. Local variations of fiber volume and porosity fraction were noticed for samples developed in each processing conditions. On the investigated samples, damages were induced by using 35 joule of drop weight impact to investigate the impact resistance of samples with respect to different processing conditions. The damage behaviour and residual flexural strength was characterized using a micro-CT and three-point bending tests respectively. Furthermore, the influence of porosity fraction on the residual flexural strength were investigated. This paper will provide necessary fundamental knowledge for future selection of processing parameters in order to have enhanced impact performance.}, language = {en} }