No abstract

Additive manufacturing of polymers via material extrusion and its future applications are gaining interest. Supporting the evolution from prototype to serial applications, additional testing conditions are needed. The additively manufactured and anisotropic polymers often show a weak point in the interlayer contact area in the manufacturing direction. Different process parameters, such as layer height, play a key role for generating the interlayer contact area. Since the manufacturing productivity depends on the layer height as well, a special focus is placed on this process parameter. A small layer height has the objective of achieving better material performance, whereas a larger layer height is characterized by better economy. Therefore, the capability- and economy-oriented variation was investigated for strain rates between 2.5 and 250 s−1 under tensile and shear load conditions. The test series with dynamic loadings were designed monitoring future applications. The interlayer tensile tests were performed with a special specimen geometry, which enables a correction of the force measurement. By using a small specimen geometry with a force measurement directly on the specimen, the influence of travelling stress waves, which occur due to the impact at high strain rates, is reduced. The interlayer tensile tests indicate a strain rate dependency of additively manufactured polymers. The capability-oriented variation achieves a higher ultimate tensile and shear strength compared to the economy-oriented variation. The external and internal quality assessment indicates an increasing primary surface profile and void volume content for increasing the layer height.

123 Production-and microstructure-based fatigue assessment of metallic AISI 304/430 multilayer materials produced by hot pack rolling B. Mitevski, S. Weiß and A. Fischer 130 In-situ tensile testing of notched poly-and oligocrystalline 316L wires 136 Effect of processing conditions on the structure, electrical and mechanical properties of melt mixed high density polyethylene/multi-walled CNT composites in compression molding S. Gach, A. Schwedt, S. Olschok, U. Reisgen and J. Mayer 148 Confirmation of tensile residual stress reduction in electron beam welding using low transformation temperature materials (LTT) as localized metallurgical injection-Part 1: Metallographic analysis T. Srinivasa Rao, G. Madhusudhan Reddy and S. R. Koteswara Rao 155 Investigation on variations in hardness and microstructure of in-process cooled 7075 aluminum alloy friction stir welds M. Farajian, V. Hardenacke, W. Pfeiffer, M. Klaus and J. R. Kornmeier 161 Numerical and experimental investigations on shot-peened high-strength steel by means of hole drilling, X-ray, synchrotron and neutron diffraction analysis G. Sun and Z. Zhou 166 Ultrasonic imaging of particle distribution in SiCp/Al composites 183 Finite element analysis of a vibration test bed frame J. Gülen and M. İskeçeli 188 Removal of methylene blue by using porous carbon adsorbent prepared from carbonized chestnut shell

Material extrusion-based additive manufacturing techniques such as fused deposition modeling or fused filament fabrication are developing from prototyping applications to serial components. The aim of this study is to properly characterize an additively manufactured polymer with the corresponding process-induced defects. To this effect, varied manufacturing orientations of fused filament fabrication were tested with a single-batch material manufactured by injection molding serving as a reference. Scans were carried out via micro-computed tomography to assess the void content and distribution with respect to quality. Local material performance was investigated via quasi-static and cyclic tests under tensile loading. The quasi-static tensile tests indicated a significant reduction of Young’s modulus, tensile strength, and strain at fracture for the additively manufactured polymer. The mechanical investigations with cyclic loading intensified this trend of clear reduced mechanical properties due to process-induced defects. The quality assessment revealed void volume contents of the additively manufactured polymer of up to 6.5 % and a void distribution dependent on manufacturing orientation. The results of this study are valuable as design guidelines for highly stressed components and serve as a basis for further characterizations of process-induced defects.

The novel, additive manufacturing technique, continuous lattice fabrication, combines the advantages of continuous fiber-reinforcement with those of additive manufacturing. This enables the generation of fiber-reinforcement within a single layer and especially along an out-of-plane load path inside all spatial dimensions. This study is a test-related evaluation of sandwich panels with lattice core structures modifying a compression test. The specimens were manufactured differentially via plug and bond and automatically using continuous lattice fabrication. Additionally, the spatial arrangement of the rods within the lattice core structure varied in terms of base area. The ultra-lightweight sandwich panels have lattice core structures with core densities < 10 mg × cm−3. The material testing was performed by a modified compression test at room temperature. The damage analysis of the single rods shows current deficits and future potentials for optimization of lattice core structures. It could be shown that sandwich panels exhibit a compression strength of up to 0.30 MPa at a core density of 6.57 mg × cm−3. Using a dimensionless lightweight index demonstrates a mechanical performance on a level comparable with that of selected core materials.