Tensile and nanoindentation tests analysis of Ti6Al4V alloy manufactured by laser powder bed fusion

Additive manufacturing (AM) technologies are widely used in the fabrication of topologically complex components with thin-walled features, such as lattice structures. In this context, Laser Powder Bed Fusion (L-PBF) is one of the most commonly used AM technologies for producing such components. In order to further expand and justify the application of these components in operation and to model their mechanical behavior, it is necessary to know the mechanical properties of the matrix material from which they are formed. Therefore, there is currently a high interest in studying the behavior of these materials when subjected to monotonic or cyclic loading. However, determining the mechanical properties of the matrix material of thin-walled structures using tensile tests is challenging on the required subsize specimens. As a micro- or even nano-scale technology, nanoindentation can be used to probe a small volume of specimen, thus allowing the mechanical properties such as Young modulus, of thin-walled structures to be determined. In this work, Young's modulus of L-PBF Ti6Al4V alloy produced using different laser power and scanning speed combinations, has been determined on nano and macro scale. By comparing obtained results at both scales, it is evident that Young's modulus values determined at nano scale are higher and more scattered when compared to results determined at macro scale. Furthermore, this study implies that a wider range or a higher number of L-PBF process parameters should be considered to model it's influence on Young's modulus with higher accuracy

Process parameters optimization in fused deposition modeling of polyether ether ketone

Fused Deposition Modeling is increasingly used for producing high-performing, creepresistant, biocompatible, fireproof, highly-stable parts from polyether ether ketone. However, the knowledge on this process is still poor and fragmented, and the lack of relevant data inhibits many applications. In this paper, the effects of the nozzle temperature, nozzle speed and layer thickness on the properties of PEEK processed by Fused Deposition Modeling were investigated by performing indentation, tensile, Scanning Electron Microscope, Computer Tomography and Energy Dispersive X-ray Spectroscopy tests on as-built samples. The outgassing behavior was also analyzed, while the synchrotron radiation was used to characterize the structure of selected samples on a hitherto unexplored scale. The samples morphology was finally used to identify the optimal process window. The results provided new insights on the process and novel data enabling new applications

A Study on the Compressive Behavior of Additively Manufactured AlSi10Mg Lattice Structures

The mechanical behavior of the metallic components fabricated by additive manufacturing (AM) technologies can be influenced by adjustments in their microstructure or by using specially engineered geometries. Manipulating the topological features of the component, such as incorporating unit cells, enables the production of lighter metamaterials, such as lattice structures. This study investigates the mechanical behavior of lattice structures created from AlSi10Mg, which were produced using the laser beam powder bed fusion (LB-PBF) process. Specifically, their behavior under pure compressive loading has been numerically and experimentally investigated using ten different configurations. Experimental methods and finite element analysis (FEA) were used to investigate the behavior of body-centered cubic (BCC) lattice structures, specifically examining the effects of tapering the struts by varying their diameters at the endpoints ((Formula presented.)) and midpoints ((Formula presented.)), as well as altering the height of the joint nodes (h). The unit cells were designed with varying parameters in such a way that (Formula presented.) is changed at three levels, while (Formula presented.) and h are changed at two levels. Significant differences in Young’s modulus, yield strength, and ultimate compressive strength between the various specimen configurations were observed both experimentally and numerically. The FEA underestimated the Young’s modulus corresponding to the configurations with thinner struts in comparison to the higher values found experimentally. Conversely, the FEA overestimated the Young’s modulus of those configurations with larger strut diameters with respect to the experimentally determined values. Additionally, the proposed FE method consistently underestimated the yield strength relative to the experimental values, with notable discrepancies in specific configurations

Induced pluripotent stem cell line heterozygous for p.R501X mutation in filaggrin: KCLi003-A

We have generated an induced pluripotent stem cell (iPSC) line KCLi003-A (iOP101) from epidermal keratinocytes of a female donor, heterozygous for the loss-of-function mutation p.R501X in the filaggrin gene (FLG), using non-integrating Sendai virus vectors. Derivation and expansion of iPSCs were performed under xeno-free culture conditions. Characterization and validation of KCLi003-A line included molecular karyotyping, mutation screening using restriction enzyme digestion, next generation sequencing (NGS), while pluripotency and differentiation potential were confirmed by expression of associated markers in vitro and by in vivo teratoma assay

A volume-tracking method for the modelling of multi-fluid flows in engineering unit operations

A numerical code is presented for the numerical simulation of multi-fluid flows in pyrometallurgical unit operations. The code, MFVOF, is a finite difference code that allows transient solutions to immiscible multi-fluid flow problems to be generated in 2-D Cartesian and cylindrical geometries. The code is based on the use of an accurate PLIC (piecewise linear interface calculation) volume-tracking scheme to track the distortions of fluid bodies, with a redistribution procedure to ameliorate the formation of subgrid-scale fluid ligaments. Other recent enhancements to the code include swirl and expansion/compression modelling. The MFVOF code is not only able to model flows with low-curvature interface traditional applications of volume tracking - it is also able to generate robust and realistic transient representations of fragmentation and coalescence involving higher-curvature interfaces. This suggests that volume tracking can become increasingly useful for multi-phase flow modelling in chemical engineering unit operations, beyond traditional civil engineering and metallurgical applications