Multi-Response Optimization of Ti6Al4V Support Structures for Laser Powder Bed Fusion Systems

Data Availability Statement: All data analyzed or generated during the study are included in this article.Copyright © 2023 by the authors. Laser Powder Bed Fusion (LPBF) is one of the most commonly used and rapidly developing metal Additive Manufacturing (AM) technologies for producing optimized geometries, complex features, and lightweight components, in contrast to traditional manufacturing, which limits those characteristics. However, this technology faces difficulties with regard to the construction of overhang structures and warping deformation caused by thermal stresses. Producing overhangs without support structures results in collapsed parts, while adding unnecessary supports increases the material required and post-processing. The purpose of this study was to evaluate the various support and process parameters for metal LPBF, and propose optimized support structures to minimize Support Volume, Support Removal Effort, and Warping Deformation. The optimization approach was based on the Design of Experiments (DOE) methodology and multi-response optimization, by 3D printing and studying overhang geometries from 0° to 45°. For this purpose, EOS Titanium Ti64 Grade 5 powder was used, a Ti6Al4V alloy commonly employed in LPBF. For 0° overhangs, the optimum solution was characterized by an average Tooth Height, large Tooth Top Length, low X, Y Hatching, and high Laser Speed, while for 22.5° and 45° overhangs, it was characterized by large Tooth Height, low Tooth Top Length, high X, Y Hatching, and high Laser Speed.This publication was made possible by the sponsorship and support of Lloyd’s Register Foundation (LRF). The work was enabled through, and undertaken at, the National Structural Integrity Research Centre (NSIRC), a postgraduate engineering facility for industry-led research into structural integrity, established and managed by TWI Ltd. through a network of both national and international universities

Support Structures Optimisation for High-Quality Metal Additive Manufacturing with Laser Powder Bed Fusion: A Numerical Simulation Study

Data Availability Statement: Data are contained within the article and Supplementary Materials available online at: https://www.mdpi.com/article/10.3390/ma16227164/s1, The “DOE set-up” file.Copyright . This study focuses on Metal Additive Manufacturing (AM), an emerging method known for its ability to create lightweight components and intricate designs. However, Laser Powder Bed Fusion (LPBF), a prominent AM technique, faces a major challenge due to the development of high residual stress, resulting in flawed parts and printing failures. The study’s goal was to assess the thermal behaviour of different support structures and optimised designs to reduce the support volume and residual stress while ensuring high-quality prints. To explore this, L-shaped specimens were printed using block-type support structures through an LPBF machine. This process was subsequently validated through numerical simulations, which were in alignment with experimental observations. In addition to block-type support structures, line, contour, and cone supports were examined numerically to identify the optimal solutions that minimise the support volume and residual stress while maintaining high-quality prints. The optimisation approach was based on the Design of Experiments (DOE) methodology and multi-objective optimisation. The findings revealed that block supports exhibited excellent thermal behaviour. High-density supports outperformed low-density alternatives in temperature distribution, while cone-type supports were more susceptible to warping. These insights provide valuable guidance for improving the metal AM and LPBF processes, enabling their broader use in industries like aerospace, medical, defence, and automotive.Brunel Innovation Centre; Core Research Programme (CRP) “Remove” project. This publication was made possible by the sponsorship and support of Lloyd’s Register Foundation (LRF). The work was enabled through, and undertaken at, the National Structural Integrity Research Centre (NSIRC), a postgraduate engineering facility for industry-led research into structural integrity, established and managed by TWI Ltd. through a network of both national and international universities

Correction: Dimopoulos et al. Multi-Response Optimization of Ti6Al4V Support Structures for Laser Powder Bed Fusion Systems. J. Manuf. Mater. Process. 2023, 7, 22

Reference of original article: Dimopoulos, A. et al. (2023) 'Multi-Response Optimization of Ti6Al4V Support Structures for Laser Powder Bed Fusion Systems',.Journal of Materials Processing and Manufacturing Science, 7 (1), 22, pp. 1 - x. doi: 10.3390/jmmp7010022.Error in Table: In the original publication [1], there is an error in Table 9. The Lower Limit of Laser Speed should be 1000 mm/s, not 100 mm/s. Error in Figure: In the original publication [1], there was a mistake in “Figure 12” as published. The value “1.13” in the warping deformation chart should be replaced with the value “0.13”. The authors state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated

An Interactive Web-Based Platform for Support Generation and Optimisation for Metal Laser Powder Bed Fusion

Data Availability Statement: Data are contained within the article and Supplementary Materials: supporting information can be downloaded at https://www.mdpi.com/article/10.3390/ma17071639/s1. Equations for support optimisation module, STL specimen_1, STL specimen_2.Powder bed fusion—laser beam (PBF-LB), a prevalent and rapidly advancing additive manufacturing (AM) technology nowadays, serves the industry by producing thin, complex, and lightweight components for various sectors, including healthcare, automotive, defence, and aerospace. However, this technology encounters challenges related to the construction of critical parts and the high overall process costs. Equally significant is the role of support structures in metal laser powder bed fusion (PBF-LB/M). The absence of supports can lead to defective and collapsed parts, while the incorrect selection of a support type or the addition of unnecessary supports results in increased material usage and additional post-processing efforts. Therefore, there is a pressing need for advanced software capable of generating appropriate support structures and predicting the thermomechanical behaviour of a part under PBF-LB/M printing conditions. Such software would be beneficial for the industry to avoid printing defects caused by high thermal stresses, minimise material usage, reduce printing time, and ensure high-quality prints. In this study, we introduce a web-based support generation and optimisation platform for PBF-LB/M. Through this platform, among other features, users can import three-dimensional (3D) parts and generate block-type support structures with diamond perforations based on the PySLM library, all within a user-friendly web environment. The first release of the platform (v0.6) is fully interactive and accessible online at no cost.This publication was made possible by the sponsorship and support of Lloyd’s Register Foundation. The work was enabled through and undertaken at the National Structural Integrity Research Centre (NSIRC), a postgraduate engineering facility for industry-led research into structural integrity, established and managed by TWI Ltd. through a network of both national and international universities

An ICT-Enabled Approach to Optimising the Reliability of Manual Ultrasonic Non-Destructive Testing

Manual Ultrasonic Testing (MUT) is the most cost effective NDT method for the in-situ inspection of aerospace structures, in particular composite structures. However, its defect detection reliability is low. Manual Ultrasonic Testing (MUT) reports may vary depending on the operator conducting the test. Its reliability is therefore greatly influenced by human factors. Nonetheless, MUT continues to play a key role in the NDT suite of techniques. Despite its simplicity, it often meets the required performance at a reduced cost. No mechanised system exists which is as dextrous as the human hand for moving a probe over complex shapes while also dynamically skewing the probe to achieve the maximum amplitude from a reflector. It is therefore worth looking at ways to improve the reliability of MUT

Letales Mittelliniengranulom - Ein Fallbericht

Einleitung: Das sehr seltene extranodale Nk/T-Zell-Lymphom vom nasalen Typ, auch "letales Mittelliniengranulom", gehört in die Gruppe der Non-Hodgkin-Lymphome, ist mit einer Epstein-Barr-Virus (EBV)-Infektion assoziiert und durch einen sehr aggressiven Verlauf charakterisiert. Die mediane Überlebenszeit beträgt 6 Monate, die 5-Jahres-Überlebensrate 22%.Methoden: Es wird der Erkrankungsverlauf eines 72-jährigen Patienten geschildert, der im März 2012 an den Nasennebenhöhlen operiert worden war. Danach kam es zu einer zunehmenden endonasalen Borkenbildung und Entzündung. Ergebnisse: Histologisch ergab sich der Verdacht auf einen M. Wegener, der laborchemisch nicht zu bestätigen war. Es wurde trotzdem eine Therapie mit Cotrimoxazol und Prednisolon begonnen. Darunter kam es zu einer Remission, die mit Azathioprin sowie Kortison in absteigender Dosierung weiterbehandelt worden war. Ca. 4 Wochen später, unter 10 mg Kortison kam es zu einer massiven Progression des endonasalen Befundes sowie zur Auftreibung der Oberlippe sowie der Wangen. Histologisch war nun ein EBV-assoziiertes, angiozentrisches bzw. angiodestruktives, peripheres T-Zell-Lymphoms vom nasalen Typ nachweisbar. Im durchgeführten Ganzkörper-CT sowie einer Knochenmarkspunktion ließ sich keine weitere Ausbreitung des Lymphoms feststellen.Es wurde daraufhin mit einer Chemotherapie nach dem Chop-Protokoll (Cyclophosphamid, Hydroxydaunorubicin, Oncovin®, Prednisolon) begonnen. Da es darunter ebenfalls nicht zu einer Besserung kam wurde auf Cytarabin (AraC) umgestellt. Darunter war der Lokalbefund langsam rückläufig, und es wurde zusätzlich noch eine lokale Radiatio angeschlossen.Schlussfolgerungen: Bislang existieren keine definierten Therapieprotokolle für diese sehr aggressive Erkrankung. Diskutiert werden eine sofortige hochdosierte Strahlentherapie versus primärer oder adjuvanter Chemotherapie.Der Erstautor gibt keinen Interessenkonflikt an

6-thioguanine selectively kills BRCA2-defective tumors and overcomes PARP inhibitor resistance.

Familial breast and ovarian cancers are often defective in homologous recombination (HR) due to mutations in the BRCA1 or BRCA2 genes. Cisplatin chemotherapy or poly(ADP-ribose) polymerase (PARP) inhibitors were tested for these tumors in clinical trials. In a screen for novel drugs that selectively kill BRCA2-defective cells, we identified 6-thioguanine (6TG), which induces DNA double-strand breaks (DSB) that are repaired by HR. Furthermore, we show that 6TG is as efficient as a PARP inhibitor in selectively killing BRCA2-defective tumors in a xenograft model. Spontaneous BRCA1-defective mammary tumors gain resistance to PARP inhibitors through increased P-glycoprotein expression. Here, we show that 6TG efficiently kills such BRCA1-defective PARP inhibitor-resistant tumors. We also show that 6TG could kill cells and tumors that have gained resistance to PARP inhibitors or cisplatin through genetic reversion of the BRCA2 gene. Although HR is reactivated in PARP inhibitor-resistant BRCA2-defective cells, it is not fully restored for the repair of 6TG-induced lesions. This is likely to be due to several recombinogenic lesions being formed after 6TG. We show that BRCA2 is also required for survival from mismatch repair-independent lesions formed by 6TG, which do not include DSBs. This suggests that HR is involved in the repair of 6TG-induced DSBs as well as mismatch repair-independent 6TG-induced DNA lesion. Altogether, our data show that 6TG efficiently kills BRCA2-defective tumors and suggest that 6TG may be effective in the treatment of advanced tumors that have developed resistance to PARP inhibitors or platinum-based chemotherapy