Aluminium to Carbon Fibre Reinforced Polymer tubes joints produced by magnetic pulse welding

Project SpIM, (2016/10605). ESA (ESA contract 4000111471/14/NL/PA). UID/EMS/00667/2019 (UNIDEMI).In this work, Aluminium AA7075-T6 to Carbon Fibre Reinforced Polymer (CFRP) tube joints using magnetic pulse welding technology were performed. The process was found suitable for joining this material combination when a rigid support is used to constrain the CFRP wall displacement. A minimum discharge energy of 2.5 kJ was seen to produce tight interfaces in tubular geometry for 1 mm of stand-off distance. A larger number of turns in the coil was found to reduce both the damages caused by the impact forces and to increase the joint axial resistance. To protect the CFRP tube from impacts and achieve a weld, an electrolytic Nickel coating was deposited over the CFRP tube. Welding was produced between the coating and the aluminium tube with no intermetallic compounds observed on the interface for the energies tested.authorsversionpublishe

A benchmark activity on the fatigue life assessment of AlSi10Mg components manufactured by L-PBF

One of the challenges associated with additive manufacturing (AM) is the definition of an assessment route which considers the main process signatures of the AM process. To this end, this work presents a complete benchmark activity for the assessment of an AlSi10Mg component produced by a laser pow- der bed fusion process, aimed at advancing the understanding of the fatigue resistance of AM materials with particular focus on the comparison between the fatigue performances of small coupons and demon- strators. Four builds of AlSi10Mg specimen geometries were manufactured to: (i) determine the fatigue curves for both as-built and machined conditions; (ii) measure the fatigue crack growth rate; (iii) produce and test under fatigue a benchmark component used as a reference for the validation of the fatigue assessment procedure. Tools and concepts of flaw tolerance were then used to perform the fatigue assess- ment of the benchmark component and were shown to be successful in the life prediction. Results obtained from this wide database (related to internal defects and surface features) show that only a fracture-based fatigue assessment is able to provide precise life estimates consistent with material crack growth properties. Eventually, all the experimental results including specimens design, analysis of frac- ture surfaces and raw tests’ data will be made available in a database which can be accessed and used by the industrial and scientific communities to calibrate and validate alternative fatigue assessment proce- dures of AM parts

Captive breeding of European freshwater mussels as aconservation tool: A review

1. Freshwater mussels are declining throughout their range. Their importantecological functions along with insufficient levels of natural recruitment haveprompted captive breeding for population augmentation and questions about the usefulness and applicability of such measures. 2. This article reviews the current state of captive breeding and rearing programmes for freshwater mussels in Europe. It considers the various species, strategies, andtechniques of propagation, as well as the different levels of effort requiredaccording to rearing method, highlighting the key factors of success. 3. Within the last 30 years, 46 breeding activities in 16 European countries have been reported, mainly of Margaritifera margaritifera and Unio crassus. Some facilities propagate species that are in a very critical situation, such as Pseudunio auricularius, Unio mancus, and Unio ravoisieri, or multiple species concurrently. Insome streams, the number of released captive-bred mussels already exceeds the size of the remaining natural population. 4. Rearing efforts range from highly intensive laboratory incubation to lowerintensity methods using in-river mussel cages or silos. Most breeding efforts are funded by national and EU LIFE(+) grants, are well documented, and consider the genetic integrity of the propagated mussels. Limited long-term funding perspectives, the availability of experienced staff, water quality, and feeding/survival during early life stages are seen as the most important challenges. 5. Successful captive breeding programmes need to be combined with restoration ofthe habitats into which the mussels are released. This work will benefit from anevidence-based approach, knowledge exchange among facilities, and an overall breeding strategy comprising multiple countries and conservation units. aquaculture, captive breeding, conservation translocation, freshwater mussel culturing, Margaritifera margaritifera, propagation, reintroduction, Unio crassusCaptive breeding of European freshwater mussels as aconservation tool: A reviewpublishedVersio

Research priorities for freshwater mussel conservation assessment

Freshwater mussels are declining globally, and effective conservation requires prioritizing research and actions to identify and mitigate threats impacting mussel species. Conservation priorities vary widely, ranging from preventing imminent extinction to maintaining abundant populations. Here, we develop a portfolio of priority research topics for freshwater mussel conservation assessment. To address these topics, we group research priorities into two categories: intrinsic or extrinsic factors. Intrinsic factors are indicators of organismal or population status, while extrinsic factors encompass environmental variables and threats. An understanding of intrinsic factors is useful in monitoring, and of extrinsic factors are important to understand ongoing and potential impacts on conservation status. This dual approach can guide conservation status assessments prior to the establishment of priority species and implementation of conservation management actions.NF-R was supported by a post-doctoral fellowship (Xunta de Galicia Plan I2C 2017-2020, 09.40.561B.444.0) from the government of the autonomous community of Galicia. BY was supported by the Ministry of Science and Higher Education (no. 0409-2016-0022). DLS was supported by the G. E. Hutchinson Chair at the Cary Institute of Ecosystem Studies. AO was supported by the Russian Foundation for Basic Research (no. 17-44-290016). SV was funded by European Investment Funds by FEDER/COMPETE/POCI- Operacional Competitiveness and Internacionalization Programme, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT-Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013. NF-R is very grateful to the University of Oklahoma Biological Survey for providing space to work in the U.S. and especially to Vaughn Lab members. Authors are very grateful to Akimasa Hattori, Allan K. Smith, Andrew Roberts, Daniel Graf, David Stagliano, David T. Zanatta, Dirk Van Damme, Ekaterina Konopleva, Emilie Blevins, Ethan Nedeau, Frankie Thielen, Gregory Cope, Heinrich Vicentini, Hugh Jones, Htilya Sereflisan, Ilya Vikhrev, John Pfeiffer, Karen Mock, Mary Seddon, Katharina Stockl, Katarzyna Zajac, Kengo Ito, Marie Capoulade, Marko Kangas, Michael Lange, Mike Davis, Pirkko-Liisa Luhta, Sarina Jepsen, Somsak Panha, Stephen McMurray, G. Thomas Watters, Wendell R. Haag, and Yoko Inui for their valuable contribution in the initial selection and description of extrinsic and intrinsic factors. We also wish to thank Dr. Amanda Bates, Chase Smith, and two anonymous reviewers for comments on earlier drafts of this manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government

HCF resistance of AlSi10Mg produced by SLM in relation to the presence of defects

Being able to predict the fatigue resistance of parts produced by additive manufacturing (AM) is a very actual and frequent open issue. The qualification of AM structural parts needs a very costly and time consuming series of fatigue tests, on both samples and full-scale parts. A proper control of the AM process allows obtaining comparable and even better fatigue resistance than standard manufacturing. Despite this, the experimental results often show a large scatter, mostly due to the presence of defects. In this framework, this work summarizes a research activity aiming at modelling the high cycle fatigue (HCF) resistance in presence of defects, focusing on AlSi10Mg produced by selective laser melting (SLM). Two batches of samples were investigated by computed tomography (CT) and tested. A lower bound resistance curve was obtained introducing artificial defects. A fatigue crack growth simulation model based on the maximum defect size is proposed, able to estimate both the life and the scatter of the data in the fully-elastic region. Moreover, knowing the size and position of all the defects inside the samples, it was possible to foresee the defect at the origin of fatigue failure and to draw a hazard ranking based on the applied stress intensity factor

Fatigue properties of AlSi10Mg obtained by additive manufacturing: Defect-based modelling and prediction of fatigue strength

Ability to predict the fatigue resistance of parts produced by additive manufacturing (AM) is a very current and frequently relevant open issue. The qualification of AM structural parts often needs a costly and time-consuming series of fatigue tests, on both samples and full-scale parts. Proper control of the AM process allows obtaining comparable and even better fatigue resistance than those obtained with standard manufacturing. Despite this, the experimental results often show a large scatter, mostly due to the presence of defects. In this framework, the present work summarizes the research activity aimed at modelling the high cycle fatigue (HCF) resistance in the presence of defects, focusing on AlSi10Mg produced by selective laser melting. Three batches of samples were investigated by X-ray micro computed tomography and tested under fatigue. A lower bound resistance curve was obtained, which introduced artificial defects of size corresponding to that of the largest occurring defects. The analysis shows that a combination of defect-tolerant design with well-established and newly proposed fracture mechanics methods is the key to expressing the relationship between the fatigue strength and material quality. This is done through suitable statistics of material defects induced by the AM process. The same concepts are then applied in a fatigue crack growth simulation model based on the maximum defect size, for estimating both the life and scatter of the data in the region of elastic material response. Based on this wide activity, it can be concluded that fracture mechanics-based analysis appears to be the tool needed for supporting the application of additive manufacturing to safety-critical components and their qualification

Qualification of AM parts: Extreme value statistics applied to tomographic measurements

reserved5siThe progressive improvement of additive manufacturing (AM) techniques enables the production of geometrically complex and lightweight parts, which explains the incredibly fast growth of AM for space and aerospace applications. The first standards require the production of witness specimens manufactured together with the components for assessment and qualification for the material control. However, one of the most critical issues is determining the âfitness-for-purposeâ of fatigue loaded parts, which is strictly related to the microstructure and defects generated during the manufacturing process. One of the most suitable techniques for detecting defects even near the surface or in thin, complex geometries is micro-computed tomography (μ-CT). This paper deals with the application of statistics of extremes for analysing X-ray CT scan measurements in view of component assessment by discussing its advantages and requirements.mixedRomano, S; Brandã£o, A.; Gumpinger, J.; Gschweitl, M.; Beretta, S.Romano, Simone; Brandã£o, A.; Gumpinger, J.; Gschweitl, M.; Beretta, Stefan

Quality control of AlSi10Mg produced by SLM: Metallography versus CT scans for critical defect size assessment

While the adoption of metal additive manufacturing (AM) is growing exponentially owing to its wide range of potential applications, its application to safety-critical and structural parts is significantly impeded by the lack of standards. Quality assessment of AM products is a crucial requirement, as the AM process induces internal defects that can have detrimental effects on the fatigue resistance.By evaluating the defect distribution, it is possible to perform a fracture mechanics assessment to estimate the fatigue strength and service lifetime of AM materials. This strategy has been successfully applied to selective laser-melted AlSi10Mg by performing X-ray micro-computed tomography (mu CT) and applying suitable statistical methods (i.e., statistics of extremes). However, it remains unclear whether complex and expensive nondestructive inspection methods (e.g., mu CT) are necessary and whether simpler and more conventional approaches (i.e., microscopy of polished sections (PSs), as prescribed by ASTM E2283) would provide equivalent information for the estimation of internal defects.In this study, the size of the most detrimental defect was estimated by performing both light microscopy on PSs and mu CT on three batches of fatigue specimens characterized by different internal porosities. The results showed that both techniques were able to pinpoint a significant difference in the prospective largest defect in a material volume corresponding to the gauge section of a specimen. However, extrapolation of the critical defect size for fatigue failure using PS data was less accurate and less conservative than that using CT data. An evaluation of the techniques with regard to time and cost indicated that mu CT allowed the investigation of larger sample volumes and the reduction of both man hours and cost