Automated procedure for determination of friction grip and bearing joint strength used for space missions

This paper presents an algorithm that calculates the nominal torque for friction grip joints, followed by its implementation in a Microsoft Excel worksheet that is automated by a macro written in Visual Basic. The algorithm outputs not only the optimum nominal torque (the value for which the margin of safety is maximum) but also the interval of acceptable values so that the user can easily choose the torque according to his preferences

End-to-end process of hollow spacecraft structures with high frequency and low mass obtained with in-house structural optimization tool and additive manufacturing

In the space sector the most decisive elements are: mass reduction, cost saving and minimum lead time; here, structural optimization and additive layer manufacturing (ALM) fit best. The design must be driven by stiffness, because an important requirement for spacecraft (S/C) structures is to reduce the dynamic coupling between the S/C and the launch vehicle. The objective is to create an end-to-end process, from the input given by the customer to the manufacturing of an aluminum part as light as possible but at the same time considerably stiffer while taking the full advantage of the design flexibility given by ALM. To design and optimize the parts, a specialized in-house tool was used, guaranteeing a load-sufficient material distribution. Using topological optimization, the iterations between the design and the stress departments were diminished, thus greatly reducing the lead time. In order to improve and lighten the obtained structure a design with internal cavities and hollow beams was considered. This implied developing of a procedure for powder evacuation through iterations with the manufacturer while optimizing the design for ALM. The resulted part can be then manufactured via ALM with no need of further design adjustments. To achieve a high-quality part with maximum efficiency, it is essential to have a loop between the design team and the manufacturer. Topological optimization and ALM work hand in hand if used properly. The team achieved a more efficient structure using topology optimization and ALM, than using conventional design and manufacturing methods

VTVL concept optimisation of the landing gear

Vertical takeoff, vertical landing (VTVL) is a subject of international interest at the moment thanks to the successful recovery of the Blue Origin vehicle. Aggressive weight targets with a short development time in the aerospace and space industry clearly need an integration of advanced computer aided structural optimization methods. Topological optimization is used from the concept phase of a design process development in order to obtain a fundamental design approach. The aim of the article is to determine the principal directions for distribution of the material for a VTVL landing gear within the specified volume in order to obtain the initial design approach. To achieve the maximum performance within the studied component, the result is then refined from a manufacturability point of view. The use of such methods notably reduces the development iterations between the design and stress departments. Thus, the overall time is reduced which translates into a lower overall cost and shorter time development from the concept to the final product

Comparative Analysis Program for Experimental and Calculated Data

This article aims to provide an interactive in-house tool to quickly asses the stress in the critical points of the aeronautical structures. The software compares the results between the stress values obtained from the experimental tests using the resistive electrical tensometry technique (RET) and the stress values calculated with FEM software. RET refers to the stress and strains measured by strain gauges applied to the critical points of the structures. The finite element analysis was carried-out with MSC. PATRAN/ NASTRAN using shell and solid elements in order to identify the critical points based on the stress and strain results. The validation of the results obtained by the finite element modelling has been made experimentally using the resistive electrical tensometry method. The results from these two methods have been compared with the in-house software developed in Visual Basic with Excel interface. The program evaluates the relative error between the experimental and calculated data at critical points

Nanofiltration Composite Membranes Based on KIT-6 and Functionalized KIT-6 Nanoparticles in a Polymeric Matrix with Enhanced Performances

The nanofiltration composite membranes were obtained by incorporation of KIT-6 ordered mesoporous silica, before and after its functionalization with amine groups, into polyphenylene-ether-ether-sulfone (PPEES) matrix. The incorporation of silica nanoparticles into PPEES polymer matrix was evidenced by FTIR and UV–VIS spectroscopy. SEM images of the membranes cross-section and their surface topology, evidenced by AFM, showed a low effect of KIT-6 silica nanoparticles loading and functionalization. The performances of the obtained membranes were appraised in permeation of Chaenomeles japonica fruit extracts and the selective separation of phenolic acids and flavonoids. The obtained results proved that the PPEES with functionalized KIT-6 nanofiltration membrane, we have prepared, is suitable for the polyphenolic compound’s concentration from the natural extracts

Highlighting the Relevance of Gut Microbiota Manipulation in Inflammatory Bowel Disease

Two different conditions are included in inflammatory bowel disease (IBD), Crohn’s disease (CD) and ulcerative colitis (UC), being distinguished by chronic recurrence of gut inflammation in persons that are genetically predisposed and subjected to environmental causative factors. The normal structure of the gut microbiome and its alterations in IBD were defined in several microbial studies. An important factor in the prolonged inflammatory process in IBD is the impaired microbiome or “dysbiosis”. Thus, gut microbiome management is likely to be an objective in IBD treatment. In this review, we analyzed the existing data regarding the pathophysiological/therapeutic implications of intestinal microflora in the development and evolution of IBD. Furthermore, the main effects generated by the administration of probiotics, prebiotics, fecal transplantation, and phytochemicals supplementation were analyzed regarding their potential roles in improving the clinical and biochemical status of patients suffering from Crohn’s disease (CD) and ulcerative colitis (UC), and are depicted in the sections/subsections of the present paper. Data from the literature give evidence in support of probiotic and prebiotic therapy, showing effects such as improving remission rate, improving macroscopic and microscopic aspects of IBD, reducing the pro-inflammatory cytokines and interleukins, and improving the disease activity index. Therefore, the additional benefits of these therapies should not be ignored as adjuvants to medical therapy

Evaluation of Keratin/Bacterial Cellulose Based Scaffolds as Potential Burned Wound Dressing

The study presents the preparation and characterization of new scaffolds based on bacterial cellulose and keratin hydrogel which were seeded with adipose stem cells. The bacterial cellulose was obtained by developing an Acetobacter xylinum culture and was visualized using SEM (scanning electron microscopy) and elementally determined through EDAX (dispersive X-ray analysis) tests. Keratin species (β–keratose and γ-keratose) was extracted by hydrolytic degradation from non-dyed human hair. SEM, EDAX and conductometric titration tests were performed for physical–chemical and morphological evaluation. Cytocompatibility tests performed in vitro confirmed the material non-toxic effect on cells. The scaffolds, with and without stem cells, were grafted on the burned wounds on the rabbit’s dorsal region and the grafts were monitored for 21 days after the application on the wounds. The clinical monitoring of the grafts and the histopathological examination demonstrated the regenerative potential of the bacterial cellulose–keratin scaffolds, under the test conditions