Mean curvature effect on the response and failure of round-hole tubes submitted to cyclic bending

This paper presents an experiment and analysis to investigate the response and failure of 6061-T6 aluminum alloy round-hole tubes with different hole diameters of 2, 4, 6, 8, and 10 mm subjected to cyclic bending at different curvature ratios of −1.0, −0.5, 0.0, and +0.5. The curvature ratio is defined as the minimum curvature divides by the maximum curvature. Four different curvature ratios are employed to highlight the mean curvature effect. It can be seen from the experimental results that the moment-curvature relationships gradually relax and become steady states after a few bending cycles for curvature ratios of −0.5, 0.0, and +0.5. The ovalization-curvature relationship depicts an asymmetrical, ratchetting and increasing as the number of bending cycles increases for all curvature ratios. In addition, for each hole diameter, the relationships between the curvature range and the number of bending cycles necessary to initiate failure on double logarithmic coordinates display four almost-parallel straight lines for four different curvature ratios. Finally, this paper introduces an empirical formula to simulate the above relationships. By comparing with experimental results, the analysis can reasonably describe the experimental results.

#RetroPIDs: The missing link to the foundation of biodiversity knowledge

The Biodiversity Heritage Library (BHL) will soon upload its 60 millionth page of open access biodiversity literature onto the BHL website and the BHL's Internet Archive Collection. The BHL’s massive repository of free knowledge includes content that is available nowhere else online, as well as accessible versions of content that are locked behind paywalls elsewhere. If we are to continue to expand our understanding of life on Earth, we must ensure that the foundation of biodiversity knowledge provided by BHL is discoverable by the tools we rely on to navigate the ever-expanding internet. These tools – search engines and their algorithms – preferentially deliver (and rank) content with good metadata and persistent identifiers (PIDs). In modern online publishing, PID assignment and linking happens at the point of publication: DOIs (Digital Object Identifiers) for publications, ORCIDs (Open Researcher and Contributor IDs) for people, and RORs (Research Organization Registry IDs) for organisations. The DOI system provided by Crossref (the DOI registration agency for scholarly content) delivers reciprocal citations, enabling convenient clicking from article to article, and citation tracking, enabling authors and institutions to track the impact and reach of their research output. Publications that lack PIDs, which include the vast majority of legacy literature, are hard to find and sit outside the linked network of scholarly research. This makes it nearly impossible to determine whether they are being cited, let alone viewed, mentioned, shared or liked. At TDWG 2020, Page 2020, Kearney 2020, Richard 2020 (and 2019, Page 2019b, Page 2019a, Kearney 2019b, Kearney 2019a and 2018, Kearney 2018), we emphasised the need to bring the historic biodiversity literature into the modern linked network of scholarly research. In October 2020, BHL launched a new working group to do exactly this. The BHL Persistent Identifier Working Group (Team #RetroPID) brings together expertise from across BHL’s global community. Over the past year, we have worked tirelessly to make it easier to find, cite, link, share and track the content on BHL, adding article-level metadata to journals and retrospectively assigning DOIs (#RetroPIDs). Most importantly, we have developed the tools and documentation that will enable the entire BHL community to take contributed content from “just” accessible to persistently discoverable. This paper will detail our efforts to retrofit the historic literature (a square peg) into the modern PID system (a round hole) and will present both the achievements and the challenges of this important work.

Response of round-hole tubes submitted to pure bending creep and pure bending relaxation

This paper presents experimental study on the response of 6061-T6 aluminum alloy round-hole tubes with five different hole diameters of 2, 4, 6, 8, and 10 mm and four different diameter-to-thickness ratios of 30, 40, 50, and 60 submitted to pure bending creep and pure bending relaxation. Pure bending creep or relaxation is defined as bending the tube to the required moment or curvature and maintaining that moment or curvature for a period of time. The experimental results of pure bending creep show that the curvature increases with time. In addition, larger holding moment, diameter-to-thickness ratio, or hole diameter results in larger creep curvature. As the curvature continues to increase, the round-hole tube eventually breaks. The experimental results of pure bending relaxation show that the relaxation moment decreases sharply with time and tends to a stable value. In addition, larger holding curvature, diameter-to-thickness ratio, or hole diameter results in larger drop of the relaxation moment. Due to fixed curvature, the round-hole tube does not break. Finally, formulas proposed by the research team of Pan et al. were respectively improved to simulate the creep curvature-time relationship for pure bending creep in the initial and the secondary stages and the relaxation moment-time for pure bending relaxation. After comparing with the experimental results, it is found that theoretical analysis can reproduce the experimental results reasonably.

PROGRESSION OF INFLAMMATORY PROCESSES IN PATIENTS AFTER IM NAILING USING BIOINERT AND BIODEGRADABLE IMPLANTS BASED ON MC-10 MAGNESIUM ALLOY

Summary. Modern medicine widely uses artificial materials to replace damaged tissues and organs. Biodegradable implants should be gradually replaced with living tissue and stay functioning within a specified period, don’t have any negative impact on surrounding tissues and a human body in general. Clinical studies of biochemical values specifying the intensity of inflammatory response to IM nailing with biodegradable implants are of clinical and scientific interest. Task of the study: to substantiate of the use of implants made of biodegradable magnesium alloy MS-10 in the dynamic IM nailing for diaphyseal fractures of the tibia. Materials and methods. The study involved 34 patients with diaphyseal tibial fractures, which resembled surgical treatment (IM nailing). Cannulated intramedullary titanium nails served as a blocking pin. The treatment included closed reposition followed with IM nailing of a tibia. To lock the nail, a screw made of magnesium alloy MS-10 was inserted in a static (round) hole in 16 patients. In 18 patients, a screw made of titanium was inserted into a static hole. The both groups passed blood sampling for studies, before and after the surgery, 2 and 4 weeks, 2 and 4 months after surgery. Biochemical blood tests were to determine the concentration of fibrinogen-monomer complexes in the blood plasma (β-naphthol test). Results. The study of the activity of AST and ALT found it lower (19 and 29%) in patients with biodegradable screws, compared to the group of patients with IM nailing locked with bioinert screws. The situation was similar with ESR, fibrinogen B and total bilirubin in the blood of patients in both groups. Conclusions. The study convincingly proves the expediency of the use of biodegradable material (magnesium alloy MS-10) to produce implants for the IM nailing for the patients with long bones’ fractures.

IMPROVING OF ROUND HOLE CUTTING PROCESS IN THE SHEET METAL

Improving existing technological processes is an important stage in the development of all industries. As a consequence, this article is devoted to the analysis of the process of flanging round holes in sheet steel. The existing typical technological process, with a detailed analysis, gives grounds for substantiating the idea of an innovative solution. Changing the sequence of the traditional flanging method will ensure high productivity and material savings. Of the many promising methods of metal forming by pressure, which include flanging of round holes, two are given for comparison: the traditional one and the improved one. The methodology of the traditional direction, worked out over the years, provides for a clear sequence of the technological process using tools for marking, centering, making a hole and using tools for flanging. The final, after the previous operations of marking the centers of the holes, punching, making holes, is the flanging stage. The tapered punch (usually a metal rod) prevents the small-diameter hole from deviating from the marking lines and ensures the centering of the punch-blank-matrix system. Following the above steps, the conventional workflow involves positioning the workpiece over the surface of the punch hole to guide the tool in the desired direction. For the manufacture of a flanged hole, a special sharpening of the working part of the punch is performed so that the diameter of the central part of the tool is equal to the difference between the diameters of the guide hole of the matrix and the inner diameter of the workpiece of the part. To avoid further displacement of the hole, the workpiece is centered by placing it on the die and the next operation is supposed to lower the punch to flang the hole. As a result, the article touches on the topic, taking into account the widespread use of thin sheet metal, including in the agricultural sector, the feasibility of using an innovative idea to improve the technological process associated with the processing of sheet material, namely thin metal sheets. It is advisable to note that, for example, a material is considered that is characterized by its versatility, namely steel. Despite numerous sources devoted to the study of improving the flanging technological process, there are a number of issues, in particular, the extension of this direction to numerous varieties of metal materials that have surfaces with and without coating, various thicknesses within thin-walled rolled products. The most significant result is the improved technological process of flanging will find application in the system of efficient servicing of agricultural machinery.