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"Metalwork"
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A Systematic Review of Outcomes Following Lisfranc Injury Fixation: Removal vs Retention of Metalwork
Background:
Following Lisfranc injury fixation, no consensus exists on whether to routinely remove metalwork. The aim of this study was to evaluate functional outcomes and complications in patients following routine removal of metalwork and in those with retained metalwork.
Methods:
A systematic review of literature (1999-2020) reporting results of metalwork removal vs retention following Lisfranc injury fixation, was undertaken. The primary outcome was functional outcomes at 1 year following index surgery. Secondary outcomes were rates of complications including unplanned removal of metalwork.
Results:
No studies directly comparing routine metalwork removal vs retention were found. A total of 28 studies reporting on 1069 patients were included. Of these, 10 studies (317 patients) reported on retention and 18 (752 patients) on routine removal of metalwork. The difference in the American Orthopaedic Foot & Ankle Society (AOFAS) score between removal and retention groups was 3.38 (95% CI 6.3-0.48), P = .02 (removal 79.97 [±16.09; 71-96]; retention 76.59 [±20.36; 65.4-94]). No difference in reported rates of infection was found between the 2 groups (0%-12% for both groups). Of the 317 patients in the retention group, metalwork was removed in 198 cases, resulting in a 62.5% unplanned removal rate.
Conclusion:
In conclusion, this systematic review found limited evidence comparing different strategies of metalwork management after Lisfranc injury fixation. A randomized controlled trial is necessary to elucidate if routine removal of metalwork confers any true benefit.
Level of Evidence:
Level IV, systematic review including case series.
Journal Article
Remembering and Remaking Christofle et Cie’s Second Empire
During the Third Republic, the French fine metalworking firm Christofle et Cie remade two of their most significant Second Empire projects, which had initially been grandiose official commissions for huge metallic table centerpieces. These works, both lost during the violence and conflagrations that marked the end of the Paris Commune, were revived in different material forms and circumstances for similar purposes of mourning and remembering. This article examines how the firm reconstituted the objects to become material witnesses to an era that was still familiar, if strongly reviled, in the late nineteenth century. Martyred and venerated, the two centerpieces in their remade forms actively negotiated the social memory of the past and secured a prominent place for the firm’s legacy in a nascent history of French design.
Journal Article
An improved multi-scale branching convolutional neural network for rolling bearing fault diagnosis
The vibration signals measured in practical engineering are usually complex and noisy, which brings challenges to fault diagnosis. In addition, industrial scenarios also put forward higher requirements for the accuracy and computational efficiency of diagnostic models. Aiming at these problems, an improved multiscale branching convolutional neural network is proposed for rolling bearing fault diagnosis. The proposed method first applies the multiscale feature learning strategy to extract rich and compelling fault information from diverse and complex vibration signals. Further, the lightweight dynamic separable convolution is elaborated and coupled into the feature extractor to \"slim down\" the model, reduce the computational loss on the one hand, and further improve the model’s adaptive learning ability for different inputs hand. Extensive experiments indicate that the proposed method is significantly improved compared with existing multi-scale neural networks.
Journal Article
Experimental and Analytical Study on Vertical Punching n Flat Plates with Stirrups
Brittle punching failures in flat plates are precluded by ensuring adequate shear strength. Typically, this is achieved by adding shear reinforcement in the design. This paper presents an experimental and analytical study of flat plates to investigate load-resisting mechanisms associated with stirrup addition. The experimental program includes four isolated flat plates with parametric variations tested under monotonic punching loads. In terms of normalized shear strength, improvements of 22% and 29% were observed in flat plates with different layouts of stirrups, respectively, when compared with the reference specimen without stirrups. The role of longitudinal and shear reinforcements in punching resistance of flat plates was assessed through strain observations. Based on test findings, a physics-based analytical procedure for punching capacity estimation is proposed and verified using a database of 72 isolated flat-plate specimens. The proposed method provided reasonably accurate capacity estimates with an overall mean test-to-estimated capacity ratio of 1.06 and a low coefficient of variation (COV) of 13%. These estimates are also compared with capacity predictions using ACI 318-19 guidelines, which resulted in an overall mean capacity ratio of 1.58 with a COV of 22%. Based on experimental and analytical results, modifications to ACI 318-19 two-way shear provisions are suggested by incorporating the key parameters in shear strength estimations, which improved the prediction accuracy to a mean of 1.25 with a COV of 13%. Keywords: ACI 318; analytical; design codes; flat plates; punching; reinforced concrete; shear strength; softened strut-and-tie (SST) model; stirrups.
Journal Article
Friction and Wear Characteristics of Fesub.3Osub.4 Nano-Additive Lubricant in Micro-Rolling
As nanotechnology has developed, some nano-additives have been employed to improve the performance of lubricants. The mechanisms of nano-additives still need to be investigated. The wear characteristics of Fe[sub.3] O[sub.4] nano-additive lubricant were investigated in this study. Different diameters of Fe[sub.3] O[sub.4] nanoparticles were mixed in basic oil using an ultrasonic mixer. The new lubricant was used for analytical tests at room temperature. The results showed that nano-lubricants with 20 nm nanoparticles increase the oil film strength. The coefficient of friction was reduced when 20 nm diameter 8 wt% Fe[sub.3] O[sub.4] nanoparticles were mixed with lubricants. The effect of surfactants and nanoparticles in the base oil was measured using numerical simulation methods. The adsorption capacity of the lubricants was significantly improved by Fe[sub.3] O[sub.4] nanoparticles, particularly when looking at the small relative atomic mass of the metal. The 8 wt% Fe[sub.3] O[sub.4] lubricant exhibited optimal tribological properties when applied in micro-rolling tests. The results showed that the surface quality of the rolled samples was significantly improved, and the rolling force was dramatically reduced. At the same time, the shapes of the samples were effectively controlled in the rolling process. Therefore, Fe[sub.3] O[sub.4] nanoparticles can improve the friction and wear characteristics of lubricants.
Journal Article
Simulation of the Kinematic Condition of Radial Shear Rolling and Estimation of Its Influence on a Titanium Billet Microstructure
The finite element method (FEM) computer simulation of the three-high radial shear rolling of Ti-6Al-4V alloy round billets was conducted using QForm software. The simulation was performed for the MISIS-100T rolling mill’s three passes according to the following rolling route: 76 mm (the initial billet diameter) →65 mm→55 mm→48 mm (the final billet diameter). The change in the total velocity values for the points on the radius of the 48 mm diameter billet was estimated while passing the rolls’ draft. The relative increase in the accumulated strain was estimated for the same points. Then, experimental shear rolling was performed. Grain sizes of the α- and β-phases were estimated in the cross section of the final billet at the stationary stage of rolling. The grain size distribution histograms for different phases were plotted. An area was found in the billet’s cross section in which the trend of change in the total velocity of the points changed. This area represented a neutral layer between the slowing peripheral segments of the billet and the accelerating central segments of the billet. Inside this neutral layer, the limits of the cylindrical surface radius value were estimated. Experimental radial shear rolling was performed to compare the experimental rolling results (the billet microstructure investigation) with the computer simulation results. The computer simulation obtained two estimations of the radius limits: 8–16 mm (based on the analysis of the total velocity change) and 12–16 mm (based on the accumulated strain’s relative increment change). The experimental rolling obtained two more estimations of the radius limits: 8.4–19.5 mm and 11.3–19.7 mm—based on the results of the microstructure investigation. It was confirmed that varying the kinematic and deformation parameters of radial shear rolling allows regulation of the thickness of the peripheral fine-grain layer and the diameter of the central coarse-grain layer of the rolled billets.
Journal Article
Preparing Thick Gradient Surface Layer in Cu-Zn Alloy via Ultrasonic Severe Surface Rolling for Strength-Ductility Balance
A gradient structure (GS) design is a prominent strategy for strength-ductility balance in metallic materials, including Cu alloys. However, producing a thick GS surface layer without surface damage is still a challenging task limited by the available processing technology. In this work, a gradient structure (GS) surface layer with a thickness at the millimeter scale is produced in the Cu-38 wt.% Zn alloy using ultrasonic severe surface rolling technology at room temperature. The GS surface layer is as thick as 1.1 mm and involves the gradient distribution of grain size and dislocation density. The grain size is refined to 153.5 nm in the topmost surface layer and gradually increases with increasing depth. Tensile tests indicate that the single-sided USSR processed alloy exhibits balanced strength (467.5 MPa in yield strength) and ductility (10.7% in uniform elongation). Tailoring the volume fraction of the GS surface layer can tune the combination of strength and ductility in a certain range. The high strength of GS surface layer mainly stems from the high density of grain boundaries, dislocations and dislocation structures, deformation twins, and GS-induced synergistic strengthening effect. Our study elucidates the effect of the thick GS surface layer on strength and ductility, and provides a novel pathway for optimizing the strength-ductility combination of Cu alloys.
Journal Article
Assessment of the Susceptibility to Material Fracture in the Cross-Wedge Rolling Process with Concave Tools
The internal cracking of forgings during the cross-wedge rolling (CWR) process is a serious limitation that prevents the correct implementation of this process. The phenomenon of material cracking in the CWR process reduces the technological and application possibilities of this highly efficient process, which can produce forgings with high geometric accuracy. This article presents the results of rolling forgings at different temperatures. An analysis of the results showed that the size of the resulting material fracture in the CWR process is related to the size of the ovalisation of the cross-section of the forging formed during rolling. On the basis of the observations made, it was proposed to realise the cross-wedge rolling process with concave tools. The use of tools with a concave geometry is intended to reduce the excessive flow of material in the rolling direction, which restrains the formation of the ovalisation of the cross-section of the forging. Numerical simulations were carried out comparing the rolling with flat tools and concave tools with different radii of the curvature. The results show that the use of concave tools reduces the ovality of the cross-section of the forging during rolling and reduces the value of the normalised Cockcroft–Latham (CL) fracture criterion.
Journal Article
Regionalism and Internationalisation in the Urartian Period
This volume details the first systematic study of 58 objects found in Yeghegnadzor in 1989, mainly metallic, including two notable bronze belts. The study, part of the Vayots Dzor Project, offers new insights into their cultural attribution, chronology, and discovery context, supported by detailed analysis and photographic documentation.
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