Mechanical Machine Research Articles

Effect of energy input on flotation of particles with different sizes: Perspective of hydrodynamics characteristics

By employing a torque sensor to measure energy input in a flotation machine, this paper investigates the flotation behavior of modified quartz particles with different sizes but similar surface hydrophobicity under various energy input conditions. Numerical simulations of the mechanical flotation machine were conducted to obtain the fluid dynamic characteristics including the flow velocity, turbulence kinetic energy, and turbulent eddy scale. With the flotation results and numerical simulations combined, the potential collision, attachment, and detachment behaviors of fine particles (―45 µm), intermediate particles (45―74 µm), and coarse particles (74―125 µm) were analyzed. The results demonstrate that under different conditions of energy input, the recovery of intermediate-sized particles was optimal for the above size fractions. As the particle size increases, the energy input required to achieve optimal recovery decreases. The flotation rate constants increase nearly linearly with energy input. Compared to the medium-sized particles in the range of 45―74 µm, finer and larger particles exhibit lower floatability. When the energy input exceeds a certain range, no stagnation zone is observed. The rupture of bubble-particle aggregates becomes more pronounced, which may be a reason why flotation recovery begins to decrease. Increasing energy input enhances turbulence energy dissipation and reduces the Kolmogorov turbulence length scale, in this study, the ―45 µm, 45―74 µm, and 74―125 µm particle sizes reached the optimal flotation performance at dp / η values of 1.35, 1.83, 2.54, respectively. The particle diameter-to-integral length scale ratio (dp/L) is also discussed as an important parameter for turbulent dispersion.

Development of Seeding Rate Monitoring System Applicable to a Mechanical Pot-Seeding Machine

In this study, we developed a monitoring system to accurately track the seeding rate and to identify the locations where the mechanical pot-seeding machine failed to sow seeds correctly. The monitoring system employs diverse image processing techniques, including the Hough transform, hue–saturation–value color space conversion, image morphology techniques, and Gaussian blur, to accurately pinpoint the seeding rate and the locations where seeds are missing. To determine the optimal operating conditions for the seeding rate monitoring system, a factorial experiment was conducted by varying the brightness and saturation values of the image data. When the derived optimal operating conditions were applied, the system consistently achieved a 100% seed recognition rate across various seeding conditions. The monitoring system developed in this study has the potential to significantly reduce the labor required for supplementary planting by enabling the real-time identification of locations where seeds were not sown during pot-seeding operations.

A MEMETIC ALGORITHM APPLIED TO INDUCTION MACHINE PARAMETERS IDENTIFICATION BASED ON AN OUTPUT ERROR

Based on an output error, several evolutionary methods have been applied to identify the parameters of an Induction Machine (IM). The main drawback of these methods is their premature convergence in many situations. To overcome this issue and achieve a more accurate solution, this paper proposes a Memetic Algorithm (MA), which combines a Genetic Algorithm (GA) and a local search method. This approach uses the Hooke-Jeeves (HJ) method for the local search as a mutation operator.GA has proven good ability in global search. The HJ method has a good ability to refine the local search and achieve the optimal accuracy solution. The proposed MA, which maintains a tradeoff between exploration and exploitation strategies, is applied to minimize the related objective function to obtain the electrical and mechanical machine parameters. The validation of the method is confirmed by an experiment carried out on an (0.4 kW) IM with parameters estimated using the measured data. Using the estimated parameters, the computed transient and steady-state currents agree well with the measured data.

Comparative analysis of 3‑D modeling programs KOMPAS-3D and AUTODESK INVENTOR using the example of the «lever assembly» assembly unit

This article discusses the operation «layout geometry» in the COMPASS-3D modeling program and adaptive technology in the Autodesk Inventor program using the example of an assembly unit. As a result of the work, a working prototype of the assembly unit in question was made. Autodesk Inventor is Autodesk»s three — dimensional solid-state and surface parametric design (CAD) system designed to create digital prototypes of industrial products. COMPASS-3D is a Russian import — independent three-dimensional design system, which is widely used for the design of products of the main and auxiliary industries in mechanical engineering, instrumentation, aircraft, shipbuilding and machine tool construction.

Preparation of Photochromic Wood Films Comprising Spiropyran-Based Wood Cellulose Scaffold Realized through Grafting and Densification

The development of smart color-changing wood could facilitate its functional application. Herein, photochromic wood films (PWFs) were synthesized by grafting 1-(2-hydroxyethyl)-3,3-dimethylindolino-6’-nitrobenzopyrylospiran onto the cellulosic skeleton structure of delignified wood using hexamethylene diisocyanate as a bridging linker, followed by the densification process. The microstructural morphology, chemical composition, photochromic properties, and mechanical properties of the prepared PWFs were characterized by scanning electron microscope, Fourier transform infrared spectroscopy, colorimeter, and universal mechanical testing machine. The photochromic capability of the wood film was positively correlated with the grafting amount of spiropyran; the color change is evident when the grafting amount is high. Furthermore, the photochromic and recovery capability of the wood film weakened after sequentially irradiating 40 times using a UV lamp and daylight lamp, which could be partially recovered after a period of rest. However, the wood film strength was negatively correlated with the grafting amount of spiropyran. The grafted spiropyran affected the hydrogen bonding between cellulose nanofibers of the wood film during densification, which caused a reduction in the film strength. However, the strength was still >120 MPa. Meanwhile, temperature and humidity affected the photochromic capability of the wood film. Thus, the developed high-strength PWF has potential applications in various fields, such as intelligent sensing, personalized design, indoor and outdoor architecture, and optoelectronics.

Double-Layered Hand-Sewn versus Stapled Intestinal Anastomosis in Patients Who Underwent Ileal Urinary Diversion in Radical Cystectomy: A Comparative and Cost Effective Study

Introduction: Intestinal anastomosis can be performed by hand suturing (single layer or double layer) or by a mechanical suturing machine. The aim of the study was to compare complications, operative time, and costs of the intestinal anastomosis techniques. Methods: A retrospective comparative study was conducted including patients who underwent radical cystectomy and uretero-ileo-cutaneostomy or vescica ileale Padovana orthotopic neobladder. Double-layered hand-sewn intestinal anastomosis (HS-IA) were performed using Vicryl stitches. Mechanical-stapled intestinal anastomosis (MS-IA) were performed with a mechanical stapler. Results: Data of 195 patients who underwent were collected. 100 (51.3%) patients underwent HS-IA and 95 (48.7%) patients underwent MS-IA. Considering the complications classified according to Clavien-Dindo, a statistical difference with higher incidence for grade one in the HS-IA both in the ileal conduit group and in the neobladder one than the MS-IA (15.8% and 8.7%, respectively, in HS-IA vs. 1.7% and none in MS-IA). There is not a significant difference in time to flatus and time to defecation. Difference is recorded in the ileal conduit groups for the length of stay (10 days, range 9–12 with HS-IA vs. 13 days range 12–16 days with MS-IA (p < 0.001). The cost of the suture thread used for a single operation was 0.40 euros, whereas the overall cost of a disposable mechanical stapler and one refill was 350.00 €. Conclusion: Both HS-IA and MS-IA are safe and effective for patients. The cost for the stapling device is 350 €, in contrast, the cost for Vicryl sutures is negligible.

CHARACTERISTICS AND OVERVIEW OF KNOWLEDGE OF CURRENT RESEARCH IN THE PRODUCTION OF HARMONIC GEARBOX

The range of applications for drives and gears stretches over numerous technological fields. The gearbox is found in every mechanical machine and represents only one small but important sub-application. Industry as a whole has a constant demand for new individual solutions tailored to solve particular problems. But again and again, it is called upon to find new ways of transmitting movements that a particular component is required to conduct so as to attain a particular result. Harmonic drive products are unique precision speed reducers playing important roles in robots, semiconductor manufacturing systems, factory automation equipment and furthermore, in aerospace equipment. The greatest benefits are the zero-backlash characteristics and the weight and space savings compared to other gears because our gear mechanism consists of only three basic parts. They are the: Wave Generator, Flexspline and Circular Spline.

Assessment of Microstructure and Investigation Into the Mechanical Characteristics and Machinability of A356 Aluminum Hybrid Composite Reinforced with SiCp and MWCNTs Fabricated Through Rotary Centrifugal and Squeeze Casting Processes

Assessment of Microstructure and Investigation Into the Mechanical Characteristics and Machinability of A356 Aluminum Hybrid Composite Reinforced with SiCp and MWCNTs Fabricated Through Rotary Centrifugal and Squeeze Casting Processes

Effect of hot-etching treatment duration on the shear bond strength of zirconia-to-resin cement.

The surface of zirconia was treated with hot-acid etching of different durations to improve its shear bond strength to resin. Zirconia discs were subjected to untreated, sand-blasting, and hot-etching treatments for 10, 30 and 60 min. The discs were bonded to the surface of bovine enamel specimens using RelyX Ultimate resin cement. The bonded specimens were divided into immediate and thermocyling aging groups according to whether they underwent thermal cycling. A universal mechanical testing machine was used to measure the shear bond strength of the specimens. One-way analysis of variance was used to determine the effect of hot-etching time on the shear bond strength. In the immediate and thermocyling aging groups, 60 min of hot-etching provided significantly higher shear bond strength than the other conditions (p<0.05).

FUNCTIONAL RELATIONSHIP OF THE PROCESSING CONDITIONS WITH PARAMETERS OF THE CONDITION OF THE SURFACES OF RAIL TEETH

A significant number of mechanical methods, machines, tools and materials for processing toothed rails determines wide possibilities in ensuring the formation of the parameters of the surface layer of the latter and determines their operational properties. Therefore, the issue of ensuring the operational properties of toothed rails depending on the parameters of the condition of the surface layer of the rails is relevant. In order to successfully solve this problem, the theoretical aspects of the relationship between the parameters of the state of the surface layer of the rails and the processes of their processing are considered.&#x0D; In contrast to well-known studies, which provided for the identification of general aspects of the connection of individual parameters of the surface layer of rails with the conditions of their processing, the authors proposed the feasibility of considering the dependence of the system of parameters of the surface layer, which determine the operational properties of toothed rails, with the conditions of their processing. This relationship is expressed in mathematical dependencies, which are the basis for the development of algorithms and programs. As a result, the solution of one of the main tasks of calculating the optimal processing processes, taking into account the provision of the necessary parameters of the state of the surface layer of toothed rails, based on their operational properties, is automated. In support of this direction, the fundamental scientific principles of the theory of geometric three-dimensional modeling of the interconnected processes of allowance removal and forming during cutting have been developed.

Combining Molecular Quantum Mechanical Modeling and Machine Learning for Accelerated Reaction Screening and Discovery.

Molecular quantum mechanical modeling, accelerated by machine learning, has opened the door to high-throughput screening campaigns of complex properties, such as the activation energies of chemical reactions and absorption/emission spectra of materials and molecules; in silico. Here, we present an overview of the main principles, concepts, and design considerations involved in such hybrid computational quantum chemistry/machine learning screening workflows, with a special emphasis on some recent examples of their successful application. We end with a brief outlook of further advances that will benefit the field.

A comparative investigation on the fundamental physical properties of UX2 (X = O, N, C, Si and S) solid nuclear fuel materials: A DFT + U study

This study investigates and compares the physical properties of various UX2 (X = O, N, C, Si and S) nuclear fuels using a combination of Density Functional Theory (DFT) and Hubbard U correction parameter (U) to accurately model the electronic structure and account for strong correlation effects among 5f orbital electrons. Spin-polarized DFT + U method is employed to optimize the structures of the considered compounds. The computational analysis reveals that UO2 and UN2 exhibit Mott-insulating properties, while the remaining UX2 compounds demonstrate metallic nature. To assess the mechanical aspects of these materials, the study evaluates their mechanical stability, Vickers hardness and machinability index through calculations of elastic constants. Notably, all the UX2 fuels are found to be mechanically stable and possess ductility. Both the two-dimensional (2D) and three-dimensional (3D) depictions of the elastic moduli for the analyzed solid fuels demonstrate the presence of elastic anisotropy. The famous Slack's equation is used to determine the lattice thermal conductivity of the UX2 fuels, providing valuable insights into their thermal properties. Among the investigated materials, UC2 exhibits the highest values of Debye temperature and lattice thermal conductivity, which amount to 412 K and 15.73 Wm−1 K−1 at 300 K, respectively. Furthermore, UN2 demonstrates the highest melting temperature. Among the compounds under investigation, UC2 and UN2 fuels exhibit the most minimal thermal expansion and the greatest heat capacity. Based on these findings, UC2 and UN2 emerge as promising alternative fuel materials to UO2 for potential use in nuclear power reactors. This research contributes to the ongoing efforts in identifying alternative fuel materials.

Molecular Structure and Properties of Sulfur-Containing High Refractive Index Polymer Optical Materials.

High refractive index polymers (HRIPs) are widely used in lenses, waveguide, antireflective layer and encapsulators, especially the advanced fields of augmented/virtual reality (AR / VR) holographic technology and photoresist for chip manufacturing. In order to meet the needs of different applications, the development of HRIPs focuses not only on the increase in refractive index but also on the balance of other properties. Sulfur-containing high refractive index polymers have received extensive attention from researchers due to their excellent properties. In recent years, not only ultrahigh refractive index sulfur-containing polymers have been continuously developed, but also low dispersion, low birefringence, high transparency, good mechanical properties, and machinability have been studied. The design of HRIPs is generally based on formulas and existing experience. In fact, molecular structure and properties are closely related. Mastering the structure-property relationship helps researchers to develop high refractive index polymer materials with balanced properties. This review briefly introduces the preparation methods of sulfur-containing high refractive index polymers, and summarizes the structure-property relationship between the sulfur-containing molecular structure and optical properties, mechanical properties, thermal properties, etc. Finally, the important role of synergistic effect in the synthesis of HRIPs and the prospect of future research on HRIPs are proposed.

Technical and Economic Examination of the Mechanical Hazelnut Collecting Machine Manufacturing

In this study, taking into account the conditions of Türkiye, it will be possible to harvest hazelnuts grown on flat and nearly flat lands, in line with ergonomic principles, with an approach that consider operator comfort and work safety, with a mechanically effective sweeping unit with high work success, which removes the kernel+husk hazelnut from the ground, some performance values of the hazelnut harvesting machine such as collecting efficiency, labor requirement, fieldwork success, product work success, and foreign material separation efficiency, which cleans the mixed hazelnuts in the separation unit at a level that does not affect the performance of the husk peeling machine and stores the cleaned grain+husk hazelnut mixture, were determined and obtained. In light of the data obtained, it is contribution to the economy is discussed. The collecting efficiency of the mechanical hazelnut harvesting machine was 93.26%, the labor requirement was 47.85 h/ha, the fieldwork success was 0.134 ha/h, the product work success was 295.92 kg/h, and the foreign material separation efficiency was 96.85%. Considering the performance values obtained, very successful results have obtained from the field trials performed with the mechanical hazelnut harvesting machine. As a result, the production of the hazelnut harvesting machine and its implementation will make hazelnut production sustainable by significantly reducing production costs, and the import of machinery that is not suitable for the conditions of Türkiye will be no longer needed.

Mechanical analysis and machinability evaluation of a new EDM-turning hybrid machining process

This study developed an accurate electrical discharge-assisted turning (EDAT) technique for Ti–6Al–4 V alloy and a precise EDAT cutting force prediction model considering theoretical multi-physics fields with metallurgical transformation. A heat-fluid coupled model of multi-pulse discharge in the EDAT process was developed to obtain the thickness of the removal layer (RL) and modified layer (ML) together with the temperature field of the cutting layer. Subsequently, the shear flow stresses under different machining parameters were obtained using the oblique cutting and flow softening constitutive models. Within the cutting layer, the pure thermal softening effect reduces the flow stresses by more than 25% in the unmodified matrix layer (UML) and by more than 60% in the ML, which is dominated by the metallurgical transformation softening (MTS) effect. Finally, the cutting force model of EDAT under multi-physical fields was established and the accuracy was verified by relevant experiments. The results showed that the increase in discharge number accelerated the rise of workpiece surface temperatures, and the small cutting parameters were favorable to the machining performance of the EDAT. The MTS effect significantly reduces cutting forces while improving the quality of the machined surface.

Preparation of elastic hydrogel films via in-situ ketalization of Poly(vinyl alcohol) and ZnO nanoparticle doped Poly(vinyl ketal) films as antibacterial surface

Cross-linked and flexible poly(vinyl acetone ketal) (PV-A-K) films have been prepared as a result of ketalization reaction and monolith formation of poly(vinyl alcohol) (PVA), which has the feature of forming films quickly and is frequently used in biological fields. In this novel method, flexible PV-A-K films have been produced simply and in a short time accompanied by monolith formation without any catalyst in acetone. The effect of acetone ratio on the physical properties (i.e., swelling and mechanical properties) of such formations has been investigated to reveal significant influences of it. In addition, zinc oxide (ZnO) nanoparticles synthesized via the solvothermal method have been doped into PV-A-K films during film preparation. The prepared PV-A-K and ZnO doped PV-A-K films have been characterized with SEM, XRD, and FT-IR. Their mechanical properties have been investigated with a universal mechanical test machine. The acetone ratio is quite effective both on the porosity and stress/strain properties of the films. Antibacterial activities of the films are evaluated against four different strains (E. coli, S. aureus, P. aeruginosa, and E. faecalis) via the disk diffusion method. The films are selectively effective against S. aureus. These highly flexible and elastic films have great potential for biomedical applications, wound dressing, and antibacterial surface preparation.

Does intramedullary elastic nail augmentation increase resistance to bending stress in plate fixation of long bones? A biomechanical study on lamb cadaveric femurs.

The aim of this study was to evaluate the bending strength of plate-screw fixation augmented with titanium elastic nails (TENs) in a simple long bone fracture model using lamb cadaver femurs. A total of 24 lamb cadaveric femurs that were osteotomized transversely from the mid-diaphysis with a bone saw were used to obtain a simple fracture model. The femurs were divided randomly into three groups. In Group 1, only plate-screw was used for fixation. In Group 2, plate-screw fixation was augmented with a 2.5-mm TEN. In Group 3, plate-screw fixation was augmented with two 2.5-mm TENs. Each bone model was positioned on a mechanical testing machine. Subsequently, three-point bending loads were applied to each bone to measure the force required for failure at the osteotomy site. The data were recorded on a computer connected to the test device and the bending strengths of all samples were calculated. There was no statistically significant difference in the bending strength (megapascals) between Groups 1 and 2 or between Groups 2 and 3 (p>0.05). However, the bending strength in Group 3 was significantly higher than in Group 1 (p<0.05). The application of intramedullary TEN during surgery in long bone fractures, combined with a bridge plate, may be helpful to strengthen the fixation stability.

The Influence of Sagittal Pin Angulation on the Stiffness and Pull-Out Strength of a Monolateral Fixator Construct.

Monolateral pin-to-bar-clamp fixators are commonly used to stabilize acute extremity injuries. Certain rules regarding frame geometry have been established that affect construct stability. The influence of sagittal pin angulation on construct stiffness and strength has not been investigated. The purpose of this biomechanical study was to demonstrate the effect of a pin angulation in the monolateral fixator using a composite cylinder model. Three groups of composite cylinder models with a fracture gap were loaded with different mounting variants of monolateral pin-to-bar-clamp fixators. In the first group, the pins were set parallel to each other and perpendicular to the specimen. In the second group, both pins were set convergent each in an angle of 15° to the specimen. In the third group, the pins were set each 15° divergent. The strength of the constructions was tested using a mechanical testing machine. This was followed by a cyclic loading test to produce pin loosening. A pull-out test was then performed to evaluate the strength of each construct at the pin-bone interface. Initial stiffness analyses showed that the converging configuration was the stiffest, while the diverging configuration was the least stiff. The parallel mounting showed an intermediate stiffness. There was a significantly higher resistance to pull-out force in the diverging pin configuration compared to the converging pin configuration. There was no significant difference in the pull-out strength of the parallel pins compared to the angled pin pairs. Convergent mounting of pin pairs increases the stiffness of a monolateral fixator, whereas a divergent mounting weakens it. Regarding the strength of the pin-bone interface, the divergent pin configuration appears to provide greater resistance to pull-out force than the convergent one. The results of this pilot study should be important for the doctrine of fixator mounting as well as for fixator component design.

Effects of controllable shock wave on particle size characteristics of tin polymetallic ore crushing products

Different minerals in tin polymetallic ores have varying degrees of grindability. When the particle size distribution of the crushed ore is unreasonable, sufficient liberation of useful minerals necessitates an increase in the grinding time, resulting in the easily grindable tin metal minerals being over-ground, further causing the loss of tin metal resources in the subsequent beneficiation process. In this study, a controlled shock wave technique based on electrical pulses was introduced to pretreated tin polymetallic ores. The effects on the physical properties of the tin polymetallic ore obtained using controllable shock wave pretreatment were investigated using an ultra-depth three-dimensional microscope, a universal mechanical testing machine, mercury porosimeter, and crushing tests. The crushing results showed that the average particle size of the pretreated ore crushing products was 17.98% smaller than that of the untreated ore crushing products. Furthermore, the particle size characteristic equation demonstrated that the particle size distribution of the pretreated ore crushing products was more reasonable. The mechanism analysis revealed that the internal structure and surface morphology of the tin polymetallic ore were fractured by the controllable shock wave based on the electrical pulse, the compressive strength of the ore after pretreatment was reduced by 91.23%, and the porosity value was increased by 5.38% compared with that of the untreated ore. Therefore, it is feasible to pretreat tin polymetallic ores with controllable shock wave before the crushing process, which reduces the ore crushing resistance and improves the particle size characteristics of ore crushing products.

Innovative tensile test for brittle materials: Validation on graphite R4550

This paper proposes an innovative ultrasonic tensile test methodology for the assessment of quasi-static uniaxial mechanical properties and tensile strength of brittle materials. An ultrasonic testing machine, commonly employed for very high cycle fatigue tests, had its control and data acquisition systems adapted to induce specimen failure in about 100 cycles, avoiding cyclic load damage. The mechanical properties are thereafter estimated with a finite element model which simulates the experimental test. The proposed method has been validated by assessing the tensile strength of graphite R4550, characterized by brittle behaviour. The mechanical properties for graphite R4550 estimated with this experimental-numerical approach were found to be close to literature values obtained in different quasi-static testing configurations, confirming the effectiveness of the proposed method and the feasibility of employing the ultrasonic fatigue testing machine for studying the behaviour of brittle materials. Furthermore, the proposed methodology eliminated issues caused by mechanical fixtures and tensile testing machine alignment, while also allowing a considerable increase of the material loaded volume when compared to that of traditional test methods. The experimental and numerical approaches are successfully validated on graphite R4550, also highlighting its capability of characterizing the material nonlinear behaviour, including viscoelasticity and asymmetrical response in tension and compression.