Journal of Modern Mechanical Engineering and Technology

Remarks on Solving Methods of Nonlinear Equations

Sha Huang — 2024-03-08

Abstract: In the field of mechanical engineering, many practical problems can be converted into nonlinear problems, such as the meshing problem of mechanical transmission. So the solution of nonlinear equations has important theoretical research and practical application significance. Whether the traditional Newton iteration method or the intelligent optimization algorithm after the popularization of computers, both them have been greatly enriched and developed through the continuous in-depth research of scholars at home and abroad, and a series of improved algorithms have emerged. This paper mainly reviews the research status of solving nonlinear equations from two aspects of traditional iterative method and intelligent optimization algorithm, systematically reviews the research achievements of domestic and foreign scholars, and puts forward prospects for future research directions.

A Flow Structure Interaction Method for Towed Cable System

Wang Zhi-bo — 2024-03-16

Abstract: The ocean towed cable system is a classic example of fluid-structure interaction (FSI). This interaction can exhibit stability or oscillation between a highly deformable moving cable and the surrounding turbulent flow. However, in dynamic simulations of towed cable systems, a constant drag coefficient for an infinite circular cylinder is often used based on experimental data. An innovative fluid-structure interaction method is introduced to obtain accurate drag distribution along cable to couple with towed system dynamics. A modified nodal position finite element method (NPFEM) coupled with Reynolds-averaged Navier-Stokes (RANS) approach has been utilized to predict hydrodynamic forces along the cable. A data exchange algorithm has been developed specifically for fluid-structure interaction within the towed cable system where the cable profile is transferred to construct the flow domain while hydrodynamics is interpolated for NPFEM analysis. A topology partition around cable is applied. A multiblock grid is generated around cable. The simulation results of the fluid-structure interaction of the towing system are verified. This FSI scheme reveals how strongly hydrodynamics determine cable dynamics and induce vortex structure vibrations around a towed cable system. Parametrically controlled structured grid generation and their applicability for complex flow fields have also been discussed. Detailed descriptions of boundary layer separation evolution around spatially distributed cable are provided. This FSI scheme reveals a real strongly hydrodynamic determined cable dynamics and vortex structure induced vibrations around a towed cable system. The proposed method enhances predictive accuracy of the towed system dynamics response.

Experimental Investigation of Oil Film Variation in Finite Line Contact Under Intermittent Motion

Haiping Li — 2024-09-19

The variation of oil film distribution in the line contact area of pin and disk was experimentally observed during a periodic intermittent motion. The study was conducted on a ball-disk optical interferometric test rig, with motion speed controlled by PLC programming. PAO40 oil was primarily used in the experiment, with the glass disk undergoing periodic motion of constant speed-deceleration-stop-acceleration, while the pin roller remained fixed. The results indicate that when the motion stops, a portion of the oil is entrapped in the center of the contact area. As the acceleration phase begins, this portion of the oil is gradually squeezed out of the contact area, and the oil film with lowest thickness at the entrance of the contact area moves towards the exit of the contact area, passing through the contact center. It can also be observed that during the entire process, an increase in speed increases the film thickness, while an increase in deceleration time, i.e., a decrease in deceleration, reduces the film thickness during the stop phase.

Application of Anal Manometry in the Planning for Anal Fistula Surgery

Xiaobin Wilson Gao — 2024-10-30

Anal fistula does not heal spontaneously without surgery, and anal function should be preserved after muscle dissection, which is a challenge even to the most experienced surgeon. In order to develop a planner for anal fistula surgery, anal manometry used in the measurement of pressures in the anal canal to investigate the anal function is reviewed. In this review paper, current techniques are described and compared with each other, and technical and clinical challenges are discussed. There are four types of catheters used to measure anal sphincter pressure: water-perfused, solid-state, air-coupled, and fiber optic catheter. Parameters acquired by anal manometry and their relationship with fecal incontinence after anal fistula surgery are discussed. Vectormanometry can provide the pressure profile along the anal canal in three dimensional space, pressure vectorgram, and cross-sectional radial asymmetry, which have more advantages than the conventional method. Understanding the technology and development of anal manometry is critical for the anal fistula surgical planning. A novel design is highly desired for 3D pressure profile measurement along the entire anal canal simultaneously without pulling the catheter.

Numerical Simulation of the Multi-Roller Skew Tandem Rolling of Unequal Wall Thickness Hollow Stepped Shafts

Yexin Huang — 2024-11-02

This paper proposes a multi-roll skew rolling forming process to address the slow forming speed of large-section shrinkage for aviation turbine shafts. Using Simufact Forming software, simulations were conducted on the GH4169 turbine shaft blank, analyzing the variations in stress, strain, and temperature fields during the forming process of a hollow shaft component with an initial wall thickness of 6mm. Additionally, we further explored the intrinsic relationship between the initial wall thickness and the depth of the concave center at the end of the workpiece. The results indicate that after multi-field coupling effects, the metal deformation of the workpiece gradually accumulates along the axial direction, reaching a peak after achieving the maximum reduction, while displaying a trend of decreasing from the outside to the inside. Additionally, there is a positive correlation between the depth of the concave center at the end of the workpiece and the initial wall thickness; as the amount of metal involved in the deformation increases, the depth of the concave center also intensifies. These findings provide an important theoretical basis for achieving flexible rolling formation of turbine shafts.

Effective Technologies for Finishing and Cleaning Processing: Innovations Based on Screw Rotors

Aleksandr Sekisov — 2024-11-26

The results of many years of scientific research in the development of machines, installations, and devices for finishing and cleaning processing of machine parts are presented. Typical diagrams of machines based on screw rotors of classes I-IV are included, along with the types of finishing and cleaning operations performed by screw rotors, requirements for the parts being processed, the processing environments, and the composition of solutions used in the finishing and cleaning of components. Additionally, the methodology and calculations for a continuous operation setup designed for finishing and cleaning parts with specified productivity are demonstrated.

The Correlation Between Wear and Lubricating Film Thickness in the Tribocorrosion of CoCrMo Alloy

Jinyu Li — 2024-12-17

Tribocorrosion modelling of passive metals considering the lubrication effect from solution is still not well studied. A lubricated tribocorrosion model for CoCrMo alloy metal-on-metal hip joints has been developed, while the generalization of this model is restricted by Dowson’s empirical correlation. This study explored the correlation between wear of CoCrMo alloy in tribocorrosion and lubricating film thickness. The results showed that the chemical, mechanical and total wear volumes of CoCrMo alloy in tribocorrosion were significantly influenced by the lubrication effect from the solution. Good correlations were obtained between the lubricating film thickness and chemical, mechanical and total wear, respectively. The new chemical and mechanical wear correlations could be used to generalize the current lubricated tribocorrosion model for CoCrMo alloy.

Development of Control Method for Abration and Evaluation of Electrocautery Device Controller

JungHun Choi — 2024-12-24

The symmetrical impedance bridge, will be suggested to yield consistent and reliable results for measuring tissue damage during electrosurgical ablation. The methods that were identified as potentially viable for ablation detection were force and displacement measurements between the electrode tip and tissue surface. These were found to correlate tissue damage due to a high degree of variability in charge density caused by contact area variation. Another method, temperature measurement via thermistors, will be found to have a response time and a non-contact method will be examined with the size constraints. The last method will be to measure and correlate changes in the power output of the ESU to tissue damage. This method will be practically examined to measure and correlate to tissue damage due to ESU power output modulation. The changes in the tissue's electrical properties can be measured directly far more easily than measuring the power output. Correlation with tissue damage tended to be strong with an error range below what can be detectable by the human eye. But the high degree of variability in the mechanical properties of tissue makes the use of force and displacement measurements difficult to implement as part of a control method for ablation control.

Self-Organization of Surface Structures during Friction Coatings Based on Forsterite

V.V. Shchepetov — 2024-12-30

In the work, the patterns of friction and wear of forsterite-based coatings were studied, and their structural-phase composition, conditions of formation and self-regulation of surface structures were determined from the standpoint of the structural-energy theory of friction. Detonation coatings developed on the basis of forsterite are characterized by high anti-friction properties. The conducted studies showed that the most appropriate application of the investigated coatings is to increase the reliability of operation of friction nodes during strengthening and restoration, for example, for moving pairs of control mechanisms, hinges of guide surfaces, cams, sliding supports, pairs with reciprocating movement, bearings, sliding guides, etc. in which the use of traditional lubricants is undesirable. Compounds of complex oxides of magnesium orthosilicate were used as the basis of composite coatings. The structural and phase composition of the coatings, the peculiarities of the formation of complex alloyed secondary structures, taking into account both the properties of the alloying elements and the structures formed by them, were established. The physical mechanism was determined and the main factors determining the level of thermodynamic graphitization were clarified. The studied self-lubricating compositions can be used both for strengthening and for high-quality restoration of worn triboelements by any technological methods using powder materials.