Mechanics

Numerical Investigation of Yield Stress and Damping Force for a Modeled Damper Using Different MR Fluids

2024-04-21T16:42:41+03:00

This article presents the yield stress, shear damping force, viscous damping force, and total damping force generated in a modeled damper using various magnetorheological (MR) fluids. The values of the generated magnetic field intensity in a modeled damper have been obtained by performing a magnetostatic analysis using ANSYS Maxwell v.16 software. All the used MR fluids exhibit growth in yield stress and damping force on increasing the input current. The magnetic field intensity values are fitted into yield stress-magnetic field intensity quadratic equations which are developed for all the used MR fluids using the least square techniques in order to compute the yield stress. The estimated yield stress is maximum for AMT RHEOTEC⁺ fluid and lowest for MRF-122EG for all input current values. The computed yield stress of in-house prepared optimal MR fluid exhibits good agreement with the commercially available MR fluids. The results exhibit that the MRF-140CG owns the largest viscous damping force (90.72 N) while MRF-122EG owns the lowest viscous damping force (13.61 N) for the modeled damper. AMT RHEOTEC⁺ fluid possesses the largest shear damping force (controllable force) as well as total damping force while MRF-122 EG is the one that exhibits the lowest value for shear as well as total damping force

Development and Research of the Laser Engraving Process in Packaging Manufacturing Technology

2025-05-08T13:28:43+03:00

The areas of application of carbon dioxide lasers in the printing industry are given. A technological process for laser engraving of packaging made of wood-fiber materials has been developed. Experimental studies of the influence of the parameters of CO₂ laser radiation on the engraving process of HDF material, which is widely used in the packaging industry, have been conducted. The dependence of the engraving depth on changes in the speed and power of laser radiation has been studied. Based on the experimental studies conducted, the main operating, technological and operational factors affecting the quality of engraving have been identified.

Synthesis and Rheological Characterization of Magnetorheological Fluids

2024-05-07T12:35:54+03:00

Magnetorheological (MR) fluids correspond to the kind of smart materials, capable of varying their rheological characteristics i.e., viscosity, yield stress, etc. on varying the magnetic field. In this article, 18 MR fluid samples utilizing various constituents are prepared and optimized with the aid of an L₁₈ orthogonal array. The synthesized samples are experimentally tested on a rotational oscillatory shear rheometer namely MCR-102 (modular compact rheometer) to obtain the shear stress values at various shear rates (0 - 1000 Sec^-1) and different currents (0 - 5 Ampere). This experimentally obtained data is fitted to the Herschel-Bulkley fluid model to estimate the On-state Yield Stress (OYS) for the tested MR fluid samples. An optimal set of the selected parameters i.e., silicon oil (carrier fluid), CI6 as the type of iron particle, 24 (Vol%) of iron particle proportion, and ethylene glycol monostearate (1.0% by volume) has been obtained using Taguchi analysis. An experimental verification test on the MR fluid with the Taguchi predicted optimal set of parameters has been performed and OYS matches well (a marginal error of 1.54%) with its statistically predicted value. The ANOVA results examine the contribution of input parameters and present that the iron particle proportion is the most prominent parameter that impacts the OYS, contributing 76.36%, followed by iron particle type which contributes 19.75%, carrier fluid with a contribution of 3.11% and additive proportion has a contribution of less than 0.1%. The OYS values for the optimal MR fluid are compared with commercially available MR fluids i.e., Lord MRF-122EG and MRF-132DG at various magnetic field intensities (0 - 164 kA/m). The comparison results exhibit that the OYS for the optimal in-house prepared MR fluid follows the same pattern as followed by MRF-122EG and MRF-132DG at all values of applied magnetic fields.

Effect of Surface Thermoelastic Deformation on the Performance of the Hydrodynamic Big-Size Step Bearing

2025-05-09T18:51:01+03:00

The multiscale lubrication analysis is presented for estimating the performance of the hydrodynamic big-size step bearing by incorporating the effects of the surface thermoelastic deformation and the lubricant molecule layers physically adsorbed to the bearing surface. The numerical calculation results show that in the condition of heavy loads and high sliding speeds, the effect of the surface thermoelastic deformation can reduce the minimum surface separation by 1 to 2 orders, while the effect of the physically adsorbed layer on the bearing surface significantly increases the minimum surface separation especially for the strong fluid-bearing surface interaction; The effect of the surface thermoelastic deformation largely modifies both the film pressure profile and the surface separation profile in the bearing; It also obviously changes the friction coefficient of the bearing. The effect of the physically adsorbed layer significantly influences the friction coefficient of the bearing only in the condition of heavy loads and high sliding speeds, which yields very low surface separations.

Multi-Objective Optimization and Design of Hydraulic and Hemolysis Performance of Micro-Axial Heart Pump

2025-04-10T15:06:53+03:00

In order to optimize the hydraulic performance of the heart pump and reduce blood damage, the effects of the main structural parameters on efficiency, head and hemolysis values was studied by CFD, outlet impeller diameter, inlet impeller blade angles, outlet impeller blade angles and blade thickness were selected as design variables using OFSD method, the efficiency, head, and hemolytic performance of the pump were taken as objective functions, the response surface method is used to fit the multivariate regression model of design variables and objective functions. Finally, the multi-objective optimization is carried out with NSGA-II genetic algorithm, one of the qualified structural parameter combinations was selected according to actual needs as the final solution of the optimization. The outlet impeller blade angles is β2=30°, the outlet impeller diameter is D2 =20 mm, the outlet impeller blade angles is β1=12.5°, and the blade thickness is δ = 1 mm. Efficiency is 74.5% , head is 96.3 mmHg, the hemolytic value is 0.0172 g/100L. The study results can provide a reference for the structural optimization of heart pumps.

Investigation on Energy Output Performance of IPMC Optical-Controlled Composite Driving Based on PLZT Ceramic

2025-04-18T18:05:13+03:00

Ionic polymer-metal composite (IPMC), as an intelligent material, exhibits advantages such as rapid responsiveness, large deformation angles, and high flexibility, leading to its extensive application in biomimetic machinery, biomedicine and other fields. In this paper, based on the previous proposed IPMC optical-controlled composite driving method under lanthanum-modified lead zirconate titanate (PLZT) ceramic configuration, the output energy characteristic is analyzed by establishing a novel model and conducting a series of experiments. The analysis and experimental results show that under different light intensities, the driving force and output deformation of IPMC with varying dimensions exhibit similar trends, both increasing gradually and reach a maximum value. Furthermore, the deformation curves of IPMC driven by light source are consistent with those driven by direct current, confirming that IPMC under light excitation also possesses stable and excellent energy output properties. Therefore, the research on the energy output of IPMC optical-controlled composite driving not only provides deeper theoretical guidance for its application in flexible driving area, but also promotes the vigorous development of IPMC in other innovative technological fields.

Enhancing Fracture Assessment of Pipe Girth Welds with Root Cracks

2024-11-27T18:30:51+02:00

Despite the widespread use of the failure assessment diagram, accurately evaluating girth weld joints with cracks remains a significant challenge within the pipeline industry, due to the mismatched strength between the parent metal and weld metal. To Address this issue, an innovative approach was proposed by converting the heterogeneous girth welds as an equivalent homogeneous structure and deriving an equivalent stress-strain relation, thereby enabling the construction of a failure assessment curve for girth welds. This study aims at enhancing the precision of defect assessment in girth welded joints. Firstly, a finite element model is developed to characterize the crack driving force in high-grade pipeline girth welds. Furthermore, an optimized calculation method is proposed for determining the reference stress and limit load of pipeline girth welds with root cracks by introducing a correction factor. Moreover, a predictive formula for the correction factor has been established based on finite element simulation results. Through rigorous numerical simulations and methodical calculation techniques, this study aims to provide guidance for the accurate evaluation of girth weld root cracks in pipeline engineering applications.

Analysis of Material Optimization and Performance Parameter Difference of Expandable Sand Screen

2025-05-15T13:19:35+03:00

Sand control technology of expansion sand screen is one of the effective methods to solve the sand problem in oil wells, due to its unique working mode, which has significant benefits in improving production and reducing costs, and has been widely used in the oilfield field. However, the operational conditions that expansion sand screens are subjected to, such as high temperatures, high pressure and high corrosion, exert greater demands on the material performance of the expansion sand screens. The advancement of this technology is predominantly constrained by the intrinsic characteristics of the material in question. In this study, five materials were selected as the base tube materials of the expansion sand screen, namely stainless steel 654SMo, stainless steel Incoloy 27-7Mo, stainless steel 2507, stainless steel Incoloy 625 and stainless steel 316L. These materials were chosen based on their performance requirements in relation to the expansion sand screen. The impact of diverse materials on the expansion performance of base tubes was investigated through a multifaceted approach, integrating tensile experiments, prototype expansion experiments, and finite element analysis. The experimental results demonstrate that stainless steel 316L is a more suitable base tube material under the condition of relatively low requirements for temperature and corrosive environment. Conversely, stainless steel Incoloy 27-7Mo is a more suitable base tube material in more demanding deep well environments. Finally, stainless steel Incoloy 625 is a more suitable base tube material for working conditions with higher requirements for corrosion resistance and mechanical properties. A comparison of the results of the finite element analysis with those of the prototype expansion experiment indicates that the volume percentage of the high stress region is a useful indicator of the expansibility of the base tube to a certain extent. The findings of this study provide a novel evaluation metric for the optimisation of parameters and the selection of materials for expandable sand screen. This has the potential to reduce costs and time during the research process.

Experimental Investigation on Fatigue Crack Propagation Under Mixed Mode Loading on Aluminum Alloy AA3033

2025-05-25T22:17:17+03:00

The phenomenon of fatigue-crack propagation is a permanent concern for designers, manufactures and users in order to ensure the integrity of structures subjected to cyclical stresses during their operational service. The concept of damage tolerance (DT) is the most commonly used for the design of structures with the prediction of fatigue life crack propagation. Most researchers have focused on studying fatigue crack propagation under mode I loading conditions. However, these structures in service are often subject to complex constraints and combined stresses that can generate local loadings in mixed modes I, II and mode III. In this regard this paper presents a study of fatigue crack propagation in mixed mode (I+II) using CTS (compact-tension-Shear) specimens for three loading angles (45°, 60°, and 90°) respectively. The mixed-mode fatigue crack propagation tests were carried out in modes I and II using the CTS specimen and Arcan loading device specially designed and constructed by our laboratory based on the Richards principle. The experimental results show that the loading angle has a significant effect on the crack growth rate and consequently on the fatigue life prediction of mechanical structure under fatigue loading.