Strojniški vestnik - Journal of Mechanical Engineering

Design and Evaluation of a Passive Compliance Control Method of an Offshore Wind Turbine Blade Grinding Robot

Xinrong Liu, Hao Li, Yu Fang, Diqing Fan — Thu, 08 May 2025 00:00:00 +0000

Robots that repair offshore wind turbine blades are susceptible to interference from different factors such as external wind, which can lead to damage to the blades by the robot during the grinding process. Therefore, the robot needs to keep the grinding contact force constant in the complex operating environment. In this study, a constant force control device that is based on a pneumatic system is designed to address this problem, and a controller that is based on an improved Active Disturbance Rejection Control (ADRC) algorithm was proposed to control this device. Based on the analysis of the mechanism of the constant force control device and according to the relative order of the system, a second-order ADRC is designed. The controller utilizes a tracking differentiator (TD) to filter the input signal, an extended state observer (ESO) to estimate the total perturbation in the system, and a nonlinear state error feedback control law (NLSEF) for compensation. In order to solve the problems of electric proportional valve dead-zone characteristics, unknown interference during high altitude operation, tilt angle changes during grinding, dead-zone compensation, and gravity compensation algorithms were incorporated into the controller. Finally, the experimental platform is built to carry out experiments under various working conditions. The experimental results show that the controller improves the system regulation time by 59%, with an overshoot close to zero, when compared with the traditional proportional-integral-derivative (PID) algorithm. Also, both the absolute value of the maximum error and the mean square value of the error have been reduced to a large extent. As a result, the controller has a better force control accuracy and dynamic tracking performance, strong interference rejection capability and adaptability, and provides a theoretical basis for practical engineering applications.

Impact of Excitation Frequency and Fill Levels on Fuel Sloshing in Automotive Tanks

Rajamani Rajagounder, Jayakrishnan Nampoothiri — Thu, 08 May 2025 00:00:00 +0000

Fuel sloshing in modern automotive fuel tanks is analyzed in this study to provide a better understanding of fuel system performance. The behaviour of sloshing waves was investigated under varying excitation frequencies and fuel fill levels using both experimental and numerical methods. A sinusoidal motion was applied to the fuel tank along its transverse axis, and the resulting wave profiles were captured using a digital camera setup. Numerical simulations were conducted using the volume of fluid (VOF) model and a user-defined function (UDF) in ANSYS Fluent to predict the sloshing wave profiles. The study reveals distinct wave patterns depending on the excitation frequency. Standing and traveling waves were observed at 0.5 Hz and 0.6 Hz, while multiple traveling waves with wave collisions occurred at 0.7 Hz. Additionally, increasing the fuel fill level (from 25 % to 60 % of tank height) significantly enhanced the damping of sloshing wave oscillations. Regression equations were developed to quantify the relationship between excitation frequency, fill level, and sloshing wave amplitude. These findings may contribute to the design of fuel tanks that mitigate sloshing effects and enhance overall vehicle performance.

The Effects of Oil Temperature and Oil Return Pressure on Oil Film Damping Characteristics of a High-Speed Solenoid Valve

Peng Liu, Qing Zhao, Shijian Peng, Wenwen Quan, Zhida Gao — Thu, 08 May 2025 00:00:00 +0000

A high-speed solenoid valve (SV) is a critical executive component in common rail fuel injection systems, where its dynamic response significantly influences the control accuracy of fuel injection. Moreover, this response is particularly affected by the damping force (DF) of the oil film between the armature and the iron core. To investigate the effects of oil temperature and oil return pressure on the oil film damping characteristics of high-speed SV, a numerical simulation approach was employed. Computational fluid dynamics (CFD) models were constructed to analyze the influence of oil temperature and oil return pressure on both the DF of the oil film and its cavitation properties across varying operational air gaps. The results indicate that as the oil temperature increases, the DF of the oil film generally exhibits a decreasing trend during the suction and release processes of the high-speed SV. Additionally, increasing the initial and residual air gaps can mitigate the influence of temperature on the DF of the oil film, thereby reducing the incidence of cavitation. Notably, the oil return pressure does not affect the DF of the oil film during the suction process. However, during the release process, the DF of the oil film increases with the oil return pressure when the residual air gap is small. At medium residual air gaps, the DF initially increases with the oil return pressure before subsequently decreasing, and is accompanied by oscillations during cavitation collapse. For large residual air gaps, the impact of oil return pressure on the DF of the oil film becomes negligible.

Optimizing Support Patch Geometries in Adhesively Bonded Single Lap Joints: A Finite Element Analysis Approach

Ahmet Çalık — Thu, 08 May 2025 00:00:00 +0000

In recent years, the preference for adhesive bonding over traditional methods like bolted or riveted connections has garnered the attention of researchers. This study employs finite element analysis to optimize the geometry and placement of support patches in adhesively bonded single lap joints, significantly reducing stress concentrations and enhancing joint strength. Initially, a comprehensive finite element analysis was conducted to numerically evaluate the influence of different support patch parameters and their positions on the strength of single lap joints (SLJs). To validate the finite element analyses (FEA), comparisons were made with existing studies in the literature and analytical solutions. The numerical results in this study reveal that the dimensions and placement of the support patch can potentially reduce the load and stress distribution in different regions of the adhesive joint, which could increase its strength.

A Numerical Simulation and an Experimental Study on the Steady-State Levitation Characteristics of a Magnetic Ball Driven by External Electromagnets in a Fluid Tube: Applications to Micromachines in Human Blood Vessels

Zhanxiang Cui, Yonghua Lu, Yun Zhu, Zezheng Wang, Ziyuan Wang — Thu, 08 May 2025 00:00:00 +0000

Research on micro-robots in the field of medicine has introduced innovative methods for treating various diseases. This study aims to expand the application of controllable micromechanical diagnoses and treatment within human blood vessels by designing a magnetic levitation ball system in a fluid-filled circular tube. The system enables a magnetic ball to be stably suspended along a specific path under the influence of an external magnetic field. Simulations of the system’s electromagnetic field, flow field characteristics, and mechanical state were conducted by using finite element software. The study analyzed the effects of the ball’s position, magnetic pole direction, driving current, and fluid flow rate on the forces acting on the magnetic ball. Joint simulations of the flow and magnetic fields were performed using the ANSYS Workbench platform, and a multi-objective optimization method was employed to determine the parameters for stable suspension. Experimental validation demonstrated the stable suspension of the magnetic ball in a fluid tube under an external magnetic field. The experiments revealed the relationships among the driving current, fluid flow rate, and the ball’s stable suspension position, confirming the effectiveness of the simulation method and the feasibility of controlling object positions within fluid tubes.

Research on a Rapid Method for Obtaining the Matching Point of the Static Operating Pressure of a Supersonic Jet in a Wind Tunnel

Peng Liu, Jinglun Cai, Xuejing Shao, Hui Jin — Thu, 08 May 2025 00:00:00 +0000

In the wind tunnel test, mismatched operating pressures can cause the jet flow field to produce expansion waves, compression waves, and wave interference. The current wind tunnel pressure matching study requires continuous adjustment of the operating pressure at the inlet and outlet to obtain an ideal supersonic jet in an expanded state, and the pressure matching workload is substantial. This study presents a numerical simulation of the flow field of a supersonic wind tunnel under different outlet pressures based on the Reynolds-averaged Navier-Stokes (RANS) method. A method for quickly obtaining the static operating pressure matching point of a supersonic jet is proposed, which can quickly determine the matching operating pressure. When the Mach number of the monitoring point on the axis of the core area of the jet is within 5 % of the standard Mach number at the nozzle outlet, the jet in the wind tunnel test chamber is in an ideal expansion state, and the outlet pressure under this condition is the standard operating pressure for pressure matching. At the same time, the flow field structures under the conditions of over-expansion, ideal expansion, and under-expansion were compared, and it was shown that the key physical parameters in the core region of the supersonic jet field under the ideal expansion state obtained by this rapid matching method were stably distributed, which allowed the uniform region of the jet to exceed the limits of the diamond region and achieve uniform flow within the boundary of the supersonic jet.

Comparison and Optimization of Burnishing Parameters in Various Machining Conditions

Thu, 08 May 2025 00:00:00 +0000

This study proposes a cryogenic diamond burnishing process and optimizes cooling parameters, including the distance to nozzle (N), nozzle diameter (D), and CO2 flow rate (Q) to minimize the maximum roughness (R), energy consumption (E), and circularity (C). The Kriging and adaptive-network-based fuzzy inference system (ANFIS) methods were ultilized to propose the response models. The CRITIC, non-dominated sorting genetic algorithm-II (NSGA-II), and MABAC were applied to calculate the weights, generate feasible solutions, and select the best optimal data. The result indicated that the optimal N, D, and Q were 15 mm, 9 mm, and 8 L/min, respectively. The reductions in the roughness, energy, and circularity were 15.5 %, 2.0 %, and 38.6 %, respectively. The roughness and energy models were primarily affected by Q, D, and N, respectively, while circularity model was influenced by the N, D, and Q, respectively. The proposed process could be used to machine different holes with minimizing environmental impacts. Lower roughness and circularity were achieved using the cryogenic diamond burnishing process. The Kriging-NSGA-II could be utilized to show non-linear data and produce the best results.

Research on the Cutting Performance of Self-Lubricating Tools with Microtexture of the Front and Back Surfaces

Yan Zhang, Haodong Sun, Qi Li, Kaiming Sun, Yuanjing Mou, Shihong Zhang — Thu, 08 May 2025 00:00:00 +0000

A novel hexagonal microtexture is proposed to enhance the cutting performance of polycrystalline cubic boron nitride (PCBN) tools. Three-dimensional models of both conventional and microtextured tools are developed, and the turning process is simulated using AdvantEdge finite element software. The effects of cutting force, temperature, and stress on tool performance are investigated. Additionally, microtextured turning tools are fabricated for orthogonal experiments to analyze the effects of different texture positions on cutting performance. When the tools with microstructures on both the rake and flank faces (T4) are used in conjunction with solid lubricants, the cutting force is reduced by 3 % to 7 %. Furthermore, implementation of microtextures decreases the friction coefficient, improves the surface quality of the workpiece, and enhance the tool’s wear resistance. Therefore, tools featuring microstructures on both the rake and flank faces, combined with solid lubricants, effectively enhance cutting performance.