International Journal of Hydromechatronics (7 papers in press)

Regular Issues

• Wear monitoring of hydraulic reciprocating seal based on contact stress  
  by Xiuxu Zhao, Jiaping Duan, Haile Tang, Appiah Emmanuel 
  Abstract: Timely and accurate monitoring of seal wear is crucial for ensuring the safe and efficient operation of hydraulic cylinders during actual operation. This study designed a fibre Bragg grating (FBG) sensor monitoring unit to achieve hydraulic cylinder seal wear monitoring based on sealing surface contact stress. Experimental research was conducted using a specially designed monitoring experimental system, and the results showed that as the wear of the piston rod seal increased, the circumferential and axial contact stresses of the seal first increased and then decreased. This study provides an effective means for further investigating the wear and performance degradation process of hydraulic reciprocating seals under actual usage conditions.
  Keywords: hydraulic reciprocating seal; contact stress; wear monitoring; fibre grating sensor.
  DOI: 10.1504/IJHM.2024.10071024
   
  
• Numerical modelling and experimental study of fluid friction torque for clearance sealing of hydraulic rotary joints  
  by Xiuxu Zhao, Jing Zhang, Kyaw Thiha Soe, Jiantao Nie 
  Abstract: In high-speed hydraulic rotary joints, the frictional torque generated by the rotation of fluid in the sealing gap can affect the fluid delivery efficiency, increase the possibility of locking between the spindle and the fixed housing, and lead to the functional failure of the rotary joint. Therefore, it is of great significance to solve this problem through the reasonable design of the structural parameters of the rotary joint. This study first derived the calculation method for the friction torque of hydraulic rotary joints from a theoretical perspective, and then studied the relationship between the friction torque of hydraulic rotary joints and structural parameters (clearance value, effective sealing length, spindle diameter) through simulation and experiment. A corresponding mathematical model was established, and the effectiveness of the model was verified with actual rotary joint products, providing a theoretical basis for optimising the performance of high-speed hydraulic rotary joints.
  Keywords: high-speed hydraulic rotary joints; gap seal; friction torque; structural parameters.
  DOI: 10.1504/IJHM.2024.10071025
   
  
• Performance-oriented structural optimisation for CDC slender valve  
  by Jinghao Wang, Pu Qin, Linguang Li, Liu Pengtao, Junjie Chen, Bing Xu, Jianjiang Zhao, Dingyao Lu, Jiang Guo 
  Abstract: The structural optimisation is a crucial step in researching the CDC proportional pilot valve; however, the influence of its structure on key performance remains unclear. This study established the mapping relation between the key performance parameters and structural characteristics of CDC solenoid valves according to the concept of high-performance manufacturing. The simulation model was established and the accuracy was verified. Modelling simulations and theoretical analyses was adopted to optimise the structural parameters based on performance. Results demonstrated that reducing the air gap between the armature and magnetic conductive sleeve increased electromagnetic force and reduced response time. The optimised electromagnetic and response characteristics are obtained when the magnetic isolating ring is placed 0.5 mm below the end face of the valve seat. After optimisation, the average electromagnetic force is increased by 7.72 N, the standard deviation is reduced by 0.36, and the response time is reduced by 4.8 ms.
  Keywords: shock absorber; CDC solenoid valve; dynamic characteristic; static characteristic; simulation; structural optimisation.
  DOI: 10.1504/IJHM.2025.10071698
   
  
• Ride comfort analysis of hydro-pneumatic suspension considering variable damping matched with dynamitic load  
  by Xuepeng Cao, Zenglu Zhao, Wenfeng Zhu, Gaoqi Lian, Min Ye, Mohammad Manjur Alam 
  Abstract: Mining trucks are frequently used in the quarrying industry, where the suspension system plays a vital role in ensuring driving stability. Addressing the limitations of traditional hydro-pneumatic suspension, which struggle to accommodate varying load conditions adequately, we propose a novel suspension structure with real-time adjustable damping. This system dynamically adapts the internal spool position and piston rod stroke to achieve self-adjustment of damping, ensuring optimal performance across different loads. We establish elastic and damping force models by considering the interaction between external vibration excitation and internal structure. Subsequently, we analyse the damping stiffness characteristics of the suspension under various load conditions, evaluating its suitability. Simulation models are then developed to validate the effectiveness of the proposed variable damping hydro-pneumatic suspension. Results indicate that, compared to fixed damping systems, the variable damping suspension offers improved ride comfort and stability across load conditions. Specifically, under full-load, peak acceleration decreases by 0.17 and stability time shortens by 1.8s, under medium load, peak acceleration reduces by 0.4 and stability time decreases by 1.4s, under no-load, peak acceleration decreases by 0.45 and stability time shortens by 0.7s. Effectively improve the smoothness under different loads and the driver’s comfort.
  Keywords: hydro-pneumatic suspension; variable damping; varying load conditions; damping matching; ride comfort.
  DOI: 10.1504/IJHM.2025.10071699
   
  
• Research progress of diesel-methanol dual fuel injector  
  by Du Huang, Yazhou Li, Lei Shi, Jiayong Zhou, Dong Li, Shuang Hu, Yong Zhou, Xuedong Wu, Xiaohu Zhou, Chaonan Xiao, Xuqing Li, Chao Qu, Sheng Jiang Deng, Tao Yang, Yu Zhen Hu 
  Abstract: Currently, methanol is globally recognised as a reliable alternative energy for achieving low/zero carbon emissions in marine engines. Marine engine manufacturers are developing diesel-methanol dual-fuel injectors, whose performance critically impacts engine power, efficiency, and emissions. This paper reviews structural and performance advancements in such injectors, highlighting their evolution from hydraulic-pressurised to electronically controlled systems. Studies demonstrate that excessive injection pressure compromises engine performance, while improper injection angles increase emissions due to uneven fuel distribution. Optimisation methods like genetic algorithms and neural networks have been employed to address these challenges. Though methanol application in marine engines remains nascent, unresolved technical issues, particularly concerning material compatibility are being targeted. Future advancements in methanol-resistant materials and gasified multiphase injection technology (e.g., in injector SAC chambers) are expected to expand dual-fuel injector applications from marine engines to broader internal combustion fields.
  Keywords: research progress; diesel-methanol; dual fuel injector; design and optimisation.
  DOI: 10.1504/IJHM.2025.10071846
   
  
• Quantitative analyses of the influence of practical aspects on hydraulic force control performance  
  by Elisa G. Vergamini, Cícero Zanette, Lucca Maitan, Leonardo F. Dos Santos, Marcos P. Nostrani, Thiago Boaventura 
  Abstract: Hydraulic actuators are a strong alternative for robotics, offering high mobility and a favourable power-to-weight ratio. However, in many industrial and robotic applications, key system parameters - such as oil temperature, hose length, supply pressure, valve bandwidth, and control frequency - can vary over time due to operational demands, wear, or environmental conditions. Despite their importance, the impact of these variations on force control performance is often underestimated. This study investigates how such parameters affect the performance of a standard PI force controller in hydraulic actuators. Using the IC2D test bench, experiments were performed with different servovalves (Moog E024 and G761) and parameters setups. Results show that pressure level and hose length significantly impact controller performance, while valve model produces less predictable effects. Control frequency has little influence. Interestingly, temperature affected force tracking in unexpected ways, with valve opening and flow rate playing a more dominant role.
  Keywords: practical aspects; hydraulic actuators; servovalves; force control performance; hydraulic force; oil temperature; hose length; valve bandwidth; control frequency; supply pressure.
  DOI: 10.1504/IJHM.2025.10072847
   
  
• Design of bearings load uniform structure and study on load uniform effect of submersible screw pump  
  by Rui Dong, Zhiqiang Wang, Beilin Han, Salvinder Singh Karam Singh, Chenxu Chen, Tianxing Tu 
  Abstract: The submersible screw pump (SSP) is widely utilised due to its low cost, high energy efficiency, and exceptional pumping performance. However, under high-speed and heavy-load operating conditions, key components such as bearings experience significant axial loads, which lead to reduced bearing lifespan and reliability. To enhance bearing lifespan and reliability, this study combines both simulation and experimental approaches to design a multi-stage bearing load uniform structure. Simulation analysis was performed on components such as disc springs. The results indicate that the multi-stage bearing load uniform structure can effectively uniform axial loads. The study also identifies that factors, such as the gap between the disc spring and the bearing as well as assembly gaps, negatively impact load uniformity. Therefore, this research offers an effective design strategy for the structural optimisation of SSPs, contributing to improved bearing group lifespan and reliability.
  Keywords: submersible screw pump; bearings load uniform structure; multi-stage bearings; load uniform effect.
  DOI: 10.1504/IJHM.2025.10072877