Abstract: With the continuous advancement of industrial automation, robotic arms have been widely adopted across various fields, making performance optimization a key research focus. As a critical component for enhancing robotic arm performance, kinematic analysis plays a vital role in achieving precise control. This study utilizes the MatlabRobotics toolbox to conduct kinematic analysis on the SNR3-C30 robotic arm. By establishing a mathematical model of the robotic arm and solving forward/reverse kinematic equations, we implemented a fifth-order polynomial interpolation algorithm for trajectory planning in the joint space. The research demonstrates that the established model accurately describes the robotic arm's motion characteristics, while the forward/reverse kinematic solution method proves effective and reliable. These findings provide crucial theoretical foundations for optimizing design and developing control strategies for the SNR3-C30 robotic arm, significantly improving operational precision and efficiency in real-world applications. This work holds great significance for advancing robotic arm technology development. Read More

Abstract: The hole-drilling method is a widely used semi-destructive technique for determining residual stresses in engineering components. This paper provides a comprehensive review of the method's evolution, fundamental principles, and modern advancements based on an analysis of key literature. The review begins by outlining the traditional application for measuring uniform surface stresses and traces its development into the incremental hole-drilling technique, which allows for the determination of residual stress variation with depth. Central to this evolution is the use of calibration coefficients, which correlate measured strain relaxation to the underlying stress state. This paper synthesizes the various analytical and computational approaches for deriving these coefficients, highlighting the pivotal role of the Finite Element Method (FEM) in modern practice. A significant portion of the review is dedicated to a critical examination of the method's inherent challenges and sources of error, which include plasticity effects at high stress levels, the influence of component thickness (particularly in thin sheets), stress biaxiality, and discrepancies between ideal and real hole geometries. The literature reveals a consistent trend towards developing sophisticated correction procedures, often integrating FEM simulations with experimental data from both traditional strain gauges and advanced optical techniques like Digital Image Correlation (DIC). Persistent challenges include the lack of standardized procedures for thin components and highly plastic conditions. Future research directions point towards the development of integrated, multi-parameter correction models, further standardization, and the fusion of numerical simulations with full-field optical measurements to enhance the accuracy and expand the applicability of this vital measurement technique. Read More

Abstract: The aerodynamic performance of centrifugal fans has been studied due to their wide application in industrial and engineering fields such as ventilation, air circulation, and thermal management. This paper investigates the performance characteristics of a backward-curved blade centrifugal fan at approximately 1000, 2000, and 2700 rpm through experimental methods. The experimental apparatus comprised a calibrated nozzle, diffuser, universal dynamometer, slide valve, and digital pressure display for precise measurement of pressure rise, volumetric flow rate, electrical power, and efficiency. By progressively altering the slide valve opening, pressure-difference versus flow rate curves and efficiency versus flow rate curves were obtained. The results demonstrated typical centrifugal fan characteristics: pressure rise initially increased then decreased with rising volumetric flow rate, while efficiency peaked at medium-to-high flow rates. To validate hydrodynamic similarity, dimensionless parameters including flow coefficient, pressure difference coefficient, and power coefficient were calculated. Results demonstrate that the dimensionless pressure and power curves at different rotational speeds largely coincide, confirming the principle of dynamic similarity. However, significant deviations occur at low rotational speeds, primarily attributed to increased friction losses, flow separation, and slip effects. This study confirms the applicability of dynamic similarity in centrifugal fans and reveals the influence of Reynolds number and efficiency variations under low-speed conditions, providing a reference for fan design optimization and performance prediction. Read More

Abstract: This study investigates the overturning stability of a self-developed, adjustable-height single-arm mobile manipulator during operations involving height variations and load-bearing tasks. Static and dynamic stability analyses were conducted to evaluate system performance. Under no-load and low-speed conditions, static stability was assessed using the gravity method. For typical operational scenarios with variable loads and changing arm heights, a dynamic stability criterion based on the Tip-Over Moment (TOM) was proposed, accompanied by the establishment of a system dynamics model and a comprehensive evaluation framework incorporating mean value and standard deviation metrics. Through co-simulations in MATLAB and ADAMS, the dynamic performance was examined under various combinations of load mass and manipulator height. Results indicate that the system maintains stability across all tested conditions. Increasing the load mass was found to enhance system stability, while elevating the arm height, despite improving the overall anti-overturning tendency, was observed to amplify moment fluctuations. This research provides a theoretical foundation for structural optimization and stable motion control of this class of adjustable-height single-arm mobile manipulators. Read More

Abstract: Selective Laser Melting (SLM) is a leading additive manufacturing technology capable of producing complex metallic components with high precision. However, the intricate physical phenomena involved, such as rapid melting and solidification, lead to challenges in process control and quality assurance, often resulting in defects like porosity and residual stress. Experimental optimization is costly and time-consuming. Consequently, numerical simulation has become an indispensable tool for understanding the underlying mechanisms and optimizing process parameters. This review synthesizes recent research on the numerical simulation of the SLM process. It summarizes key findings on the modeling of melt pool dynamics, heat transfer, and fluid flow, highlighting the influence of primary process parameters—laser power, scanning speed, and hatch spacing—on the thermal behavior and resulting part quality. The paper discusses various modeling approaches, from continuum-based Finite Element Methods (FEM) to particle-level Discrete Element Methods (DEM), and the application of different heat source models. Key challenges, including multi-scale/multi-physics coupling, computational expense, and model accuracy, are identified. Finally, future research directions are proposed, emphasizing the potential of hybrid physics-based and data-driven models, and the integration of simulation with in-situ monitoring for real-time process control and defect prediction. Read More