Mechanical Design Research Articles

Challenges and solutions in the mechanical design of the KM3NeT ARCA Base Module

The goal of KM3NeT ARCA is to search for astrophysical neutrinos with a neutrino telescope operating on the bottom of the Mediterranean Sea, at 3500 m depth, for more than 15 years. A key component of the neutrino telescope is the Base Module (BM) which is built with a titanium cylindrical container hosting optics, electronics and power boards. From a mechanical point of view the BM must be water tight and resistant to an external water pressure up to 350 bar, be able to stand all mechanical stresses along its life, provide excellent corrosion resistance for 15 years at least in sea water and be able to host all internal components safely, by guaranteeing an adequate heat dissipation. The tests performed for the qualification of the mechanical design are presented here. The first BM is successfully operating underwater since 2015.

Design and kinematics analysis of a parabolic cylinder deployment mechanism with modular over-constrained triangular pyramid

Space missions require novel mechanisms that can have compact form in complex space environments. This study proposes a modular triangular pyramid parabolic cylinder deployment mechanism. The modular deployable unit contains an over-constrained triangular pyramid deployable mechanism and a symmetrical trapezoidal Bricard linkage that drives the longitudinal and transverse motions of the mechanism. A cable net is added between two symmetrical linkages to form a parabolic cylindrical reflector and is analyzed by the force density method. The Denavit-Hartenberg (D-H) coordinate method is used to analyze the kinematic characteristics. Based on the analytical solution for the angular displacement, the degrees of freedom of the mechanism are derived from screw theory. Subsequently, the angular velocity and acceleration of the joint points are obtained. Finally, kinematic models of the modular triangular pyramid parabolic cylinder deployable mechanism are established, and the accuracy of the theoretical model is verified using a numerical method. This novel parabolic cylinder deployable mechanism will have a significant influence in aerospace domain. Crucially, the work has value to design deployment mechanism for parabolic cylinder antenna.

Effects of the nozzle design parameters on turbulent jet development of active pre-chamber

Active pre-chamber turbulent jet ignition is one of the most promising technologies for developing low- or zero-carbon engines. However, the relevant fundamental studies are far from adequate, particularly for the independent impact of the pre-chamber design parameters on the jet characteristics in the absence of combustion in the main chamber. In this study, the hot turbulent jet characteristics of the pre-chamber fueled with the premixed CH4-air are studied by the double-pass Schlieren imaging. The effects of the pre-chamber nozzle design parameters, including the orifice diameter, total orifice cross-sectional area, and orientation are clarified. The results reveal that the pressure difference between the pre-chamber and main chamber depends on the total orifice cross-sectional area. The effects of the orifice diameter and total orifice cross-sectional area on the penetration rate exhibit a trade-off relation, while the orifice diameter has a more pronounced effect on the hot jet projection area than the total orifice cross-sectional area. Compared to the inclined orifice, the penetration velocity of the straight orifice is faster at the initial hot jet ejection stage. These results are expected to be valuable references for the pre-chamber design and understanding of the ignition mechanisms of active pre-chamber.

Cellular gradient algorithm for solving complex mechanical optimization design problems

In mechanical optimization design problems, there are often some non-continuous or non-differentiable objective functions. For these non-continuous and non-differentiable optimization objectives, it is often difficult for existing optimal design algorithms to find the desired optimal solutions. In this paper, we incorporate the idea of gradient descent into cellular automata and propose a Cellular Gradient (CG) method. First, we have given the basic rules and algorithmic framework of CG and designed three kinds of growth and extinction rules respectively. Then, the three evolutionary rules for cellular within a single cycle are analyzed separately for form and ordering. The best expressions for the cellular jealous neighbor rule and the solitary regeneration rule are given, and the most appropriate order in which the rules are run is selected. Finally, the solution results of the cellular gradient algorithm and other classical optimization design algorithms are compared with a multi-objective multi-parameter mechanical optimization design problem as an example. The computational results show that the cellular gradient algorithm has an advantage over other algorithms in solving global and dynamic mechanical optimal design problems. The novelty of CG is to provide a new way of thinking for solving optimization problems with global discontinuities.

EnzyACT: A Novel Deep Learning Method to Predict the Impacts of Single and Multiple Mutations on Enzyme Activity.

Enzyme engineering involves the customization of enzymes by introducing mutations to expand the application scope of natural enzymes. One limitation of that is the complex interaction between two key properties, activity and stability, where the enhancement of one often leads to the reduction of the other, also called the trade-off mechanism. Although dozens of methods that predict the change of protein stability upon mutations have been developed, the prediction of the effect on activity is still in its early stage. Therefore, developing a fast and accurate method to predict the impact of the mutations on enzyme activity is helpful for enzyme design and understanding of the trade-off mechanism. Here, we introduce a novel approach, EnzyACT, a deep learning method that fuses graph technique and protein embedding to predict activity changes upon single or multiple mutations. Our model combines graph-based techniques and language models to predict the activity changes. Moreover, EnzyACT is trained on a new curated data set including both single- and multiple-point mutations. When benchmarked on multiple independent data sets, it shows uniform performance on problems affected by mutations. This work also provides insights into the impact of distant mutations within activity design, which could also be useful for predicting catalytic residues and developing improved enzyme-engineering strategies.

Vibration damping by enhancing of magneto-rheological damper performance using novel smart fluid

The objective of the present work is to improve the speed and vibration characteristics of tracked vehicles via a semi-active suspension system that uses a Magneto-Rheological (MR) damper. MR damper is designed, manufactured, and tested with different harmonic excitations. The MR damper reliability under high-frequency stresses is considered in the mechanical design phase as well as the configurations and dimensions of the damper. Two fluid samples DELTA and GAMA are prepared, which differ in carrier fluid dynamic viscosities to have different rheological properties and tested to determine the dynamic characteristics of the damper. The damper’s ability to isolate vibration is measured by MTS. The investigation performed not only clarifies MR fluid characteristics but also proves the fact that the fluid is non-Newtonian with good rheological properties. One of the two fluid samples called DELTA is found to have the required properties. The MR damper filled with this DELTA shows a significant increase in damping force according to the excitation current and is much higher than the conventional passive suspension damping force. The proposed damper can cope with the increase in both magnitude and frequency of the input, which represents the speed of the truck and roughness of the road. Upgrading the suspension system of the vehicle from a passive damper to a manufactured semi-active MR damper with MR fluid DELTA can increase the damping force that the passive damper produces by 207% in compression stroke and 136.2% in rebound stroke at the same testing conditions.

Image reconstruction method based on wavelet fusion in electrical capacitance tomography with rotatable electrode sensor

In this paper, an image reconstruction method based on wavelet fusion in electrical capacitance tomography with a rotatable electrode sensor is proposed. This method can weaken the effect of the relative position distribution between the electrodes and the phantom object, thus improving the quality of the reconstructed image. To investigate the reliability of the proposed image reconstruction method, a new mechanical design of a rotatable 12-electrode sensor is introduced. The rotation of the 12-electrode sensor is accomplished by stepping motor and gear sets, which can easily change the measurement position of the electrodes. Five independent datasets of 66 capacitance measurements can be obtained by rotating the electrode sensor 4 times with an angle of 6°from the initial position. Then solving the inverse problem for each of the datasets, 5 reconstructed images are obtained. Finally, the wavelet fusion algorithm is used to fuse the reconstructed images. To verify the validity of the method, this paper evaluates the error case of rotational accuracy, the error case of measurement data and the case of real experiment, respectively. The experimental results indicate that the method can reduce the artifacts in the reconstructed images and improve the quality of the reconstructed images. Meanwhile, this processing method can enhance the shape and edge contour of the measured phantom.

Optimizing cross-regional electricity transaction concerning transmission charges: A new market mechanism design

Given the unbalanced distribution of power resources and demands in geography, cross-regional electricity transactions alleviate the conflict through the long-distance power supply. To ensure sustainable, efficient transactions, the market mechanism addressing the unavoidable transmission charges is essential for balancing the interests of all parties. This research designs a mechanism based on the Generalized Vickrey-Clarke-Groves (G-VCG) and threshold value setting considering generators' withholding behavior and power transmission charges. The theoretical analysis proves that this mechanism maximizes social welfare while satisfying individual rationality, incentive compatibility and weak budget balance. It can encourage all participants to report truthful information and motivate more power generation. Numerical studies of the PJM electricity market also demonstrate the effectiveness of this mechanism in the electricity market. The proposed mechanism contributes to new guidance and practical references for achieving fair and efficient transactions in the crossing-regional electricity market and improving the vigor of market participants.

Mechanical performance simulation and optimal design of carbon fiber composite B-pillar

This study primarily concentrates on the layer optimization and structural refinement of carbon fiber composite B-pillars. In the initial phase, an initial layer configuration for the carbon fiber composite material B-pillar was devised, followed by comprehensive finite element numerical simulations. The weight of the B-pillar was effectively diminished by 44.9% compared to its metal counterpart, while maintaining consistent performance across diverse operational conditions. Subsequently, an advanced layer thickness optimization model was formulated, incorporating the innovative ‘super layer’ concept. Integration of simulation software, such as ISIGHT and ABAQUS, facilitated the determination of optimal layer thickness and ratio for the composite material. The layer order was systematically optimized through the application of a discrete particle swarm optimization algorithm based on exchange order, adeptly addressing issues related to discontinuous design variables and potential combinations. The incorporation of a ply drop-off structure laying scheme was derived, resulting in an impressive weight reduction of 57.5%. In the final phase, adherence to NCAP side collision testing standards enabled a comprehensive evaluation, where in various indicators including deformation mode, intrusion amount, and intrusion speed were employed. The results substantiate that the composite B-pillar exhibits equivalent side impact resistance to the original metal B-pillar, ensuring robust passenger protection.

Design and performance of a triaxial load cell for conical picks

Measuring the load on picks in mining operations poses a significant challenge, which hinders the optimization of cutting mechanism design. To address this issue, a unified load measurement model was initially developed using angular transformation. Subsequently, the measuring-point positions were determined based on the principles of large strain and ease of measurement, using Finite Element Analysis. By analyzing the strain law of the measuring-point positions, a sensor layout scheme was designed, which led to the development of a triaxial load cell. Utilizing the piecewise least squares method and BP neural network, the calibration and decoupling were performed. The findings indicated that the BP neural network effectively reduced the error. Finally, cutting experiments were conducted. The error was less than 8 %, effectively identifying the load variation characteristics when cutting materials with different hardness. The results demonstrate that the designed triaxial load cell can accurately and reliably capture cutting loads.

Research on the Application of Intelligent Optimization Algorithm in Mechanical Design

Research on the Application of Intelligent Optimization Algorithm in Mechanical Design

Research on the technical principles and applications of massage robots

Massage robots, as innovative therapeutic devices, have garnered significant attention and application due to technological advancements and society's increasing focus on wellness. However, amidst this progress, gaps persist in fully understanding their capabilities and optimizing their functionalities, highlighting the need for further research in this domain. This paper focuses on exploring the intricate technical principles, mechanical structure, sensing technology, and intelligent control systems of massage robots, with the aim of providing both theoretical foundations and practical insights for researchers and practitioners in this field. Specific inquiries encompass the elucidation of working principles, emulation of human massage techniques, mechanical design considerations, applications of sensor technology, and implementations of intelligent control systems within massage robots. Employing a blend of literature review, comparative analysis, and experimental validation, this paper aims to not only deepen the understanding of massage robot functionality but also contribute to the advancement and refinement of this technology, fostering innovation and growth within the industry.

Replication to first-year undergraduate students’ knowledge of academic misconduct

Student academic misconduct continues to vex higher education institutions in the United States and internationally. The COVID pandemic learning environment yielded more rather than less reports of student academic misconduct. Substantial empirical research has considered the nature of academic misconduct in higher education institutions by identifying its antecedents and correlates. But given the reproducibility crisis in social research, the quality of knowledge that students have on academic misconduct warrants further empirical corroboration. With the intent to replicate, this study used Quantitative Content Analysis to examine 2631 written responses from first-year undergraduate students as they participated in academic misconduct programming implemented by a public university in the United States. Results reported a staggering proportion of first-year students possess piecemeal (at best) or non-existent (at worst) knowledge over citations/references and cheating. Furthermore, such proportions are uneven according to specific college membership. Results corroborate prior research that first-year undergraduate students hold limited understanding of academic misconduct in its premises, patterns, and processes. In turn, results support the design and use of systematic preventive mechanisms to address academic misconduct among higher education institutions.

Building an Educational Automated Mechatronics-Based Sorting System

This paper discusses the development of an automated sorting machine designed as a comprehensive mechatronics educational project. The project integrates mechanical and electrical design, incorporating a robot arm, a microcontroller, sensors, and actuators. The sorting machine uses color identification to sort wooden blocks of three different colors. The blocks are stacked and dropped onto a conveyor belt by a hopper system that employs a solenoid actuator and a servo to release one block at a time at specific intervals. As the belt runs continuously, each block passes under a color sensor, which monitors the color and signals one of three servo-powered mechanical arms to guide the block into the appropriate chute. Each chute is equipped with a capacitive proximity sensor that sends a voltage signal to the robot controller, queuing commands for the robot to pick up the blocks from the bottom of each chute and return them to the hopper to form a continuously running sorting system. This paper details the design and integration of the system’s various elements and the development of the control software. The designed system can drop blocks every 8.05 s, sort each block within 5 s of being sensed, and return them to the sorting system every 12 s. It has a color-sensing accuracy of 97%, with a failure rate of around 7%. The system achieved quick and reliable sorting using various low-cost, accessible, and open-source parts. The project exemplifies a cost-effective solution suitable for mechatronics education, demonstrating the numerous challenges involved in developing automated sorting systems.

Synergistic ductility deformation and helical design of carbon nanotube fiber composites

Twisting attracts more attention in adjusting the mechanical behavior and failure mechanism of materials, which could be implemented to understand and design the deformation behavior of helical structures. Herein, we developed a general helical model to theoretically investigate the mechanical response and geometric evolution of twisted carbon nanotube (CNT) fiber. The in-situ experimental results of CNT fibers in scanning electron microscopy were used to verify the correctness of the theory. For the structure with a large helical angle, the interfacial force and uncoordinated interlayer deformation during elongation are the key factors determining its unique tensile-torsional coupled motion. By helical design, the elongation and deformation of brittle fiber in composite structure can be delayed to achieve synergistic fracture with ductile fiber. The breaking order of these two fibers under stretching can be further regulated by changing the degree of twisting. Based on these theoretical results, the outer brittle fibers could also be used to predict the tensile necking and fracture locations of inner ductile materials. This approach can be achieved by changing the helical geometry and failure strain, and this work would throw light on the mechanical design of multi-layer cables and fiber composites.

Mechanical Properties and Design Methods of Pedestrian Suspension Bridges Research Status Report

Mechanical Properties and Design Methods of Pedestrian Suspension Bridges Research Status Report

Flexural behavior of laminated H-beams in modular constructions: Numerical and analytical studies

Modular steel construction (MSC) has become an important development direction of the construction industry thanks to the faster construction speed and recyclability. The laminated steel beam is one of the key structure characteristics of MSC, which can enhance the structural integrity by strengthening the interaction between the adjacent beams in vertically stacked modules. In this study, numerical and analytical studies were carried out to explore the flexural behavior and design method of the laminated H-beams in MSC. Firstly, finite element models were established and verified based on the previous experimental study on flexural behavior of the laminated square steel tube beams and laminated channel steel beams. Afterwards, finite element analysis was conducted on flexural behavior of the laminated H-beams with different connecting bolts. The results showed that the flexural capacity and stiffnesses of the laminated H-beams were significantly improved by increasing the number of the connecting bolts in the bending-shear sector. The flexural behavior of the laminated H-beams was discussed including the failure mode, load-deflection curves and slippage of the superimposed surface to reveal the co-bending mechanism. In addition, parametric analysis was performed to reveal the influence of the position, number and diameter of the connecting bolts on flexural behavior of the laminated H-beams. Finally, a theoretical model on flexural capacity of the laminated H-beams was developed to determine the neutral axis and derive the flexural capacity of the laminated H-beams. The calculation formulas were verified to be reliable by comparing the theoretical analysis results with the numerical ones. The present study is beneficial to consummating the mechanical behavior and design method of MSC.

Trustful double auction design for Peer-to-Peer energy trading between interconnected micro-grids with supply–demand imbalance

Peer-to-Peer (P2P) energy trading between Interconnected Micro-Grids (IMGs) presents a promising approach for enhancing the economic advantages for prosumers while mitigating supply–demand imbalances within individual Micro-Grids (MGs). This paper proposes a trustful double auction mechanism for P2P energy trading among prosumers in IMGs, structured into two distinct stages. Initially, concurrent auctions are conducted within each MG to facilitate intra-grid trading, followed by subsequent auctions facilitating inter-grid trading across IMGs. We figure out the allocation and pricing rules that satisfy the required properties in mechanism design even when the auction consists of two stages. Given that energy transactions across IMGs entail non-negligible power losses, equitable allocation of these losses among prosumers is paramount. To address this, we integrate a fair cost distribution methodology into our auction mechanism, implemented by an iterative algorithm. Rigorous analysis substantiates our proposed auction mechanism’s incentive compatibility, individual rationality, and budget balance, thereby fostering truthful and voluntary prosumer participation while averting potential market deficits. Numerical analysis underscores the efficacy of our approach, showcasing a significant improvement in P2P transactions and supply–demand balance enhancement compared to trading solely within individual MGs.

Recent Advancements in Geothermal Energy Piles Performance and Design

Geothermal energy piles or ground heat exchange (GHE) systems embrace a sustainable source of energy that utilizes the geothermal energy naturally found inside the ground in order to heat and/or cool buildings. GHE is a highly innovative system that consists of energy loops within foundation elements (shallow foundations or piles) through which a heat carrier fluid circulates, enabling heat extraction or storage in the ground. Despite the innovation and potential of GHE systems, there are significant challenges in harmonizing their thermal and mechanical designs due to the complex interactions involved. This review critically examines state-of-the-art design methodologies developed to address these complexities, providing insights into the most recent advancements in GHE performance and design. Key findings include innovative techniques such as advanced numerical modeling to predict thermomechanical behavior, the use of different pipe configurations to optimize heat transfer, and strategies to minimize thermal stress on the foundation. Additionally, this review identifies research gaps, including the need for more comprehensive full-scale experimental validations, the impact of soil properties on system performance, and the long-term effects of thermal cycling on pile integrity. These insights aim to contribute to a better understanding of the thermomechanical behavior of energy piles, ultimately facilitating more accurate and effective design solutions.

Design and performance analysis of the 4UPS-RRR parallel ankle rehabilitation mechanism

Abstract. Ankle sprains are among the most common musculoskeletal injuries. Patients often require systematic rehabilitation training to expedite tissue healing and facilitate joint recovery. However, such training places high demands on medical staff, involves a lengthy process, requires considerable labor, and suffers from a shortage of skilled rehabilitation personnel. To address the need for effective ankle joint dysfunction rehabilitation training, this study analyzes the bone structure and movement mechanism of the ankle. Drawing on the parallel mechanism configuration, we propose a 4UPS-RRR parallel ankle rehabilitation mechanism. The rotation center of the rehabilitation mechanism can be highly coincident with the rotation center of the human ankle joint. The structure and degrees of freedom of the mechanism were designed and analyzed using screw theory. Additionally, a kinematic model of the mechanism was established. The mechanism's workspace was mapped by constraining the linear actuator length and spherical joint rotation angle. Furthermore, the mechanism's dexterity was assessed through the establishment of its Jacobian matrix, with the correctness of the kinematic model verified through simulation. Finally, an experimental platform was utilized to test the maximum range of robot motion, confirming the practicality of the ankle rehabilitation mechanism.