Mechanical Design Method Research Articles

A Numerical and Theoretical Investigation of the Flexural Behavior of Steel–Ultra-High-Performance Concrete Composite Slabs

The steel–Ultra-High-Performance concrete (UHPC) composite slab is a new type of structure made of steel and UHPC connected by pegs, and its flexural mechanical properties and related design methods need to be further investigated. Firstly, a detailed numerical model of the steel UHPC composite slab is established and validated based on previous flexural behavior experimental research. Secondly, the flexural failure mechanisms of steel–UHPC composite slabs are clarified through finite element analysis. Under positive bending moments, when the degree of shear connection is lower than 100%, the ultimate load capacity of the composite slabs is determined by the shear capacity of the pegs. On the contrary, there are no significant changes in the load-carrying capacity of all the specimens, but there is a slight increase in stiffness. Under negative bending moments, the load-bearing capacity, stiffness, and crack resistance of the composite slab are improved as the degree of shear connection and reinforcement ratio increase. Finally, the method used to calculate the flexural capacity of steel–UHPC composite plates under positive and negative bending moments with high accuracy is proposed based on the analytical results. This paper provides a theoretical basis for the design of flexural performance of steel–UHPC composite slab.

Research on Top-Down design of launcher fairing mechanism equipped on Air-to-Ground missile carried by UAV

Abstract Reconnaissance/Strike Unmanned Aerial Vehicle (UAV) is advanced strike unmanned equipment with long range. Tube-launched technology is one of the commonly used launch technologies for air-to-ground missiles carried by UAVs. Traditional launchers sealed by sealing film have disadvantages in aerodynamic characteristic and launch safety, restricting the combat effectiveness of UAVs. In this article, the influences of airspeed and aspect ratio on aerodynamic characteristics of fairing are studied based on CFD. The relationship between the aerodynamic drag torque and the open angle of fairing is established. A top-down design method of fairing mechanism is proposed which is capable of reducing aerodynamic drag, opening transmission path and being reset automatically. The virtual prototype of the fairing mechanism is built and mechanical dynamics analysis is carried, verifying the rationality and feasibility of the design. The effects of the fairing mechanism on the lift-drag ratio and the range of one advanced reconnaissance/Strike UAV is displayed that the values are improved by 15.2% and 613 km, respectively.

Lattice-like Mechanical Metamaterials Structure Design Method Based on Convolutional Neural Network and NSGA-II Algorithm

Abstract Lattice-like mechanical metamaterials have excellent mechanical properties such as ultra-low density, high specific strength, and high energy absorption, and have broad application prospects in key components of platforms such as armored vehicles, helicopters, and aerospace vehicles. Aiming at the problem of inverse design of superstructure cellular structures, a study on the design method of cellular structures was carried out. Firstly, based on the uniqueness of cellular structural characteristics and the principle of comprehensive information, the cellular structural characteristic matrix and the cellular macroscopic mechanical characteristic matrix of coupled cellular configuration and structural parameters were proposed respectively; then, with the cellular structural characteristic matrix as input data and the macroscopic mechanical characteristic matrix of the cell as output data, a superstructure material performance prediction model based on convolutional neural network was established; further, with the minimum error between the specified target value and the predicted value of the macroscopic mechanical characteristic parameter as the criterion, a multi-objective optimization function was established; finally, the performance prediction model was combined with the fast non-dominated algorithm (NSGA-II algorithm) with elite retention strategy to construct a superstructure cellular structure design model, and the effectiveness of the structural design model was verified by case studies.

Reconfiguration and compensation design method for single-DoF closed-chain leg mechanism

Compared with a wheeled robot propelled by a rotary drive, a legged robot equipped with multiple motors on a single leg possesses superior adaptability, while at the cost of high energy consumption and less velocity. Inspired by the California mite, the design method of reconfigurable closed-chain leg mechanism with single degree of freedom (DoF) is proposed for effective striding and smooth propelling. Furthermore, the lower-mobility closed-chain leg mechanism is more appropriate for obtaining high frequency and fast movement with the merits of simple control system and rotary drive. Firstly, a reconfigurable design is performed in the swing phase for a high-knee motion intermittently driven by a walking motor through dynamic coupling. Secondly, its fluctuations in vertical displacement and horizontal speed are compensated through the contact outline curve and variable speed input in the supporting phase. Finally, the simulated performance is analyzed and compared, and a prototype is fabricated for fluctuating and obstacle-crossing experiments.

A novel design method of a nonlinear elastic mechanism for series elastic actuators

Series elastic actuators with increasing nonlinear stiffness(NlSEA) have promising applications in human-machine interactions for the existence of a nonlinear elastic mechanism that supplies inherent safety and can implement high torque resolution under low load and quick dynamic response under high load. In this study, a novel design method for a nonlinear elastic mechanism that can be applied in NlSEA is proposed. By combining the S-shaped cantilever beam and specialized cam surface, this study proposed an analytical approach to design a nonlinear elastic mechanism satisfying a given stiffening torque-deformation relationship. The geometric parameters constraints were discussed to support parameter determination. Two kinds of cases of nonlinear elastic mechanisms with increasing and constant stiffness characteristics were conducted to verify the effectiveness and generalizability of the proposed design method by simulations. Moreover, a nonlinear elastic mechanism with an increasing stiffness characteristic was designed and a prototype was fabricated. A torque-deformation verification experiment, regulation response experiments, and sinusoidal tracking experiments were conducted to verify the accuracy, response performance, and tracking performance of the prototype. The designed nonlinear elastic mechanism has a large torque-to-mass ratio in a compact and lightweight structure.

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

As the quality of life improves, travelling becomes a hotspot of life, and pedestrian suspension bridges, as a new highlight of tourism, are both convenient and ornamental. The structural system arrangement is crucial to the performance of suspension bridges. Based on the computational theory of suspension bridges, this study explores the influence of the arrangement on the static and dynamic performance and proposes an optimisation scheme. By comparing different design methods, the design process is simplified and the scope of application is clarified. This result will provide an important reference for the future design of suspension bridges and help the development of tourism.

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.

Research advances in fiber‐reinforced concrete‐filled steel tube columns

SummaryFiber‐reinforced concrete‐filled steel tube (CFST) adopts the microskeleton and bridging effect of fibers, thereby optimizing the confinement effect between the steel tube and concrete core while reducing the concrete core friability. This structure offers a viable solution for solving the interface disengagement and insufficient ductility problems of conventional CFSTs. For further theoretical research and engineering application, the mechanical properties of fiber‐reinforced CFSTs under different loading conditions are reviewed. The research results are summarized, and future research scopes are suggested. The literature review shows that adding fibers improves the ductility of CFSTs significantly but the bearing capacity only slightly. The bond strength between steel tube and concrete core is enhanced by fibers, and the degradation in the bond strength is simultaneously delayed. However, in existing research, the mechanical properties and design method are still inadequate. More experimental works, further theoretical analyses, and numerical simulation should be undertaken to establish the quantitative relations between the generalized fiber parameters and structural performance of CFSTs. Future research should propose a unified design theory of fiber‐reinforced CFST structures based on service performance requirements.

Design and experiment of multi-locomotion tensegrity mobile robot

Multi-locomotion tensegrity mobile robots have garnered significant attention in recent research due to their strong terrain adaptability and high stiffness-to-mass ratio. However, the lack of effective design method limits the application range of these robots. In this article, a mechanism design method for the multi-locomotion tensegrity mobile robot is proposed. Firstly, based on the characteristics of worms, mechanism design objectives for the tensegrity robot are put forward from three perspectives, namely bionics, motion law and tensegrity characteristics. Accordingly, the mechanism design process is conducted from two sections in terms of the design of multi-locomotion tensegrity units and the splicing of the identical units. In the mechanism design for the tensegrity units, the rod distribution is firstly determined on compliance with the proposed design objectives, followed by the determination of cable distribution with force-balance analysis method. On this basis, two identical multi-locomotion tensegrity units are axially spliced, and a series of multi-locomotion tensegrity robotic mechanisms can be acquired naturally. Finally, examples are provided, and simulations and experiments are conducted to demonstrate the effectiveness of the proposed mechanism design method.

Strength design of built-up radially battened columns subject to axial compression and arbitrary directional bending moment

Built-up radially battened columns (RBCs), comprising several identical circular steel tubes interconnected by multiple radial-shaped battens, represent an innovative column design that combines aesthetic appeal with exceptional load-bearing capacity. This makes them well-suited for architectural applications in large public buildings such as stations and airports. The axial compressive strength design methods for the built-up RBC have been extensively explored in the authors' prior studies. However, in real-world engineering applications, built-up RBCs may experience simultaneous axial compression and varying directional bending moments, particularly when considering potential eccentric compression or wind and earthquake loads in public buildings. Currently, strength design methods for this loading condition are still lacking. To address this deficiency, this paper primarily delves into the failure mechanism and strength design methods for built-up RBCs experiencing combined axial compression and arbitrary directional bending moments. Initially, the sectional strength of the built-up RBC is investigated by using a shell finite element model (FEM) for the built-up RBC. It is revealed that the compression-bending sectional strength of the built-up RBC exhibits significant differences with varying bending directions and tube numbers. Moreover, in some bending directions, the M-N sectional strength curve of the built-up RBC exhibits convexity. By integrating theoretically derived equations grounded in the principles of materials mechanics with FEM numerical calculations, concise and practical design equations are proposed for accurately predicting the sectional strength of the built-up RBC under combined axial compression and arbitrary directional bending moments. Subsequently, The buckling strength of the built-up RBC is studied using the FEM, considering initial geometrical imperfections consistent with first-order flexural buckling and accounting for geometric nonlinearity. It is noted that the bending direction of the built-up RBC may deviate during loading. Besides, the M-N buckling strength curve of the built-up RBC is not as convex as its M-N sectional strength curve. Based on calculations from numerous examples, practical design equations for predicting the buckling strength for the built-up RBC under axial compression and any directional bending moments are introduced. The key findings of this paper contribute to the compression-bending strength design of RBCs, enriching RBC design theory and promoting the widespread application of built-up RBCs in actual engineering projects.

Advancements and Challenges in Underwater Soft Robotics: Materials, Control and Integration

This article focuses on the progress of underwater robots and the importance of software architectures in building robust and autonomous systems. The researchers underscore the challenges linked to implementation and stress the need for comprehensive validation of both reliability and efficacy. Their argument is on the extensive implementation of a globally applicable architectural framework that complies with established standards and guarantees interoperability within the field of robotics. The research also covers advancements in underwater soft robotics, which include the development of models, materials, sensors, control systems, power storage, and actuation techniques. This article explores the challenges and potential applications of underwater soft robotics, highlighting the need of collaboration across many fields and advancements in mechanical design and control methods. In the last section of the paper, the control approach and algorithms used to underwater exploration robots are reviewed. Particular attention is given to the application of Proportional Integral Derivative (PID) control and the incorporation of Backpropagation Neural Network (BPNN) for PID parameter determination.

Study on the Mechanical Properties and Design Method of Frame-Unit Bamboo Culm Members Based on Semi-Rigid Joints

The frame-unit bamboo culm structure system offers a novel approach to bamboo structure, combining advantages like reduced construction times and simplified joint designs. Despite its benefits, there is limited research on its mechanical properties and computational methodologies. This study conducted bending performance tests on simply supported frame-unit bamboo culm structures, revealing that the bending stiffness of the structure increases with the number of bolts in the edge joints, though with diminishing efficiency. Based on the experimental observations, a calculation model for this type of structure was established, proposing formulas to describe the stiffness relationships between the corner joints, edge joint, and the overall structure. Numerical simulations calculated the stiffness of the edge joint as a function of the number and placement of bolts, indicating that positioning bolts closer to the outer side enhances edge joint stiffness. By inputting the various rotational stiffness values of corner joints into the simulations and stiffness formulas, consistent total stiffness values were obtained, validating the proposed stiffness relationship formulas. The average stiffness values of the corner joints were derived from these formulas and experimental data, and the rotational stiffness of other types of corner points can also be obtained using this method. Furthermore, a finite element computational method tailored for this structural system was introduced, converting the actual structure into a beam element model for calculation. The equivalent joint forces can be distributed to various components of the actual structure, resulting in the internal force distribution of bamboo culms and bolts in the actual structure, thus achieving the design of the components. The calculated displacement values obtained from this method are close to the displacement values in the experiment, proving the feasibility of this method.

Design Method of Cam Five-bar Paper Picking Mechanism of Packaging Machine Based on Position and Orientation Constraints

Design Method of Cam Five-bar Paper Picking Mechanism of Packaging Machine Based on Position and Orientation Constraints

Analysis of the manufacturing of concrete paving blocks with by-products from thermoelectric power plant

The key factor in constructing urban roads applying interlocking concrete block pavement (ICBP) is to employ an appropriate design method for better effectiveness. Concrete paving blocks (CPB) can also be manufactured using industrial by-products. Then, this paper aims to analyze CPB with coal bottom ash (CBA) from a Thermoelectric Power Plant through mechanical characterization and design methods for ICBP. To this end, tests, such as void index, water absorption, compressive strength, and elasticity modulus, were done on CPB for each mixture. Furthermore, empirical and mechanistic-empirical design methods for ICBP were applied. Then, four dry concrete mixtures (two with CBA and two without CBA) were designed with two water/cement ratios (0.63 and 0.73) to produce rectangular CPB measuring 20 cm × 10 cm × 8 cm (length × width × thickness) by a vibro-press machine. Furthermore, ICBP sections were designed, applying six simulations from empirical and mechanistic-empirical design methods. The results showed that the mixtures A73 and B73 with more water, i.e., water/cement ratio of 0.73, presented higher characteristic compressive strength at 28 days (25.34 MPa and 15.88 MPa, respectively) than the other mixes A63 and B63 with less water, i.e., water/cement ratio of 0.63 (these two mixes showed 15.85 MPa). Furthermore, the CPB application for bike paths or parking areas was allowed according to the Australian specification of 15 MPa for compressive strength test. Also, all ICBP sections from the mechanistic-empirical design required approximately 24.9% fewer materials for the sub-base layer than the empirical process. Finally, the CPB application is possible for areas with light traffic, and the ICBP technology was more feasible with the mechanistic-empirical design method.

Design and Simulation of Autonomous Up-and-down System for Transmission Line Live Operation Robot with the UAV Assistance

Aiming at the current bottleneck problem that restricts the practical application of robot system engineering in transmission line live operation, in order to improve the on-line and off-loading efficiency of live working robots on transmission lines and improve the practical level of the robot system as a whole, this paper proposes a design and operation method of autonomous on-line and off-loading mechanism of double-arm live working robots based on UAV assistance. Firstly, the realization process of autonomous up-and-down of the robot was analyzed, based on which the structure of the auxiliary hook of the up-and-down system and the lifting winch were designed. Then, the force analysis was carried out on the up-and-down process of the robot, and the appropriate winch drive motor was selected through theoretical calculation. In order to ensure the rationality of the up-and-down process, the operation motion planning was carried out on the up-and-down of the robot. Stress analysis and simulation were carried out on the maximum load bearing point of the auxiliary hook and the walking wheel mechanical arm under different states, and the results showed that the hook and the robot arm could meet the requirements of the robot loading and unloading, and the whole robot loading and unloading system was designed reasonably. Compared with the traditional loading and unloading system designed in this paper, the loading and unloading efficiency could be improved. It has important theoretical significance for the development of the physical system of robot uplink and down.

Sensorless Control With Adaptive Speed Observer Using Power Winding Information for Dual-Stator Winding Induction Starter/Generator

This paper presents a speed-senserless control strategy with an adaptive speed observer using power winding (PW) information for dual-stator winding induction starter/generator (DWIG), in order to improve speed estimation precision and starting-generating performances. Based on the principle of model reference adaptive system (MRAS), an improved rotor-flux-based reference model is proposed by utilizing the electromagnetic link between the control winding (CW) and PW, the PW voltages are used to estimate rotor flux without necessity of stator resistance and filter parameters. The improved speed observer is less parameter-sensitive and can reduce the estimation error, especially in low-speed starting process with load. The parameter design method of the adaptive mechanism of proposed speed observer based on stability analysis is also given. The distribution of dominant pole of the speed observer is modified to obtain good tracking ability. Based on the improved speed observer, a speed-sensorless starting-generating control strategy is investigated, in which the estimated speed is not only used in speed control in starting process but also in staring-to-generating switching process. The simulation and experimental results verify the validity of the proposed speed observer and the speed-sensorless control strategy.

Design method of irregular-shaped concrete-filled steel tube column joints with inner semi-diaphragm

This paper studies the mechanical behavior and design method of the irregular-shaped concrete-filled steel tube column to H-shaped steel beam joints with inner semi-diaphragm (ICFSTC-Joint) by numerical and theoretical investigation. ICFSTC-Joint was proposed and tested in the authors’ previous paper, which can be adopted in steel-concrete composite structures. Firstly, the tensile and compressive bearing capacity of ICFSTC-Joint under the tension or compression of a single beam flange is investigated. Secondly, based on the tensile and compressive bearing capacity, the bending capacity of the ICFSTC-Joint under the bending exerted by a complete H-shaped beam is investigated. Finally, the interaction between multiple ICFSTC-Joints is considered. The FE model verified by the hysteretic experiment of ICFSTC-Joint is adopted in the parameter analysis. The parameter analysis involves the height of beam, width and thickness of beam flange, height and thickness of diaphragm, thickness of column wall, length of column limb and axial compressive ratio. Based on the parameter analysis results, the mechanical models of ICFSTC-Joint under various conditions are established. The complete set of design method as well as some constructional requirements are finally established through the theoretical derivation of mechanical models and fitting the FE investigation results and exhibit good precision.

Investigation of Gas-liquid Separation Experiment of Electric Pump Drainage and Gas Extraction Unit in High Gas-liquid Ratio Gas Wells

Given the prominent problem of water in the Tarim basin of China with high formation temperature and large water production, a preferred scheme of electric pump drainage and gas extraction unit for gas fields with a high gas-liquid ratio is proposed by the mechanical principle and structural design method. Then, the corresponding electric pumps were developed, and the drainage and gas extraction scheme of a permanent magnet electric pump unit with gas-liquid separation in the way of an inverted deflector is designed. Through indoor experiments simulating the downhole gas-liquid ratio environment, the gas-liquid separation ability and adaptability of the design scheme under different good conditions are verified. The results obtained demonstrate that the cable connection process can meet the requirements of high-pressure resistance (≥25 MPa), and the gas-liquid separation effect is very good in vertical wells by adopting the inverted deflector scheme. The separation effect exceeded 90% under different working conditions (production from 30 to 150 m3/day and inhalation gas-liquid ratio from 50% to 95% and even higher) in the experiment with high gas content. The results will promote the gas recovery rate of high gas-liquid ratio gas fields and improve extraction efficiency.

Analytical approach to piezoelectric model synthesis with the use of Cauer’s method for system design

Background: Piezoceramic materials have unique property which enables direct and bilateral conversion between mechanical and electrical energy. This ability facilitates significant miniaturisation of technology and opens many opportunities in design of new actuators and energy harvesters. Mathematical modelling of piezoelectric modules is notoriously hard due to complex constitutive equations defining mechanical and electrical energy conversion. Methods: The article presents research on a new synthesis method based on the Cauer’s method for electrical and mechanical system design. Mechanical damping is introduced with the use of Rayleigh’s approximation. A discrete electromechanical model is formed based on the Mason’s piezoelectric model. As an additional element of the research, a non-standard model analysis method using edge graphs and structural numbers is employed to investigate potential reductions in computational requirements for model analysis. Results: The electromechanical model analysis has shown an error of 5% in relation to the resonance target. The calculated peak in magnitude of displacement at the resonant frequency was well above the capability of a 3.5mm thick piezoelectric plate. The proposed non-standard method of analysis gave identical results in terms of obtained resonance frequencies. The calculated magnitude of vibrations was varying by 50 – 58%. Conclusions: The synthesis method presented in this paper allows an approximation of piezoelectric parameters of a real system based on the created mathematical model. Currently this method is subject to a considerable error in the determined vibration amplitudes of the system, but it allows a coarse approximation of the parameters while having a very limited number of input data. The additional method of analysis based on structural numbers offers a promising alternative to matrix calculations but requires a more thorough investigation of the computational power required to determine whether it can compete with existing algorithms.

A survey on the mechanical design for piezo-actuated compliant micro-positioning stages.

This paper presents a comprehensive review of mechanical design and synthesis methods for piezo-actuated compliant micro-positioning stages, which play an important role in areas where high precision motion is required, including bio-robotics, precision manufacturing, automation, and aerospace. Unlike conventional rigid-link mechanisms, the motion of compliant mechanisms is realized by using flexible elements, whereby deformation requires no lubrication while achieving high movement accuracy without friction. As compliant mechanisms differ significantly from traditional rigid mechanisms, recent research has focused on investigating various technologies and approaches to address challenges in the flexure-based micro-positioning stage in the aspects of synthesis, analysis, material, fabrication, and actuation. In this paper, we reviewed the main concepts and key advances in the mechanical design of compliant piezo-actuated micro-positioning stages, with a particular focus on flexure design, kineto-static modeling, actuators, material selection, and functional mechanisms including amplification and self-guiding ones. We also identified the key issues and directions for the development trends of compliant micro-positioning stages.