Design pertains to the conceptualization and planning of engineering solutions. The fundamental distinction between humans and animals lies in humanity′s capacity for creative thinking, designing and manufacturing tools, as well as developing and applying complex linguistic cultures and technological innovation capabilities throughout labor processes. Design evolves alongside the progress of human civilization, requiring knowledge, materials, tools, computation, experimentation, and manufacturing, while simultaneously transforming and advancing design philosophies and methodologies. Each stage of design relies on certain core scientific foundations, key technologies, and mathematical computation methods. Innovative design is boundless, continuously advancing with the progress of human society, with its development trends and direction being unequivocal: digitization, networking, greening, and intelligent sustainable development. While design innovation is limitless, Earth's resources are finite. Thus, designers must adhere to the laws of scientific development, respect nature, ethics, market economy, and the heritage of human civilization. They must uphold principles of fairness, justice, and transparency, abide by professional ethics of honesty and integrity, persist in deepening reform and opening-up, actively assimilate scientific achievements and advanced design concepts and methods created by nations and peoples worldwide, and innovate to develop “excellent Chinese designs”. This will lead and comprehensively advance modernization in the new era, making continuous new contributions toward realizing the Chinese Dream of the great rejuvenation of the Chinese nation!

Soft robots, with their excellent human-computer interaction features, offer a new tool for intestinal diseases detection. However, the existing soft robots rely on external control systems connected via cables, causing discomfort to patients during the detection process. Therefore, an earthworm-like cordless soft robot was proposed. The robot was equipped with a flexible pressure sensor and a wireless micro-camera, could perform controllable movements in intestinal-like environments, monitor changes of environmental pressure, and detect the foreign objects in the environment through visual. The robot was composed of a front-end radial motion actuator, a central axial motion actuator and a rear-end radial motion actuator, integrated with a compact control circuit board and 4 micro-pumps inside. By controlling the on/off of 4 air pumps via Bluetooth, the expansion and contraction of 3 motion actuators could be achieved, causing the robot to deform itself and enabling it to move in a intestinal-like environment. Experimental results demonstrated the robot's ability to move in both rigid and flexible tubes at a speed of 0.75 mm/min, and to effectively measure the changes of environmental pressure in real time. Additionally, the Fast RCNN (faster region convolutional neural net) algorithm was employed to process images captured by the robot, achieving precise identification of foreign objects in intestinal-like environments. This cordless soft robot has excellent human-computer interaction capabilities, providing a novel and patient-friendly approach for intestinal diseases detection.

Aiming at the problems of low operation efficiency and high safety risks in the manual cleaning process of the complex steel structures at the top of converter station valve halls, a cleaning robot featuring the split multi-unit structure and the clasp-arm mechanism has been proposed based on axiomatic design theory, and its feasibility is verified through prototype experiments. Firstly, the function-structure model of the robot and the corresponding design matrix were constructed. The independence axiom was applied to ensure the independence of functional requirements, while the information axiom was used to optimize the design solution. The mobile unit of this robot adopted a split three-unit multi-clasp-arm structure, which could cross obstacles located above and below the steel structure and walk on steel beams in different directions by steering. The cleaning unit adopted symmetrically arranged three-degree-of-freedom cleaning arms, which could meet the cleaning demands of various areas in the valve hall. Then, based on the actual layout of the steel structure at the top of valve hall, the obstacle-crossing and steering motion postures of the robot were designed for specific scenarios, and a complete motion control system was also designed. Next, a mechanical analysis was conducted on key components of the robot. Meanwhile, the structural layout analysis and topology optimization were carried out on the components that significantly affected the overall performance, which achieved compact and lightweight structure, thereby enhancing the operational stability of the robot. Finally, the robot prototype experiments were carried out on the steel structure at the top of valve hall. The results showed that the robot could stably complete obstacle crossing, steering and cleaning tasks on steel structures. It could cross obstacles with a maximum height of 712 mm, and the cleaning speed exceeded 100 m²/h. The designed robot can effectively enhance the cleaning efficiency and operational safety of steel structures at the top of converter station valve halls, which has good engineering applicability.

Bistable origami structures have broad application prospects in solving practical engineering problems due to their characteristics such as rapid transformation, negative stiffness and energy storage capacity. At present, the configuration design and steady-state characteristic regulation of bistable origami structures mostly focus on size parameters such as crease length and the angle between adjacent creases. However, the steady-state characteristics of some origami structures are minimally affected by size parameters, and there are often certain restrictions on the overall structure size in practical applications. For this purpose, taking the Miura origami structure as the research object, the influence law of parameters such as the crease length, the angle between adjacent creases and the initial folding angle on the potential energy barrier was analyzed based on the potential energy equation. It was found that the initial folding angle had the greatest impact on the steady-state characteristics of the Miura origami structure. Then, the influence of size-independent parameters such as the crease forming angle and the pre-folding angle on the initial folding angle was analyzed through experiments, and the changes in steady-state characteristics such as the unstable output force and instability time of the Miura origami structure under different crease forming angles were demonstrated. Finally, taking the water-based origami robot based on the Miura origami structure as an example, its swimming speed was increased by 70% by changing the crease forming angle while remaining the size parameters unchanged. The research results provide a new approach for the performance regulation and practical application of bistable origami structures.

In order to decrease the power demand of drive motors in the transmission systems of high-power hybrid tracked vehicles, an innovative design method for a bilateral motor coupling mechanism based on the steering power reflux characteristic was proposed. Taking the dual-planet and triple-planet gear configurations as the research objects, a topological graph theoretical model incorporating kinematic and dynamics constraints was established. The power reflux characteristics under the straight-line driving and steering coordinated condition were transformed into the mathematical criteria for configuration parameters. Using topological synthesis and parametric analysis, six viable configurations were selected. Combined with the steering regenerative power transmission conditions, a multi-objective performance evaluation was conducted, and it was found that the dual-planet gear configuration attained the best in terms of coupling mechanism efficiency and steering power regenerative utilization rate. A electromechanical coupling dynamics simulation model for tracked vehicle was established, and tests on the vehicle's straight-line driving power performance and steering capability were conducted. The results showed that the optimal configuration could achieve a coordinated control with a yaw angle tracking accuracy of over 94% and a longitudinal speed error of less than 2.1%. The research results have provided a novel technical approach for the design of high-power-density hybrid tracked vehicle transmission system.

To enhance the obstacle-crossing ability and environmental adaptability of conventional tracked mobile mechanisms, a planetary underactuated transformable tracked mobile mechanism is proposed, which is composed of a tracked driving wheel train and a planetary gear train, and has three motion modes: straight arm mode, orthogonal mode and transition mode. This tracked mobile mechanism adopts underactuated pattern, and realizes rapid obstacle-crossing response based on the least energy consumption principle. Firstly, the kinematics analysis was conducted on the tracked mobile mechanism. The relationships among center-of-mass height, ground contact area and track deformation under three motion modes were obtained, and its applicable environment was analyzed. Then, a dynamics theoretical model of the tracked mobile mechanism was established, and its maximum trench-crossing width and maximum protrusion-surmounting height were calculated. Meanwhile, the relationship between the deformation of the tracked mobile mechanism and the driving torque required for obstacle crossing was analyzed. Next, based on the dynamics simulation model of the tracked mobile mechanism, the obstacle-crossing simulation analysis was carried out, and the obstacle-crossing simulation process and the driving torque variation curve were obtained. Finally, a principal prototype of the tracked mobile mechanism was built and relevant experiments were carried out to verify the feasibility of its structural design. The results show that the designed planetary underactuated transformable tracked mobile mechanism can achieve the functions of rapid obstacle-crossing and adaptation to complex terrains by controlling its own deformation, significantly improving the obstacle-crossing ability and environmental adaptability of the tracked mobile mechanisms.

Concrete 3D printing, as a rapid and precise additive manufacturing technology, is gradually demonstrating unique advantages in the construction industry. However, concrete 3D printing involves a variety of process parameters (such as printing speed, extrusion speed, layer height and line spacing), and there are complex coupling relationships among these parameters, making it difficult to precisely control the quality of the deposition line state. To address this problem, a machine learning model (BWO-SVM-AdaBoost) based on the beluga whale optimization (BWO) algorithm, support vector machine (SVM) and ensemble learning algorithm AdaBoost was proposed to investigate the relationship between the process parameters of concrete 3D printing and the deposition line state. The BWO-SVM-AdaBoost model was trained and tested based on a dataset consisting of 400 samples, and its prediction accuracy on the training set and the test set reached 99.76% and 95.19%, respectively. Furthermore, the Bayesian optimization algorithm was applied to refine suboptimal printing process parameters and the optimal combination of parameters was generated, thereby effectively enhancing the precision and stability of printed components. The research results provide a novel and effective approach for the systematic optimization of concrete 3D printing process parameters, which can lay a theoretical foundation for achieving high-quality printed structures.

To address the issues of volume redundancy, high manufacturing difficulty and potential failure risks in the traditional design of 175 MPa ultra-high pressure wellhead equipment due to the absence of specification standards, a structural evaluation and lightweight design research on the critical component 6BX flange of wellhead equipment was conducted. Taking the 6BX flange with a diameter of 280 mm and employed in 175 MPa wellhead equipment as the research object, the 6BX flange produced by a certain company was evaluated in terms of material properties, gasket sealing strength and other factors. The relationship between the hydrostatic test pressure and the structural strength and dimensions of flange was explored, and the influence factors of flange dimensions were revealed. Under the premise of ensuring safety, an optimization scheme for lightweight was proposed, and the rationality of the optimized structure was verified by the finite element method. The research results indicated that the flange structure designed by the traditional method could meet the actual use requirements, but it had an excessively large structure volume, making installation inconvenient. Excessive wall thickness would make the material processing more difficult and risky, and using standard BX gasket also posed the risk of sealing leakage. The flange structure dimensions was influenced by multiple factors. The main controlling factor for the dimensions of large-diameter flange structures was the hydrostatic test pressure, followed by the neck thickness. It was recommended to design the neck thickness according to the elastic-plasticity theory. For the 175 MPa ultra-high pressure wellhead equipment, the ratio of the inner and outer diameters of flange was recommended to be 2 and a widened BX gasket should be adopted. The proposed flange structure optimization scheme was reasonable, significantly reducing the weight of the flange, and also offering a certain safety margin. It was recommended to reduce the hydrostatic pressure test pressure for the 175 MPa ultra-high pressure wellhead equipment from the original 1.5 times the rated pressure to 1.25 times. The research results provide a theoretical basis for the design of the 175 MPa ultra-high pressure flange structure.

Focusing on the reliability modeling of G100 silicone rubber insulation parts for electrical connector under long-term storage conditions, this study analyzed and revealed at the microscopic level that the primary cause of insulation resistance degradation was the oxidation and hydrolysis reactions of polymeric molecular groups in the material matrix induced by environmental temperature and humidity. Based on molecular dynamics and the law of mass action, the change of the carrier concentration of G100 silicone rubber under the effect of temperature and humidity was analyzed, and a physical model for the failure of G100 silicone rubber was established. By applying the central limit theorem, a storage reliability model for G100 silicone rubber insulation part was constructed. The validity and rationality of the constructed model were verified through A-D (Anderson-Darling) and goodness-of-fit tests, supported by scanning electron microscopy and Fourier-transform infrared spectroscopy. The research results provide a theoretical foundation for evaluating the insulation reliability of G100 silicone rubber for electrical connector under long-term storage conditions.

To study the failure modes and mechanical properties of self-piercing riveted-bonded (SPR-bonded) composite joints in acidic environments, the 0.02 mol/L NaHSO₃ solution was used as the corrosion medium to conduct dry-wet alternate immersion corrosion tests on similar and dissimilar SPR joints and SPR-bonded composite joints. Subsequently, the static mechanical properties of the joints under different corrosion cycles were explored through static tensile tests, and the corrosion behavior at the gaps during the riveting forming process of joints was studied by means of scanning electron microscope. The results showed that the corrosion effect had an impact on the failure displacement of the SPR joint, and the static strength and stiffness of the SPR-bonded composite joint were both superior to those of the SPR joint. The bonded structure was more sensitive to the corrosion effect, which gradually reduced the failure load of the SPR-bonded composite joint, resulting in the failure load of the SPR-bonded composite joint being borne by the riveted structure in the middle and later stages of corrosion. The dissimilar joints exhibited relatively poorer stability compared to similar joints. The incorporation of adhesive effectively inhibited the transformation of failure modes of dissimilar joints in corrosive environments. The adhesive had a certain inhibitory effect on the corrosion in the overlap area between the upper and lower plates of the joint. The scratches on the riveted hole wall of the upper plate would accelerate the corrosion at the contact surface between the outer side of the rivet tube leg and the upper plate. The selection of SPR-bonded composite joints helps to enhance the static strength and corrosion resistance of riveted structures, thereby prolonging their service life. The research results provide theoretical support for the application of riveting technology in acidic corrosive environments.

In view of the problems of complex operation process and limited detection diameter range of existing quality inspection equipment for mining wire ropes, an on-line intelligent non-destructive testing instrument suitable for multi-diameter mining wire ropes has been designed and developed, which mainly includes an open-loop permanent magnetization system, hardware peripherals, application software and filtering algorithms. According to the physical characteristics of permanent magnetic flux leakage detection, a two-dimensional finite element simulation model of the permanent magnetization system with open-loop magnetic circuit characteristics was established through the ANSYS Maxwell software. The damage characteristic curves of the magnetized wire rope under different lift-off values were analyzed, and the optimal lift-off value was determined. In order to improve the noise reduction effect, a signal waveform smoothing processing method based on difference limit filtering algorithm was proposed. The results of multiple groups of tests show that the designed non-destructive testing instrument for multi-diameter mining wire ropes can effectively identify the broken wire damage of wire ropes with different diameters, and the average relative error of damage position detection is 0.36%, which has broad application prospects.

After the operation of China's high-speed railway, the geometric shape of the ballastless track structure on some lines has change to different degrees due to the long-term dynamic load of trains and the complex service environment, resulting in poor smoothness of the lines and seriously affecting the safe operation of trains. To solve this problem, by analyzing the existing restoration technologies and the functions of rope saw cutting equipment, and combining the characteristics of "restricted space" and "skylight point" short-time operation in the high-speed railway maintenance, the functional requirements of rope saw cutting equipment for the geometric shape restoration of ballastless track structures were proposed. A new multi-functional rope saw cutting equipment that could achieve lightweight modularity, autonomous movement, non-segmented horizontal cutting and bi-directional conversion cutting was developed and successfully applied in engineering practice. The results showed that the maximum static stress and displacement of the new rope saw cutting equipment were 94.5 MPa and 2.1 mm, both less than the allowable values (235 MPa and 4 mm). The first five natural frequencies of the equipment were significantly different from the standard vibration frequency of the main motion motor at 25 Hz, indicating that it had good static and dynamic characteristics. The comprehensive construction efficiency of the new rope saw cutting equipment was approximately twice that of the existing equipment, and its cutting accuracy and operational stability met the design requirements. The designed rope saw cutting equipment provides a convenient and efficient cutting tool for the ballastless track structure disintegration of high-speed railways in operation, which is of great significance for quickly restoring the alignment of high-speed railway and ensuring the normal and safe operation of trains.

In response to the current problems of "no machines available, no machines easy to use" and poor agricultural production capacity in hilly and mountainous areas, the design and performance analysis of a soil groove test trolley in hilly and mountainous areas have been carried out. Firstly, the mechanical system, data acquisition system and control system of the soil groove test trolley were designed. Then, the passing ability of the soil groove test trolley was analyzed based on the RecurDyn-EDEM coupling simulation. Finally, the overall performance of the soil groove test trolley was tested and analyzed. The simulation results showed that the soil groove test trolley started to accelerate at t=0 s, and its travelling speed reached 0.7 m/s at t=2.7 s. Then, the travelling speed began to decrease sharply until the end of simulation, and the final travelling speed fluctuated around 0.1 m/s. During the simulation process, the limit spring could provide a friction force of approximately 700 N, and the resultant force of the suspension device reached 6 665 N. The simulation results preliminarily verified the rationality of the soil groove test trolley design scheme. The test results showed that the angular acceleration of the power output shaft of the soil groove test trolley was 14.74 rad/s2, and there was an error of 15 to 20 r/min between the actual rotational speed and the target rotational speed. The maximum travelling speed of the soil groove test trolley could reach 1.6 m/s, with a required braking time of 2.61 s and a corresponding braking distance of 1.62 m. When the soil groove test trolley travelled at a target speed of 0.2 m/s and was used in conjunction with a Sanqi excavation shovel for simulation test, it could reach the target speed within 2 s, and the measured maximum working resistance was 2 990.07 N. The above test data all meet the design requirements, which can provide theoretical basis and reference for the design of soil groove test trolleys in hilly and mountainous areas.

Aiming at the problem that the current bearing accelerated life test device is difficult to accurately restore the influence of factors such as shaft current damage, friction and wear on servo motor bearings under service conditions, a servo motor bearing accelerated life test device considering shaft current damage is designed. This test device could simulate the performance degradation process of servo motor bearings under the influence of factors such as shaft current damage, friction and wear, while collecting and analyzing relevant monitoring data in real time to realize visual characterization of the performance degradation process of servo motor bearings. The analysis test of bearing damage caused by shaft current and the bearing accelerated life test based on service conditions were carried out by using the test device. The results show that the designed test device has the function of accurately simulating the service conditions of servo motor bearings, which can provide equipment support and test conditions for the reliability research of such bearings.

With the advancement of heavy duty trucks toward higher speed, increased load capacity, enhanced safety, and improved comfort, more stringent requirements have been placed on the performance of the clutch friction plates. This study focused on the preparation process and performance of rubber-modified resin matrix friction materials for dry clutch plates, and a systematic performance comparison was conducted between styrene butadiene rubber-modified phenolic resin matrix friction materials (SBR-PF) produced through the sol-gel method and nitrile butadiene rubber-modified phenolic resin matrix friction materials (NBR-PF) produced through the extrusion-compression method. The friction behaviors of two materials at different temperatures was investigated through friction and wear tests, and wear mechanisms were analyzed in combination with scanning electron microscopy. Additionally, the prepared friction plates were subjected to standardized heat fade and judder tests on clutch benches. The results demonstrated that NBR-PF exhibited significantly higher stability in friction coefficient at elevated temperatures compared to SBR-PF, along with superior wear resistance. As temperature increased, the wear mechanisms of both materials transitioned from abrasive wear to a combination of oxidative wear and fatigue wear. NBR-PF displayed exceptional thermal fade resistance and anti-judder characteristics. In heat fade tests, the friction coefficient of SBR-PF began to decline sharply at approximately 330 ℃ and dropped below 0.2 at approximately 380 ℃, whereas NBR-PF maintained a friction coefficient above 0.2 even at 400 ℃. In judder tests, the average torsional vibration attenuation coefficient of SBR-PF exceeded the standard value at 200 r/min, and its maximum torsional vibration attenuation coefficient exceeded the standard value at 200 r/min and 500 r/min. The average torsional vibration attenuation coefficient and the maximum torsional vibration attenuation coefficient of NBR-PF under different conditions were lower than the standard values. This research results provide new ideas for the preparation of environmentally friendly friction materials and technical support for the comprehensive performance optimization of clutches.