In the product conceptual design process, clearing design task and using the digital twin technology can better handle a large number of user data, monitor function operation, analyze target products, and promote the generation of design solutions. Firstly, the design task was taken as the entry point, user factors were introduced, task analysis method and scenario decomposition method were integrated to decompose the design task, and task flow models in the task domain was constructed. Secondly, the fuzzy comprehensive evaluation method was used to quantify the design task, clarify the design task, further decompose the design task, and the physical domain entity task scenario model was constructed. Based on the trend of task flow, interactive channels and virtual domain data types were analyzed to build the virtual domain task scenario model and complete the construction of digital twin model based on design task. Based on the direction of task flow, interactive channels and virtual domain data types were analyzed to build the virtual domain task scenario model and complete the construction of digital twin model based on design task. Finally, this method was applied to the construction of digital twinning model of intelligent classification trash can, which expanded the application of digital twinning in conceptual design. The design quality of product can be improved by integrating user factors into the design task during the conceptual design stage of products.

In order to analyze the vibration mechanism of horizontal well completion pipe string and the influence of different gas production on the vibration of completion pipe string, the vibration test of completion pipe string under different gas production was carried out.The strain gauge test technique was used to collect the vibration strain data of the completion pipe string in horizontal and gravity directions under different gas production, and the modal analysis method was used to process the test data and obtain the pipe vibration response. The results showed that in the initial stage of gas well opening, the string was prone to make large vibration due to water hammer effect, and then the pipe vibration was gradually weakened with the steady intake of air. The flow velocity of the bending section of the completion string was not uniform and the vibration was relatively large. The force acting on the pipe in the horizontal direction and gravity direction was different, so the pipe vibration in the horizontal direction was more severe than the vibration in the gravity direction. The vibration displacement, vibration frequency and displacement standard deviation of the completion pipe string increased with the increase of gas production, however the modal order was the same under different production under the test conditions. Therefore, appropriately reducing the number of gas well opening and closing, the inclination angle of the curved portion and the gas production were beneficial to reduce the collision and wear between the completion pipe string and casing and enhance the safety of the string. The research results can provide reference for reducing the vibration of completion pipe string in production practice.

Floating production storage and offloading (FPSO) is a highly integrated and modular high-end marine engineering equipment that integrates oil and gas production, storage and export. In the extreme sea conditions in the South China Sea, the safety and stability of FPSO module stools directly affect the safety of offshore oil and gas production operations. Based on the hydrodynamic analysis and theoretical analysis of seakeeping, the motion response law of FPSO in extreme sea conditions in typical sea areas of the South China Sea was studied. Dynamic mechanical analysis of the whole FPSO module combined with the finite element method and the strength analysis and safety evaluation of the module stools were carried out. A test mode with a scale ratio of 1∶10 was designed using similar theory, and the test of simulating sea conditions was carried out with a six-degree-of-freedom platform. The result showed that with the increase of the severity of sea conditions in the South China Sea, the amplitude of rolling motion increased, the deformation and stress on module stools increased and the stress concentration phenomenon was obvious. The stress was mainly concentrated on the diagonal brace bracket and its yield strength met the standard requirement. The relative errors of the maximum stress test value and simulation value of key points of ZD1-N₃ and ZD2-N₄ were 16% and 10% respectively, which proved that the finite element dynamic mechanical analysis result had high accuracy. Increasing the thickness of rib plate and improving the structure of stool were effective ways to improve the structural strength of stool. The research provides theoretical guidance for the design and construction of FPSO module stool.

The rocker arm is the key executive component of the shearer, which plays the role of adjusting the height of the drum to cut the coal rocks. The rocker arm will produce strong vibration under complex working conditions. In order to investigate the transverse vibration characteristics of the shearer rocker arm, firstly, a theoretical model of the shearer rocker arm and its connecting parts was constructed. When modeling, the rocker arm, the drum, the small rocker arm and the height adjustment cylinder of the shearer were simplified to a beam model, a concentrated mass, a rigid rod and a spring damping system, respectively. Secondly, the transverse vibration differential equation of the shearer rocker arm was constructed according to the Euler-Bernoulli beam theory, and the constraint equation was established based on the equivalent replacement principle. Thirdly, the harmonic function method was applied to solve the transverse differential vibration equation of the shearer rocker arm, and the analytic formula of the natural frequency of each mode was obtained. Finally, a shearer model was used to carry out the modal test for the rocker arm, which was compared with the theoretical calculation results for verification. The results showed that the natural frequencies of the first six order modes of the rocker arm calculated by the theoretical model were 1 129, 7 036, 7 118, 17 756, 19 800 and 30 100 Hz, and the natural frequencies of the first six order modes of the rocker arm measured through the test were 1 078, 6 268, 6 310, 15 886, 18 939 and 27 714 Hz. The errors of the calculated values relative to the test values were 4.73%, 12.25%, 12.81%, 11.77%, 4.55% and 8.61%, respectively. All errors were less than 15%, which were within a reasonable error range. The research results show that the established transverse vibration model of the shearer rocker arm has certain accuracy and practicability, which can provide theoretical support for the structural optimization of the shearer rocker arm.

In order to investigate the wind-induced swing characteristics of the transmission line jumper wire to guide the reasonable arrangement of jumper wire and reduce flashover trip accidents caused by the wind-induced swing of jumper wire, the finite element wind vibration response analysis and wind tunnel test for the jumper wire of a 500 kV transmission line were carried out. Firstly, using the time-domain finite element analysis method, the wind vibration response of the 500 kV transmission line jumper wire was analyzed, and the influences of different wind speeds, different wind direction angles and the installation of suspension insulator string on the wind-induced swing characteristics of the jumper wire were studied. Then, based on the similarity theory, an aeroelastic model of 500 kV transmission line jumper wire was developed. The wind tunnel test was carried out and the results were compared with the finite element analysis results. The results showed that the wind-induced swing displacement of the jumper wire increased with the increase of wind speed and wind direction angle, which presented a direct proportional function relation with the wind speed. With the increase of wind direction angle, the increase amplitude of wind-induced swing angle of the jumper wire decreased. The installation of suspended insulator string could effectively inhibit the wind-induced swing of the jumper wire. The analysis results of the wind-induced swing of transmission line jumper wire can provide a basis for the theoretical study of wind-induced vibration of jumper wires and the actual construction of transmission lines.

Double-disc and linear-groove (DDLG) lapping method is a new method of precision machining the rolling surface of cylinder roller by using a flat-end lapping disc and a lapping disc with several linear grooves as lapping tools. During the machining process, cylinder rollers are fed continuously along the linear groove and continuously rotate driven by the friction torque of two lapping discs. The selection of lapping disc material is the basis for the construction of double-disc and linear-groove lapping equipment. In order to determine the material combination of the lapping disc that is suitable for the double-disc and linear-groove lapping method, relevant researches are carried out based on the friction and wear experiment. Firstly, based on the friction principle, the influence of the movement state of the cylinder roller and the friction characteristics of the lapping disc material on the lapping effect was analyzed, and the screening conditions for the friction coefficient of the lapping disc material were determined. Secondly, the friction coefficient, wear resistance and chip removal performance of various materials, such as cast iron, 45 steel, brass, polytetrafluoroethylene (PTFE), polymethyl methacrylate (PMMA), 125% cast iron-based consolidated abrasive and 125% resin-based consolidated abrasive were tested by friction and wear experiments under lapping conditions. Finally, a double-disc and linear-groove lapping test bench was built to verify the rationality of the material selection method based on the friction and wear experiment by observing the rotation of the cylinder roller. The results of friction and wear experiments showed that the cast iron and 45 steel had large sliding friction coefficients and high lapping efficiency, but its wear resistance was poor, which were suitable for the upper lapping disc material for large removal occasions; plexiglass had a large sliding friction coefficient, good wear resistance and high lapping efficiency, which was suitable for the upper lapping disc material for small removal occasions; PTFE had a small sliding friction coefficient and good wear resistance, which was suitable for the straight groove material of lower lapping disc; the sliding friction coefficient of consolidated abrasive varied greatly and it was easy to block, so it was not suitable for the lapping disc material. The research results can provide a feasible material selection basis for the design of double-disc and linear-groove lapping equipment.

In order to explour the bearing capacity of high contact-ratio spur gears, the two rows of staggered spur gear with longitudinal contact-ratio was taken as the research object. Based on the change law of dynamic normal force between the teeth obtained through the dynamics analysis and the meshing point position of the gear, the tooth root bending stress was calculated by the finite element analysis method, and the tooth surface contact stress was calculated by the Hertz formula. The caculating results showed that, compared with the static woking condition, when considering the dynamics effect of the gear transmission system, the maximum tooth root bending stress of the high contact-ratio spur gear increased by 22.49%, and the maximum tooth surface contact stress increased by 10.94%; compared with the involute standard spur gear, the maximum tooth root bending stress of the high contact-ratio spur gear was reduced by 17.08%, and the maximum tooth surface contact stress was reduced by 43.79%. The results show that the strength of the high contact-ratio spur gear is greatly improved, and its application potential is huge.

The cage is one of the important components of the angular contact ball bearing, and the unreasonable design of the guide clearance and pocket clearance will cause the instability and resonance of the bearing. Aiming at the above problems, on the basis of theoretical analysis, combined with the dynamic contact and deformation relationship among the ball, the cage and the raceway, the explicit dynamics model of 7005 type angular contact ball bearing was established in the ABAQUS software. The dynamic response curves of the inner ring, the cage and the ball of the angular contact ball bearing under the specific working conditions were extracted. At the same time, the slip rate, the deviation ratio of centroid whirl velocity and the natural frequency of each order vibration mode of the angular contact ball bearing cage with different guide clearances and pocket clearances were studied. In order to verify the accuracy of the established explicit dynamics model of angular contact ball bearing, the simulated values and the theoretical values of the linear velocity of each component of the high-speed angular contact ball bearing were compared. The results showed that with the increase of guide clearance, the slip rate, the deviation ratio of centroid whirl velocity and the natural frequency of each order vibration mode of cage decreased simultaneously, and the stability of cage was enhanced, but the risk of resonance increased; with the increase of pocket clearance, the slip rate of cage increased, the deviation ratio of centroid whirl velocity did not change significantly, the natural frequency of each order vibration mode decreased, the stability of cage decreased, and the risk of resonance increased. Furthermore, the maximum error between the simulated value and the theoretical value of the linear velocity of each component of the high-speed angular contact ball bearing was only 0.099 6%, which verified the accuracy of the established explicit dynamics model. The research results provide a theoretical basis for the optimal design of high-speed angular contact ball bearing cages.

Eucommia ulmoides is of high economic and medicinal value. Using grafting method can improve the survival rate of seedlings when cultivating, so as to obtain varieties with high medicinal value. However, due to the lack of automatic grafting equipment for eucommia ulmoides, the manual grafting method is mostly used when cultivating. Aiming at the problems of high labor intensity and unstable cutting speed and grafting success rate during long-term work in manual grafting, based on the research of eucommia ulmoides manual grafting technology, a matrix cutting system of eucommia ulmoides grafting robot was designed to improve the cutting rate and the grafting success rate. Firstly, the structure composition and working flow of the matrix cutting system of eucommia ulmoides grafting robot were analyzed based on the principle of mechanical design. Then, according to the analysis of the cutting method for the rootstock, the cutting mechanism and the clamping mechanism of the matrix cutting system were designed based on the pressure cutting method, which could complete the cutting of four rows and four rows of eucommia ulmoides rootstock seedlings at one time. At the same time, based on the traditional PLC (programmable logic controller), the control system of the matrix cutting system was designed, which had two modes of manual control and automatic control. Finally, the designed matrix cutting system of eucommia ulmoides grafting robot was used to carry out cutting tests and compared with the manual cutting method. The test results showed that the matrix cutting system of eucommia ulmoides grafting robot was stable and reliable, and could realize the manual control and the automatic control. Under the premise of the suitable size of eucommia ulmoides rootstock seedlings, its cutting speed could reach 517 plants /h, which was 1.1 times of the manual cutting speed; its average cutting success rate could reach 92.58% and the cutting effect was stable, which improved the grafting rate of eucommia ulmoides under a certain extent; the operator was more skilled, the cutting success rate of the system was higher. The research results can provide theoretical basis for the application of grafting robots in the plant cutting and grafting.

The design of the mechanical structure and hydraulic system of the tubular turbine governor has certain particularities. In order to improve the control performance of the tubular turbine governor, the tubular turbine governor of Chongqing Tongnan Hydropower Station is taken as the research object, and its mechanical structure and hydraulic system are designed. Firstly, the main mechanical components and the main adjustment functions and characteristics of the hydraulic system of the newly designed governor were introduced. Then, the structure and function of the main distributing valve with self-resetting function and the accident distributing valve that met the closing requirements of tubular turbine units were mainly analyzed. At the same time, a selection design method of the main distributing valve based on the relationship between the flow and the pressure drop was proposed, and the control window shape of its bushing was analyzed. Finally, through the governor field performance test, the rationality of the design of the mechanical structure and hydraulic system of governor was verified. The research results can provide references for the design of governors and the hydraulic system of turbines.

The key to hydride vapor phase epitaxy (HVPE) process is to ensure constant temperature field and high accurate control of the heating furnace. However, there are some problems such as large overshoot, low temperature control accuracy and long adjustment time in the temperature control process because the temperature control process of HVPE growth equipment involves multiple heating temperature zones, coupled with the delay caused by temperature measurement elements and the temperature conduction of heating resistance furnace. In order to achieve the precise control of the temperature in the reaction chamber of HVPE growth equipment, fuzzy logic was applied to the PID (proportion integration differentiation) control, and the fuzzy self-adaptive tuning PID controller in each temperature zone of the system was proposed. According to the actual equipment and corresponding technical requirements, a temperature control system of HVPE growth equipment was developed based on PLC (programmable logic controller), temperature control circuit and fuzzy self-adaptive tuning PID controller. The Simulink simulation results and measured results showed that the fuzzy self-adaptive tuning PID control could be applied to the temperature control system of HVPE growth equipment, and the control effect was better. The research indicates that the designed temperature control algorithm and temperature control system can well meet the technological requirements of GaN material growth, which has certain practical value.

Aiming at the problems of low automation level and poor human-machine interface interaction of current hot stamping equipment, a three-dimensional parametric design method was used to design the structure of the automatic hot stamping machine. Taking the Mitsubishi's new generation FX3GE series PLC (programmable logic controller) and the T5L smart touch screen as the core, the network control system of the automatic hot stamping machine was built, which realized the high-speed and high-precision drive of servo motor and cylinder, PID (proportion integration differentiation) temperature control and multi-parameter human-machine data interaction. Aiming at the problem that the traditional fixed-path sequential instruction programming mode could not meet the requirements of the small-batch customized production mode, a control program design method for the automatic hot stamping machine based on the finite state machine (FEM) model was proposed. Firstly, the functional planning and modular design of the automatic hot stamping process and the distribution, quantity and logical sequence of the movement stations were carried out, and a hierarchical finite state machine model was established. Secondly, according to the state transition events and state transition conditions, a state transition diagram of hot stamping action was constructed. Finally, the state transition diagram was mapped to the adjacent linked list variable space based on the idea of graph theory, and the variable configuration was used to drive the adjacent linked list, so as to complete the traversal and topology expansion of the state transition graph. The simulation results show that, compared with the traditional instruction programming model, the control program design method for the automatic hot stamping machine based on the finite state machine model not only improves the development efficiency and the configuration programming level, effectively reduces the maintenance cost of the control program, but also ensures that the sequence actions of the servo motor and the cylinder will not interfere or cross, and improves the reliability of the control system, which has broad prospects of engineering application.

Aiming at the problem of large geometry size and low sensitivity of defect detection of the traditional differential eddy-current probe, a runway-type differential eddy-current probe was designed on the basis of the traditional differential eddy current probe, which was composed of two induction coils with the same size and reverse connection wrapped by a runway-type excitation coil. Firstly, the COMSOL Multiphysics simulation software was used to establish a runway-type differential eddy-current probe model, and the difference of eddy-current field distribution between the runway-type differential eddy-current probe and the traditional differential eddy-current probe was compared. The detection sensitivity of two kinds of differential eddy-current probes under different defect depths and scanning angles was studied.Next, a runway-type differential eddy-current probe and a carbon-steel plate defect specimens were made, and the detection sensitivities of the runway-type and traditional differential eddy-current probes were compared by experimental testing. The test result showed that the runway-type differential eddy-current probe had a more compact structure and higher defect detection sensitivity compared with the traditional differential eddy-current probe. The research result can provide reference for the optimization design of small size and high precision differential eddy-current probe.

In order to study the dynamic characteristics of eddy current shock absorbers of wheeled vehicles under the impact load during travel, a permanent magnet eddy current shock absorber is designed based on the eddy current theory. Based on the equivalent magnetic circuit model and Maxwell’s equations, the relationship between the magnetic induction intensity at the air gap on the surface of the conductor tube and the damping force was analyzed. At the same time, the static and dynamic magnetic field distribution of the permanent magnet eddy current shock absorber was studied by using the finite element method, and the influence of various structural parameters on its damping characteristics and the indicator characteristic curves under different moving speeds were analyzed. By establishing a 1/4 vehicle suspension dynamics model and a random road excitation model based on Gaussian filtered white noise, the dynamic characteristics of the permanent magnet eddy current shock absorber under the impact load during travel were analyzed. The results showed that the demagnetization and speed accumulation of magnetic induction lines would occur in the magnetic field of permanent magnet eddy current shock absorber under the dynamic conditions, and the structural parameters had a great influence on the damping characteristics. The permanent magnet eddy current shock absorber had fast response speed, constant and stable compression and recovery damping force, which could efficiently and quickly eliminate the road surface excitation of wheeled vehicles when off-road and the impact load of vehicle-mounted weapons when shooting, and could effectively suppress vehicle body vibration. The research results are of great significance for improving the off-road mobility of wheeled vehicles and the shooting accuracy of vehicle-mounted weapons.