With the gradual shift of oil and gas exploration to deep, ultra-deep and complex rock formations, the existing mechanical drill bits have the problems of low rock breaking efficiency and high operating cost. Therefore, a new type of laser-PDC (polycrystalline diamond compact) drill bit was proposed to achieve efficient rock-breaking and energy-saving and cost-reducing. Using finite element method and based on the HJC (Holmquist-Johnson-Cook) constitutive model of rock, a nonlinear dynamic model of laser-PDC drill bit joint rock-breaking was established, and simulation research on laser-PDC drill bit joint rock-breaking was conducted. The simulation results showed that the radiation effect of laser generated higher temperature and greater prestress in the radiated area of rock surface, which in turn formed interpenetrating damage zones on the rock surface, reduced the strength of the rock, and was more conducive to cutting teeth to break the rock; compared with non-laser single PDC drill bit, laser-PDC drill bit experienced a 24.8% reduction in anti-torque during rock breaking, a 10.5% reduction in axial acceleration fluctuation, an increase in drilling displacement of 8.67 mm, and an increase in drilling speed of 112.79%. A laser-mechanical joint rock-breaking experimental bench was built to conduct laser-PDC drill bit joint rock-breaking experiment. The experimental results showed that laser-PDC drill bit joint rock-breaking had better drilling stability and continuity, greatly improving the rock-breaking efficiency. The research results can provide theoretical and technical support for the development and application of laser-mechanical rock-breaking technology.

Vehicle brake disc is a key components in vehicles. In the process of emergent brake, relations among brake press, parameters of the entire vehicle and adhesive coefficient between tire and road surface influence the distributionof brake disc friction temperature field greatly. Through FEA simulation, effects of different brake operating conditions on distribution of transient friction temperature field is discussed. The results show that ignoring change of friction heat flow intensity will bring large deviation to temperature field simulation. Initial kinetic energy of brake and the process of friction increasing are the key factors to influence temperature field of disk surface.

PDC (polycrystalline diamond compact) bit is the main rock-breaking tool in oil and gas drilling field, which has the advantages of high abrasion, high rate of penetration and high rock-breaking efficiency. As a cutting unit, PDC cutter determines the rock-breaking performance of PDC bit. The purpose of PDC bit cutter arrangement is to determine the spatial position of each PDC cutter on the bit, so that the bit has excellent performance and reliable life when drilling and breaking rock. PDC bits designed based on different cutter arrangement technologies show different rock-breaking performance during drilling. Therefore, the PDC bit cutter arrangement technology has been widely concerned by scholars at home and abroad. At present, a large number of scholars have made corresponding research on the cutter arrangement technology of PDC bit since its birth, but there is still a lack of systematic summary. For this reason, based on the literature about PDC bit cutter arrangement technology at home and abroad in recent years, the development process of PDC bit cutter arrangement technology since its birth was summarized, mainly including the early cutter arrangement stage, the classical cutter arrangement stage and the modern cutter arrangement stage. Through analyzing and summarizing the development process of PDC bit cutter arrangement technology, it was pointed out that the cutter arrangement technology of PDC bit in composite PDC bit, compatible intelligent PDC bit, long-life PDC bit, force-balanced PDC bit, PDC bit under impact and vibration and PDC bit in special formation represented the future development trend. The research results can provide some reference for the subsequent research of PDC bit cutter arrangement technology, and are expected to promote the further development of PDC bit cutter arrangement technology.

Fatigue failure of metal components is a common form of failure in industry. In order to improve the prediction accuracy of fatigue life of components, aiming at the influence of average strain on fatigue life under low cycle fatigue load, a low cycle fatigue life prediction model considering average strain was established based on the continuum damage mechanics and its irreversible thermodynamic framework, by introducing the Ramberg-Osgood cyclic constitutive model and using equivalent intrinsic damage dissipation work as an equal life condition. In order to compare and verify the effectiveness and progressiveness of the new model, the new model, modified Ohji model, Sandor model and Wei-Wong model were used to predict the low cycle fatigue life of 45 steel and 2124-T851 aluminum alloy with superimposed average strain, and compared with the corresponding test results. The results showed that the prediction results of the new model were in good agreement with the experimental results, and its prediction effect was better than the existing models. The fatigue life prediction method based on the intrinsic damage dissipation theory provides a new idea for the fatigue life prediction of metal materials.

In order to solve the problem of difficulty in testing and performance verification of compliant mechanisms in the process of optimal design, the mechanical properties of thermoplastic polyurethane (TPU) material were studied by 3D printing technology. The effects of material hardness and print fill rate on the mechanical properties of TPU material were analyzed, and the better 3D printing parameters of TPU material were obtained. Using single factor and two factor tset combined with variance analysis, the primary and secondary factors that significantly affect the flexibility of TPU specimens were identified as TPU material hardness and print fill rate. Combined with the mechanical property test data of TPU material, the mapping relationships between the material parameters and material hardness, print fill rate of four commonly used hyperelastic material constitutive models, i.e. Mooney-Rivlin, Yeoh, Ogden and Valanis-Landel, were obtained. The results showed that with the increase of TPU material hardness and print fill rate, the flexibility of the specimens decreased; among the four hyperelastic models, Ogden model has a good prediction effect on the mechanical properties of TPU specimens under different printing parameters; there was no significant difference in the predictive effect of the four models under the same TPU material hardness and different print fill rates. The research results can provide reference for 3D printing and finite element simulation analysis of TPU material, and provide reliable technical support for the test, performance verification and sample production of compliant mechanisms in the design process.

Aiming at the key issues in the overall development of snakelike robots, including material selection, structure design and motion realization, a new multi-joint snakelike robot was developed. This snakelike robot was composed of 11 two-degree-of-freedom orthogonal joints, which could achieve three-dimensional high biomimetic motion while ensuring flexibility. The basic gaits of snakelike robot such as meandering, wriggling and tumbling were designed by using the serpentine curve, and an improved obstacle surmounting gait was further proposed. At the same time, the gaits of the snakelike robot were simulated in the V-REP software, and the motion trajectories and efficiency of different gaits were compared. Finally, through the gait experiment of the snakelike robot prototype, the influence of each control parameter in the gait model on the motion waveform and speed of the snakelike robot was analyzed, and the reliability of the body structure and control system of the snakelike robot was verified. The research results have important theoretical significance and practical guiding value for realizing the gait planning and motion control of snakelike robots.

In order to realize the customization, reusability and economy of atomization assisted CVD (chemical vapor deposition) cavity, and meet the actual requirements of high-quality single crystal Ga₂O₃ thin film preparation, a new atomization assisted CVD cavity was designed and developed. The cavity was mainly composed of reaction chamber module, cooling module and buffer chamber module. Ga₂O₃ thin films were prepared by using a new cavity and a conventional cavity, and then the X-ray diffraction (XRD) patterns analysis and its surface morphology observation by atomic force microscope (AFM) were carried out. The experimental results showed that the new cavity could produce better performance α-Ga₂O₃ and β-Ga₂O₃ thin film; the half-peak widths of (006) crystal plane of the α-Ga₂O₃ thin films prepared by the new cavity and the conventional cavity were 0.172° and 0.272°, respectively, and the surface roughness was 25.6 nm and 26.8 nm, respectively. It could be seen that the α-Ga₂O₃ thin film made with the new cavity had better crystallinity, surface smoothness and density. Through the design of the new cavity, a stable environment conducive to the growth of single crystal Ga₂O₃ thin film was constructed, which provided a reliable path for the optimization of the preparation process of Ga₂O₃ thin film. The research results provide a reference for the preparation of high-quality metal oxide semiconductor films.

Aiming at the difficulties of on-line fault diagnosis of centrifugal pumps in nuclear power plants, a fault diagnosis method based on wavelet pack decomposition and random forest is proposed. Firstly, the wavelet pack decomposition was used to decompose the vibration signal in the radial vertical direction of the centrifugal pump motor drive end into three layers, and the sub-band energy features were extracted. Then, the time-domain statistical features were extracted based on the waveform data of centrifugal pump vibration signal, and combined with wavelet packet energy features as inputs for the random forest model. Finally, the random forest model was trained with centrifugal pump vibration dataset collected from vibration test, and the centrifugal pump fault diagnosis model was formed. This model was compared with machine learning models such as support vector machine, logistic regression, K-nearest neighbor and Gaussian Naive Bayes on the same centrifugal pump vibration dataset. The results showed that the constructed model could accurately identify different operating states of the centrifugal pump, such as normal operation, impeller damage, impeller blockage and motor bearing fault, and exhibited better classification performance. The fault diagnosis method based on wavelet packet decomposition and random forest can effectively extract features from vibration signals and realize fault classification, which has certain feasibility and effectiveness for on-line fault intelligent diagnosis of centrifugal pumps in nuclear power plants.

Multidisciplinary Design Optimization (MDO) is the lastest and most active field of complex system design at present, which draws more and more attention from industry and research institutes. After explaining the definition of MDO, the research content of MDO technology is analyzed and the status abroad is summarized. And then comparison between the research situations domestic and abroad is carried out. Finally, the existing problems and the developing trend in the future in MDO are proposed.

Aiming at the diversity and the flexibility of PDC (polycrystalline diamond compact) bit cutter design, a new reversal design method was put forward to improve the scientificity and efficiency of the PDC bit cutter design. The defective bit which cannot have ideal performance was used as the prototype bit. Second, the PDC bit cutter parameters were calculated based on the prototype bit. According to the PDC bit cutter parameters, the simulation model was used to analyze the reasonability of cutter parameters. For the results, according to the optimization model of wear rate and lateral force, the PDC bit cutter parameters were optimized. The research results show that the calculated parameters of cutters are accurate. Meanwhile, the optimized PDC bit has better performance. The reverse design and optimization methods provide a new design idea for the PDC bit customized design.

 Actively driving an inner micro-robot by an outer magnetic field for diagnosis is a feasible and crucial driven method. However, How to generate suitable outer magnetic is a complex problem. Comparing with the common methods adopting assembled electromagnetic loops to generate a driving field， an innovative and simple method was presented， by which permanent magnets were assembled to generate a rotational magnetic field. The circumferentially arrayed permanent magnet was adjusted to the corresponding original azimuth， and then synchronization rotation generated rotating magnetic field in the center of the array to work as the driving field of micro-robot. Furthermore， theoretic analysis and numeric calculation of the magnetic induction intensity distribution of the array center was carried out and a test-bed was established. The experimental results indicate that when circumferentially array six cubic magnets with 50 mm×50 mm×18 mm at the diameter of 275 mm， an even magnetic field of 0.012T can be generated in the central space，±50 mm×±50 mm×±20 mm， of the array. This magnetic field rotates with the same velocity as the outer magnet does， but in the reverse direction. The method， with wide application foreground， can be applied to generate a magnetic field to drive a micro robot， for diagnosis and treatment．

Aiming at the problems of insufficient automation and limited vision and observation angle of existing power tunnel inspection robots, a parent-child automatic inspection robot was designed. Among them, the master machine of inspection robot with mobile function could complete the main routine inspection work, and it had the ability to surmount and avoid obstacles; the slave machine with climbing function could complete the survey task under complex environment and extreme angle conditions. The slave machine and master machine could cooperate to complete the automatic inspection of the entire power tunnel. Firstly, based on the overall functional requirements, the specific form of each module of the inspection robot was proposed, and the hierarchical design of its automatic inspection logic system was completed. Then, the power tunnel operation environment was established in the ADAMS (automatic dynamic analysis of mechanical systems) software based on the virtual prototype technology, and the structure of the inspection robot master machine was optimized by combining the results of kinematic simulation analysis, so as to improve the stability of the robot operating in the tunnel and ensure that the sensors carried by the robot could work normally. The results showed that the inspection robot could run smoothly after the optimization of the master machine structure, the jitter amplitude of the sensor platform was within 5 mm, and all the sensors could work normally, which verified the rationality of the robot design. The relevant theoretical research results can provide reliable technical support for the development of the power tunnel automatic inspection robot physical prototype.

Load is a factor that cannot be disregarded during the running of rolling bearing, and loads with distinct characteristics will exert varying impacts on the reliability of bearing. In response to the stochastic time-varying nature of equivalent dynamic loads borne by rolling bearings, a reliability life evaluation method of rolling bearing considering dynamic time-varying loads was proposed to solve the problem of low evaluation accuracy caused by ignoring the time-varying bearing load in traditional methods. Based on the grey prediction model, the analysis model of the stochastic time-varying process of the bearing equivalent dynamic load was constructed, and the small sample load data was forecasted and supplemented. On this basis, an reliability life evaluation method of rolling bearing based on dynamic stress-strength interference model was proposed, and the working interval of dynamic load was obtained, so as to obtain the bearing reliability life interval. The reliability life test of cylindrical roller bearing NU206E was carried out to verify the proposed method. The results showed that, compared with the traditional method, the bearing life evaluation value obtained by the proposed method was close to the test values with higher accuracy and shorter evaluation time, and the life interval covering the most test values could be obtained. The method combining gray prediction model and dynamic stress-strength interference model has good engineering application value, and provides a new idea for reliability evaluation of rolling bearing under variable load conditions.

Digital modeling, system simulation and optimization in the automotive production process are of great significance for improving the quality and efficiency of automotive production. In order to solve the common problem of low resource allocation efficiency caused by data link breakage in automobile manufacturing enterprises, a new type of digital pedestal system was proposed based on the painted body storage (PBS) of automobile, to achieve data chain integration and multi-source heterogeneous data fusion. At the same time, a vehicle sequencing strategy for PBS was designed, taking into account the constraints of the final assembly process on sequence optimization. The PBS outbound sequence was obtained by a genetic algorithm, and then the inverse ordinal pair was used as a reference index for PBS lane layout. The effectiveness of the proposed method and strategy was verified by applying the PBS system based on digital pedestal system to a certain automotive manufacturing enterprise. The research results provide a reference for enterprises to build internal integrated manufacturing platforms and design specific workshop units.

Stable and continuous visual posture measurement data is of great significance for improving the work efficiency of coal-mine tunneling equipment. Currently, posture measurement methods for tunneling equipment based on visual information face issues such as cumbersome calibration process of cooperative target during station transfer and inability to perform automatic continuous measurements. Aiming at this problem, an automatic calibration method for station transfer based on binocular vision is proposed. Firstly, the HSV (hue, saturation, value) color segmentation and point-line feature extraction technology were employed to process the red features of the cooperative target, so as to obtain the image information of the cooperative target. Then, a calibration solution model for station transfer was designed, and the binocular vision measurement method was used to obtain the spatial parameters of the cooperative target. Finally, based on the characteristic that the relative position between the camera and the cooperative target was unchanged during the calibration process, the L-M (Levenberg-Marquardt) algorithm was used to optimize the spatial parameters of the cooperative target, and the optimization results were applied to the visual positioning system to complete the calibration for station transfer. The experimental results showed that the position measurement error of the tunneling equipment body after the calibration for station transfer was within 50 mm, and the attitude angle measurement error was within 0.6°. The proposed automatic calibration method for station transfer based on binocular vision meets the accuracy requirements of the visual positioning system for coal-mine tunneling equipment, which can provide theoretical support for the research of rapid tunneling technology.

In order to study the feedback efficiency of driving motor for electric vehicle and test the feedback efficiency expediently,the PMSM (permanent magnet synchronous motor) energy feed-back system based on sliding mode control algorithm is proposed.It can control the input voltage and current to drive another motor with the same features to generate.Based on the theory of en-ergy feedback,the energy feedback simulation model for PMSM driving system was established, which consisted of the sliding mode and variable structure control block,the space vector block and the PMSM numerical simulation model.And then,the energy feedback simulation model for PMSM system was simulated and analyzed.The simulation results showed that the proposed en-ergy feedback method could obtain about 70% feedback efficiency.That's meant that the pro-posed energy feedback method was feasible.Then,the hardware-in-the-loop (HIL) test system with dSPACE controller for PMSM energy feedback was built.The proposed energy feedback method was verified by the hardware-in-the-loop (HIL) test system.The test results showed that the obtained feedback efficiency was 60% 80%.The test value was very close to the offline simu-lation value.Obviously, the test results not only verify the accuracy of energy feedback simulation model for PMSM,but also prove the feasibility of the energy feedback for the driving motor of electric vehicle.In addition,the proposed energy feedback method can provide more choices for current energy feedback mode.And,the hardware-in-the-loop test system also can provide some technology support for PMSM platform test and real-vehicle test research.

Aiming at the shortcomings of rigid robot arm in fruit and vegetable picking, a flexible picking robot arm with simple structure and flexible movement was designed. Firstly, the kinematics model of the flexible picking robot arm was established based on the equal arc hypothesis, and the forward and inverse kinematics analysis from joint space to operation space and from driving space to joint space was carried out, as well as the decoupling analysis between the flexible joints. Then, the kinematics models of the flexible picking robot arm were numerically calculated by using MATLAB software, and the virtual prototype model of the flexible picking robot arm was established by ADAMS software. The kinematics simulation was carried out under the same working conditions as the theoretical analysis, and the accuracy of the theoretical analysis results was verified. The simulation results showed that the flexible picking robot arm could move flexibly and coordinatedly. The research results can provide a basis for the subsequent motion control of flexible robot arms.

According to the entire design requirements and restraints of a certain solid propellant rocket motor, design method of nozzle contour is put forward. In this method, muzzle internal flow field, pressure against nozzle wall and temperature variation under different pressures are analyzed by applying Computational Fluid Dynamics (CFD), one-equation model: S-A Turbulent Model and finitevolume method. According the results of computation of flow field, instantaneous propulsion of motor is gained, which is compared to the result of ground test.

Aiming at many coupled problems in product design based on axiomatic design, both axiomatic design and TRIZ are synthetically applied. A general decoupling method in axiomatic design by using the contradiction matrix of TRIZ is proposed and the process of the decoupling design was illustrated by the decoupling problem of the pile driving machine.

Crane is one of the eight special equipment, the rationality of its structural design is crucial for the safe operation, quality improvement, and efficiency enhancement of the equipment. Therefore, an optimization design method of metal structure of bridge crane based on structural function derivative coefficients was proposed. Firstly, the interpretive structure model was used to accurately describe the interactions and influence relationships between different parts of the crane, the structure complexity of the crane was analyzed to identify and optimize the parameters that had a significant impact on the strength of metal structure of the crane. Secondly, based on the finite element simulation, the structural function derivative coefficients were combined with fitting functions to find the optimal combination of design parameters. Finally, a 300/100 t-30 m bridge crane was taken as an engineering example, and the mass of the whole crane was reduced by 2 035.113 kg through simulation, and the effectiveness of the proposed method was verified. The optimization design method of metal structure of crane based on structural function derivative coefficients solves the problem that the complex interactions between various parts of crane is ignored in the traditional optimization method, and can realize the lightweight design of metal structure on the basis of ensuring the safety of crane service.

In order to design a large angle bending actuator with a simple structure, convenient production and easy modeling, a soft multi chamber bending actuator with a fan-shaped chamber structure was proposed. The actuator was made of super-elastic material. The functional relationship between input air pressure and bending angle was established based on the Yeoh model. The simulation of the bending actuator under different air pressures was carried out using Abaqus. The effects of structural parameters such as chamber end radius, chamber wall thickness, the angle between chamber ends, groove depth, and bottom thickness on the bending angle were analyzed. The soft actuator was manufactured and an experimental platform was built. The bending performance of the actuator was tested. The input air pressure was 0-65 kPa, and the bending angle was 0-218°. The simulation results were basically consistent with the experimental results. A flexible gripper with adjustable claw length was designed based on a bending driver, and its clamping effect on objects of different sizes, shapes, and masses was tested. The experimental results verified the practicality of the designed driver and gripper, and the driver had good bending performance. The research results can provide reference for further research on software drivers.

Multi-source uncertainties, such as random loads, manufacturing errors, and installation inaccuracies, influence mechanical system during the service processes, resulting in the deviation of system response, which seriously affects the operation stability and system reliability. In practical engineering, it is very difficult to collect high-quality data of complex mechanical systems on a large scale. For this reason, the sample size of the obtained data is usually small, and its uncertainty is difficult to quantify using probability models. Furthermore, when mechanical systems operate under certain specific conditions, the data may cluster in certain areas, exhibiting distinct clustering characteristics, which leads to challenges for the uncertainty analysis and measurement of mechanical system under these conditions. To address the above issues, an uncertainty analysis method for mechanical systems based on a multi-cluster ellipsoidal model was proposed to accurately quantify the uncertainties of system parameters with clustering characteristics, so as to achieve the rapid evaluation of system response uncertainty. In order to accurately quantify the small sample data with clustering characteristics, the multi-cluster ellipsoidal model was employed for uncertainty modeling. Based on the parameter interval information, the sensitivity analysis of the mechanical system was conducted to determine the main parameters that affected the performance of the mechanical system. The upper and lower boundaries of the mechanical system response were obtained by using multi-cluster ellipsoidal model and the sequential quadratic programming algorithm to achieve the uncertainty propagation of system parameters. The accuracy and effectiveness of the proposed method were verified through three numerical examples and one radar system engineering example. The research results indicate that the hyper-ellipsoidal clustering method has high computational efficiency and accuracy when addressing the uncertainty of mechanical system performance under limited samples.

Reliability test intensifying coefficient of automotive proving ground is the base to establish test rule， scientific theory and method can get the precise intensifying coefficient. A mathematical model for calculating reliability test intensifying coefficient of motor vehicle was derived on the basis of Miner linear cumulative damage law and then this model was modified according the factors triggering fatigue. Damage factor statistical quantity and frequency factor statistical quantity were introduced into the mathematical model， which made the physical meaning of the multiple factors more exactly. Combining the data of load on the truck working on the intensifying road of Chang'an University automotive proving ground， the integrative intensifying coefficient was obtained through calculation on various roads. This theory and calculating method have common reference value for other automotive proving ground．

After discussing demand characteristics of footwear product (FP), four fundamental types of mass customizations (MC) of FP are presented. Then technical system of MC of FP is constructed. This paper focuses on development design technology of MC of FP, which provides a solution for shoe enterprises to realize MC manufacture mode.

In the supporting and leveling structure of big tonnage optical instrument, manpower leveling is replaced by automatic one. Non-interference method f three-point-supporting and mechanical lags controlled by computer is selected for leveling. The method and principle of automatic supporting and leveling is presented. The 13 different instances possibly appearing are listed and then the method for confirming the beginning state and benchmark is put forward. The whole structure of mechanical lag and parameter calculation of its main parts are introduced. The result indicates that mechanical lag structure is not only compact but can support and level steadily, and the adopted three-point-supporting and leveling are brief and fast.