Mobile robots can replace people into dangerous environments such as fire and earthquake sites for terrain exploration and casualty search, but most robots are difficult to adapt to obstacles, right-angle walls, wall transitions and other complex terrain at the same time, and their control systems are relatively complex, requiring external energy input. Therefore, a deformable mobile robot with multiple functions, relatively simple control and no tethering was designed. Firstly, taking the 2-bar 4-cable tensioning integral structure as the basic unit, the body of the tensioning integral structure which could realize bending deformation was designed. Secondly, based on the analysis of adsorption force and structural parameters, the negative pressure adsorption device was designed and combined with the deformable body to form the overall structure of the robot. Then, the kinematic analysis of the robot was carried out, and the mapping relationship between the robot pose and the motor angle was obtained. Based on this, the robot's gaits of wall surface transition, traversing the narrow space from the wall surface and flipping up steps were planned. Finally, the robot prototype was developed, and the robot movement experiments were carried out according to different terrain, and the rationality of the robot gait planning was verified. The research results provide a certain reference value for the design and manufacture of multi-functional mobile robots.

Aiming at the problems of poor forming quality and long printing time of concrete 3D printing components, a path planning algorithm based on continuous vertex partitioning was proposed. Firstly, the continuous vertex partitioning method based on Hamiltonian circuit was used to divide the print area into several continuous regions to ensure that the print nozzle would not pass the same vertex many times during the printing process, thus avoiding the problem of repeated printing and poor forming quality. Then, the genetic algorithm was used to search each region, and the shortest printing path was determined through iteration and optimization. The experimental results showed that compared with other path planning algorithms, the proposed algorithm could significantly reduce the empty travel and start-stop times of the print nozzle, and shorten the printing time by more than 10%, which effectively improved the forming quality and printing efficiency for concrete components. The concrete 3D printing path planning algorithm based on continuous vertex partitioning solves the problems of poor forming quality and long printing time of concrete components by effectively dividing the print area, intelligentiy searching the shortest path and combining the optimal path, which can provide strong technical support for the development and application of concrete 3D printing technology.

Aiming at the problems of large changes in longitudinal pitch amplitude and longitudinal pitch angle caused by the flow field when the remotely operated vehicle (ROV) sails at high speed, a method for achieving high speed underdriven ROV operated with zero longitudinal pitch or slight longitudinal pitch by matching and selecting structural parameters of the extended chassis and the tailplane was proposed. Based on the lattice Boltzmann method (LBM), a six-degree-of-freedom simulation experiment was carried out by using the wall adaptive refinement algorithm combined with the structural parameters of the ROV to simulate the ROV sailing motion. The numerical analysis for the ROV with different height of extended chassis and tailplane was analyzed numerically to obtain the relationship between the structural parameters of extended chassis and tailplane and the longitudinal pitch amplitude and longitudinal pitch angle. By comparing the rotating torque of ROVs with similar sailing performance, the relationship between ROV stability and tailplane height was determined under the same extended chassis conditions. The orthogonal experiments for structure optimization of the extended chassis and tailplane were conducted, and the longitudinal pitch data of the ROV under different experimental schemes were fitted by using genetic algorithm. Combined with the actual requirements, the height of the extended chassis and tailplane was determined, and the correctness of the ROV longitudinal pitch design scheme was verified by the actual test. The results showed that the reasonable match of the extended chassis and tailplane structure could effectively reduced the longitudinal pitch amplitude of underdriven ROVs, so as to achieve slight longitudinal pitch sailing motion of ROVs without amplitude compensation. The research results can provide reference for improving the longitudinal pitch motion of relevant underwater devices.

The construction of supporting wheel-track-ground multi-body coupling system is an important link for the travelling smoothness study of tracked robots. Taking the unilateral five- supporting wheel tracked robot as the study object, the theoretical estimation model for tracked robot vibration was established on the basis of the nonlinear suspension system model and the road excitation considering the track filtering effect. Then, based on the simulation experiments of the tracked robot under working conditons with different road levels and different driving speeds, the effects of driving speed and road excitation on the vertical vibration of the robot body and its supporting wheels were quantitatively analyzed by the root mean square value. Finally, the theoretical vibration estimation model and dynamics simulation model of the seven-degree-of-freedom semi-vehicle were verified by external road experiments. The results showed that the vertical vibration of the tracked robot body increased linearly with the increase of driving speed and road roughness, and the track had a filtering effect on the road excitation. The vertical vibration acceleration of the tracked robot body centroid and the supporting wheel 1, 3, 5 were most sensitive to the road excitation, and the power spectral density amplitude of the vertical vibration acceleration of the robot body was the largest when the frequency was about 19 Hz. As the supporting wheel 5 was close to the driving section, the polygonal effect generated by the track engaging with the active wheel made its vertical vibration larger than that of the other supporting wheels. The combination of theoretical modeling, simulation analysis and external experiment provides a new idea for the study of vibration response characteristics of tracked robots under different road conditions.

In order to realize the multi-modal motion of continuum robotic arm and solve the problem that the existing robotic arm can only achieve single bending or rotation, a single-module multi-degree-of-freedom flexible continuum robotic arm based on rolling contact is designed. The rolling contact module was used as the skeleton structure of the bending module in the continuum robotic arm, and the rotating module was installed in the bending module to form a multi-degree-of-freedom robotic arm with independent bending and rotation motions. The kinematics model of the continuum robotic arm was established by the segmented constant curvature method, and its stiffness, bending and rotation properties were analyzed. A continuum robotic arm prototype was prepared, and experiments were carried out on the robotic arm to unscrew bottle caps, switch on the fan, and grasp the object by avoiding obstacles in the three-dimensional space. The experimental results showed that different tasks in complex spatial environment could be accomplished by the combined motion of bending and rotation, which reflected the advantages of the composite motion mode. The designed continuum robotic arm has multi-modal motion, which provides a new idea for the design of multi-degree-of-freedom continuum robotic arms and expands the application scenarios of continuum robotic arms.

Conventional robotic hands usually require drives to continuously provide torque or force to maintain grasping state. If the drive fails, the robotic hand cannot grasp the object stably. To solve these problems, a passively-triggered bistable robotic hand based on origami is proposed. The robotic hand was composed of a grasping mechanism with single-degree-of-freedom and a driving mechanism with bistable characteristics. Based on the kinematics models of the grasping mechanism and driving mechanism, the structure of robotic hand was designed according to the requirements of grasping state, and the energy barrier could be adjusted flexibly by setting the stiffness parameters of the torsion spring. Finally, the drop capture experiments were carried out to verify the grasping performance of the designed robotic hand. The results showed that when the drop height was 400 mm, the grasping motion of the robotic hand was not triggered; When the drop height was 440 mm, the robotic hand successfully grasped the object; When the drop height was 480 mm, the robotic hand failed to grasp the object although the grasping motion was triggered. The experimental results not only validate the ability of robotic hand to grasp objects of a certain size stably without driving, but also reveal the existence of energy barriers under different external shocks. The passive-triggered bistable robotic hand based on origami has potential applications in passive and adaptive robots.

At present, the 3D printed concrete field is still hampered by numerous issues that impede its large-scale industrial production and application. Among these, pores stand out as the most prevalent defect. Consequently, there is an urgent imperative to develop pertinent detection technologies for enhancing the printing quality of concrete. Aiming at the existing 3D printed concrete interface pore detection methods that mainly rely on subjective experience of individuals, and have disadvantages such as long-time consumption, high cost and large computational resource consumption, a lightweight intelligent pore detection method is proposed by introducing a deep learning-based object detection algorithm. Firstly, the traditional image processing algorithms were employed to preprocess the 3D printed concrete interface pore images, and the pore image dataset suitable for the target detection algorithm was constructed. At the same time, based on the characteristics of the constructed dataset, the anchor-box calculation method was optimized to acquire anchor boxes that were better suited to the interface pore targets, so as to improve the detection accuracy. Then, within the backbone network of the detection method, the ShuffleNetv2 network was utilized for multi-scale feature extraction, and part of the network was removed to reduce the network depth and the number of calculation parameters, thereby enhancing the pore detection efficiency. Finally, in order to improve detection precision, the polarized self-attention mechanism module was incorporated into the feature extraction network to enhance the attention to the pore target while maintaining high resolution. Experimental results demonstrated that the proposed method could effectively complete the intelligent detection of 3D printed concrete interface pores. Through comparing with various detection algorithms, it was found that multiple performance indicators of the method were improved, and the detection efficiency was significantly boosted. The research results can provide some data support for the subsequent quality control and performance evaluation of concrete.

The water-cooled wall of boiler in thermal power plants needs to be inspected and cleaned regularly. Using water-cooled wall robot can improve the efficiency of inspection and cleaning. In view of the complex working environment of water-cooled wall, a new type of water-cooled wall robot was developed. The robot structure and working principle were introduced. In order to ensure the robot to move flexibly and have reliable suction on the water wall, an electric permanent magnet wheel was designed. Through Maxwell simulation and experiment, the current excitation required to magnetize/demagnetize the electric permanent magnet wheel and wheel suction were obtained, and the electric permanent magnet wheel magnetize/demagnetization circuit was designed. The control system of the robot body was introduced, and the experimental platform for lateral walking of the robot was built to verify the cooperation and stability of the robot motion. The experimental results showed that the inner and outer legs of the robot could adsorb and move forward alternately, and realize the gait of lifting, stepping and dropping legs, and the movement was stable. The magnetic force was produced when the robot droped its legs and disappeared when it lifted its legs. The robot had both adsorption stability and movement flexibility. The electric permanent magnet wheel had simple structure, small size, small mass, less power consumption, and could provide about 150 N suction. The research results provide a reference for the application of wall-climbing robot in the cleaning and detection of water-cooled walls.

As a vital component of the magnetic adsorption wall-climbing robot, the structure of the magnetic adsorption module usually affects the overall mass and adsorption stability of the robot. Aiming at the problems of complex magnetic circuit coupling relationship and complicated optimization design of magnetic adsorption modules, a magnetic adsorption module structure optimization method is proposed by combining virtual simulation technology, surrogate model and dung beetle optimization algorithm to improve the efficiency of magnetic force calculation and optimization design process. Firstly, the structure design scheme for the wall-climbing robot was introduced, and through the simulation analysis of the existing Halbach array magnetic circuit modes, it was determined that the three-magnetic circuit mode had relatively high adsorption efficiency. At the same time, the magnetic force simulation model of the magnetic adsorption module was experimentally verified based on the initial parameters, which laid the foundation for establishing subsequent surrogate models. Then, an optimization model with the robot's adsorption stability and structural parameters as constraints and the lightweight of the magnetic adsorption module as objective was established. A fourth-order response surface model between the magnetic force and the structural parameters of the magnetic adsorption module was established by the optimal Latin hypercube design, ANSYS parametric modeling and surrogate model technology, and its credibility was verified. The structural parameter optimization model of the magnetic adsorption module was solved by using the dung beetle optimization algorithm. The results showed that the prediction error of the established surrogate model was tiny, and the relationship between the magnetic force and the structural parameters of the magnetic adsorption module could be well expressed. After optimization, the mass of the magnetic adsorption module was reduced by 12.7%. Finally, the correctness of the optimization process was verified through robot load experiments. The research results can provide reference for the magnetic force analysis and structure optimization of other magnetic adsorption robots.

Soft pipeline robots with anchoring-telescoping motion mechanism are typically constructed from flexible materials such as silicone and hydrogel, which can realize anchoring and telescoping in the pipeline through the deformation of flexible materials and have good flexibility. However, due to the viscoelasticity and hysteresis of flexible materials, the soft pipeline robot usually exhibits small force and slow response speed, which is difficult to store and release a large amount of mechanical energy quickly, and the crawling speed is slow. In order to solve this problem, a soft pipeline robot that can realize fast crawling is designed. This robot was composed of an anchoring module and a telescoping module. The anchoring module employed flexural deformation of the flexible belt to achieve the anchoring in the pipeline, while the telescoping module utilized the soft continuum structure with tower springs as main part to facilitate extension and contraction. According to the experimental measurement, the maximum crawling speed of the robot in the pipeline was 102 mm/s and the maximum anchoring force was 76.4 N. The robot was capable of stable crawling in pipelines with inner diameter of 90-120 mm, and had good adaptability to different shapes of unstructured pipeline environment. The results demonstrate that the designed robot can not only achieve bidirectional crawling in horizontal and vertical pipelines, but also quickly pass through S-shaped pipelines, which can provide new ideas for the design and research of soft robots in unstructured pipelines.

Considering the influence of the uncertain parameters of central pattern generator (CPG) model on the kinematic stability of hexapod robot, an optimization design method for the kinematic stability of hexapod robot based on a probability-interval hybrid model was proposed. Firstly, the numerical model of the hexapod robot was established, and the CPG model of the hexapod robot was established based on the Matsuoka and Kimura models. Secondly, the uncertainty variables of the CPG model were described by the probability-interval hybrid model, and the kinematic stability optimization mathematical model of the hexapod robot was also constructed. Then, Karush-Kuhn-Tucker (KKT) optimization condition and the second order fourth moment method based on the maximum entropy principle were used to decouple the kinematic stability optimization design problem of the hexapod robot, and the three-level nested optimization design problem was transformed into a single-level optimization design problem, which realized the efficient solution of the optimization problem. Finally, the kinematic stability approximate model of hexapod robot was established based on radial basis function, and the optimal design solution was obtained by genetic algorithm. The results showed that the proposed method could effectively solve the optimal parameters of the CPG model and improve the kinematic stability of the hexapod robot. Therefore, this method has high application value in the field of robot motion control.

The repair of large-skin wounds has been a difficult problem to be solved urgently. At present, the commonly used repair methods are mainly autologous skin transplantation and wound dressing treatment, but these methods cannot simultaneously meet the needs of large-skin repair and customized repairment. The in situ skin printing technology provides a new idea for the repair of large-skin wounds. However, the existing bioprinting equipment has small printing range and low printing precision, which cannot realize the shape printing of large area of skin tissue. In order to solve the above problems, an in situ skin printing system composed of Stewart parallel robot, linear module mechanism, print head and 3D scanner was proposed. The Stewart parallel robot could achieve high-precision skin in situ printing as printing driving device due to high repeated positioning precision and low cumulative error. The Stewart parallel robot had six degrees of freedom and could adjust the printing angle in 3D space, allowing bioink to fully cover the skin wounds along the skin surface, which was beneficial for wound repair. In order to analyze the feasibility of the designed in situ skin printing system, the workspace of the parallel robot was calculated by numerical method, and the working range of the in situ skin printing system was obtained and verified through printing experiments. The experimental results showed that the parallel robot operated according to the specified path, and the print head could stably inject bioink during the printing process. The working range of the in situ skin printing system was basically consistent with the workspace of the parallel robot, which met the needs of repairing large-skin wounds. The research results lay a theoretical foundation for the subsequent animal experiments on large-skin repair.

Aiming at the shortcomings of traditional sliding mode control in trajectory tracking of boom-type roadheader, such as slow global convergence and significant chattering, an improved sliding mode control method based on novel reaching law is proposed. By introducing lateral deviation and heading angle deviation of the roadheader body and adding power reaching term to the traditional exponential reaching law, the rapid convergence of trajectory deviation and chattering reduction for the roadheader were achieved. At the same time, the boundary layer method was employed to further suppress chattering, which addressed the problem of chattering easily caused by the product term of sign functions in the reaching law. The existence, reachability and stability of the novel reaching law were analyzed, and the interval of disturbance steady-state error was derived. Considering the uncertain disturbance of the roadheader, the simulation comparison was conducted between traditional sliding mode control method and improved sliding mode control method. The results indicated that the control accuracy, convergence speed and anti-interference ability of the improved sliding mode control were superior to the traditional sliding mode control. Finally, an experimental platform was set up to test the performance of the roadheader trajectory tracking control system, which verified the feasibility and effectiveness of the improved sliding mode control method. The research results can provide important reference for the intelligent control of mining equipment in the harsh environment of underground coal mine.

In order to solve the problems of slow movement, poor environmental adaptability and single gait of rescue robots, a quadruped bionic mobile robot was designed according to the physiological structure of turtle and goat. Firstly, according to the characteristics of turtle crawling on soft ground and goat's strong movement ability, two gaits imitating turtle crawling and goat walking were planned for the robot to adapt to different environments and improve the robot's movement performance. Then, the dynamics analysis for the robot outrigger was carried out, and the quantitative relationship between the robot joint torque and motion performance parameters was obtained by establishing a dynamics model. Finally, the feasibility of the robot's gait and the robot's adaptability to the environment were verified by simulation and prototype experiments. The results showed that the designed robot had stable structure and reasonable gait planning, which could adapt to different complex terrains. The research results can provide important reference for the design and development of bionic robots.

Transrespiratory biopsy is a common surgery for diagnosing pulmonary nodules. However, due to the risk of infection of respiratory diseases and joint restrictions during manual operation, the diagnosis and treatment method combined with medical and engineering has gradually become a development trend. In order to realize the flexible movement, precise positioning and stable intervention of the flexible body in the complex bending and dynamic environment of the bronchial lumen, a master-slave collaborative remote control robot mechanism design was adopted to simulate the doctor's operating habits in traditional surgery, and an integrated mechanism principle prototype that could simultaneously control the bronchoscope and biopsy forceps was designed and build, which realized the dual-machine cooperative control for minimally invasive diagnosis and treatment through the bronchus. Then, based on the Cosserat rod theory, the force-position mapping relationship, pose and working space of the flexible end-effector of the robot were simulated and solved by MATLAB software, and the real pose of the flexible end-effector of the robot in the remote minimally invasive biopsy operation through the bronchus was analyzed by experiments, as well as the actual operation effect of the robot, which verified the accuracy of simulation results. The research results can provide a theoretical basis for multi-instrument collaborative control of transnatural duct biopsy.

In order to solve the problems of low efficiency and heavy computational workload during the optimization design process in the existing airfoil geometric parametrized modeling methods, a deep learning-based airfoil parametrized modeling method was put forward. In this method, the two-dimensional airfoil images converted from coordinate points of airfoil upper and lower surfaces in the airfoil database of the University of Illinois at Urbana-Champaign (UIUC) were taken as the input. Firstly, the convolution operations were used to extract geometric features of a large amount of airfoil images. Then, the extracted geometric features were classified and compressed by multi-layer perceptron, and the airfoil shape was compressed into several simplified fitting parameters. Finally, the airfoil image was restored and the coordinates of points on the upper and lower surfaces of airfoil were output by a decoder. On this basis, the influence of the number of fitting parameters on the geometric accuracy of airfoil was discussed, and a convolutional neural network (CNN) structure with six fitting parameters was determined. At the same time, the fitting accuracy of the proposed method was verified by the computational fluid dynamics numerical simulation. Finally, the visual airfoil geometry design software was developed to adjust and modify the fitting parameters, and the influence law of each fitting parameter on the airfoil shape was summarized. The results indicated that all the six fitting parameters had a global impact on the airfoil shape, and the new airfoil design space could be obtained by adjusting the six fitting parameters individually or jointly. This research results can provide technical support and theoretical guidance for airfoil optimization design.

Wind turbine blade is the core component of wind turbines. The blade bolt is not only the part that bears complex stress, but also the part that bears the highest load. In order to avoid potential hazard and economic loss caused by bolt breakage, an axial stress measurement system for in-service bolts based on ultrasonic guided waves is designed, which can achieve accurate measurement of axial stress for various types of bolts. Firstly, the group velocity dispersion curve of ultrasonic guided wave was obtained through numerical calculation, and a linear mathematical model of bolt axial stress and ultrasonic guided wave acoustic time was established based on the Hooke's law and acoustic elasticity effect. The effectiveness of ultrasonic guided wave stress measurement by single longitudinal wave transducer was verified by simulation in COMSOL software. Then, in view of the modal aliasing of ultrasonic guided wave echo signals and the interference of noise on the measured results of ultrasonic guided wave acoustic time in actual measurement, the denoising algorithm based on echo compensation was used to denoise the actual measurement signal. The empirical wavelet transform algorithm was used to decompose the modal of ultrasonic guided wave echo signal, and the cross-correlation method was used to obtain the accurate acoustic time of ultrasonic guided wave modal. Finally, the precise measurement of axial stress for 18 types of bolts within the 30%-90% yield strength was completed through experimental tests, and the relative measurement error was less than 2%. The research results are helpful to improve the bolt assembly process and standardize the worker's operation process.

Coastal blue carbon ecosystems such as mangroves, salt marshes, seagrass beds and seaweed fields are important natural carbon sinks for mitigating global climate change. Under various anthropogenic and natural threats, the coastal blue carbon ecosystems have been degraded on a large scale, so the restoration and enhancement of the carbon sink function of the coastal blue carbon ecosystem is an issue that needs to be solved urgently. According to the categories of coastal ecosystems, the main coastal blue carbon sink technologies and equipment were summarized. The comprehensive benefits of coastal blue carbon ecosystem sink enhancement were analyzed from the aspects of carbon sink enhancement benefit, economic benefit and eco-benefit. Future research should focus on the optimization of the observation system for the distribution and sink of coastal blue carbon ecosystems, the improvement of species optimization and planting methods, as well as the impact of emerging blue carbon ecosystems carbon sequestration technologies on eco-environment, so as to further consolidate and enhance the carbon sink of blue carbon ecosystems s, and help realize the goal of “carbon peak” and “carbon neutrality”.

Detection range and ranging accuracy are the key performance indicators of radar. Under actual service conditions, they are greatly affected by uncertain factors such as internal signal transmission loss and external signal interference of radar system. Improving its accuracy has become an important topic in the field of radar research. In order to evaluate the influence of the above uncertain factors on the radar performance, the uncertainty analysis of radar detection range and ranging accuracy was carried out. Firstly, the radar detection range and ranging accuracy models considering signal transmission loss and signal interference were established; secondly, the interval model was used to quantify the uncertainty parameters to realize the uncertainty measurement under the unified framework of internal and external parameters; then, the accurate response surface models of detection range and ranging accuracy were constructed, and the influence of multi-dimensional parameters on detection range and ranging accuracy was sorted by using Sobol' global sensitivity analysis method; finally, the subinterval decomposition analysis method was used to obtain the radar detection range and ranging accuracy range, and the results were compared with those calculated by Monte Carlo simulation method to verify the effectiveness of the proposed method. Reasonable tolerance and threshold values are set for radar detection range and ranging accuracy, which can improve the efficiency of radar performance analysis and reduce the cost of performance analysis.

The structure of high-parameter large-scale amusement rides is varied, the movement forms are complex, and the failure modes are numerous. Their service health management and control involves risk assessment, detection and monitoring, fault diagnosis, life assessment, health assessment, use management and many other aspects. The safe operation of the rides can be fundamentally guarantee only by establishing a comprehensive and systematic health management and control technology system. Taking the high-parameter large-scale amusement rides as the research object and equipment failures, faults and accidents as the problem orientation, a systematic and scientific health management and control technology system was designed. The technical problems to be solved and the research direction of service health were analyzed from four aspects: health management and control index system, detection and monitoring key technology, health assessment key technology, health recovery and maintenance.The research results provide ideas and guidance for the whole industry to carry out relevant technical research.

The classical fracture phase-field model is a variational method based on brittle fracture theory, which cannot accurately characterize the quasi-brittle fracture behavior of composite material. Based on this, a multi-phase-field model was proposed to describe the multi-pattern cohesive fracture behavior of fiber reinforced composites material. A hybrid cohesive fracture phase-field model was proposed by reasonably defining the phase-field driving force and the damage constitutive relationship for the anisotropic material, and the corresponding evolution equation and strength criterion were derived. The model was used to simulate the crack propagation and failure of three kinds of composite plates. The results showed that the proposed multi-phase-field model could effectively simulate the multi-pattern cohesive fracture behavior of composite material, and had high application value.

Cone bit in deep drilling is subject to multiple factors such as high temperature, high pressure, friction and corrosion during deep well drilling, which directly affect the service life of the seal ring, and then affect the life of the bit. Therefore, the sealing test technology of cone bit was studied. Firstly, the sealing test machine of cone bit was designed, and its functional modules were designed; secondly, the sealing performances of O-shaped rubber seal ring and radially symmetrical flat rubber seal ring under the influence of multiple factors were analyzed by finite element method, and the contact stress judge criterion and von Mises criterion were used to evaluate and compare the seal ring performances; finally, the life test of the seal ring under the action of multiple factors was carried out, and the experimental results were compared with the simulation results. The experimental results verified the feasibility and reliability of the test machine for cone bit sealing test. The designed sealing test machine of cone bit can predict the service life of cone bit seal ring, and has a broad application prospect in engineering.

Submarine pipelines laid in the seabed are often suspended due to natural or man-made factors such as ocean current erosion and ship anchoring, which can easily cause pipeline deformation, corrosion, damage, cracking and leakage, seriously affecting the safety of pipelines. Aiming at the suspension internal detection for DN200 submarine pipelines, an internal detection robot was designed, and its dynamics analysis was conducted. Meanwhile, a flexible pipeline-soil coupling model was established by combining ANSYS and ADAMS software, and the internal detection simulation analysis for suspended pipelines was carried out. The fast Fourier transform and the short-time Fourier transform were used to process the vibration response signal of the internal detection robot under complex excitation coupling conditions, and the effective identification of the suspended pipeline section was realized by analyzing the vibration acceleration of the robot. The research results provide a new idea for the internal detection of oil and gas pipelines in suspension.

In order to quantitatively evaluate the remanufacturability of piston pump, the fatigue life was studied with the piston pump as the research object. The rigid-flexible-liquid joint simulation model of the piston pump was established, and the effects of rotational speed and load pressure on the maximum stress and fatigue life of the piston pump were studied. The results showed that the maximum stress on the piston pump increased exponentially with the rotational speed increasing, while the fatigue life of the piston pump decreased exponentially. With the increase of load pressure, the maximum stress increased linearly, and the fatigue life decreased logarithmically. Based on the fatigue life analysis of the piston pump, a technical evaluation system with remaining life and parts processability as indexes was established, and economic and environmental indexes were comprehensively considered. A quantitative evaluation model and method for the remanufacturability of the piston pump were proposed, and engineering application analysis was carried out to verify the rationality and feasibility of the proposed method.

Aiming at the problems of the traditional triple eccentric butterfly valve to withstand a certain differential pressure or reverse pressure of full differential pressure, an all-metal hard sealing bidirectional zero-leakage triple eccentric butterfly valve is studied and designed. The valve is long-life and energy-saving, and it adopts the triple eccentric principle to solve the defect that the sealing surface of the traditional eccentric butterfly valve is still in sliding contact friction at the moment of opening 10o and closing, which realizes the effect that the sealing surface of the butterfly valve separates at the moment of opening and seals at the moment of closing contact. Firstly, the unbalanced torque and allowable differential pressure of the designed butterfly valve were analyzed theoretically, and the pressure, velocity and flow trace of the fluid in the butterfly valve chamber with different openings were analyzed through fluid flow simulation. The variation curves of the maximum pressure and maximum velocity at the inlet and outlet of butterfly valve with the valve opening were obtained. Then, the thermal temperature and resultant heat flow cloud maps of the butterfly valve were obtained through thermal stress simulation analysis, and the distribution of thermal stress, thermal strain and safety factor of the butterfly valve as well as the variation curve of its maximum thermal stress with fluid temperature were analyzed, which verified that the thermal stress of the butterfly valve met the requirements. Finally, the butterfly valve body pressure test and positive and negative high-pressure sealing test were carried out. The test results showed that there was no visible leakage and deformation of the butterfly valve body, and the measured leakage was zero, indicating that the compressive strength and sealing performance of the butterfly valve met the use requirements. The research results provide a basis for the reduction of contact and friction, the decrease of opening torque and the extension of service life of triple eccentric butterfly valves, and the proposed all-metal hard sealing structure provides a new idea for the research of bidirectional zero-leakage sealing of triple eccentric butterfly valves.