Actual Test Results Research Articles

Calculation model for bearing capacity of steel-CFRP composite pipeline under internal pressure

The Carbon Fiber Reinforced Polymer (CFRP)-wrapped steel pipeline system is emerging as an alternative for the repair and long-distance transportation of oil and gas. This system is recognized as a composite material. Under internal pressure, the pipe predominantly undergoes circumferential stretching. This study derives the tensile constitutive model of the steel-CFRP composite material using uniaxial tensile tests and the rule of mixtures. Subsequently, utilizing this newly calibrated constitutive model, a computational model to assess the internal pressure capacity of the steel-carbon fiber composite pipe was established. Finally, a comparison between the theoretical outcomes of the computational model and the actual internal pressure test results revealed a high degree of correlation. This holds substantial significance for the design and practical implementation of this novel composite pipeline system.

Development of the Design Frame to Predict the Peak-G and Duration Time in Gas-Gun Tests

The gas-gun test is a experimental approach employed to validate the operational or structural stability when subjected to the impact energy encountered during launch or target collision. Predicting the outcomes of the gas-gun test has traditionally relied on empirical knowledge, due to numerous factors such as the bird assembly’s shape, weight, material, and flight velocity. However, due to the nonlinearity and complex interactions between these variables, numerous tests are necessary to identify the necessary requirements, resulting in significant expense and time consumption during the process. The objective of this study is to forecast the variations in impact energy in future tests by developing a numerical model and analysis that aligns with the test outcomes, utilizing the ABAQUS Explicit. The outcome of the numerical analysis produced a framework that anticipates the peak g and the duration of the actual gas-sun test results, throughout post-processing techniques using FFT and LPF filters.

CubeSat standardized modular assembly method and design optimization

In order to solve the deficiencies of traditional board-level assembly CubeSat, such as low modularity, complex assembly process and poor scalability, a sandwich module assembly structure and method with no drive components is proposed, which can achieve quick connection and flexible assembly between modules. First, the proposed CubeSat standard module can be compatible with the standard interface of traditional CubeSat. The 4-in-1 interface of Mechanical-Electrical-Thermal-Data does not occupy the internal space of the standard module, and the electrical and thermal interfaces meet the requirements of CubeSat in-orbit work. Secondly, in order to improve the reliability of the connection between the modules, a plug-in connection scheme of the mechanical interface was designed. Finally, a genetic algorithm was used to optimize the interface size, so that it has better plug-in performance. The simulation results show that the performance of the male interface of titanium alloy material is the best, and the error between the finite element analysis and genetic algorithm results is less than 4.8 %, which is consistent with the actual tensile test results of the optimized prototype, and meets the mechanical requirements of the launch process and space orbit operation for CubeSat. The test results can guide production and provide a reference for subsequent engineering applications of CubeSat modular assembly.

Shear behavior of web huge rectangular opening RC beams

Abstract Opening in the web of reinforced concrete (RC) beams will destroy the integrity of the beam and weaken the mechanical properties of the RC beam, such as the bearing capacity and stiffness. The three-point loading test and finite element analysis were carried out on 10 RC beams with a huge rectangular opening in the web. The effects of stirrups around the holes on the shear properties of RC opening beams, such as bearing capacity, deformation capacity, and stirrup strain, were studied, and the shear transfer mechanism of RC beams at the openings was explained by using the strut-and-tie model. The finite element test results are consistent with the actual test results, as shown by the results. When the hole width is small, the reinforcement of stirrups at the hole side can significantly improve the shear capacity of the specimen, but it can also cause chord shear failure. When the hole height is small, with the strengthening of the chord stirrup, the ultimate bearing capacity of the specimen increases, but it can still result in hole-side shear failure. The curve of stiffness degradation is approximately logarithmic. Moreover, according to the finite element stress vector diagram, the shear transfer mechanism of the perforated beam based on the strut-and-tie model has been proved.

Ocena tehnika mašinskog učenja za Nd - IAG Laser i TIG zavareni nerđajući čelik 304

Nd: YAG Laser and Tungsten Inert Gas (TIG) welding processes are the most promising joining techniques used for stainless steel (SS) alloys due to their significant weld characteristics. In this study, the effect of two process parameters (weld power and travel speed) on the mechanical properties (ultimate tensile strength and microhardness) of the weldment is investigated. Two different machine learning techniques, namely Adaptive Neuro-Fuzzy Inference System (ANFIS) and Unified Convolutional Neural Network (UCNN) are also evaluated for prediction of mechanical properties and defect detection through the image processing technique, respectively. A correlation has been performed between these two machine learning approaches with the experimental values. The training data sets are developed for the machine learning techniques, and the obtained results of (ANFIS) and (UCNN) models are related to the actual experimental values. The output of both developed models (ANFIS & UCNN) showed a good agreement with the actual experimental test results. The predicted tensile and microhardness values from the (ANFIS) model were found to greatly agree with the Peak Signal-to-Noise Ratio (PSNR) values from the (UCNN) model. However, owing to the increase in the applications of welding processes in industries, the utilization of machine learning techniques would be more efficient when compared with the other traditional methods that are being adopted.

Constitutive modeling and simulation of polyethylene foam under quasi-static and impact loading

In this paper, quasi-static and dynamic compression experiments were carried out on polyethylene foam by a universal material testing machine and a drop tower impact device. The mechanical response characteristics and energy absorption capacity of polyethylene foam under quasi-static and moderate strain rate (4 × 10−3–102s−1) loading conditions were obtained. An improved constitutive model of strain-rate term coupling strain and strain rate was established based on the Sherwood–Frost phenomenological constitutive model and Johnson–Cook constitutive model. Low Density Foam model combined in the finite element software ABAQUS with the improved constitutive model was used as the parameter definition of polyethylene foam material in the simulation. The drop-tower impact tests at different heights were simulated, and the simulation results were compared with the actual drop tower impact test results. The results showed that the peak acceleration errors between simulation and experiment were less than 7.1%, verifying the accuracy of the constitutive model. This study provides a method of constitutive models and finite element simulation to the performance of polymer foams.

Co-optimization of magnetic abrasive finishing behaviors of zirconium tube surfaces with Fe-6.5 wt% Si/SiC abrasives using BP neural network and response surface methodology

A novel abrasive of Fe-6.5 wt%Si/SiC composite was prepared for magnetic abrasive finishing (MAF) to achieve fine machining of zirconium alloy tubes. The optimized parameters of magnetic pole speed R= 16.0 r·min−1, tube speed Q= 1220.5 r·min−1, abrasive quality P = 119.3 g, and machining gap N = 2.30 mm were obtained by response surface analysis. The BP neural network model was used to predict the optimal machining effect of MAF. It showed that the predicted results of BP neural network model are quite close to the actual test results, with an error of 7.526%. Finally, the roughness of zirconium alloy tube was reduced from 0.207 µm to 0.113 µm, resulting in a 45.41% improvement rate. Fe-6.5 wt% Si/SiC composite abrasive was an efficient magnetic abrasive to improve the surface quality of zirconium alloy parts.

Design and Study of Mechanical Cutting Mechanism for Submarine Cable Burial Machine

This paper aims to explore the current state of research on submarine cable burial machines and proposes a novel mechanical burial machine design employing a chain-type structure based on a combination of theoretical considerations and practical requirements. Through theoretical analysis, simulation, and experimental studies, the cutting process of the mechanical burial machine is investigated in detail, with special attention given to the seabed conditions in the Northeast Asia region. Starting from the dynamic process of the blade–soil interaction and the working mechanism of the blade–soil system, an accurate and reliable model for the seabed rock–soil stress is established, along with a fast computation method. A destructive analysis of rock–soil mechanical cutting is performed, elucidating the influences of the cutting depth, cutting angle, and chain blade cutting speed on cutting resistance. This paper provides reference parameters for the design of chain-type trenching devices under different seabed conditions, and adjustments are made based on simulation experiments and actual soil trenching test results. These analyses contribute practical and reliable guidance for the design and optimization of submarine cable burial machines.

Impact of mirror local defects on system scattering in telescopes

To calculate the scattering impact of scratches on space-based telescope systems accurately, this study proposes fitting scratch scattering using an anisotropic scattering model based on actual test results. The stray light nonuniformity and total stray light of each mirror in a Cook-type off-axis three-mirror system was calculated. A scratch illuminated with unit radiation power can generate a maximum stray light level of 7 × 10-5 and can obscure dark targets with a brightness ratio of 1 × 10-5 to 8 × 10-5. Furthermore, as the wavelength decreases, the total stray light generated by this scratch can reach 5.7 × 10-4 when illuminated with unit radiation power in the 200 nm ultraviolet band. Such scratches on the mirrors of an off-axis three-mirror telescope cause 7–8 times higher nonuniformity of stray light than roughness scattering, decreasing signal-to-noise ratio and affecting target recognition and image processing.

FE-based Simulation of Radiated Noise for a Rotating Tire

Today, the significance of reducing pass-by noise is increasing steadily due to EU labeling regulations and the demands of car makers. As a result, numerous companies are actively conducting research to minimize pass-by noise. In this paper, we introduce a finite element method (FEM) prediction technique for reducing pass-by noise, aimed at reducing the time and cost involved in manufacturing, testing, and verifying pass-by noise. We have created a tire FE model that incorporates the full pitch sequence of the tire pattern, and used it to predict airborne noise (ABN) generated by air pumping and vibration due to the grooves in the pattern. The simulation environment was designed to match the test conditions in Hankook's anechoic chamber, and we compared the frequency spectrum of the simulation results with the actual test results. In conclusion, we have successfully performed FEM simulation of radiated noise, which accurately reflects the noise generation mechanism of rotating tires. This has improved the simulation accuracy for predicting airborne noise.

An Intelligent Controller Based on Extension Theory for Batteries Charging and Discharging Control

The main purpose of this paper is to develop an intelligent controller for the DC-link voltage of bidirectional soft-switching converters used in the batteries with equalizing charge and discharge control. To accelerate the equalizing charge and discharge speed of batteries, the DC-link voltage controller of the bidirectional converters is designed based on extension theory. Firstly, the photovoltaic module arrays (PVMAs) are used with the intelligent maximum power point tracker (MPPT) for supplying the power to the load side. Through the bidirectional soft-switching converters, the PVMAs will be allowed to carry out the uniform charging and discharging for the storage battery in order to achieve the intended energy storage and auxiliary power supply functions. In terms of the controller design, the quantitative design techniques are utilized, by which the P-I controller parameters will be designed for the converter when attempting to achieve the same control performance at different working points. As a next step, the aforesaid parameters are used together with the extenics theory. Based on the variation in the output power of the bidirectional converter and that in the voltage of the storage battery, it allows the system to find out the intended P-I controller parameters that will be approximate to the prescribed control performance when operating under different working conditions. As a result, the P-I controller will be provided with more efficient control flexibility and control performances. Finally, actual test results demonstrated that the response time of the proposed intelligent extension controller is shortened by 3% compared to the quantitative design of the proportional–integral (P-I) controller. Based on the proposed quantitative design of an intelligent controller for uniform charging and discharging management of batteries, the sustainable utilization of renewable sources of energy can be improved. At the same time, the better economic benefit of the energy preservation system is obtained. In addition, it also prolongs the life cycle of batteries, and then enhances the reliability of the batteries.

Financial Risk Prediction based on Time Series

In this paper, the data mining method based on time series is applied to financial risk prediction, the corresponding model is established, and the predictive ability of the model is tested according to the real financial data of K company. The actual test results show that the time series method is suitable for the prediction of financial data with regular periodic changes, and it has high accuracy.

Seismic behavior of the brick masonry rural building strengthened with polypropylene grid cement mortar coating: Shaking table tests

Brick masonry structures are widely applied around the world, especially in Chinese rural areas, but their seismic performance is not satisfactory due to high brittleness of material and poor integrity of structure. Accordingly, a low-cost and highly efficient strengthening method for brick masonry structure is needed. This paper presents the shaking table tests for a 1/2-scale single-story brick masonry rural building strengthened with polypropylene grid cement mortar coating. The damage states of the test model under earthquake motions with different intensity were observed. The dynamic characteristics including natural frequency and damping ratio were discussed. The seismic response, such as acceleration, displacement, torsion angle, base shear and hysteretic energy dissipation, were analyzed. The results show that the weak areas of the test model were the corners of windows and door, the intersections between longitudinal wall and transverse wall and the top of longitudinal walls. With the input PGA of 1.0 g, the natural frequencies of the test model in the X and Y directions decreased to 93.1 % and 88.2 % of the initial values, respectively, the damping ratio in the X and Y directions increased to 2.56 and 1.61 times the initial values, respectively, and the maximum story drift and horizontal torsion angle were 1/122 and 0.0037 rad, respectively. The comparison between actual earthquake damage and test results showed that the use of polypropylene grid cement mortar coating to strengthen brick masonry rural building could result in good seismic behaviors.

Metal-based electrocatalysts with data-driven designed particle size for hydrogen evolution

Metal-based catalysts are currently at the forefront of hydrogen evolution catalysts, yet the influence of particle size on their catalytic activity is intricate. In this study, we compiled a database using actual test results and employed interpretable algorithms to analyze the relationship of catalyst factors with their catalytic properties. Our analysis revealed a bowl-shaped correlation between the measured overpotential and the particle size of metal-based catalysts, with the optimal size falling within the range of 1.5 to 3.0 nm. To corroborate the algorithmic analysis, we synthesized nanoalloys using an ultrathin carbon layer, which effectively restricted the movement of metal atoms at high temperatures. The series of materials prepared displayed a consistent pattern in their measured overpotential, aligning with our algorithm’s prediction. Notably, the 2.0 nm PtCoNi catalyst achieved superior catalytic performance with lower precious metal content than commercial Pt/C. Further data-driven analysis indicates that the size-dependent catalytic activity is shaped by the balance between metal-support interaction and the exposure ratio of the active site. This study underscores the efficacy of merging a data-driven approach with precise control of material synthesis to analyze complex catalytic systems, providing a potent tool for future exploration in the field.

PFC–FLAC coupling-based numerical simulation of triaxial test on soybean granular material

A discrete-continuous (PFC–FLAC) coupling method was used in this study to simulate laboratory triaxial tests with soybean granular material. The mesoscopic mechanical parameters of the soybean granular material were calibrated by comparing them with actual laboratory test results, and the validity of the modeling method was verified. Subsequently, the particle motion law and mechanical mechanism of the soybean granular materials were analyzed based on the particle displacement field, velocity field, and force chain network. The results showed that the coupled PFC–FLAC method could better describe the macroscopic stress–strain relationship, deformation damage characteristics, and shear strength mechanical indexes of soybean granular materials. With increasing confining pressure (50–200 kPa), the bulging deformation of the specimens changed from uniform to concentrated but uneven. The particle contact number and maximum particle contact stress increased by 19.3 and 48%, respectively. Additionally, variations of the macroscopic properties of the specimens with microscopic parameters were revealed. Under the same conditions, the change in the peak stress of the specimen was proportional to the interparticle friction coefficient. Moreover, the slope of the stress–strain curve increased gradually with an increase in the effective modulus.

Fluid identification and tight oil layer classification for the southwestern Mahu Sag, Junggar Basin using NMR logging-based spectrum decomposition

The intricate distribution of oil and water in tight rocks makes pinpointing oil layers challenging. While conventional identification methods offer potential solutions, their limited accuracy precludes them from being effective in their applications to unconventional reservoirs. This study employed nuclear magnetic resonance (NMR) spectrum decomposition to dissect the NMR T2 spectrum into multiple sub-spectra. Furthermore, it employed laboratory NMR experiments to ascertain the fluid properties of these sub-spectra, aiming to enhance identification accuracy. The findings indicate that fluids of distinct properties overlap in the T2 spectra, with bound water, movable water, bound oil, and movable oil appearing sequentially from the low-value zone to the high-value zone. Consequently, an oil layer classification scheme was proposed, which considers the physical properties of reservoirs, oil-bearing capacity, and the characteristics of both mobility and the oil-water two-phase flow. When applied to tight oil layer identification, the scheme's outcomes align closely with actual test results. A horizontal well, deployed based on these findings, has produced high-yield industrial oil flow, underscoring the precision and dependability of this new approach.

Design and simulation analysis of physical heat dissipation structure for welding robot controller

In order to understand the physical heat dissipation structure of welding robot controllers, the author proposes a research based on the design and simulation analysis of the physical heat dissipation structure of welding robot controllers. The author first analyzed that the design of welding heating system is the key to the research of welding robot heating technology, which is divided into the design of induction heating system temperature control circuit and temperature control program. The induction heating system is closely related to power electronics technology, with inverter design and soft switching technology being the focus and difficulty of this chapter. Secondly, using modular design methods, an induction heating system with a frequency of 450KHz and a power of 100 W is designed. This part is connected through an optocoupler and an induction heating system for power regulation and temperature control. Starting from designing the minimum system of a microcontroller, through keyboard input, temperature signal processing, analog-to-digital conversion, and finally to digital tube display output, the design of each module of the temperature control circuit was completed. Finally, in order to verify the effectiveness of the design, actual heat dissipation testing is required. By establishing an appropriate testing environment in the laboratory, the temperature changes and heat dissipation efficiency of the controller under different working conditions can be measured. Based on the actual test results, further adjustments and improvements can be made to the design to meet the heat dissipation needs of the welding robot.

Study on Mechanical Calculation Method of Injection-production String in Changqing Gas Storage

on the basis of previous studies, According to the working conditions of injection and production wells in gas storage,this paper selects the mathematical model of the downhole string suitable for Changqing gas storage under the effects of piston, axial force, expansion, temperature and spiral bending. The mechanical analysis and calculation of injection-production string under simulated working condition and actual working condition are carried out by using corresponding mechanical analysis software, and the parameters such as the axial load, triaxial Factor of safety, minimum absolute triaxial Factor of safety, string elongation, string shortening are given, according to the calculation results, the safety strength of injection-production string is checked, and the load safety criterion for production and operation of string is given.Field Test and calculation of injection-production string are carried out. According to the actual test results, the deformation rule of the injection production string under the actual gas injection condition is summarized, and compared with the results calculated by the software, which verifies the accuracy of the calculating software and forms the method of the strength check of the injection and production string. It can provide effective evaluation means for the safe operation of injection and production string in gas storage. The safety failure of the injection and production pipe string is reduced, the safety and efficient operation of the gas storage is ensured.

Seismic risk-based optimization of tension-only shape-memory alloy device for steel moment-resisting frames

This study introduces the seismic risk-based design of SMA devices for steel moment-resisting frame buildings. The investigation begins with the numerical representation of the device which includes SMA wires exhibiting super-elastic stress–strain response, along with steel components. The model is then compared against an actual test result. Accordingly, several four-story steel-frame buildings are numerically characterized, all designed to withstand similar seismic loads. This includes a control frame building (Bare-SMF), a frame building with SMA devices using a traditional design approach (SMA-D), and a frame with buckling restrained braces (BRB-D) for comparison. As the traditional design method relies on the first modal shape and static loads, the pushover analysis results for all structures possessed similar amount of strength and deformation capacity. However, the nonlinear time history analysis revealed inconsistencies in the responses of the retrofitted buildings (SMA-D and BRB-D) when compared to Bare-SMF. To address this issue, a seismic risk-based design approach that combines nonlinear time history analysis on a steel moment-resisting frame and the particle swarm optimization algorithm is employed. By using this approach, the SMA brace quantities were determined such that the cost of SMA devices can be minimized while the life-cycle probability of collapse and demolition is smaller than that of Bare-SMF. As a result of the risk-based design approach, three brace quantities are determined according to a decision maker’s attitude against the seismic risk. As a result, the cost of SMA devices could be reduced by more than 40% while maintaining a significant reduction in the life-cycle probability of collapse and demolition.

A Numerical Gear Rolling Test Method for Face-Hobbed Hypoid Gears

A numerical gear rolling test (NGRT) method for actual tooth surfaces was proposed. The non-uniform rational B-spline (NURBS) fitting method was adapted to reconstruct the actual tooth surface, and the instant meshing point as well as the transmission error of two meshing gears were solved. The instant contact ellipse boundary of each meshing point can be accurately searched, and then the contact pattern formed by a series of contact ellipses on the actual tooth surface can be obtained. Finally, the rolling test experiment for a pair of hypoid gears was conducted to verify the feasibility of the proposed method. The result shows that the contact pattern obtained is consistent with the actual rolling test result, the relative errors of the transmission error amplitudes were only 4.5% and 5.3% for the drive and coast sides, respectively, and the contact ellipse of the actual tooth surface is not necessarily a standard ellipse and the instant contact path is not necessarily a straight line. This NGRT method helps to reduce equipment and time costs in closed-loop gear manufacturing, which is of great significance for mass production.