bluuebunny/crossref_metadata_2025 huggingface dataset:
An adjustable envelope based EMD method for rolling bearing fault diagnosis
Authors: Hu Y F , Li Q
Published: February 2021

Empirical mode decomposition (EMD) can decompose complex non-stationary signals into the sum of several intrinsic mode functions (IMF), and it is widely used in fault diagnosis of mechanical devices. In order to solve the mode mixing problem and enhance the fault feature extraction ability, an adjustable envelope based EMD (AE-EMD) method was proposed. Firstly, the envelope fitting method is replaced by rational Hermite interpolation, which can effectively avoid the outstanding over and undershoot problem in the conventional fitting curve. Secondly, the optimal parameter in the AE-EMD is searched by grey wolf optimizer (GWO) using the maximum Kurtosis index as the objective function. Then, the AE-EMD method combined with the Hilbert envelope spectrum is employed to extract the fault characteristic frequency. Case study demonstrates that AE-EMD can restrain the mode mixing effectively, and it also has better fault feature extraction ability compared with the conventional EMD. This proposed method has potential significance to the fault diagnosis and condition-based maintenance (CBM) of rolling bearings in the large and complex equipment.
Optimal Design of Multi-Stress Accelerated Degradation Test within Irregular Test Region
Authors: Guo Jinyan , Yang Zhaojun , Chen Chuanhai , Tian Hailong , Luo Wei , Yu Lijuan
Published: February 2021

Motorized spindle is the key functional part of the computer numerical control machine tool and its lifetime determines the reliability level of the machine tool to a great extent. Many efficient plans have been obtained for electronic products but how to design an efficient accelerated degradation test plan for the motorized spindle is still a problem to be solved. In this paper, considering the condition that the loaded stresses of the motorized spindle in practice may not reach their highest levels simultaneously, a novel optimization design method of the accelerated degradation test is proposed within the irregular test region. The orthogonal design theory and the uniform design theory are applied to determine the alternative test plans within the irregular test region for different numbers of stress levels. A numerical example is presented to illustrate the effectiveness of the proposed method. Finally, the sensitivity analysis is conducted to assess the robustness of the optimum plan on parameter variation.
Failure Analysis of Intelligent Door Lock Master Control Chip
Authors: Lin Yang , Jiang Xia , Rong Li , Shiman Xiao , Huasheng Wu , Qi Peng
Published: February 2021

In recent years, smart door locks having password keyboards, fingerprint recognition and communicating function have seen explosive growth. A large number of enterprises engaged in the manufacture of the intelligent door locks, followed by the associated after-sales problems, and the product without power, no reaction phenomenon caused by the failure of master control chip is relatively common, which greatly affects the user experience. In this paper, a mainstream smart door lock products on the market as the research object, a series of failure analysis and root cause search were executed to find the reasons of failure. The research shows that the main reason for the non-power supply and non-response of the intelligent door lock after sale is the fault of the main control chip. The main control chip fails due to the lack of electrostatic protection, which is directly related to the improper production and assembly process.
Reliability Assessment of Machine Tools Considering Multi-effects of Working Conditions
Authors: Hu Wei , Yang Zhaojun , Chen Chuanhai , Wu Yue , Xie Qunya , Zhu Xiaocui
Published: February 2021

Undertaking varying working conditions is common for a machine tool. One single reliability model for determining a single effect is not suitable for the reliability evaluation of machine tools due to the multi-effect of working conditions on the reliability of machine tools. This paper proposes a generalized model using hazard functions and Weibull distribution to assess the reliability of machine tools under different effects of working conditions. This model considers three effects, including the proportional hazard, time, and additive hazard effects. The distribution of time effect is discussed. Furthermore, a secure parameter estimation method is presented to calculate the proposed reliability model. A case study based on field data is presented. The proposed model is compared with classical reliability models. The result shows that the proposed model has better goodness of fit for the realistic cumulative distribution of machine tools.
A short review of reliability-based design optimization
Authors: Dawei ZHU , Jinyu ZHOU , Chunqiu LIU , Zhiling WANG
Published: February 2021

Reliability-based design optimization (RBDO) has become an important branch of reliability engineering after decades of development. In recent years, reliability optimization design methods considering uncertain factors have emerged in an endless stream. This article summarizes the research status and basic principles of RBDO problems. According to the different RBDO methods, the mathematical models of the double-loop method, single-loop method, and decoupling method and their respective advantages and disadvantages are detailed from the perspective of the optimization process. It also focuses on the analysis of several kinds of RBDO bottleneck problems, and discusses the existing related methods and possible solutions.
Damage Behavior of 30CrMnSiA Steel under Coupling action of Marine Atmospheric Environment and Tensile-compressive Load
Authors: Luo L Z , Zhou K , Li X F , Fu Z X , Teng J P
Published: February 2021

The coupling test of marine atmospheric environment and tensile-compressive load for 30CrMnSiA steel was carried out with the coupling test equipment of marine atmospheric environment and tension, compression and bending load. The damage behavior of 30CrMnSiA steel on the coupling action of marine atmospheric environment and tensile-compressive fatigue load was discussed. The metallographic results showed that the damage behavior characteristics of static test and coupling test were consistent. The decrease of tensile strength, proof strength plastic extension and percentage elongation after fracture of 30CrMnSiA steel were accelerated by the coupling action of marine atmospheric corrosion and tensile-compressive fatigue load. And the accelerated ratio of the coupling test was more than 10 times that of the static exposure test. The fracture morphology results showed that the fracture of the coupling test was corrosion fatigue fracture, and the cracks of 30CrMnSiA steel in the coupling test extended from the fatigue source to the core, forming directional corrosion fatigue damage.
Research on Health Management Technology and Application of Lifting Machinery
Authors: Liu Guansi , Ding Keqin , Jin Hui , Chen Li
Published: February 2021

Lifting machinery is a key facility for the development of modern industry. It’s not noly an important support for the construction of major national projects but also one of the core competitiveness of my country’s equipment manufacturing industry. With the development of large-scale, high-parameterization and intelligentization of lifting appliances, technologies such as safety monitoring and health monitoring have been gradually applied to industrial fields such as ports and metallurgy. In order to further develop the data-driven health management technology and engineering application of cranes, on the basis of elaborating the health management needs of cranes, the current status and development trends at home and abroad, we explored and proposed a technical framework for health management of cranes, and analyzed the lifting Key technologies such as machinery safety monitoring, health monitoring, health status diagnosis, failure trend prediction, and predictive maintenance decisions. Finally combined with a 200t casting crane in a steel plant, carried out safety monitoring and data-driven diagnosis, prediction and system visualization management. The results show that: the hoisting machinery health management system can monitor and monitor in real time and carry out early warning and forecasting to avoid the occurrence of unexpected accidents; based on predictive maintenance decisions, it helps enterprises to reasonably arrange maintenance cycles and maintenance methods to reduce the maintenance cost of the enterprise; reduce hoisting machinery downtime Time to enhance the effective value of assets; and enhance the level of enterprise information management.
Ply Parameters Optimization and Strength Reliability Analysis of Wind Turbine Blade
Authors: Yu Zelin , Sun Pengwen
Published: February 2021

As the critical component of capturing wind energy, the performance and reliability of blade are directly related to the safe, stable operation and service life of wind turbines. The performance of the blade is mainly determined by the ply parameters, so it has important valueto study the optimization method of ply parameters and the analysis method of strength reliability of wind turbine blade.In this paper, the load of a 1.5MW wind turbine bladeunder the DLC1.5g-2 working condition is calculated and its finite element model is established. Combined with engineering practice, the investigation range of ply parameters is determined, the test scheme is designed by using the mixed level uniform experiment method, and the blade strength is analyzed. Based on the polynomial regression analysis method and simulation results, the quadratic mathematical model between the ply parameters and the Tsai-Wu failure factors is established, and the range of ply parameters is optimized by mean value analysis method and interaction analysis method. On this basis, the ply parameters are regarded as random variables, and the structural performance function of blade failure is constructed. The reliability of the blade is predicted by the first-order second-moment method. The results show that the blade is reliable in the range of optimized ply parameters. The work provides the method and technical support for the laminate structure design and optimization of wind turbine blade.
Analysis of Low Temperature Compression Characteristics of Rubber Seal Strip of Shelter based on ABAQUS
Authors: Huang P , Wang Y S , Li Y , Tao J Y
Published: February 2021

The extreme low temperature of the alpine region is easy to have a bad effect on the sealing performance of the rubber seal strip of the shelter. In this paper, ABAQUS software is used to simulate and analyse the compression characteristics of the seal strip of the shelter at 23°C and -55°C, the Von Mises stress and the surface contact stress at two different temperatures are obtained. The result shows that the compression performance of rubber seal strip is sensitive to the extreme low temperature, and it is prone to low-temperature failure. The simulation results in this paper can provide an important reference for the subsequent low-temperature environmental test, so as to more comprehensively analyse the low-temperature failure mechanism of the rubber seal strip of the shelter in the alpine region.
Big Data Fast Analysis Method of Random Stress Spectrum for Crane Equipment
Authors: Ding Ke , Chen Li , Liu Guansi
Published: February 2021

With the increase of service time, the random stress spectrum of crane equipment causes cumulative damage. Cumulative damage induced crack initiation is one of the important failure modes of crane equipment. Through the rapid analysis of the random stress spectrum obtained in real time by the structural health monitoring system of lifting equipment, the cumulative damage of the structure can be analyzed and the remaining life of the structure can be predicted. In this paper, based on the traditional rain flow counting method, the big data fast analysis method of random stress spectrum is studied by adopting stack data structure. The program of fast rain flow counting method based on stack structure with two parameters is compiled. The fast rain flow counting method based on stack structure is used to analyze and calculate the big data of stress monitoring collected by the structural health monitoring system of metallurgical crane, and the stress amplitude-mean-frequency matrix of the hot spot area of fatigue damage of the main girder is obtained, which lays an important foundation for the health status diagnosis of metallurgical crane equipment.
A Deep Belief Network and Dempster-Shafer Theory Multiclassifier for Reliability of Wind Turbine System
Authors: Yu Bin
Published: February 2021

Object. Reliability of wind turbine system could be made by predicting the status of power system in case it could remind engineers to fix in advance. There are multiple variables associate with system. An approach for classification according to these variables needed. Method. I proposed a deep belief network and Dempster-Shafer Theory (DBN-DS) by multiclassifier for whether wind turbine system needed to fix. DS would make a correct decision delete from DBN when model outputted incorrect result. And diagnose the wind turbine system to make a correct decision. Result. The new method was validated on wind turbine system data in 42-day intervals. The accuracy of SVM, KNN, MLP, DBN and DBN-DS were 95.1%, 96.1%, 91.2%, 97.0% and 97.5% respectively. Conclusion. This DBN-DS was more efficient that KNN, MLP, SVM and DBN. The performance was high because of binary Restricted Boltzmann Machines. The proposed method may be effective in decision support for diagnosing the wind turbine system.
Optimization of spline bearing capacity considering the influence of assembly sequence
Authors: Zhao Q Y , Yu T X , Song B F
Published: February 2021

Splines have been widely using in aerospace and other fields. Their reliability has important impact on the capability of mechanical equipment. When a slot on the internal spline is combined with different teeth on the external spline due to machining errors,, different tooth clearances are generated. Therefore, when the spline is assembled in different sequences, the loads on the spline teeth will be different, which can affect the bearing capacity of the spline. However, in the actual assembly process of the spline, this effect has not been considered. To overcome the issue as listed above, a method for optimizing spline assembly sequence is proposed. First of all, the calculation method of the tooth clearances depended on the spline assembly sequence is established. Then, a spline load distribution model is proposed, and the spline assembly sequence is optimized by the maximum clearance method. Compared with the traditional random assembly method, the results show that the mean value of the maximum nominal tangential force of the spline is reduced by 25%. The obtained results can be used to guide the high reliability design of the spline.
Research on Bearing Life Prediction Method Based on EMD and Gray Model
Authors: Hailong Ma , Zhen Li
Published: February 2021

In order to predict the residual life of bearing based on practical signals, the Empirical Mode Decomposition (EMD) is proposed and it is used to decompose the signal and filter out the invalid frequency components in the signal. The root means square (RMS) values of the pre-processed life cycle data samples were calculated. It is used to describe the health status of bearings and form a list degradation characteristic quantity. Then the list is used to train the Grey Model. The characteristic quantity trend is estimated by the trained Grey Model. It is verified by testbed and engineering practice. The results show that this method can predict bearing life effectively and with high precision.
Investigation of The Reliability and Sensitivity of the Wear Resistance of Ball Screws
Authors: Zhou Chang-Guang , Xi Jing-Yao , Chen Bin-Bin , Feng Hu-Tian
Published: February 2021

Based on the traditional Archard wear theory, a novel wear model of ball screws was established by considering the actual contact condition between the ball and the raceway. According to the stress strength interference theory and the improved first-order second-moment method, the model of the reliability and sensitivity of the wear resistance of ball screws was proposed. The numerical example of both the reliability and sensitivity of a typical miniature ball screw (1004) in a small satellite was presented. The unit sensitivity was defined and proposed to better indicate the influence of different parameters on the wear resistance of ball screws, based on which the 1004 ball screw was redesigned and the wear resistance reliability of the ball screw was improved by 21%.
Research on sampling schemes of Weibull distribution product life test
Authors: Li Zhewen , Shen Guixiang , Zhang Yingzhi , Mu Liming , Zheng Jun
Published: February 2021

According to Weibull distribution timing truncation test, considering that it is difficult to have a strictly defined complete failure samples in engineering practice, so the life sampling schemes of censored failure samples are discussed. Here, we have considered random right censored samples with different censored ratios. Compared with other sampling studies, this paper is not limited to explore more sampling theories, but uses SPSS software to give the specific operation processes of three sampling schemes: simple random sampling, two-stage sampling and Bayes sampling considering the minimum total cost, as well as the discussion on the verification analysis of the sampling accuracy. In order to simplify the estimation of Weibull distribution parameters, the estimated parameters are obtained by the probability plot analysis of Minitab software, thus the error between the sample’s MTBF (Mean Time Between Failure) and the overall MTBF is calculated. The sensitivity of Weibull distribution parameters is obtained by Minitab software. Finally, according to the accuracy of the three sampling schemes with different censored ratios, the optimal life sampling decision is obtained, which may provide sampling reference for the decision makers.
Ergonomics Optimization of Heavy Commercial Vehicle
Authors: Zhang S Y , Pang R Y , Liu C
Published: February 2021

Optimize the cab seat height of the heavy commercial vehicle and the maneuverability of the shift lever. Method: The mathematical model of human sitting posture and upper limb operation were established. The Chinese human body size was corrected by the combination of height growth rate and height linear ratio. Under the constraint of sitting posture, the H-point fitline model of the 5th, 50th and 95th percentile male drivers in China was obtained, and the optimal H-point range and SgRP point height were determined. The problem of high seat height has been optimized. At the same time, a operating lever layout position model is established; The actual measurement was made in the Class A vehicle, and the shift lever arrangement position was redefined. Conclusion: The height adaptability of the seat is improved; the operating comfort of the shift lever is improved; the visible area of the instrument panel becomes larger, and the 10th percentile male driver in China has a larger blind spot.
Evaluation and Optimization Strategies of Environmental Protection Performance for Passenger Seats of EMU
Authors: Jia Xu , Zhan Xue , Zhou Xinhong , Chen Chuanhai , Jin Tongtong
Published: February 2021

Passenger seats of Electric multiple-unit (EMU) influence environmental performance. Formaldehyde and other volatile organic compounds in the nonmetallic material of the seat is volatized. Toxic gas is produced by seat material combustion. This study chooses a typical passenger seat and proposes optimization strategies based on the experiment. First, the source of seat formaldehyde and volatile organic compounds is determined through a test. Four optimization strategies, including foaming pretreatment, foaming formula improvement, binder optimization, and bioenzyme spraying, are proposed. Second, the source of toxic gases in the seat is determined through a combustion test on the seat and its nonmetallic materials. Moreover, the optimization strategy for controlling the material of seat fabric is formulated.
Research on the Plan of Plane Line Replaceable Units Based on FSMC Model
Authors: Jiang Zi-han , Wang Zhuo-jian , Li Zhe , Li Yuan , Li Hao
Published: February 2021

The line replaceable unit (LRU) is a direct carrier of the fighter’s field replacement and maintenance strategy. It is reasonably and accurately divided into modules, which can quickly locate the fault location, reduce maintenance support time, and improve the efficiency of maintenance support Improve combat effectiveness. Aiming at the problem of the LRU division method in the aircraft design stage, this paper proposes an FSMC aircraft LRU division method based on function-structure-maintainability-coupling, comprehensively uses fuzzy clustering and other methods to evaluate and analyse the LRU division scheme, and compare different LRU schemes Use availability of the aircraft to perform simulation analysis. The research results show that the established on-site replaceable unit evaluation model can solve the problem of fighter aircraft LRU division schemes in the context of actual combat, and provide model support and empirical reference for further research on aircraft LRU division design research.
Study on Risk Assessment Method of Flight Operation Environment with SVR
Authors: Zheli Cai , Zixuan Wu , Weizhen Luo , linlin Li , Kaiye Gao
Published: February 2021

Flight operation control still can be improved in some aspects. For example, solve the problems of risk-related factors and complicated assessment methods in flight operation, reduce the potential risk caused by the difference of subjective judgment of personnel, and improve the airlines’ ability to control flight operating risks. In order to achieve these improvement, this study proposes an environmental risk assessment method for flight operation control based on support vector regression machine. The method includes the following steps: (1) firstly, the flight phases are divided; (2) secondly, the main environmental factors of each phase are determined and the data normalization rules are set according to business knowledge; (3) lastly, the model is trained with historical flight data from an airline company, to assess the environmental risk in take-off and landing phase during flight operation. The experiment results prove the validation and efficiency of the model which has been applied to flight operation risk assessment in practice.
Field Test of Online Leakage Noise Monitoring for Pressure Water Pipeline
Authors: Lin Tianxiang , Ye Guanlin , Feng Shaokong , Zhu Xinmin
Published: February 2021

In order to study the applicability of leakage noise (vibration) monitoring method, an online leakage monitoring test was carried out on a large pipeline. In the test, the emptying valve on the pipeline was used to simulate the leakage point, and the vibration signal caused by leakage was monitored by the hydrophone and other floating cables installed in the pipeline. By controlling the opening degree of the emptying valve, the different degrees of leakage between 10L/s and 105L/s was simulated, and the monitoring data for 10 minutes were recorded from 5 minutes before valve opening. The analysis results of the test data showed that although the environmental background of the monitoring was very disturbing, the leakage could be detected when the leakage degree was more than 0.05% of the pipeline flow. The monitoring results also showed that the noise caused by the leakage of large buried water pipelines was mainly transmitted in the form of vibration along the soil around the pipeline.
Research on reliability of cabin structure of a launch vehicle under road impact
Authors: Wang Teng , Han Rui , Qi Kexin , Zhang Yuxin , Gong Qi
Published: February 2021

A certain type of launch vehicle cabin not only bears the weight of the launching device, but also withstands the transient impact transmitted by the chassis, which is caused by the rough road. As an intermediate link, its structure should have sufficient strength and reliability. The structural strength of this type of cabin frame is simulated and calculated by using the finite element analysis method. The impact conditions are identified to ensure that the simulation input shock conditions can cover the actual impact situation through driving experiment. The simulation results show that the structure is reliable and the structural performance meets the requirements.
A remaining useful life prediction method for complex systems based on multi-index fusion with MC and HSMM
Authors: Zhang D F , Ran Y , Zhang G B , Jin C X , Li S L
Published: February 2021

Remaining useful life (RUL) estimation is the core and basic of system Prognostic and Health Management (PHM) and also a challenging for complex systems. It is necessary to use performance indicators that are closely related to system status for analysis, due to the Multi-indicator different characterization change of system degradation, different detectability and the degree of correlation caused by system coupling. As the system status degradation shows certain scientific laws in macro, their would be certain random relationship between the system status degradation and RUL. To address these problems, the concept of imperfect condition monitoring followed by the concept of key performance indicators in order to reduce the blindness of analysis object selection. The condition degradation probability index is proposed to represent the status degradation degree of the system, whose future trend is fitted by Markov matrix obtained by the improved algorithm as a implementation of mapping condition monitoring data to CDPI. Finally, the system RUL estimation method at time t combined the hidden semi-Markov model with improved forward variable is given to realize the mapping CDPI to RUL. Experiments are carried out to validate the key concepts of the developed methods, and results suggest the effectiveness.
Optimization design of shaped charge based on improved genetic algorithm
Authors: Tang Cheng , Xue Biao , Wang Li-Xia
Published: February 2021

In order to improve the design efficiency of shaped charge, reduce the number of tests and shorten the development period, an improved genetic algorithm is introduced in the design process of shaped charge. Compared with the design scheme in the iterative process of traditional optimization design, the improved genetic algorithm introduces the multi parent crossover operator, randomly selects N individuals, forms the subspace, and hybridizes N individuals in the subspace to form a new individual. Because of the number of individuals involved in the hybridization, it is easier to calculate the optimal solution, and has stronger optimization ability. Taking a shaped charge as an example, the structural parameters of shaped charge are optimized by the improved genetic algorithm. After the optimization, it is verified by the vertical static armor breaking test of shaped charge, The results show that the optimization design method of shaped charge structure based on the improved genetic algorithm is reasonable and feasible, and the operational and technical indexes of the optimization scheme meet the requirements.
Fleet Maintenance Strategy Planning with Time Windows Integrated with Multi-Agent and Wolf Pack Reinforcement Learning
Authors: Xinrui Ma , Haixu Li , Zheng Zhou , Bo Chen
Published: February 2021

Selective maintenance is a widely used strategy to identify and perform the maintenance actions necessary for fleet mission success. Aiming at the problem of maintenance strategy planning with time windows (MSPTW) which is common in short-term operation plan, a fleet maintenance strategy planning approach based on multi-agent and reinforcement learning is studied in this paper. Based on the four kinds of foraging behaviors including migration, summon and attack in traditional Wolf Pack Algorithm (WPA), the intelligent behavior is redefined, and a new wolf pack algorithm for solving the MSPTW is designed. In order to seek the best path planning, a mathematical model with the aim of minimizing the total cost (fixed cost, transportation cost, waiting cost and penalty cost) is constructed utilizing the fitness and penalty function.
Quantitative damage imaging in plates based on SH0 mode tomographic approach
Authors: Ahmad Mubarak , Liu Zenghua , Basit Abdul , Bin Wu , He Cunfu
Published: February 2021

Exploring the non-dispersive property, the fundamental shear horizontal mode SH0 can be widely used in the detection and monitoring of defects in plate like structures. To combine an approach of ultrasonic guided waves and a tomographic technique by adapting a reconstruction algorithm for the probabilistic inspection of damage (RAPID) using a double-turn coil omnidirectional shear horizontal wave magnetostrictive patch transducer (OSH-MPT) with three different kinds of array arrangements is presented here for imaging. SH0 can propagate in a composite material through bonding double-turn coil OSH-MPT. To get the information about a damage, RAPID can be utilized based on direct wave of SH0 mode. It is advantageous to monitor a composite plate where the velocity of direct waves depends on the propagation direction. In this paper, a surface simulated defect, using a small cylinder, in a composite material is quantitatively evaluated by using shear horizontal mode tomographic approach. Using modified approaches, to eliminate the effect of uneven probability distribution of the array (UPDA) in RAPID, imaging is obtained. Three different array setups of transducers have been tested to monitor the influence on the images. It has been presented that the image generated by the proposed approach with the optimal transducer array and shape factor, β, calculation method has great influence on the real defect shape. To improve the imaging results threshold is selected based on the receiver operating characteristic (ROC) curve. The proposed approach can be used to detect, locate and image the surface defects in plate like structures.
Ergonomic Reliability Assessment for Operation Process of Medical Device Interface Design Based on OAT and CREAM
Authors: Liu Xin , Liu Zheng , Xie Ziyu , Chen Pengqing
Published: February 2021

This paper uses OAT (Operator Action Tree) and CREAM (Cognitive Reliability and Error Analysis Method) to analyze the interface design of medical equipment according to human error, discuss how to accurately describe the operator’s failure behavior, determine the development sequence of important human factors events and the feasible calculation method according to the system response, establish a complete ergonomic reliability assessment modeling by example demonstrations. This study can better describe the relationship between software interface reliability and ergonomic reliability. In addition, this paper makes improvement on the cognitive reliability and error analysis. In this paper, based on the basic concept and core idea of CREAM method, MADM (Multi-attribute Decision-making) is used to improve the weighting factor value of CPCs (Common Performance Conditions) provided by CREAM method. After the OAT model building based on the operation process of medical device interface design, the adjusted failure probability prediction analysis method is applied to obtain the failure probability of OAT basic events, which makes CREAM method more suitable for the medical device accident analysis and risk assessment in complex environment.
Prediction of fatigue crack growth life based on a new fusion model
Authors: Chen G L , Cheng J M , Jin H
Published: February 2021

A novel method based on filtering algorithm is proposed to predict fatigue crack growth life of metal structures under repeated loading. Three parts, including improvement of the two-parameter exponential formula, the improved two-parameter exponential formula parameter estimation and residual life prediction, are involved in the proposed method. The improved two-parameter exponential formula is discretized to establish a parameter estimation physical model of state space. Then, the uncertainty parameters α, β and crack length a in the state space physical model are determined according to the crack propagation data obtained by monitoring/detection and the filtering algorithm, to reduce the influence of uncertain factors such as environment and operation conditions on the prediction of fatigue crack growth life of in-service metal structures. Finally, the discretized improved two- parameter exponential formula are employed to predict the growth life of fatigue crack. An example is presented to test the validity of the proposed method. The result demonstrates that the proposed method is available to well deal with the uncertainty of fatigue parameters in the process of fatigue crack growth with the improved two-parameter exponential formula, and the particle filter algorithm can accurately predict the growth residual life of fatigue short crack.
Storage Life Evaluation and Aging Mechanism Analysis of Epoxy Resin Potting Materials
Authors: Zhao Q C , Li C , She Z X , Li Q , Sun Y M , Zhao F C , He J X
Published: February 2021

The tensile shear samples of potting epoxy resin materials were accelerated under 90°C, 100°C and 110°C temperature conditions. The tensile shear strength was used as the aging characteristic index during the aging test. After normalizing the data in the descending section, the storage life evaluation and analysis is performed based on the Arrhenius model. The retention rate of tensile shear strength is 50% as the critical failure condition. The storage life at 25°C is predicted to be 21.7 years. During the thermal oxygen aging process, the epoxy bonding material’s adhesive interface first undergoes post-curing reaction under the action of heat, and then undergoes oxidative degradation under the action of thermal oxygen. The sample interface is more susceptible to oxidative degradation than the interior. In the oxidative degradation stage, the part of the epoxy resin connected to the hydroxyl group is oxidized to the aldehyde group, and the methylene group connected to the N in the curing agent is oxidized to C=O, forming C=O in the amide, and the molecular backbone is broken And produce low molecular weight polymers.
Research on Prediction of Middle-frequency Ship Cabin Noise Based on Improved Statistical Energy Method
Authors: Ming Zhi-mao , Zhang Bo , Zhao Ke-lun , Xia Xue-bao
Published: February 2021

The ship vibration and noise calculation in middle-frequency region has always been a difficult point in engineering. The statistical energy method assumes that the coupling between structures is weakly coupled, which in turn limits its application in the calculation of ship’s middle frequency vibration and noise. In order to improve the vibration and noise calculation accuracy of statistical energy method in middle-frequency region, the equivalent coupling loss factors (ECLFs) between ship sub-structures were calculated based on the energy flow method (EFM), and the ECLFs were substituted into the statistics energy balance equation. The ship’s middle frequency cabin noise was calculated by the improved statistical energy method and compared with the measured values. The results show that the predicted values of the cabin noise are in good agreement with the measured values, which extends the application of the statistical energy method in the ship’s middle frequency cabin noise prediction.
A Framework to Integrate Prognostics and Health Management into Performance-Based Logistics
Authors: Zhu Xi , Hu Qiwei , Bai Yongsheng
Published: February 2021

Performance-based logistics (PBL) has achieved widespread success as a new logistics strategy, but not all PBL projects have been successful. This article summarizes the reasons for the failure of PBL and the advantages of Prognostics and Health Management (PHM), furthermore, analyses the necessity of integrating PHM into PBL. The innovation of this article lies in the establishment of a process framework to integrate PHM into PBL, and a specific evaluation method is given to evaluate the effect of PBL after using PHM, which make PBL gain more benefits or turn into a victory.
Response of the interface between the ball and the raceway of rolling bearing under starved lubrication
Authors: Bian Z , Song C , Meng L H , Zhou Q H
Published: February 2021

The interface state of the rolling bearing contact pair often directly determined the service performance of the bearing for the aviation equipment, the ball-raceway contact interface would develop from the homogeneous lubrication to starved lubrication when used for a while, the plasto-elastohydrodanamic lubrication analysis model was used to describe the ball-raceway contact interface lubrication condition. The influence of the normal pressure, the rolling speed and the service time to the ball-raceway contact interface wear behavior was investigated by the gearbox and rolling bearing on condition of starved lubrication, it was found that the centre region of the raceway generated concave residual deformation, while the convex residual deformation occurred at the lubrication region’s edge and its surrounding region, the groove and scratch marks were emerged on the contact surface of ball and raceway, which were accelerated produced by the normal load and rolling speed of rolling bearing, besides that the ball-raceway contact interface assumed adhesive wear behavior and the wear width became gradually larger over the time.
Improving the risk Assessment of FMEA in Foamed Asphalt preparation Plant based on Intuitionistic Fuzzy
Authors: Luo Zhun , Cheng Hai-Ying
Published: February 2021

Taking foamed bitumen preparation equipment as the research object, aiming at the shortcomings and shortcomings of traditional failure mode and effect analysis (FMEA) method, this paper proposes a method to improve FMEA based on intuitionistic fuzzy. This method converts N expert language variables into corresponding intuitionistic fuzzy numbers to represent the failure mode and risk factor weight evaluation information. Combined with intuitionistic fuzzy weighted geometric operators and improved Hamming distance, the traditional FMEA method is improved to determine the bubble Risk order of failure mode of asphalt preparation plant. The results show that: asphalt pipe blockage, asphalt tank cracking and tapered rod end fracture are the three highest failure modes for foamed asphalt preparation equipment.
Precise reliability analysis base on static pose error of 6 degree of freedom serial robot
Authors: Hu Ming , Wu Mei , Zhou Xuwu , Yang Jing , Wang Bingxu , Li Jian
Published: February 2021

Taking the JLRB20 industrial robot as the object, the improved D-H modelling method is used to establish the positioning error model of the robot, the reliability of the static pose error of the robot is analysed, and the reliability evaluation index of the static pose error of the robot is established. By analysing the precise reliability base on static pose error of the robot, it is determined that the joint rotation angle has the greatest influence on the accuracy of the static attitude error of the robot end, which provides a basis for improving the reliability of the static pose error of the robot.
A Monte Carlo Expectation Maximization Algorithm for Statistical Inference of Weibull Process with Left Censored Data
Authors: Hu Jun-Ming , Huang Hong-Zhong
Published: February 2021

The Weibull process plays an important role in the failure analysis of repairable systems. In practice, there exists a situation that the data collected are incomplete. Some of the failure data are missing due to various reasons. Statistical inferences of a Weibull process with incomplete data using Monte Carlo expectation maximization algorithm is proposed. The estimation procedures are derived. A case study is performed to illustrate and compare the performances of this algorithm. It is observed that this method is effective and can simplify the estimation.
Vibration indicator-based graph convolutional network for semi-supervised bearing fault diagnosis
Authors: Wang S H , Xing S B , Lei Y G , Lu N , Li N P
Published: February 2021

Since fault diagnosis has entered the big data era, deep learning has been more and more widely studied to diagnose faults of rolling element bearings. Generally, existing methods require labeled data for training before they can be used to recognize faults. However, in real scenarios, massive data are usually unlabeled data rather than labeled ones, because labeling data is always a tough issue and consumes much human labor. In order to fully take advantage of the massive unlabeled data, this paper proposes a vibration indicator-based graph convolutional neural network (VI-GCN) for fault diagnosis. The VI-GCN is applied to a benchmark dataset of bearing faults. Experimental results indicate that it is promising for bearing fault diagnosis when there are few labeled data.
Reliability analysis of ballast cleaning device based on fuzzy FTA and FMEA
Authors: Wang J , Cui Z X , Li S D , Yang T , Cheng H Y , Na R S
Published: February 2021

On the basis of analyzing the fault tree diagram of the ballast cleaning device of railway switch ballast cleaning machine, the fuzzy fault tree of the ballast cleaning device is established by blurring the probability of bottom event. Introducing grey fuzzy analysis correlation method, using the normal fuzzy comprehensive evaluation method of combining the theory and experts, quantitative and qualitative analysis, the fuzzy fault tree based on fault tree’s minimum cut sets, the fuzzy importance degree of the basic events, calculation of each failure mode and the top event correlation, figure out the influence of the top event to occur to the larger events and failure mode. Then FMEA method is used to analyze the key parts of ballast cleaning device such as gripper and sprocket, and corresponding compensation measures are put forward according to the specific failure reasons.
Research on Quality Surveillance in Digital Design Environment
Authors: Duan Bo , Yuan Shuo
Published: February 2021

This paper studies the definition of product quality surveillance in a digital design environment, analyzes the characteristics and new requirements of quality surveillance, and proposes the main contents of quality surveillance in these aspects, including digital design process in the aspects of quality information management, quality problem handling, digital prototype management, technical status management, data exchange and conversion. Finally,we put forward the methods of quality surveillance in digital design process.
Roughness and mechanical properties of electron-beam surface modified and TiN/TiO2-coated Ti6Al4V alloy
Authors: Nikolova M P , Ormanova M , Tonev D , Petrov P
Published: February 2021

In this study, we used PVD deposition of TiN/TiO2 coatings on polished and electron-beam-treated Ti6Al4V alloy to explore the changes in the surface roughness and mechanical properties of the coated systems. After the electron-beam treatment (EBT), the average surface hardness and roughness (R

a
) increased from 323±5.62 HV0.2 and 0.14±0.004 μm up to 387.5±9.33 HV0.2 and 1.58±0.05 μm, respectively. After coating with 3.7-μm thick TiN/TiO2, the average S

a
roughness and nanohardness of the film on the polished substrate reached 0.87±0.1 μm and 13.05±2.07 GPa while that on the EBT was equal to 1.57±0.2 μm and 9.02±2.15 GPa, respectively. However, the comparison of the coefficient of friction (COF) evolution of the substrates and the coated specimens indicated a COF decrease by about 0.18±0.03 for the coated EBT alloy as compared with the polished and EBT substrates, whose average COF were 0.45±0.04 and 0.38±0.06, respectively. A high average COF (0.68±0.16) was registered for the coated as-received alloy because of the gradual and complete wearing off of the film during the test. These results indicate that the combination of initial EBT of the Ti6Al4V alloy with PVD deposition of a TiN/TiO2 coating could substantially improve the roughness and tribological properties of the coated systems.
Surface modification of Co-Cr-Mo alloys by electron-beam treatment
Authors: Valkov S , Parshorov S , Andreeva A , Nikolova M , Petrov P
Published: February 2021

We present a study on the possibility of modifying the structure and properties of Co-Cr-Mo alloys by using the electron-beam surface modification technique. The technological parameters were optimized in order to obtain the highest cooling rate without melting the surface. The samples were characterized in terms of their phase composition and microstructure by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The surface roughness was evaluated by atomic force microscopy (AFM). The corrosion properties were investigated by electrochemical tests. It was found that the treatment process leads to a transition in the phase composition, from ε + γ to a single-phase γ structure. The electron-beam surface modification process causes an increase in the surface roughness and a significant improvement of the corrosion resistance.
Biogenic ferroxides derived from Leptothrix bacteria for applications in electronics, biomedicine and biotechnology
Authors: Angelova R , Slavov L , Blagoev B , Ghelev Ch , Iliev M , Groudeva V , Nedkov I
Published: February 2021

The present work is focused on studying by-products derived from the metabolism of bacteria of the Leptothrix genus, which are among the first described microorganisms associated with the iron cycle in nature. The products of their metabolism are nanostructured biogenic iron oxides in the form of precipitating powders and sheath structures. The sheath structures can be considered as an organic matrix in which inorganic crystallites are discretely dispersed. We used X-ray diffraction, magnetic measurements, light microscopy and scanning electron microscopy to characterize biogenic products formed in a silicon iron glucose peptone medium under laboratory conditions. The studies showed a lack of significant differences between the naturally obtained and the artificially synthesized biogenic sheaths, i.e., an adequate laboratory technological process had been developed. From the point of view of nanoelectronics application, these biogenic by-products are unique because they are biocompatible, have specific electromagnetic properties and are potential candidates for various applications in biomedicine and electronics.
Structural and mechanical properties of Ta-based coatings deposited on polymers for biomedical applications
Authors: Donkov N , Zykova A , Safonov V , Dudin S , Yakovin S , Petrov P , Rabadzhiyska S
Published: February 2021

The polypropylene meshes currently used for hernioplasty induce severe chronic inflammatory reactions over a long-term period of use. These processes lead to scarring and have a negative effect on the connective tissue and the abdominal walls. It is well-known that the biocompatibility of polymer surfaces might be improved by surface modification. We report on the structure and composition of nanostructured Ta, Ta2O5 and TaON coatings deposited on polypropylene in correlation with their mechanical properties. The elemental distribution and chemical composition of the coatings were analyzed by energy dispersive X-ray spectroscopy. The coatings cross-sectional structure and morphology were observed by electron scanning microscopy. Mechanical tests were performed of the polypropylene and of the samples with Ta-based coatings to evaluate the Vickers hardness and the elastic modulus. The coated samples exhibited higher nano-hardness and elasticity values, significantly exceeding the values of untreated polypropylene samples. The Ta-based coatings deposited by magnetron sputtering improve the mechanical characteristics and biocompatibility of the polypropylene materials in view of, e.g., hernia repair.