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The distribution of failures is crucial in reliability engineering, and the applicability of a single distribution is limited. In complex systems, a mixture distribution is more appropriate. This article introduces the 3CAW distribution, which provides a more flexible failure rate function, especially a bathtub-shaped failure rate with a long constant region, which is suitable for more complex systems. This article discusses the use of maximum likelihood estimation to estimate the unknown parameters of the 3CAW distribution, and calculate reliability and failure rate as reliability indicators. The cross-entropy method is used to find the global optimum of the logarithmic likelihood function and compare it with single distributions such as the Weibull distribution. The results show that although the model is complex, it has the highest logarithmic likelihood function value and the highest fitting accuracy. The cross-entropy method reduces the difficulty of parameter estimation, making it worth further promotion in engineering practice.

In order to estimate the mechanical components′ response reliability under interference of dynamic correlative stress-strength, the Copula function and random process theory were introduced to establish dynamic reliability model. Due to the complexity of random integral, the random process degenerates into random variable, and then the reliability at a fixed time was calculated based on the discretization thought. Furthermore, the function fitting optimization method was adopted to make the reliability value continuous. At the same time, according to model complexity and fitting residual, the optimal reliability function fitting method was selected. Finally, the typical verified example indicates the effectiveness and feasibility of this method.

In order to improve the working reliability of the biomimetic robotic fish, put forward a gradient reliability robust optimization design method method which is applied to the biomimetic robotic fish.Taken the bionic killer whale as the research object, based on the flapping wing motion theory, the dynamic load of the bionic killer whale was obtained by using MATLAB.Based on the theory of reliability sensitivity design, robust design theory and the theory of performance degradation, established optimization evaluation function of bionic killer whale, obtained the influence of the bionic killer whale’s design variables to reliability sensitivity gradient.The improved quantum evolutionary algorithm was used to optimize the design, the optimal solution of caudal fin propulsion mechanism was obtained.The results show that the absolute value of sensitivity of the design variables is decreased, the reliability is improved and the structure is more robust. This paper combine the flapping wing movement theory, the reliability sensitivity design theory, the reliability-based robust design theory, the theory of performance degradation and improved quantum evolutionary algorithm were combined, put forward a gradient reliability robust optimization design method method which is applied to the biomimetic robotic fish, it provides theoretical method and data support for the reliability analysis and design of bionic robot fish.

Aiming at the dynamic mechanical system with multiple failure correlation, the copula function is used to describe the correlation of failure modes among units, and a reliability model of dynamic mechanical system with multiple failure correlations is proposed. The reliability problem of complex system is transformed into multiple two-dimensional pair copula functions by using R-Vine copula function. The optimal R-Vine structure is selected by using MST algorithm. The time-varying parameters in the model are described by nonparametric kernel density estimation（KDE）. The common series parallel system（hybrid system） in mechanical system is modeled and analyzed. Finally, the effectiveness of the model is verified by an example of spacecraft open and close shafting.

Guided by the uncertainty theory, this paper considers the complex and variable working conditions of tents and expounds the feasibility of finite element analysis under the condition of uncertainty of both material and working conditions. It then proposes the topology optimization based on reliability. The scheme takes the reliability index as the constraint condition and transforms uncertain parameters into deterministic parameters, and then the variable density algorithm topology optimization is performed. Taking two typical structure frames of military and civil tents as examples, respectively, the stress of the frame under wind load is considered, and the feasibility of the design scheme and algorithm logic is verified. The results of the mechanical simulations show that the scheme not only obtains the ideal results, but also avoids repeated iterative scheme trial calculations, thus significantly reducing the time costs and workload of the R＆D process, thus promising optimal promotion value and applicability in the engineering fields.

In order to accurate reflect the highly non-linear relationship between structural parameter uncertainty of frame and its responses, and promote reliability design level of frame. A multi-objective reliability optimization design method based on GA weighted network is proposed. Firstly, establish the parametric analysis model of the frame and carry out the experimental design. After that, the sample data of frame responses and uncertain parameters are obtained. Secondly, the initial BP neural network between responses and uncertain parameters is established. Furthermore, using mathematical model to express BP neural network. On this basis, four kinds of weight coefficients are introduced. Then the GA method is used to find optimal combination mode of weight coefficients, so as to improve the accuracy of the initial BP neural network model. Moreover, make the internal relationship between frame responses and uncertain parameters more accurate. Finally, taking the multi index failure probability of the frame as the objective function, the optimization model is constructed. And the multi-objective reliability optimization design of frame is carried out. The results show that there is a better uniformity of prediction results between improved model and test sample. The absolute error of maximum stress response is less than 1 MPa of them under standard working condition. The new frame parameter combination which is obtained by this method not only improve the frame comprehensive reliability, but also provides a reference for the adjustment and optimization of its design parameters.

Embedded smart bearing is a kind of structural unit with the characteristics of self sensing, self diagnosis, self-adaptive and self-regulation, which is one of the development directions of high-end bearing at home and abroad. Based on Ioannides-Harris theory, the load distribution of rolling bearing is analyzed. Combined with the finite element simulation model, the influence of outer ring grooving on bearing reliability is analyzed, and the radial grooving structure of outer ring of rolling bearing is determined. According to the theoretical analysis and numerical simulation, the embedded bearing vibration monitoring system is designed by combining the vibration sensor with the bearing body. By using the bearing life testing machine, the bearing life test is carried out and the vibration signals of smart bearings with different structures are collected. The experimental results show that the amplitude of vibration signal of smart bearing is higher than that of traditional bearing pedestal monitoring method, and it can effectively monitor the running state of the bearing; compared with the structure of axial grooving, the service life of the proposed smart bearing is similar to that of the ordinary bearing, which provides a new method for the condition monitoring and fault diagnosis of the rolling bearing.

Fatigue life of filled natural rubbers used in isolators is very dispersive owing to many uncertainties such as loads and temperature. Conventional crack initiation methods and crack propagation methods to determine fatigue life of rubbers are insufficiently to characterize the phenomenon; thus, probabilistic methods are desired in practical engineering. Based on the test data of uniaxial tensile fatigue experiment of rubbers, the cumulative distribution function and probability density function of residual fatigue life corresponding to two typical probability distribution models of three parameters Weibull distribution（3 PWD） and logarithmic normal distribution（LND） were derived and applied to the prediction of residual life reliability, in order to determine the minimum required under different probability distribution model of sample number and working condition number. The results showed that 3 PWD was more suitable to characterize the probability distribution of rubber fatigue life. The minimum values of the number of rubber fatigue test samples and the number of working conditions are distributed between 4 and 6. The log mean should be preferred for subsequent fatigue analysis when determining the median life. The research can provide guidance for the anti-fatigue design and test of rubber vibration isolators.

As a kind of bionic robot fish,bionic killer whale played an important role in ocean development and scientific investigation. Based on the flapping wing movement theory,the bionic killer whale’s mechanism was analyzed,its instantaneous load was simulated by MATLAB. Based on the stress-strength interference theory,the bionic killer’s load reliability state function was established,the reliability index and reliability of bionic killer whale was calculated,combined with the reliability sensitivity analysis theory,the dimensionless sensitivity was obtained,analyzed the influence of the bionic killer whale’s design variables to reliability sensitivity gradient. This paper provides the theoretical basis,accurate data support and an effective numerical calculation method for the design and optimization of the bionic underwater robot with flapping wing theory as the propeller,which has important practical engineering significance.

Fatigue scatter factor is the reliability index of aircraft structure life,which is used to describe the reliability of analysis and test results. When average spectrum is used for durability analysis,the scatter factor is generally set as 4,corresponding to 99. 9% reliability. In the case of using severe spectrum,the scatter factor is between 2 and 4,but the specific value is not clear in aircraft strength specification. By referring to a larger number of relevant research and according to the results of scatter study on component-level fatigue tests,the fatigue scatter factor of aircraft structures under severe spectrum was clarified,which lays a foundation for the application of durability severe spectrum in fatigue design and full-scale test of military aircraft.

Taking single stage double suction centrifugal pump ASP150-355R as the research object,the rotor structure and accessory parts were modeled by Pro/Engineer. Through the static analysis and fatigue life analysis of the rotor structure by the finite element software ANSYS Workbench,the maximum damage location and the minimum number of fatigue life cycles are obtained,which correspond to the results of static analysis and verify the correctness of fatigue analysis. The ANSYS APDL command flow is used to parameterize the modeling of the rotating shaft and generate the probability analysis file. The reliability of the rotating shaft is analyzed by ANSYS PDS module. The result shows that the reliability of the pump shaft under certain confidence is 0. 936 when the confidence is 95%,the reliability of the rotating shaft structure is 0. 936. The pump group is stable under the design condition,and the working performance of the rotor meets the design requirements. The research results have certain reference value for the performance of similar pumps under design conditions.

Considering the dispersion of the material properties and load,the collaborative analysis of the air-cooled turbine blade low-cycle fatigue reliability was done using the distributed collaborative response surface method. The deterministic analysis of the turbine blade was completed by the finite elements software. The total strain amplitude and mean stress response surface was established using the artificial neural network and the material life response surface using the linear hetero-variance regression method. The blade life response surface was established by collaborating with the two response surfaces. The low-cycle fatigue reliability analysis of the blade was completed using the Monte-Carlo method. Comparing with the traditional response surface method,the distributed collaborative response surface method is more accurate.

The reliability of composite laminates is analyzed by universal generating function method. Load,strength parameters universal generating function,complex operators and the corresponding performance structure functions are defined,the resistance of the single layer,resistance sequences and system resistance universal generating function are constructed respectively. The reliability analysis model of laminates is established based on the last ply failure criterion. In the complex operation of universal generating function, K-means clustering and like terms collecting techniques are used to reduce computational costs and improve efficiency. This method is applicable to the reliability assessment of structural systems,in which there are many random variables（ including non-normal random variables）,the performance function is non-linear,and failure correlation between resistance sequences of laminates that contain common failure elements and failure elements within the resistance sequences due to sharing the same random load source is considered. Two examples are given. The reliability value is close to the Monte Carlo simulation results. The new method can provide a new idea for reliability analysis of composite laminates.

In order to realize the rapid reliability evaluation of long-life and high reliability products at a normal stress level, the reliability statistical model of Arrhenius—Weibull was established, by using the Weibull distributions products with the consistent failure mechanism and a log-linear acceleration life test model between characteristic life and stress level. The minimum variance of the product median lifetime estimate at normal stress level as optimum object was considered, the number and quantity of test stress level, samples allocation proporation and censoring time at each stress level are determined as design variables, put forward a reliability optimum scheme of time-censoring constant-stress ALT（CSALT） for weibull distributions. The Fisher Information Matrix is obtained for constructing asymptotic confidence intervals for the model parameters. As the example analysis shows that the reliability optimum scheme of CSALT is effective.

In order to solve the problem of reliability sensitivity analysis of tracked vehicle transmission gears in the presence of different failure modes, the random perturbation theory, the fourth moment method and Edgeworth series are employed to calculate the statistical correlation and reliability index of each performance function of the failure modes, and the reliability of the failure modes of the mechanical component with the arbitrary random distribution parameters. According to the future that only a few potential failure modes existed in the component and the overall fails when a failure mode occurs in parts, the failure of the component is regarded as the failure of a series system. On this basis, the calculating formulas of reliability sensitivity of the mean and variance of random variables are derived with the gradient method. The example illustrates that this method could effectively estimate the reliability sensitivity of mechanical components with multiple failure modes and provide reference for the optimization design of mechanical components.

The fatigue crack growth（FCG） phenomenon always exists in large mechanical structural. Influenced by varied kinds of random factors, the safety evaluation of structure in FCG is under great uncertainty. Based on the reliability theory, this article derived the joint limit state equation of fatigue failure and static strength failure, and the parameters which have great influence on the fatigue crack growth rate（load level, crack initial length and material parameter） were selected by the sensitivity analysis. And then these parameters were regarded as random variables. On this basis, the optimization mathematical model of reliability index was established, and then the reliability index under the multiple failure modes of structure was calculated in every cycle based on the SQP method. A specific computation example was given, and the curve of reliability criterion in multiple failure modes was used to compare that in single failure mode. The results indicated that the reliability analysis based on multiple failure modes was reasonable, and the evaluation of reliability could be obtained in fatigue crack growth process.

A reliability analysis method for complicated mechanical system is proposed which is based on Copula Bayesian network. Since the variables in complicated mechanical system are numerous and correlated to each other,the traditional analysis methods are incapable to solve the problems. However,the Copula Bayesian network takes advantage of both Copula function and Bayesian network,it can takes the correlation of variables into consideration by using Copula function,and makes probability inference of reliability at the same time. The CBN structure was transformed from BN at first,and then local t-Copulas were modeled based on the marginal distributions and correlation coefficient matrix of variables. The reliability of an jack-up gearbox was analyzed by CBN,and the correlated structure of nodes was obtained. The failure probability of gearbox was calculated by CBN,and the result showed that it was more secure and accurate than the traditional BN method.

Roller is an important task of the coal winning machine cutting coal institutions,its structure and motion parameters will directly affect the working efficiency and working reliability of coal winning machine.Based on virtual prototype technology coal winning machine the coupled model is established,through dynamic simulation of coal winning machine equivalent stress values of key parts;Simulation different drum rotating speed,drawing speed,cylinder helix Angle,and the cutting line spacing they cut the shell and the equivalent stress value of planet carrier,the roller structure and motion parameters on reliability of key parts of coal winning machine cutting part influence trend;Combined with neural network technology,with different roller structure and motion parameters of the equivalent stress of key parts of coal winning machine values as the neural network training sample,the helix Angle of optimization design,stress value of key parts in the hour of cylinder helix Angle.The research for the drum more accurate theoretical foundation for the selection of structure and motion parameters,has certain engineering application value.

In order to meet the design requirements of large wind turbine gearbox with high reliability,good dynamic characteristics and high robustness,based on the system dynamic model and considering the correlation among the failure modes,a multi-objective optimization design mathematical model is developed from the perspective of system dynamics,reliability,robustness and volume. An engineering example is present,the simulated annealing particle swarm optimization（ PSO） and interior penalty function method are used to solve the problem. The results show that the optimized design method and optimized design parameters can significantly improve the dynamic characteristics,reliability and robustness,and reduce the volume in the multi-stage transmission system of the load split type wind power increasing box.

Reliability and fuzzy theory was applied to analyze the contact fatigue reliability of cylindrical helical gear. Furthermore, the calculation method has been improved. The reliability for contact fatigue of cylindrical helical gear after working a period of time was obtained used Matlab as a tool for numerical simulation and it has been compared with the results based on general approaches. The result shows that the improved method is more comprehensive consideration than general methods. Moreover, it provides a reference for reliability calculation of the gear.

To improve the problem that the conventional design results of planetary gear transmission could not guarantee all of objectives were the optimal, aiming at the shortcomings that adaptive particle swarm optimization algorithm easily produced infeasible solution and fell into local optimum, an adaptive particle swarm optimization algorithm based on multi-level penalty function with dynamic change penalty coefficient was proposed. The algorithm set the penalty function as a multi-level penalty function and the penalty coefficient could be adjusted with the iterative process. The reliability and others were taken as the constraint conditions, the volume, the contact ratio and the transmission efficiency as the objective functions. Combined with the ideal point method to construct the evaluation function for multi-objective optimization. The results show that the volume is decreased by 41.87%, the contact ratio is increased by 2.643%, and the transmission efficiency is increased by 0.1563%. The improved particle swarm optimization improves the defects of original algorithm, and each objective is reasonably optimized.

A newly-developed precision seeder,model 2BFQ-6,combined multiple field tasks of seeding rapeseed,including straw chopping,rotary tillage,fertilizing,precision sowing,and straw covering into a single operation,has been expanded and applied in major rapeseed producing areas of China. Unfortunately,its reliability does not meet the need of production,which restricts its popular. In this paper,product reliability test and fault analysis of the combined seeder was proposed to improve its product reliability. A brand new seeder was conducted to work in rice stubble field lasting longer than 30 hectare in Jianli County,Hubei Province,in 2013. Trouble-free working time and area,phenomenon of the fault,repair time and the cause of the fault of the seeder in the course of the work were recorded and used for fault characteristics analysis. The results show that the key components of the seeder,like the main frame,gearbox and rotary drive axis have not fault yet,even if they are undertaking the most of load in working. The facts prove design reliability of the seeder is relatively high. By contrast,the glitches frequently appear initially,which is certainly abnormal. It caution that manufacturing process should be improved,especially for sprockets assembling and welding. Another significant finding is that the bolted connection of rotary blade and base would be loosen at a period of 5. 9-hour,which lead to the fault of the rotary tillage unit. Fault analysis indicates that the period of early fault is 30 hours and the fault rate conform to the feature of a bathtub curve. Real productivity of the seeder is 0. 36 hm~2/h,one working shift productivity is 2. 16 hm~2/d and the availability coefficient of the seeder was nearly 70%. When assembling and welding process are improved,weak components and unreasonable belt drive structure are revised and the connection of rotary blade and base are preventative maintained,the availability coefficient will be increased more than 97% and the real productivity of the seeder will be promoted to 0. 45 hm~2/h.

As the protection of key component of the Shearer,torque shaft has a significant impact on the performance of the reliability and fatigue life of the shearer. Shearer’s flexible virtual prototype coupling model of torque shaft,rocker arm shell,planet shafts and carrier was established,combined with the actual working condition,pro-and post drums ’ load files were obtained. Based on the " shearer’s load simulation program ",shear stress and strain contours of the torque shaft were obtained by ADAMS. Based on neural network and reliability sensitivity theory,the torque shaft shear stress and strain ’s sensitivity of unloading groove structure parameters were obtained. To shearer traction speed and torque shaft shear stress and displacement as constraints,optimize the unloading groove. Results show that when the shearer traction speed is greater than 12. 2367m/min,the torque shaft fracture in time,could improve the reliability of coal winning machine and service life.

Aiming at the problem of long time of vehicle engine reliability life test,the grey system forecasting theory is used to forecast vehicle engine reliability life test data,and the unbiased grey GM（ 1,1） power model for engine reliability life test data is proposed. By examining the overall distribution function equality of test data sequence and forecasted data sequence,it is confirmed that the proposed unbiased grey GM（ 1,1） power model can be effectively used for the prediction of engine reliability life test data. The example results show that the grey theory forecasting method for the prediction of engine reliability life test data has high precision,and distribution function parameters of test data sequence and forecasted data sequence are very close. Using the proposed method can shorten engine reliability life test time and save test cost.

The drum ’s load calculation program of the staggered and sequential arrangement has been developed by MATLAB based on the shearer cutting mechanics model,which can get drum load spectrum,cutting performance parameters and the rate of lump coal under 5 typical working conditions;Shearer loading performance of two picks arrangement were analyzed by three-dimensional discrete element software PFC;The reliability of the key parts of the coal machine under different conditions has been analyzed Based on the PRO/E,MATLAB,ANSYS and ADAMS.The results show that:When the coal is cutting coal gangue,the pick should be used in sequential order,the load fluctuation is small and the reliability is high;Under normal conditions,the sequential pick arrangement of shearer can improve the lump coal rate,the cutting area will increased 1.99 times and the founder rate will increased 21% compared with the sequential type.

The influence of thermal cycle loading on optoelectronic PCB（Printed Circuit Board） reliability was presented.In product conceptual design stage,the three-dimensional finite element model of photoelectric PCB was established.The finite element analysis was carried out under thermal cycle loading which defined by GJB 150.5-86.The influence includes solder joints reliability of optoelectronic PCB,optical coupling efficiency and optical fiber reliability.The following results are obtained.First,the maximum stress of solder joint and optical fiber ribbon is in the security range and the structure is not destroyed.Second,photoelectric coupling efficiency is not changed significantly,which guarantees the stability of the optical transmission.It proves the feasibility of the design scheme and promotes the engineering applications of photoelectric interconnection technology.

For the gear transmission mechanism of a slat,based on S-N curve and linear cumulative damage theory,the reliability fatigue life caculation formula of gear contact can be obtained.In order to realize the global influence of the basic random variables on the distribution of the response performance function completely,the global sensitivities are proposed,which can provide effective theoretical guidance for optimazation and reliability design of gear.

The reliability of the reaction force developed in the lubricated revolute joint for a slider-crank system considering realistic joint characteristic,namely,joint with clearance and lubrication in the revolute pair,and the randomness of the system parameters is presented. The continuous approach and the hydrodynamic theory are used to evaluate the contact force for the case of joints modeled as a contact pair with dry contact and the force generated by lubrication action respectively. The system dynamic model was set up based on Newton-Euler method,The prediction accurary of Support Vector Machine Regression is difficult to reach the target accurary because the selection of parameters isn’t accurate. In order to overcome this limitation,the parameters are pretreated through Genetic Algorithm to get the optimum parameters values. Then approximate function relation between random parameters and performance function is derived and the reliability of the reaction force developed in the lubricated revolute joint of the crank-slider mechanism is discussed by Monte-Carlo method. Finally,take an example to verify the feasibility and effectiveness of the proposed method.

The 3D model of spindle reducer box of Boring and Milling Machining Center was established. The gear transmission was analyzed. The thermal load was found by calculating the heat flow of the gear and the heat generated of bearing.The calculated heat convection coefficient was defined as the boundary condition. The temperature field of the spindle reducer box was simulated. By thermal-structure coupling analysis,the thermal deformation results of the box and gears were obtained.Finally,the reliability of spindle box was verified according to the comparison of the simulation result against the nominal clearance.

As one of core components of machine tool,the reliability of spindle is very important for improving machine tool quality. According to spindle performance degradation mechanism analysis,the acoustic emission signal is used to monitor and study the performance state of spindle. A reliability evaluation method is proposed for the long-life and less failure sample problem based on machine tool degradation path models. At last,this method is used to solve the machine tool spindle reliability assessment,which integrates virtual augmented sample method. It effectiveness and practicability is proved through experiment results.

In order to improve dynamic reliability and work efficiency of shearer,the rigid-flexible coupling model of SL1000 shearer was constructed,the stress and reliability information of rocker shell were obtained through dynamic simulation;Based on BP neural network,the rocker arm shell’reliability of other conditions were predicted,and the relationship between it and coal seams consistent coefficient、tract Dion speed、roller cutting depth were analyzed,and the traction speed of shearer was optimized. The combination of virtual prototyping technology and BP neural network provides a new concept and convenient method for the prediction of shearer’work reliability,and it has important theoretical significance and engineering application value.

Optimization research on reliability of the catenary system and preventive maintenance strategy is the key to ensure the safe operation of the electrical railway. The choice of preventive maintenance strategy is more conducive to develop maintenance program of catenary system. Analyzing the catenary system based on fault tree analysis model and using different parameters’ Weibull distribution to describe the device failure probability of the various parts of the catenary system. The optimization function of preventive maintenance strategy on the catenary system based on reliability constraints is deduced.According to three years’ measured fault data of Changsha section,the parameters of Weibull distribution which describe the various parts of the catenary system is fitted,the maintenance costs of the catenary system in Changsha section were calculated according to the model of optimization on preventive maintenance strategy. Conclusions showed that: appropriately increasing maintenance times can reduce maintenance costs; high reliability requires will increase maintenance times and repair costs significantly. The maintenance strategy optimization model and the calculated results provide a useful reference for the Maintenance of the catenary system.

Put forward a kind of skin structure crane optimization design method based on reliability analysis. Considering the randomness of size parameters,material properties and wind load in the skin structure crane design,using Monte-Carlo method of Latin hypercube sampling（ LHS） technique to calculate the reliability of structure system. Through probabilistic sensitivity analysis to determine the optimal design variables,with the total quality of metal structural system of skin structure crane as the goal,to optimize the design by using the finite element analysis software ANSYS,relative to the initial design the quality of skin structure is reduced by 23. 8%,the overall reliability is used effectively,avoids the local reliability surplus,saves manufacturing cost.

In response to the need for management system of the pressure vessel of gathering and transportation in the offshore oil platform,the pressure vessel with oblique nozzles was researched by using Ansys and the local notch stress and strain approach.The computational methods for predicting the lifetime crack initiation and reliability was given. The lifetime crack initiation and reliability results of 60 degree-oblique nozzle was obtained in order to accomplish an example. The region of crack initiation was researched. The various dimensionless structural parameters affecting the lifetime crack initiation, which are the angle of inclination,the ratios of nozzle diameter / shell diameter,the ratios of shell thickness / nozzle thickness,the ratios of shell diameter /shell thickness,was studied. These research show that the local notch stress and strain approach which needs strain data of material and structural fatigue notch factor and structural stress-strain loading history can apply to predict the lifetime crack initiation and reliability of the real weld effect and the combined effect of multiple load to oblique nozzle. In the simple FEM models the region of crack initiation occurs at the crotch corner in the meridional direction of the cylindrical shell. The result narrow the search scope to cracks in real situation. The lifetime crack initiation is decreased with the smaller angle of inclination,the larger ratios of nozzle diameter / shell diameter,the larger ratios of shell thickness / nozzle thickness,the larger ratios of shell diameter / shell thickness.The results of the lifetime crack initiation is remarkably decreased when the angle of inclination is 30 degree. Considering the local notch stress and strain approach with inherent dispersion,the proposed approach which predicts the lifetime crack initiation with certain reliability is a simple and effective method. The research results can provide some referential value in order to formulate and optimize maintenance strategy of the pressure vessel of gathering and transportation in the offshore oil platform.

3-D finite element models of SOP（ Small Outline Package） were constructed,in which Anand visco-plasticity constitutive equation was used to describe the mechanic behavior of solder joint. The solder joint deformation and stress distribution with five kinds of lead shapes were researched. The experimental program for the identification of numerical simulation was performed with three kinds of lead shapes. Both experimental and simulation results showed that the solder joint life is closely related with lead shape. The lead shape with low stiffness can decrease the stress apparently. With decreasing the bending radius or increasing the standoff height,the component reliability will be enhanced. The numerical simulation result was congruous with experimental testing data,can able to reflect the factual behavior of SOP accurately.

Gear transmission system is a series system. However,it is different from the traditional series system in many aspects such as the relationship between system and elements,the manner for the system functioning,the time-dependent system configuration,etc. System classification is discussed firstly to meet the demand of system reliability modeling. For the purpose of system reliability analysis,a gear transmission system is taken as a time-dependent varying configuration system,which is different from the traditional series system with changeless configuration in space. According to different function,different configuration and different load characteristics,specific system oriented reliability analysis and modeling method are studied.Taking simple gear transmission system as an example,several system reliability models are developed,the reliability variation with load number and the differences between the new model and traditional model are illustrated.

Depending on the form of mechanism,the hinge wear and rod end bearing wear are considered respectively,and the self-lubricating rod end bearing wear model are established.Then the over-center locking reliability analysis model of four bar linkage mechanism is built under the "effective lever length theory"and "continuous contact model"hypothesis,besides,a reliability analysis method of over-center locking considering the initial clearance and wear is presented.The results show that the failure probability of mechanism over-center locking will rapidly increase after a certain number of cycles; the reliability of mechanism over-center locking will be significantly improved by using self-lubricating rod end spherical plain bearing.

Based on the coal rock cutting theory,simulated the load characteristic of the roller in the process of during coal rock; with the flexible-body dynamics as the theoretical basis to establish rigid-flexible coupling model of cutting unit,simulate the process of height adjustment by ADAMS and get the load response of link point; used Workbench to get the stress distribution of ranging arm when the link point force is maximum during the process of height adjustment; with linear cumulative damage rule as the theoretical basis,used Workbench to estimate the fatigue life of the ranging arm to verify the results of the reliability analysis and load response analysis.This paper provides a new method to research on dynamic characteristic and reliability of shearer cutting unit.