In the mechanical product development stage， the ability to work or the life of the mechanical product under the prescriptive conditions are predicted by mechanical reliability design method， the basic task of which is to propose mathematical model and method of practical calculation. The theory of mechanical reliability design was expounded by integrating reliability theory of history and current status. A series of theory and methods， such as reliability optimization design， reliability sensitivity design， reliability robust design， reliability testing and traditional design methods combined with the reliability design， were explained clearly and systematically. All of these studies provided systematic and unitized theories and methods for mechanical reliability design．

To solve the problem of tedious modeling and difficult programming of traditional reliability simulation model， the reliability modeling process employing ExtendSim was designed based on reliability block diagram(RBD). A two units parallel repairable system was presented as an example in the case study， and the simulation models using two policies were built， namely “deadly repair” policy and “instant repair” policy. The comparison with analytic model shows that the reliability models are believable. The modeling method in this paper can be easily mastered by ordinary technicians and has a certain application value.

In order to improve mechanical electronics system reliability， a multi-objective optimization model based on reliability indices and cost (volume et al.) was constructed. Adaptive Multi-Objective Differential Evolution Algorithm (AMODE) was proposed. The algorithm proposed chaotic crossover ratio and adaptive scaling factor， improved quick sort algorithm was employed to build Pareto optimal solutions， and the shrink of an external archive was achieved based on crowding distance， which was used in NSGA-II. The Pareto optimal solutions were obtained by AMODE. Multiple attribute decision making method TOPSIS was adopted to rank these solutions. An actual project solution shows that less parameters of AMODE need adjust and the algorithm can obtain uniformly distributed Pareto optimal solutions. The result based on multiple attribute decision making method-TOPSIS is reasonable and feasible．

Reliability design directly affect the level of free-running submarine model test system design success. Based on the analysis of the self-propulsion task and system contitution of the free-running submarine model， a free-running submarine model test system reliability analysis was carried out. Reliability model of phased-mission systems theory was used to establish the system task reliability analysis and calculation model， integrating the free-running submarine model test system design constraint conditions， and combining with the concept of desirability function. A redundant system reliability optimization model was established and solved by using particle swarm optimization method. The example proves that the model is available and credible．

In order to obtain nominal stress of weld under arbitrary combination of tension and bending load， stress and strain transformation coefficient of combined nominal stress of tension and bending was introduced， and fatigue data of weld based on pure tension nominal stress was transformed to that based on combined nominal stress of tension and bending with the same damage by means of stress concentration factor of tension and bending. Combined calculation stress of tension and bending was transformed to combined nominal stress by introducing element size effect factor to eliminate stress concentration in finite element model of weld. With the above transformations， transformation coefficient of combined calculation nominal stress of tension and bending was introduced， and combined calculation stress of tension and bending was transformed to the nominal stress based on pure tension load test so that the fatigue data of weld based on pure tension nominal stress could be used to evaluate welded structure directly. Calculation results show that transformation coefficient of combined calculation nominal stress of tension and bending is related to ratio of tension and bending， ratio of stress concentration factor of tension and bending， and element size effect factor of tension and bending caused by finite element modeling. Proper selection of element size will make the element size effect factor of tension equal to the ratio of stress concentration factor of tension and bending and the element size effect factor of bending equal to one， which makes the transformation coefficient of combined calculation nominal stress of tension and bending be identical to the element size effect factor of tension and independent to ratio of tension and bending.

Particulate material simulation technology can observe the motion condition of the bulk material， analyze the material's motion mechanism and the forces which act on the materials， it also can estimate the wear condition which means the remaining useful life. Besides， it can optimize the transfer system. Different calculation methods of bulk material transfer were compared; the steps of modeling and model checking using Discrete Element Method (DEM) method were built. Due to the problem of excessive computation time required by DEM calculations， the discrete element simulation was carried on in the condition of reducing shear modulus and increasing particle size. After comparing the experimental results and computing time of DEM with normal condition， it shows that the methods of reducing shear modulus and increasing particle size can reduce the time of DEM simulation on the premise of having no affection on the result. A simulation model established in EDEM software realized the visualization of material flow in transfer process. The effects of the material transfer in the straight line chute， polyline chute and the curved line chute are compared. Simulation results show that variable radius is better for material transfer and “U” type chute cross-section can reduce the misalignments in transferring the bulk material．

For the purpose of optimizing the dynamic characteristics of constant power variable pump， the mathematic models of variable displacement mechanism was constructed， according to the analysis of the structure and principle of the Rexroth's axial piston variable pump—A8V0 pump. Then the AMESim simulation model was founded， and the influence of two survey springs' parameters on dynamic characteristics was analyzed. Through the analysis of the shortcoming of current permanent power regulation with two springs， variable governing mechanism with three springs was raised. The simulation results indicate that the amplitude variation of variable displacement mechanism with two springs after optimization reduces from 24.1% before majorization to 7.3%， it's still not able to realize the ideal permanent power regulation; but amplitude variation of three spring's structure after optimization is only 3.9%. The research gives new mentality for the performance optimization of the constant power variable pump．

Travel mechanism of tracked vehicle requires high performance and has complex structure. For the problem of large friction power loss and low efficiency， internal and external resistance and power loss were analyzed， function modules and structure of the power loss analysis system were designed， and a power loss analysis system for travel mechanism of tracked vehicle was developed. The system can help to match power of driving motor through analyzing power loss of travel mechanism of tracked vehicle， and then guide the driving motor selection， simultaneously improves the efficiency of prototype design and the power loss analysis for the crawler travel mechanism．

Shock wave overpressure test technology is developing rapidly. As site environment of the shock wave overpressure test was quite poor，the paper proposed a design of shock wave overpressure acquisition system based on FPGA and wireless communication， in order to improve the flexibility and reliability of the test system.The paper first introduced the development situation of overpressure signal acquisition， specifically elaborated design ideas of overall program and the key techniques(power management optimization，ZIGBEE module，optical fiber module，etc)， and also analyzed the advantages，  high efficiency，low false trigger rate，flexible remote control，which was brought by using FPGA，wireless communication， optical fiber modules.The system had been a pefect application in the several real explosion experiments of shooting range.Experimental results show that it has high flexibility, reliability and stability．

The IR imaging system in the field circumstance is affected by the internal equipment dispelling hot and the exterior circumstance temperature changing. The key of all kinds of IR imaging systems' effective working is how to solve these questions such as the machine structure distortion and imaging quality unsteadiness.Based on the IR imaging system features， its temperature adaptability was researched in the machine structure design and optics structure design sections， and a reasonable structure was designed. The last contrast experiments show that the undershooting of the system adopting temperature adaptive design is 17% of that no adopting temperature adaptive design. The system can entireties satisfy the system temperature stability request and can ensure the good imaging quality．

In a certain airplane working process， it often happened that counterweight-components fractured， the roller flied out and damaged engine， which was a serious threat to flight safety. In order to analyze the cause of counterweight-components fracture， the impact of rapid manipulation of engine throttle on crankshaft torsional vibration was analyzed base on working principle of counterweight. The mechanism of roller impact washer was studied based on coupled torsional axial vibration theory and the experiment verification has been completed. The finite element calculation model of counterweight-components with impact load was established， the mechanical properties of counterweight-components was tested， and the strength analysis of counterweight-components has been completed based on safety factor method of fatigue strength. Research results show that the rapid manipulation of engine throttle causes excessive swing-angle of counterweight， which works in nonlinear swing. The counterweight swing frequency and the crankshaft torsional vibration frequency are greatly different， so the effect of the counterweight eliminating crankshaft torsional vibration is poor. The crankshaft generates strong torsional vibration， and this vibration is coupled as crankshaft axial vibration， causing the roller generate high frequency shock to washer. Under impact load， the fatigue strength of washer is the smallest in counterweight-components， fatigue fracture easily happens in washer. Appropriate improve of washer fatigue strength is in favor of avoiding fatigue fracture and improving reliability of counterweight-components

Filter is an important element in micro-circuit and it has been widely used in practical. The novel H-shaped DGSs(defected ground structure)were proposed based on traditional ones， and their transmission characteristic were investigated. Then a low pass filter was designed using the novel proposed structures. The simulation and measurement results match perfectly，and the measured results show that the 3 dB cut-off frequency of the designed filter is 8.9 GHz， its insertion loss is smaller than 0.3 dB，and the biggest side lamella of return loss is better than 20 dB. Additionally， the low filter has many other advantages such as the simple structure， the small volume， the low cost. So， this ultra-wideband low pass filter can be widely used in microwave circuits.

In order to realize the application of tachometer reflection prism in the dark environment， the improvement of electronic tachometer reflection prism has been carried out.  LED light emitting diode was introduced into the reflection prism as the device of backlight， and the feasibility of this device was verified by experiments. Firstly， this paper introduced the structure as well as working principle of the reflection prism， and then explained the advantages of light emitting diode and the design of improved circuit diagram. Finally， it also verified the feasibility of this improved device through experimental results. The experiments had tested whether the device could affect the measurement or not from two aspects， temperature and distance. The results of the two different room temperature proved that the temperature of the device has no impact on the measurement while the results of distance tests also proved that the device would not influence the distance measurement. All the above conclusions have proved the feasibility of this device．

The gear is a special kind of load in ultrasonic machining， which has specific requirements in vibration mode and frequency， moreover， its vibration characteristics and natural frequency have great influence on processing frequency of the system. Due to the large size and heavy weight of the gears， also that its size can not be changed， the existing design theories of vibration system such as full resonance theory， quality replacement theory and local resonance theory are not suitable for ultrasonic gear honing. In order to solve this problem， the theory of Mindlin's moderate-thick plates， ultrasonic solid horn designing and mechanical impedance were applied to study the vibration characteristics of transformer composed of solid horn and gear， and the mechanical impedance of horn and gear were derived. Then frequency equation of transformer was obtained based on the impedance-matching principle. The design theory and method are feasible and design result obtained by the suggested method is accurate，which are verified by comparing the results of design examples with that of finite element analysis and experiment. The method solves one of the key technical problems for ultrasonic machining．