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Shot peening technology is used to improve the fatigue strength of materials and parts, and is one of the most effective surface engineering techniques to prolong fatigue life. In this paper, according to the finite element simulation analysis of shot peening, a randomly distributed multiple-shot finite element model was established. The superimposed effects of multiple projectile impact craters in shot peening are fully considered. The effects of shot velocity, shot peening angle and shot coverage on the residual stress field and surface roughness were studied. The alloy steel 20MnTiB, widely used in the automotive industry, was used as the raw material to process the specimens. The shot peening tests of different process parameters were carried out. The test results verified the correctness and accuracy of the random distribution model of multiple-shot. The shot-peening simulation model proposed in this paper allows a more accurate analysis of the effect of shot-peening parameters on the surface residual stress field and helps to quickly set the correct shot-peening process parameters. This paper further investigates the effect of shot peening parameters on fatigue life, providing a basis for the rational development of shot peening solutions.

High-speed trains have a large amount of ancillary equipment, which is suspended from the underside of the train by means of a suspension structure. Due to the large mass of the ancillary equipment, the suspension structure is subjected to various loads during train operation and there is a risk of fatigue failure. In this paper, the stress distribution at the suspension point and the lo-cation of the maximum stress point under load are investigated in detail based on actual test loads at the suspension point and finite element simulation analysis. In order to further investigate the fracture failure of the suspension points, experimental studies were carried out. Firstly, static strength tests were carried out to obtain the load–displacement curves of the structural members and to determine the fracture strength of the structure based on the displacement sensors, and secondly, fatigue tests at different stress levels were carried out to obtain the load–life curves of the structural members and to investigate the probabilistic load–life curves at different reliability levels. The test results show that the structural component has a high fracture strength of 65kN, while the conditional fatigue strength is relatively low, corresponding to a load level of 12.5kN at a median life of 106 cycles. The above research work provides the necessary basis for the design, optimization and reliability assessment of the suspension structures of high-speed trains.

The compressor blade-disk system of an aero-engine is a complicated system with numerous components, and the failures of components are related. To evaluate its reliability accurately and efficiently, a fatigue reliability assessment method to handle the issues with failure dependency between components was proposed. Firstly, the finite element analysis was carried out considering the dispersion of load and material; secondly, the probabilistic distributions of stress, strain, and fatigue life of components were fitted by the response surface method; finally, the multi-component failure-dependent reliability model (MCFDM) of the compressor blade-disk system was established based on the dependent failure system reliability theory. Based on this model, the fatigue life of the blade-disk system at varying reliability levels and the reliability and failure probability at varying specified life levels were calculated. The results of MCFDM are compared with those of the independent failure reliability assessment model(IFM) and the traditional Monte Carlo method(MCM). It is demonstrated that the system reliability calculated by IFM is too optimistic, while MCM requires a large number of samples based on the finite element model directly. In comparison, MCFDM can offer results with sufficient accuracy and higher efficiency.

In order to realize the high-quality work requirements of welding robots, based on the actual working conditions, the seven-degree-of-freedom series welding robot is taken as the research object, we design and determine the relevant technical parameters of it, and establish the kinematics model in D-H coordinate system. The micro-displacement synthesis method is introduced, and the static pose error model and reliability calculation model of the robot are established. The influencing factors of the accuracy of the welding robot's pose accuracy are analyzed and the sensitivity of the influencing factors was obtained. Finally, based on Monte-Carlo simulation method, the link parameters of the welding robot are taken as an example to verify the reliability of the position and accuracy of the welding robot, and the relevant results are obtained. The work in this paper is of some guiding significance in reliability design and assessment of a welding robot.

Escalators are now more and more widely used around the world. As escalator accidents occur from time to time, it is very important to analyze the structure and reliability of escalators. This paper studies the structure and reliability analysis methods of typical escalators. By applying parametric analysis methods, the efficiency and accuracy of escalator structure analysis are greatly improved. Because the failure of each structural member of the escalator truss system is dependent, this paper applies the dependent failure reliability modeling method and analyzes the reliability of the escalator truss system. The results show that the reliability analysis method of the truss system after considering the dependent failure is more reasonable. The above research work has certain reference significance for the design and analysis of escalators.

High-speed trains are now the most important medium- and long-distance mode of transport in many countries, and green economy is one of the important directions of high-speed train design. Aluminum alloy material is widely used in various structural parts of high-speed trains due to its advantages of high strength and low density, etc. As the speed of high-speed trains is getting faster and faster, the load on the car body structure is getting bigger and bigger, the safety, reliability and longevity of aluminum alloy structure has received wide attention. In this paper, the stress distribution, maximum stress value and maximum stress point position of aluminum alloy structural members of high-speed trains are analyzed in detail based on the real load situation, and the influence of stress level on train operation is analysed. The above work has certain reference significance for the design of high-speed train.

A new method based on Dynamic Bayesian Network (DBN) is proposed to assess the car engine reliability because of the limitation that the existing reliability analysis methods can only be used in static system reliability assessment. Firstly, define the failure mode and effect analysis table (FMEA) and the failure rates of the main components of the car engine and construct Bayesian network (BN) model. Secondly, combine the original BN model with time information and assess the reliability of the systems by using the advantages of BN in terms of the multi-state variables and uncertainly relations. The method is able not only to compute the reliability indices of car engine but also to carry out the fault detection easily to recognize the weakness of the system. This research is meaningful for reliability design and prediction of car engine.

A gear transmission system such as a gear train is a series system in sense of reliability evaluation, while it is different from a traditional series system such as a chain. Therefore, the conventional series system reliability model is not appropriate for gear transmission system. Based on the time-dependent configuration and the time-dependent loading path of a gear train, system specific reliability modeling technique is presented, by which a gear train is taken as a time-dependent series system, consisting of different components (gear teeth) in different time intervals. To illustrate the application of the reliability analysis method, several time-dependent series system reliability models are developed for different types of gear trains, the reliability estimation results are compared with those obtained by traditional series system reliability model.