In the reliability designing procedure of the vehicle components, when the distribution styles of the random variables are unknown or non-normal distribution, the result evaluated contains great error or even is wrong if the reliability value R is larger than 1 by using the existent method, in which case the formula is necessary to be revised. This is obviously inconvenient for programming. Combining reliability-based optimization theory, robust designing method and reliability based sensitivity analysis, a new method for reliability robust designing is proposed. Therefore the influence level of the designing parameters’ changing to the reliability of vehicle components can be obtained. The reliability sensitivity with respect to design parameters is viewed as a sub-objective function in the multi-objective optimization problem satisfying reliability constraints. Given the first four moments of basic random variables, a fourth-moment technique and the proposed optimization procedure can obtain reliability-based robust design of automobile components with non-normal distribution parameters accurately and quickly. By using the proposed method, the distribution style of the random parameters is relaxed. Therefore it is much closer to the actual reliability problems. The numerical examples indicate the following: (1) The reliability value obtained by the robust method proposed increases (>0.04%) comparing to the value obtained by the ordinary optimization algorithm; (2) The absolute value of reliability-based sensitivity decreases (>0.01%), and the robustness of the products’ quality is improved accordingly. Utilizing the reliability-based optimization and robust design method in the reliability designing procedure reduces the manufacture cost and provides the theoretical basis for the reliability and robust design of the vehicle components.

A nonlinear rotor system with complex structure in engineering is studied and the finite element analysis software and the multi-body dynamics simulation software are used to establish and analyze the parametric dynamic model of the rigid-flexible rotor system.The dynamic simulation of the rotor system is carried out and the dynamic stress model for reliability analysis is established on the basis of artificial neural network(ANN) technique,stochastic perturbation method,reliability design and reliability-based sensitivity design theory.Thus,an efficient method is proposed to compute the reliability-based sensitivity of the non-linear rotor system with complex structure.The influence degree of the designed parameters on the reliability of rotor system is discussed,and the sensitivity of reliability to the mean value and variance of original random parameters is obtained.On condition that the units of original random parameters are different,the sensitivity is transformed into dimensionless value and each basic random variable is then sequenced by the influence degree of reliability.The proposed method provides theoretical reference for the mechanical product design,thus having realiseic significance and theoretical value.

To improve the reliability effectively, the reliability sensitivity method is researched with considering that a mechanical system or component may fail in many modes, which is simplified to be a series system model. It is supposed that all ultimate state functions in multi-failure modes are normal distribution. A computation module for total reliability is established. A kind of computation method for reliability sensitivity in multi-failure modes is built based on that in single failure mode. A pin connection component that may fail in shear fracture, bruise on pin or hole surfaces, or in any assemble with two different modes is computed, and the reliability and sensitivity of the component are estimated. Consequently, it is found that the most effective method to enhance the reliability was to enhance the crushing strength of the pin.

A gear’s finite-element model has been set up according to the parameter functions of the involute and tooth root curve, single and double tooth meshing region have been obtained according to the results of contact analysis. A tooth root’s bending stress has been calculated when meshing in the ultimate position in single tooth meshing region, and this stress has been contrasted with the results of a classical method as the maximum of a circle. The results of theoretical method were far away from that of finite-element calculation before being modified and were a little larger than the later after being modified. Reasons leading to this difference have been analyzed.

Supposing that three or more failure modes arise synchronously to be very small probability event,the relationship between limit state functions was established for different failure modes by using linear regression method.A double integration model was built for reliability calculation of mechanical components at dependent failure modes.The model can be used after a linear transformation if a square,cube or exponential relationship appears between the limit state functions.Pin reliability was computed at dependent failure modes by the model and validated by the Monte Carlo method.The result confirms the validity of the double integration model.

The T4 impeller for cracked gas compressor, a megaton device, is studied in this paper. The parametric finite element model is established using finite element software. On the basis of the artificial neural network (ANN) technique, the stochastic perturbation method, the differential matrix and the reliability theory, some point physical dimension are defined as basic random parameters. The reliability analysis model is established with the criterion that the maximum stress of the T4 impeller is no more than yield strength of material. The influence degree of the parameters on the reliability of the T4 impeller is obtained by the sensitivity analysis and the non dimensional analysis, which provide more theoretic evidence for the impeller design in engineering practice.

Utilizing finite element software, an universal program has been worked out by the APDL, and it can output the heat dissipating capacity of appointed surfaces in analysis software. The program is so powerful that it can calculate the heat dissipating capacity of heat conductor in which the heat transfer two-dimensionally or three-dimensionally even if the heat conductor is anisotropic, which is difficult to calculate with the mathematic analysis method. The method mentioned in the paper can diminish the inaccuracy caused by the predigestion with the mathematic analysis method. The calculation principle of the program was introduced in detail. Comparing the result of the program with that got by mathematic method, it was indicated that the calculation error of program is very small.

Vibration characteristic of direct drive A/C bi-rotary milling head is been analyzed by finite element method (FEM), former four order vibration modes of the milling’s structure are given. The influence of the swing angle of the A-axis to the natural frequency of the milling head is analyzed. The natural frequencies when the milling head is working are interval values, the first order natural frequency is [120.48, 122.91], the second order natural frequency is [139.68, 142.08], the third order natural frequency is [328.68, 331.9], the fourth order natural frequency is [369.68, 372.45]. This computing provides technological support for design and improvement of this type of milling head.

Notice of Retraction After careful and considered review of the content of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE's Publication Principles. We hereby retract the content of this paper. Reasonable effort should be made to remove all past references to this paper. The presenting author of this paper has the option to appeal this decision by contacting TPII@ieee.org. Stress intensity factor of thermal fatigue crack was calculated within one cycle by using finite element method in consideration of the multi-linear kinematic hardening characteristic of a material. The affection of loading sequence to stress intensity factor was studied under circularly variational temperature by comparing to that in one cycle. The low temperature cycle can not affect the stress intensity factor of latter cycles with high temperature; but high temperature cycle can affect the stress intensity factor of latter cycles with low temperature, and make it be equal to that of the high temperature cycle.

To solve well the problem of reliability of a nonlinear system in engineering practice,the design of reliability is theoretically combined with sensitivity analysis on the basis of the stochastic perturbation theory of reliability design to modify the formula to compute the reliability-based sensitivity with normally distributed stochastic parameters,thus making the modified computing formula more adaptable to the nonlinear structural system in engineering practice. With the parameterized computation program provided,the relationship between structural reliability and the mean value of basic random variables is given. A numerical example verifies that the computational accuracy of the sensitivity based on structural reliability to the mean value of basic random variables is greatly improved by the modified formula referring to the highly nonlinear ultimate state equations,with a more exact reference provided theoretically for engineering practice.

In a direct-drive high-power A / C-axis bi-rotary milling head,torque is transferred by two parallel connected rotary direct drive motors in C-axis, therefore, the length of C axis is inevitable large, moreover, the transmission components of it are bearing high torque. Through analyzing the twist stiffness of the transmission components in C-axis by the finite element method, the result that the torsion deformation of the sleeve accounts for a large scale in transmission components of C parts is found. In the permitted extent structural design of C-axis, the stiffness of transmission components in C parts is increased effectively through shortening the sleeve and lengthening its external diameter.

The dynamic performance of numerical control (NC) machine is not only basis of evaluation for the vibration resistance and stability, but also theory basis of optimizing dynamic performance, and improving processed quality. As digital design method, visual design realizes "visibility" during the whole design process, increases design efficiency and guarantees the quality, which make visual design preferred design method in large mechanical engineering. In this paper, the analysis of dynamic performance on NC machine and visual design method will be integrated, taking a NC machining center built by Shenyang machine tool group as a study case, the dynamic visual design flow to be proposed, including the design purpose, content and design methods, finally, the dynamic performance of visual simulation we have done, taking the strength, inherent characteristics and harmonic response into account, offers the foundation about structural performance optimization on the machine.