Applied Mechanics and Materials Vols. 635-637

Abstract: Fire risk of gas pipeline leakage is high.The factors contributing to gas pipeline leakage most are third party damage, corrosion, design and incorrect operation. The accident consequences of gas pipeline leakage and quantitative risk assessment method of gas pipeline leakage consequence are analyzed. In order to achieve quantitative fire risk assessment of gas pipeline leakage, flash fire model, vapor cloud explosion model and thermal radiation damage criterion are analyzed. Firstly, the gas leakage quantity is estimated. Then, the heat radiation estimate flux, the thermal dose and damage range are got by using flash fire model, vapor cloud explosion model and the thermal radiation damage criterion respectively.Combined with an example of gas pipeline, damage ranges of different disaster patterns are estimated according to different gas pipeline leakage pattern. Through comparing the accident consequences of gas pipeline leakage, this paper provides some reliable scientific references for gas pipeline management departments.

Abstract: As a core feature of high-end CNC machine tools, the torque carrying performance of five-axis milling head directly affects the machining accuracy and reliability. Through theoretical analysis and derivation, combining experimental prototype, the A/C-axis cutting torque formula of five-axis milling head on woodworking is obtained. The reliability analysis provides a theoretical basis for drive motor selection and five-axis milling head structural optimization and improvement.

Abstract: This paper presents a method for probabilistic sensitivity analysis of mechanical components or structural systems subject to random uncertainties in loads, material properties and geometry. The bi-variate dimension reduction method is applied to compute the response moments and their sensitivities with respect to the distribution parameters of basic random variables. Saddlepoint approximations with truncated cumulant generating functions are employed to estimate the probability density functions and cumulative distribution functions of the random responses. The rigorous analytic derivation of the sensitivities of the probability of failure of the systems under consideration with respect to the distribution parameters of basic random variables is derived. Finally, the practicality and efficiency of the proposed method are demonstrated by an application example.

Abstract: Aimed at the characteristic of mechanical equipment, a reliability prediction method based on physical character and stress, load is proposed. The influence of anticipative use environment, abrasion and other potential degenerate cause is considered adequately in this method. The influence of material to the part is also confirmed in this method. in addition, the formula between failure and structure, size, material, craftwork, stress, load is established. At last, taking seals as an example, the process is expounded. A new thought is provided to prediction of mechanical equipment reliability.

Abstract: Obtain the weight of risk factors at all levels based on AHP analysis model,optimize the third edition of Pipeline Risk Management Manual to establish a new index system.Bring in the matter-element and extension model,according to the established index system and expert scoring results , calculate the correlation function values of each risk characteristics to each of the risk levels,using the figures to reach the risk level of the city pipeline.Through living example shows that this evaluation method is correct.Compared with the general evaluation method,the matter-element and extension analysis model overall consider the weight of the risk factors,expert score and the grade index system.This evaluation method is more accurate compared with the general evaluation.

Abstract: In order to predict the failure probability of a complicated structure, the structural responses usually need to be estimated by a numerical procedure, such as finite element method (FEM). To reduce the computational effort required for reliability analysis, response surface method could be used. However the conventional response surface method is still time consuming especially when the number of random variables is large. In this paper, a Fourier orthogonal neural network (FONN)-based response surface method is adopted to solve the reliability analysis of the automobile engine. The working process of the connecting rod is simulated with UG software, the dynamics analysis on crank-connecting rod-piston mechanism is performed with ANSYS and ADAMS software, with FEM analysis results, the stress information of the critical point of the structure can be obtained, so the performance function of the structure can be established. The FONN method is used to fit the performance function as well as its derivatives, so as to calculate the reliability of the structure.

Abstract: The leak less distant transportation of large amounts of hazardous matters (for example natural gas) through a pressurized pipelines is a serious challenge. The pipeline should be able to withstand the full range of ambient conditions as well as the Earth’s crust movements, varying soil chemical state at present and after months or years of exploitation. During the previous years the formal risk assessments were carried out on the base of the failure intensity. Since that time the procedure of the risk assessment has become more sophisticated. At present risk management is being more and more mandated by regulations.

Abstract: The area of security affects the entire life cycle of the machine from design, manufacturing, installation, adjustment, maintenance all the way to its disposal. Clearly, the longest as well as the most dangerous stage of the machine, is its own operation and maintenance. At this stage it is necessary to assess the risks associated with its use and possess the documentation so as to use the machine safely. These materials are the basic documentation, which is the subject of familiarization and practical training of the employees rather than immediate use of the machine. This article describes the risk analysis of the machinery and its application to risk management particularly the process of training and educating the employees.

Abstract: According to the geometric meaning of the structural reliability index, an unconstrained optimization model with structural reliability index and design point is obtained by exterior penalty function method. The Powell method, golden section method and extrapolation method are used to solve the unconstrained optimization problem. The proposed method not has to deal with the any derivative of the limited state function, and can been used to obtain structural reliability index and design point of the strong nonlinear limit state function, which first-order reliability method (FORM) may fail to converge. Three examples are given to compare penalty function method with the difference methods. The results show that the given method is simply, effective and precise enough.

Abstract: When vortex-induced resonance happens, the amplitude is big enough to affect the comfort and safety of the structure using, also it can cause fatigue damage to the structure. Being in the tube full of flowing natural gas, the thermo well may vibrate and be damaged. In this paper, based on the theory of vortex-induced vibration, by using ANSYS (FEA software), the author will test and verify whether the vortex-induced resonance will occur on the thermo well according to one example. Keywords: vortex-induced vibration; thermo well; vortex shedding frequency