Key Engineering Materials Vols. 353-358

Abstract: Goal setting safety legislation for high pressure systems was first introduced in 1973 and retained in the High Pressure Safety Management Law in Korea. This has enabled a move towards inspection strategies based on the risk of failure. This trend towards a risk based approach is being supported by extensive plant operating experience, improved understanding of material degradation mechanisms, and the availability of fitness-for-service assessment procedures. RBI (Risk-Based Inspection) is very effective and efficient of the inspection and maintenance techniques. In particular, RBI will be found how to apply both inspection interval as a result of RBI implementation and re-inspection interval of pressurized equipment defined by the High Pressure Safety Management Law in Korea. The objectives of this paper are to develop an enhanced KGS-RBITM program to resolve shortcoming inclusive of the above issue and to evaluate the risks of equipments in Naphtha Cracking Center (NCC) which is a typical facility of petrochemical plant using the KGS-RBITM program. The results of the risk assessment and re-inspection interval of internal opening using KGS-RBITM program are useful in determining the inspection planning.

Abstract: Establishment of a reasonable expert system integrated developing environment (ES-IDE) is a critical factor for developing ES promptly and effectively. By current investigation and analysis of related technology, a kind of IDE for fault diagnosis expert system (FDES) on the base of Protégé+CLIPS+Eclipse tool-chain was brought forward. The model of FDES was realized by Protégé and described by ontological analysis method. Combined with CLIPS, inference engine and knowledge base (KB) were realized and applied to diagnose and deduce, the developing period of ES core framework was shortened, and flexibility of system was increased. Based on component principle, every system module was encapsulated in form of Eclipse plug-in, so users can reconstruct and reconfigure to compile and make ES application instance uniformly according to their specific demands. Industry experiments prove that this system can generate FDES in a shorter period, has strong transplanting ability and friendly human-computer interface.

Abstract: Aiming at some problems in the fields of industry monitoring technology (IMT) such as bad dynamic ability and poor versatility, this paper brought forward a kind of intelligent Status monitoring and Fault diagnosis Network System (SFNS) based on UPnP-Universal Plug and Play. The model for fault diagnosis network system was established according to characteristics and requirements of IMT network, and system network architecture was designed and realized by UPnP. Using embedded system technology, real-time data collection node, monitoring center node and data storage server were designed, and that supplies powerful real-time data support for SFNS. Industry fields experiments proved that this system can realize self recognition, seamless linkage and other self adapting ability, and can break through the limitation of real IP address to achieve real-time remote monitoring on line.

Abstract: Stochastic finite element method and reliability technique are used to determine the safety degree of the turbine blade with parametric uncertainty. The material, geometric parameters and rotating speed of blade exhibit notable random fluctuations, so the conventional deterministic analysis of blade can’t provide complete information. The stochastic analysis can tackle the uncertainties in structural parameters and obtain the probabilistic characteristic of the vibration characteristic. In this paper, the study focuses on the reliability assessment of the blade with uncertainty parameters based on the stochastic finite element method (SFEM) and the mean-variance method. The perturbation stochastic finite element method (PSFEM) is used to calculate probabilistic characteristic of the natural vibration of the turbine blade. Based on the stochastic finite element method, the mean-variance method is used to calculate the resonance reliability of the blade. The example shows that the present method is valid.

Abstract: Rubber material properties and useful life evaluation are very important in design procedure to assure the safety and reliability of the rubber components. In this paper, the heat aging effects on the material properties and useful life prediction of rubber material for refrigerator component were experimentally investigated. The accelerated heat aging tests were carried out to predict the useful life of NBR and EPDM, which is used in refrigerator component. Compression set results changes as the threshold are used for assessment of the useful life and time to threshold value were plotted against reciprocal of absolute temperature to give the Arrhenius plot. By using the compression set test, several useful life prediction equations for rubber material were proposed.

Abstract: The purpose of this study is to investigate the high temperature creep life of Waspaloy using the Initial Strain Parameter Technique (ISPT). The creep tests were performed at the elevated temperatures from 550oC to 700 oC. Constant stress creep tests were carried out in the experiment. The initial strain was measured for one minute after loading. The creep life of Waspaloy was calculated using the creep life prediction equation of ISPT. The confidence level between the experimental rupture time and the calculated rupture time using the ISPT is within 95%. So, the results show that the creep life prediction by the ISPT was a good agreement with LMP method.

Abstract: A method to predict impact load caused by drop impact of thin cone-shaped structures is investigated. The Hertzian contact theory and the spherical shell theory are applied for modeling the contact stiffness of the impact tip of the cone. Experiments and finite element simulations are performed for several cones to evaluate the accuracy of impact load prediction. It is shown that appropriate choice of contact stiffness model depending on the curvature and thickness of impact tip of the cone is necessary in order to predict the impact load accurately.

Abstract: Wind-induced vibration of tall buildings have been of interest in engineering for a long time. Wind-induced vibration of a tall building can be most effectively controlled by using passive control devices. The tuned liquid damper(TLD) is kind of a passive mechanical damper, which relies on the sloshing liquid in a rigid tank. TLD has been successfully employed in practical mitigation of undesirable structural vibrations because it has several potential advantages: low costs, easy installation in existing structures, and effectiveness even against small-amplitude vibrations. Shaking table experiments were conducted to investigate the characteristics of the shallow water sloshing motion in a rectangular tank. To increase the damping ratio of the rectangular water tank, triangle sticks were installed at the bottom of water tank. This installation increased the damping ratio by amaximum of 40-70%.

Abstract: An appropriate choice of building shape and architectural modifications can result in the reduction of motion by altering the flow pattern around a building. Tapering which is one of aerodynamic devices has been known to be effective to reduce acrosswind response [1, 2]. The exterior wind loading patterns on claddings are sensitive to the building shape. When a building has a tapered cross section along the height, the influence of the exterior wind loading patterns on the wind-induced high-cycle fatigue damage of the cladding fastener of the tapered building needs to be found. In this study, the fatigue damage of the cladding fastener of a non-tapered building and two tapered buildings is estimated by using the rainflow cycle counting method and Miner’s rule. The fatigue damage is compared with one another in order to investigate the influence of the tapered cross section on the fatigue damage of cladding fasteners on side faces of tall buildings

Abstract: The action of wind pressures is a major consideration in the design of cladding and its connections to building structures. Non-Gaussian environmental loads often may appropriately be reduced to Gaussian loads through the central limit theorem, e.g., integral loads on a building under wind loads. However, for the design load of cladding and its connections to building structures the Gaussian assumption is not valid and loads remain non-Gaussian, especially in separated flow regions. When the loads differ significantly from Gaussian distribution, they may lead to increase expected damage. In this study, the wind-induced high-cycle fatigue damage of a cladding fastener subjected to non-Gaussian local wind pressures and corresponding simulated Gaussian local wind pressures is estimated by using the rainflow cycle counting method and Miner’s rule. The fatigue damage is compared with each other in order to investigate the influence of non-Gaussian local wind pressures on the fatigue damage of a cladding fastener on the side face of a tall building.