Advanced Materials Research Vols. 118-120

Abstract: Flange is a common part in engineering, and it is tedious to build the 3D models of flanges repeatedly. Nowadays 3D modeling softwares are widely used in many engineering fields such as mining machinery, transportation and petrochemical. In practical engineering, it is necessary to compute the reliability of a flange. For these reasons a reliability design system of flange was developed with VC and Protoolkit. In this system, we only need to input several parameters to build a flange model and to compute its reliability. Also it is easy to determine the key sizes of a flange with an appointed reliability. The application of the software shown that using the software can improve the work efficiency and decrease the labor intensity of designers.

Abstract: Fatigue limit measurement is investigated experimentally on the grade B cast steel for Chinese railway freight car bogie frames. Small sample up-and-down test method was employed for the present study. Results reveal that fatigue cracks initiated mostly from the material cast shrinking cavities. Distinct river-like flowers and second cracks appeared on fracture surface in perpendicular to fatigue crack path. Lots of dimples are distributed in transient fracture district to indicate that present material is ductile. Maximum likelihood approach is applied for measuring the probabilistic fatigue limits, in which the limits are defined as the fatigue strengths following normal distribution at an expected fatigue life. Statistical parameters are then estimated by a likelihood function method. A comparison analysis to the existent conventional, Dixon-Mood and Zhang-Kececioglu approaches indicates that the maximum likelihood approach is the approach meeting the definition.

Abstract: In this study, based on ASME Code Section III, France RCC-MR, ANSYS simulation and experimental data, ratcheting and ratcheting boundary are obtained to determine allowed loading of primary auxiliary pipeline in nuclear power plant. A software of pressurized water reactor auxiliary pipeline anti-ratcheting design is compiled. The calculation method to determine the boundary of ratcheting effect is proposed in order to provide a basis for pipe structural design. This work focuses on the work of the establishment of the structure of software system. The structure mainly composed by three program modules, i.e. the database module, data computing module and data display module. The function of each module and the relationship between the modules are explained. An example to determine ratcheting boundary is presented in the paper.

Abstract: The ratcheting strains of the straight and elbow piping under two kinds of loads—pressurized piping under symmetric cyclic bending and pulsating cyclic pressure were analyzed based on Chaboche constitutive model. The locations of the maximum ratcheting strain were determined. The ratcheting boundaries of the two piping structures under two kinds of loads were compared and calculated by the C-TDF method. For the pressurized piping under symmetric cyclic bending, the allowable bending load increases from E90S to E90L under the same pressure. In the higher cyclic pressure range, the allowable pressure have little difference under the same bending load which indicates that the bend moment have a bit effects on the ratcheting boundary in the higher cyclic pressure range.

Abstract: Corrosion-fatigue failure of aluminum alloy stringer on the tour airplane servicing in the coastal environment of the Fiji Islands was discussed. Through analysis on surface topographies and components of aluminum alloy structure and consideration of service environment, it showed that the chloride ions, the aging failure of structure coating and the applied stress are the main reasons for corrosion fatigue failure of aircraft aluminum alloy structure. The corrosion-fatigue crack propagation rate of structural components in the coastal environment was analyzed by derivation of crack expansion formula. Findings showed that the corrosion-fatigue crack will expand rapidly until the structure fractures after the aircraft aluminum alloy structure operates nearly 10800 cycles during the crack growth phase. According to the corrosion-fatigue failure analysis of aluminum alloy structure, some improvements were proposed to slow down the corrosion-fatigue failure of aluminum alloy structure in the coastal environment.

Abstract: Based on order moment method and improved Monte-Carlo method, this paper mainly studies the importance sampling method which combines with the first-order second-moment method, including how to get the sampling barycenter, how to get the importance distributing function and how to control sampling precision. Finally, the method studied in this paper is applied in actual engineering example and the verification result shows that the method is correct and effective and has higher engineering practical value.

Abstract: Three-dimensional finite element model of a cracked bolted joint has been developed in the non-linear finite element code MSC.Marc and attempts were made to validate it by comparing results with those of experiments and other finite element. Issues in modeling the contact between the joint parts, which affect the accuracy and efficiency of the model, were presented. Experimental measurements of load transfer were compared with results from finite element analysis. The results show that three-dimensional finite element model of cracked bolted joint can produce results in close agreement with experiment. Three-dimensional effects such as bolt titling, seconding and through-thickness variations in stress and strain are well represented by such models. Three-dimensional finite element analysis was also used to study the effects of hole mod and crack on the load transfer behaviour of single lap bolted joints. The results show that hole mode has big effect on load transfer of cracked bolted joint. In the whole progress of crack growth, the load transfer through bolt 1 decrease, and almost all of the load duduction of bolt 1 transfer into blot 2 rather than into bolt 3.

Abstract: The rolling contact behaviors between LMA, S1002 and XP55 wheelset and track in static rolling contact are analyzed using the rolling contact theory of three-dimensional elastic bodies with non-Hertz form and numerical program of CONTACT. The numerical results indicate that three kinds of wheel treads have different difference of rolling radius and equivalent taper. The rolling contact behaviors between three kinds of wheel treads and CHN60 rail have obvious difference. The comprehensive analysis indicates that the matching effect of LAM wheel tread and CHN60 rail is relatively superior. Furthermore, it is suggested that new wheel tread should be designed and optimized for the high-speed railway.

Abstract: At the present time, as the steam conditions and capability of the supercritical power unit increasing, the unit reliability is an important factor for the unit efficiency. High temperature, thick walled pipes are widely used in power plants and chemical plants. In this paper, life of the welded joint was predicted by the methods of skeletal point (SP) rupture stress rupture stress, which was calculated by finite element method (FEM). For the life prediction of welded component, the continuum damage mechanics was employed too. The life prediction of the welded joint by SP rupture stress was compared with the life prediction by the method of continuum damage mechanics (CDM). The research results showed that the two predicted methods were consistent. So, it can be concluded that the SP rupture stress can be used for predicting life of the high temperature welded component. The SP rupture stress method was used conveniently for the structure of power plant or other high temperature components.

Abstract: The main task of this paper was to evaluate the influence of hardfacing technique and service temperature on the fatigue properties of heat-resistant steel X45CrSi9-3 coated with Co-based alloy Stellite 12. The results of rotating bending fatigue tests showed that at room temperature (RT), the fatigue strength of specimens welded by the acetylene gas welding (AGW) was lower than that of specimens welded by the plasma transferred arc welding (PTAW). For PTAW specimens, the fatigue strength at 500oC was much higher than that at RT. Two failure modes were presented, one was termed as the coating failure mode at RT and the other was termed as coating-interface failure mode at 500oC. The fatigue life prediction was conducted by using a modified Murakami’s model.