Papers by Author: Feng Hui Wang

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Authors: Tie Jun Liu, Yong Zhang, Gang Li, Feng Hui Wang
Abstract: In design of solar powered aircraft wing panel, vibration properties of wing panel should be considered, especially for the peak value of dynamic response. In this research, a viscoelastic damping layer is built for vibration isolation, wing panel finite element models of stiffened and no-stiffened structures base on fiber-reinforced laminates with damping layer in the middle are built. Natural frequency and displacement response are analyzed with different thickness of damping layer and structures. Result shows natural frequencies decrease as thickness increased, and that of laminates are lower than stiffened structure. The maximum displacement response value decreased when thickness increased and that of laminates is higher than structured with stiffer. The presented work is helpful for type selection and designing of solar powered aircraft wing panel.
Authors: Feng Hui Wang, Kang Lou, Yong Jun Wang
Abstract: When to test the failure stress of Solid Oxide Fuel Cell system, bending approach is consider as one of the convenient ways. The failure stresses are calculated by the elasticity multi -layered theory, in which the neutral axis is determined by the mechanical properties of materials and the thickness of the layers. When cooling from the sintered temperature, residual stresses arise in the multi-layered system due to the mismatch of the thermal expansion coefficients, in this case, the thermal elastic theory point out that the neutral axis depends on residual stress. In this paper, the effect of residual stress on the shift of neutral axis and consequently the failure stress of SOFCs presented, the finite element method was also employed to calculate the SOFCs before and after reduction. The results show that the residual stresses has a distribution along the thickness of the layers, the neutral axis also shifts with the residual stress and the external bending moment, when to test and value the bending stress, the shift of neutral axis should be considered.
Authors: Feng Hui Wang, Ying Xi Wu
Abstract: The dependence of strength on notch radii of ceramic components is presented. The strength is exponential decay as the notch radius decrease, the smooth specimen that corresponds to the infinity notch radius topped the fracture strength, but the lowest value relys on the micro feature of the materials. Plotted the strengths on Weibull and Normal probability paper, the fitness coefficients reveal that the strength of smooth specimen, as the past literatures indicated, follows Weibull distribution, but the strength of notched specimen follows Normal distribution better. Such result is due to the fact that the decreasing notch radius reduces and limits the effective original fracture volume, when the notch becomes a slim crack, the weakest link place becomes deterministic.
Authors: Feng Hui Wang, Qiong Wu, Ying Xi Wu, Sheng Yin Song
Abstract: Casing drilling technique which has been dramatically developing is a revolution in petroleum industry and has aroused great concerns. The fatigue failure of casing thread connection is a critical issue for using. Therefore, to study the fatigue failure of casing connection is an important issue for understand the life of casing drilling. For the notched element, how to estimate the life and which parameter (equivalent stress, equivalent strain ,or the strain in the root )represent the damage under fatigue condition is still a problem. The purpose of this paper is to investigate the fatigue life of notch element under multiaxial stresses and to find out the damage parameter so as to predict the life of notch element. First specimen were machined with the same notch geometer dimension as the casing thread connection, fatigue tests with tension and torsion loading were carried out by fatigue test machine , for stress levels designed to obtain S-N lifetime curve. The stress and strain for the connections subjected to proportional loading were analyzed by elastic-plastic finite element method. The stress-strain state for notched specimens subjected to constant amplitude proportional multiaxial loadings was also calculated and analyzed by the finite element model. Take the equivalent stress, equivalent strain and the strain by FEM in the root into the prediction model, the strain by FEM has a good agreement with the experiment.But the results from the equivalent stress and equivalent strain also in good agreement with the experiment and is thought to be a simple prediction way.
Authors: Xiang Zhao, Feng Hui Wang
Abstract: The mechanical properties, such as hardness and elastic modulus, are determined by a work of indentation. The work of indentation method works well even though pile up is observed because of the use of the energy dissipated or work done during the indentation. In this work, nanoindentation tests are carried out for the anode layer of half-cell structure of solid oxide fuel cells(SOFCs), the typical mechanical properties are derived by the work of indentation.
Authors: Ming Li, Feng Hui Wang, Ping Wei Chen, Kang Lou
Abstract: In the present paper, integrity assessment is made to the defects in weld metal zone of pressure piping of X52 steel using the two basic routes, FAD and CDF, which are provided in the European flaw assessment procedure SINTAP. Based on the experimental data various analysis levels of SINTAP are discussed, including the uncommonly used J-integral level in particular. Furthermore, to meet the need of the reliability assessment of pressure piping containing defects in engineering applications, probabilistic procedures are employed to obtain several probability curves with given survivability on the J-integral level with respect to the great scatter of the tested fracture toughness which is required in the J-integral level analysis.
Authors: Feng Hui Wang, Yong Zhang, Hong Wang
Abstract: In recently years, ruby fluorescence spectroscopy has been demonstrated as a powerful technique for monitoring residual stress evolution in the thermally grown oxide scale in thermal barrier coatings(TBC) systems. The measured residual stresses, in turn can be used to monitor evolution of damage in the coatings. Effective use of this technology for real time damage monitoring require the identification of strength in measured stresses that can be used as indicators of damage evolution.the present work focuses on studying the evolution of residual stresses in TBC systems during oxidation. The coating are atmospheric plasma sprayed (APS), the residual stress were measured at different oxidation time and to identify critical features so as to be used as indicators of failure in TBCs.
Authors: Feng Hui Wang
Abstract: Stress intensity factor of crack ahead of notch is important for understanding the failure of this kind structure. In this paper, a model is proposed to calculate the stress intensity factor of crack ahead notch configuration under bending load, the modeling value were verified by the data from literatures and experimental data of this paper, the trend of the value from model is agreement with that from experiments.
Authors: Xia Wang, Feng Hui Wang
Abstract: The performance of half-cell for anode supported Solid Oxide Fuel Cells (SOFCs) is necessary to wide use of SOFCs. This work is to study the reduction degree of anode and the residual stress changes that occur during hydrogen reduction on the different temperatures and in different times. The porosity of the specimens with oxidation is less than that of the reduction one. There is no Ni phase in the sample before hydrogen reduction. After hydrogen reduction on 1000°C for 6 hours, there is no NiO phase in the sample. It reveals the NiO has been reduced into Ni completely. We also investigate residual stresses in the electrolyte layer using X-ray diffraction. The residual stress value of electrolyte is about -844.1MPa before reduction. After hydrogen reduction on 800°C for 9 hours, the residual stress is decreased to -474.8MPa. So the reduction temperature can choose as 600°C and the reduction time can choose as 9 hours.
Authors: Jian Ye Huang, Feng Hui Wang
Abstract: Keeping the water-repellent stability of superhydrophobic surface is necessary in application. Based on the total reflection of Cassie interface and vacuum technique, the superhydrophobic stability of the lotus leaf and an artificial material was investigated. The results show that during the Cassie-Wenzel transition, primary wetting transition occurs at a certain pressure that in accordance with theoretical prediction. However, when the air film is entrapped between microstructures, stability of water-repellency was greatly enhanced, and part of the wetting transition can be recovered when the pressure was released. Due to the micro-and nanoscale hierarchical structures, the lotus leaf shows better water-repellent stability and dewetting property than the artificial superhydrophobic surface when the hydrostatic pressure was applied and released.
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