Prof. Liyang XieSchool of Mechanical Engineering,
Northeastern University, China
Speech Title: On Probability Distribution of Material Strength and Robust Parameter Estimation
Abstract: Material strength is a random variable with a threshold much greater than zero. Therefore, the commonly used normal distribution, log-normal distribution and two-parameter Weibull distribution are not appropriate. This paper uses the three-parameter Weibull distribution to describe material strength, presents a simple parameter estimation method according to small size samples. The method is based on the error performance that the differences between the scale parameter values calculated with the different sample values based on erroneous location parameter values and shape parameter values are the parameter values dependent. By minimizing the differences, the right location parameter and parameter are identified, and the scale parameter is obtained. To guarantee the robustness of the parameter estimation result, a robust minimum value critical is applied. Simulated parameter estimation results show that this method is better than the conventional maximum likelihood method and least squares method.
Keywords: Material strength, Three-parameter Weibull distribution, Parameter estimation, Small size of sample.
Prof. Ambrish SinghSchool of New Energy and Materials,
Southwest Petroleum University, China
Speech Title: New Materials and Methods to Monitor Corrosion
Abstract: Corrosion is a global problem causing accidents, failures and shutdown of the industries and oilfield reservoirs. The worldwide economic loss is enormous due to corrosion and still there is no proper solution to mitigate it. All the available methods can delay or mitigate the process of corrosion for some time but cannot stop it fully. Use of inhibitors is one of the available methods which are cheap, and easy to use. Modern methods play vital role in elucidating the mechanism of corrosion inhibition, the determination of corrosion rate, and elucidating the mechanism of corrosion inhibition. The talk will mainly focus on modern electrochemical techniques including Electrochemical Impedance Spectroscopy (EIS), Potentiodynamic Polarization (Tafel,) and Electrochemical Frequency Modulation (EFM) as an effective method to understand corrosion inhibition mechanism. To. explore additional information through electrochemical frequency modulation, new experiments were conducted to observe a trend with and without inhibitor. Modern methods are not complete without discussing the micro-electrochemical techniques including Scanning Electrochemical Microscopy (SECM), Scanning Kelvin Probe (SKP), Localised Electrochemical Impedance Spectroscopy (LEIS), and Scanning Vibrating Electrode (SVET) that provide the information about the localized electrochemical nature. Surface analyses are also important to confirm the mitigation phenomenon of the inhibitor. The importance of different methods including scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle studies shall be highlighted to vindicate the mechanism of corrosion mitigation. Moreover, to confirm the data obtained from the experimental studies the significance theoretical studies such as including DFT and Molecular Dynamic studies will also be highlighted.
Keywords: EFM, Inhibitor, SVET, AFM, SKP, LEIS.
Assoc. Prof. Xu LiHubei Key Laboratory of Theory and Application of Advanced Materials Mechanics,
School of Science, Wuhan University of Technology, China
Speech Title: Experimental Study and Characterization on the Mechanical Behavior of Uncured Rubber under the Planar Tensile Deformation
Abstract: The overall mechanical behavior of uncured carbon black filled was investigated under planar tension at finite deformation. Experimentally, thin sheet specimens were manufactured and submitted to different scenarios of cyclic tensile loading. A non-contact optical technique, called Automated Grid Method, was employed to get the uniform deformation in the center region of rubber sample, while the displacement of whole field is heterogeneous in planar test. Consequently, the precise stress-strain responses at different strain rates were achieved. These results indicate the complicated properties of uncured rubber associating with hyper-elasticity, viscous flow, hysteresis and Mullins effect, which are almost dependent on strain rate. On the other hand, by consideration of the kinematic decomposition taking account into hyper-elastic energy storage and plastic flow criterion, an improved parallel network model was put forward to characterize the nonlinear mechanics of this material. The fitted results consist well with measured curves of both planar and uniaxial cyclic tests. Moreover, the prediction ability of constitutive model was evaluated by comparison with data issued from the single loadings and relaxation conditions. This work would be beneficial for gaining a satisfactory understanding on the multi-modes performance or mechanism of uncured rubber materials.
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