Advances in Fracture and Materials Behavior

Paper Title Page

Authors: Z.N. Yin, X.S. Ma, Tie Jun Wang
Abstract: Split Hopkinson Pressure Bar (SHPB) experiments are carried out to study the deformation behavior of acrylonitrile-butadiene-styrene (ABS) resin at elevated temperature and high strain rate. The temperature and strain rate considered are 293K and 343K and 8.0×102s-1, 2.7×103s-1 and 1.0×104s-1, respectively. The curves of engineering stress and strain at different temperatures and different strain rates are experimentally obtained. The effects of temperature, strain rate and the fraction of ABS on the deformation behavior of ABS resin are discussed in detail. Then, a rate and temperature dependent phenomenological constitutive law for ABS resin is developed.
Authors: W.C. Lee, Chae Sil Kim, H.O. Choi, Y.G. Jung, Jung Il Song
Abstract: This article proposes a novel simulation technique to predict the reasonable dynamic characteristics of a suspension seat for heavy machinery using a commercial multibody dynamic analysis code, ADAMS. The dynamic model is simulated with the specific condition such as sinusoidal and sweep input. The experiment test for actual suspension seat is conducted for reviewing the dynamic simulation model with same input condition. As the simulation results shows good agreements with experimental test results, the dynamic analysis model is reasonable and will be very helpful for predicting the dynamic characteristic for the suspension seat for heavy machinery and for designing the other type seats with the other suspension mechanism types.
Authors: Bin Li, Zong De Liu, Li Ping Zhao, Yi Min Ma
Abstract: Molybdenum coatings are commonly used in the industry for protection against wear. With an aim to investigate the erosion properties of this coating, molybdenum coating was sprayed onto both AISI 1045 and nickel-based superalloy (GH3039) substrate by electro-thermal explosion ultra-high speed spraying process. Phase composition, microstructure and microhardness of the coatings were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and microhardness tester, respectively. Erosion tests of the coating at different particle impingement angel and material sample temperature were performed on a GW/CS-MS type tester. The high erosion resistance of the coating can mainly be attributed to high hardness, low porosity and metallurgical bonding between the coating and the substrate.
Authors: Shi Xiang Hou, Zong De Liu, Dong Yu Liu, Li Ping Zhao, Yi Min Ma
Abstract: A new method, electro-thermal explosion ultra-high speed spraying, was utilized to produce the Mo-Si or Mo-Si-B coatings. Experimental results showed that submicron-grain pure MoSi2 phase coating and boron alloyed MoSi2-MoB2 multiphase coatings were in-situ synthesized on GH3039 nickel-based superalloy substrate. Erosion-resistance test of GH3039 nickel-based superalloy and MoSi2-based coatings were performed under high temperature(800°C) with GW/CS – MS erosion wear tester. Quartz sand was employed as erosive material. Experimental results showed that the erosion-resistance of the MoSi2-based coatings is better than that of the GH3039 nickel-based superalloy.
Authors: Jing Jing Liu, Zong De Liu, Li Ping Zhao
Abstract: With aim to investigate the effect of the content of Ni on erosion behavior of the TiC-xNi coating at elevated temperatures, The TiC-xNi (x=0, 5, 10, 15 , 20wt.%) composite coatings were in-situ synthesized on nickel-based alloy substrate by the self-developed electro-thermal explosion ultra-high speed spraying (EEUSS) device with the cored wire. Erosion properties of the coatings were assessed by the erosion tester under 90° incidence angle and 650°C. X-ray diffraction (XRD) and microhardness tester were used to investigate the coating phases and microhardness. The coatings consisted of TiC phase and Ni binder phase, as well as the residual C. The microhardness of TiC-xNi coating with the Ni content from 5 wt.% to 20wt.% decreased with the increase of the content of Ni. Elevated temperature erosion test indicate that the spiculate quartz particles impact the surface of the coating which lead to the loss of material. The erosion resistance of the TiC-xNi coatings increased first and decreased afterwards with the increase of the content of Ni. The relative erosion resistance of coating with 10 wt.% Ni addition is excellent which is about 2 times than that of TiC-20Ni coating under 650°C and 90° incidence angle.
Authors: Chao Hua Fan, Yu Ting He, Hong Peng Li, Feng Li
Abstract: Genetic algorithm is introduced in the study of network authority values of BP neural network, and a GA-NN algorithm is established. Based on this genetic algorithm-neural network method, a predictive model for fatigue performances of the pre-corroded aluminum alloys under a varied corrosion environmental spectrum was developed by means of training from the testing dada. At the same time, a fuzzy-neural network method is established for the same purpose. The results indicate that genetic algorithm-neural network and fuzzy-neural network can both be employed to predict the underlying fatigue performances of the pre-corroded aluminum alloy precisely.
Authors: Koichi Minagawa, Keisuke Hayabusa, M. Ridha, Kenji Amaya, Shigeru Aoki
Abstract: An inverse problem is analyzed where corrosion of rebars is detected from a small number of potential data measured at the surface of concrete structure. Because the shape and number of corrosion in rebars are not known in advance, usual inverse analysis method in which the shape and number of corroded part are assumed is not available. In this research, the genetic algorithm (GA) is employed without any assumption. The fitness in the multi-step GA is defined as the inverse of difference between experimental and numerical potential values, and is evaluated by the boundary element method (BEM). To reduce the computational time, the net elements, which have been recently developed by the authors for corrosion analysis of net structures, is used together with the multi-step GA. It is shown by a simulation that the multi-step GA with net elements are successfully employed in the inverse analysis.
Authors: Kazuhiro Suga, Masato Yoshida, M. Ridha, Shigeru Aoki
Abstract: This study proposes a monitoring method for corrosion on reinforced concrete structure using inverse analysis approach. At first, we define an inverse problem to identify the real and imaginary parts of the concrete conductivity and the impedance between concrete and steel. The observation of the inverse problem is the electric potential on the concrete structure surface when the AC impedance measurement is performed. The observation condition, such as layout of observation point and type of observation, of the inverse is optimized. The optimization is achieved by minimizing the average of eigen values of a posteriori estimate error covariance matrix based on the Kalman Filter estimation algorithm. We show a numerical simulation to solve the inverse problem on the optimized observation condition to evaluate the effectiveness of the condition. The simulation shows the real parts of the concrete conductivity and the impedance are well identified but imaginary parts of them are not. To overcome this difficulty, we evaluate the sensitivity of the imaginary part of the impedance to the real part and the imaginary part of the electric potential. We find the possibility that the observation of the imaginary part of the electric potential improves the estimation. Finally, a numerical simulation is performed under the optimized observation condition considering the above discussion. In the numerical simulation shows that considering the sensitivity of the parameters to the potential improves the solution on the inverse problem.
Authors: Shigeru Aoki, Kenji Amaya, Satoshi Imamori
Authors: Hajime Adachi, Kazuhiro Suga, Masanori Hayase, Shigeru Aoki
Abstract: A numerical simulation of corrosion in a tube is performed with the solution velocity effect taken into account. A two dimensional tube, the cross-section of which is widening or narrowing with increase in distance, is considered. The velocity distribution in the tube is calculated with the Finite Volume Method (Open FOAM), and the derivatives of velocity with respect to the distance from the tube wall is determined at any location of the tube. The corrosion rate of the tube wall is estimated under the assumption that the corrosion rate depends on the velocity gradient, i.e. , it is estimated by solving the Laplace equation under the boundary conditions given with the polarization curves measured under various velocity gradients. The Boundary Element Method (3D-CAFE) is used to solve the Laplace equation. It is shown that the distribution of corrosion rate, including the maximum corrosion rate and its location, is different between the widening and narrowing tubes, even if the average velocities in the two tubes are equal.

Showing 201 to 210 of 240 Paper Titles