Papers by Keyword: Elastic Modulus

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Authors: Chao Sun, Zai Fa Zhou, Wei Hua Li, Qing An Huang
Abstract: In this paper, a direct and simple method to characterize the elastic modulus of individual layers for composite films by in situ measuring of MEMS test structures is presented. The structure is composed of a set of microactuators which contains a rigid plate with two supporting composite beams. A model is developed to describe analytically the relationship between the force and the deflection of microactuators by electrostatic measurements, and the elastic modulus of multi-layered beams with different widths are evaluated. FEM simulations are implemented to validate the accuracy of the relationship between the on-load voltage and the capacitance between the microactuator and the electrode on the substrate. Test structures are fabricated using CMOS-MEMS process and experiments are to be carried out soon.
Authors: Min You, Jia Ling Yan, Xiao Ling Zheng, Ding Feng Zhu, Jing Rong Hu
Abstract: The effect of the adhesive thickness and elastic modulus on the stress distribution in the mid-bondline of the adhesively-bonded steel/steel joint under impact loading is analyzed using 3-D finite element method (FEM). The results show that the stress distributed in bondline near the interface was significantly affected by the adhesive thickness and the elastic modulus. When the thickness increased from 1 mm to 2 mm, the values of all the stress components increased evidently along the upper edge of the adhesive but decreased significantly along the lower edge near the loading face. When the elastic modulus of the adhesive was increased, all the stresses increased along either the upper or the lower edge. It is clear that the suitable thickness and the elastic modulus of the adhesive are very important when the adhesively bonded joints subjected to the impacting load.
Authors: Bo Yuan, Qun Feng Liu, Cai Lin, Xiao Feng Chen
Abstract: In this paper, a high order strain gradient (HSGE) model is constructed to predict the bending size dependence of the elastic property of nanofibers under three-point tests. The model can be applied to explain the size dependency in bending test for polymeric nanofibers.
Authors: Xin Feng Wang, Qing Quan Liao, Fang Xie, Yi Tao
Abstract: Electrode printing screen is an important component in electrode printing manufacturing equipment. Its mechanical properties directly related to printing electrode precision and equipment life, so it is necessary for calculation of mechanics performance analysis. In this paper, by using material mechanics knowledge, the equivalent elastic modulus calculation formula of electrode printing screen is derived and can be applied to mechanical analysis and calculation of electrode printing screen.
Authors: Juan Zhang, Yuan Zhang, Ke Qiang He, Wei Gong Chen
Abstract: As an exploration and extension of load/unload response ratio theory, unload/ load response ratio theory (ULRR for short) is introduced firstly, and the relationship between ULRR (Y′) and elastic modulus (E for short) is obtained. Based on the basic theory of damage mechanics,the relationship between ULRR and damage variable (D for short) is set up and analyzed with the relationship between E and D. The unloading and loading experiments on a two-story structure carried out in the University of Naples in Italy are introduced;and calculated damage variable is compared with that calculated by Zhang Langping who put forward Weibull distribution as random distribution function. The results show that damage variable of the structure keep highly consistent with calculations of these two methods. Therefore, the relationship between Y′and D provides a new approach to a health assessment to catastrophic failure of large-scale structures and prediction of engineering.
Authors: Hong Chang Qu, Peng Zhang
Abstract: Concrete is a three-phase material consisting of cement paste matrix, discrete inclusions of sand (aggregate), and an interfacial transition zone (ITZ) between the matrix and the inclusions. In order to calculate the elastic properties of the ITZ of cement mortar, We model the material as a composite formed by a matrix with embedded spherical particles; each surrounded by a concentric spherical shell. With help of the generalized self-consistent method (GSCM), equations of bulk modulus and shear modulus of ITZ are deduced, and Elastic properties of ITZ are computed by using experimentally known elastic properties of the composite. It is found that the shear modulus of ITZ is about 50% of that of the cement paste matrix.
Authors: In Kyu Kwon
Abstract: Structural columns are very important members in steel buildings. An evaluation of fire resistance performance of the column is essential to sustain the structural stability in a fire situation. However, the length of columns is dependent on various architectural design variations. Therefore, the fire resistance can be different according to the length of column. In this study, to suggest the adequate fire resistance performance of structural columns by difference of length, an analysis was done based on an ordinary structural steels, SS 400, and hinge to hinge boundary condition. The result showed that the longer the column was, the less the fire resistance.
Authors: Xin Zhu Zhou, Jian Jiang Ding, Jian Jun Zheng
Abstract: Owing to their importance to the assessment of reinforced concrete structures, it is of great practical significance to predict the elastic moduli of concrete with interfacial cracks. The intention of this paper is to present an analytical solution for the elastic moduli of cracked concrete. According to the theory of stereology, the 2D scalar crack density is expressed as an explicit function of the aggregate area fraction and the central angle of interfacial cracks. For uniformly oriented and mutually interacted interfacial cracks, the effective medium method is used to derive the relative elastic moduli of cracked concrete. Based on the numerical results, it is found that the relative elastic moduli decrease with the increase of the aggregate area fraction and/or the central angle of interfacial cracks. It is also found that the relative elastic moduli are independent of the minimum aggregate diameter, the maximum aggregate diameter, and the aggregate gradation.
Authors: Yun Jae Kim, Ja Choon Koo, Seong In Moon, Young Jin Kim
Authors: Sung Rok Ha, Kyong Yop Rhee, H.H. Shin
Abstract: It is well-known that the mechanical properties of nanocomposites are better than those of conventional composites. One of problems in fabricating nanocomposites is a dispersion of nanoparticles in the composites. In this study, the effect of MMT content on the tensile characteristics of trifunctional silane-treated MMT/epoxy nanocomposite was investigated. It was found that the tensile strength and the elastic modulus increased by over 24% and 83%, respectively, as the content of MMT increases from 2wt% to 10wt%. The improvement of tensile strength and modulus with increasing content of MMT occurs because the reinforcing effect of MMT becomes greater than the deteriorating effect due to the interfacial debonding between MMT and epoxy as the MMT content increases.
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