Papers by Keyword: Elastic Modulus

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.

Abstract: In paper describes a method of optimization the stress state of an elastic beam, subjected to the simultaneous action of the central application of concentrated force and bending moment. Optimization method based on solving the inverse problem of the theory of elasticity of inhomogeneous bodies, the essence of which is to determine the law of changing the modulus of elasticity on the beams height for which stress state will be given.

Abstract: As one of most widely used structure, the behavior of masonry is influenced by its composition especially the mortar. In this paper, a series of compression tests was carried on masonry both with mortar (MP_m) and without mortar (MP_ds). Based on the results, the ultimate compression strength and elastic modulus has been compared firstly; after that, the failure mode of each prism was achieved, finally a finite element model was built for the numerical analysis on MP_ds. Results showed that compared with the MP_m, the elastic modulus of MP_ds has been reduced 30% which means the erosion of mortar should be considered when research on the historic masonry structures. The finite element model can simulate the compression strength and failure mode accurately, which showed great potential for the further parametric analysis.

Abstract: The properties of the concrete with super-fine steel slag were compared with those of the pure cement concrete. Results show that the concrete with 20% super-fine steel slag has similar compressive strength, elastic modulus, and permeability with the pure cement concrete at the age of 28 and 90 days. The addition of super-fine steel slag tends to decrease the initial slump of concrete, but it has a good ability of prevention of slump loss. The concrete with super-fine steel slag has similar anti-carbonation capacity with the pure cement concrete. The concrete with 30% super-fine steel slag has lower compressive strength, lower elastic modulus, and higher permeability than the pure cement concrete.

Abstract: Human teeth are exposed to various chemical and mechanical factors. From mechanical point of view it includes attrition, abrasion or their combination. Teeth and dental restorative materials are subjected to normal and shear loads. Therefore the contact-based stresses during mastication and teeth wear are of considerable importance. In order to study wear behavior of enamel, dentine and two dental restorative composite materials scratch test at various contact conditions was employed. Hardness and elastic modulus were measured using nanoindentation with spherical and pyramidal indenters. Residual wear tracks were observed using laser scanning confocal microscopy.

Abstract: The lattice constants of crystal are the basis of the valence electron structure calculation with the bond length difference method of the empirical electron theory of the solid and molecules. However, the lattice constants change with temperature and pressure. In this paper, according to the nature of thermal expansion of crystal and generalized Hookes law, the relationships among lattice constants, temperature and pressure are established by using linear thermal expansion coefficient and elastic constant. Taken the lattice constants of hexagonal graphite as an example, the calculation results agree with experimental data greatly, which prove the viability of this calculation method.

Abstract: This paper investigates the mechanical properties of potassium dihydrogen phosphate (KDP) crystals with the aid of nanoindentation using a conical diamond indenter. It was found that when unloading is after the first pop-in, the common method of obtaining elastic modulus from the unloading curve of nanoindentation is no longer applicable, because the unloading is inelastic. The study revealed that the pop-in could be due to dislocation nucleation and propagation, and that the first pop-in occurs under a stress below that of the major dislocation burst. Hence, the macroscopic yielding point, which is usually regarded as the onset of plasticity of a material, is nanoscopically not a critical point of the first dislocation in KDP. The study found that the elastic modulus of KDP indenting on its (001) plane is 52.8±3.8GPa. The hardness of the material is 1.89±0.05GPa.

Abstract: A virtual material model of joint interfaces was established based on the Hertz contact theory and fractal theory, this model was improved by considering the influence of the elastic-plastic deformation of asperities and ameliorating the calculation methods of the elastic modulus. The simulation results of elastic-plastic considered and elastic-plastic unconsidered were compared, moreover, the finite element simulation results and experimental results were compared to fully explain the necessity of considering the influence of the elastic-plastic deformation and the the correctness of the method to calculate the elastic modulus. The research suggested that under a same load the elastic modulus of the model considering the influence of the elastic-plastic deformation was slightly larger than the un considering one, which means it could describe the characteristics of joint interfaces more accurately.

Abstract: The research of the nano-mechanical properties on mono-crystalline silicon by nanoindention technology is reported in this paper . Using the calculation method given by Oliver and Pharr, the hardness and the elastic modulus of mono-crystalline silicon are gained from the load-penetration depth curve. The simulation on mono-crystalline silicon in the plastic phase is carried out by ABAQUS. Based on the bilinear constitutive law and approximate relationship between the hardness and the yield strength, the obtained load-penetration depth curve through the finite element method is compared with the materials actual load-penetration depth curve and good correlation is achieved.

Abstract: Application of Digital image correlation method (DIC) to measure the elastic modulus and Poisson ratio of rubber under compression is investigated in this paper. Surface images of the rubber surface subjected to various loading were captured using a CCD camera. DIC is subsequently used to obtain displacement field by correlating the images captured before and after deformation, and then the average compression strain is obtained by fitting the displacement using linear plane. The slope of each set of applied stress versus measured strain data is calculated by least-squares linear regression. The elastic modulus and Poisson ratio obtained from DIC, are compared to that determined from the dial gauge, which shows that they are in good accordance with existing data. Experimental results clearly show that DIC is suitable for accurate measurement the elastic modulus of rubber.