Papers by Keyword: Stress Field

Abstract: Basing on coupled thermal conduction and groundwater advection conduction, this paper analyzed the effects to the temperature field and the stress field caused by the Vertical U-tube exchange used in ground source heat pump. And then this paper analyzed the relationship between heat influence radius and thermal conductivity and groundwater advection velocity. Also, we obtained the simple formula which can estimate the heat radius of influence. Basing on coupled thermal conduction and solid mechanics analyzed the stress field caused by thermal expansion. The results show that: without groundwater advection, the heat radius of influence linear correlate to the thermal conductivity; the radius will obviously expand when the groundwater advection velocity is not too small; the stress field caused by thermal expansion near the U-tube is much larger than the farther region and it will trends to balance with the distance increasing.

Abstract: In the ANSYS finite element analysis with large-sized computer there is always a need for repeatedly modeling some similar questions. By using both the ANSYS for a secondary development platform and visual basic 6.0 for a visual operation interface, an APDL language is generated, so that a parametric modeling can be realized. With the help of the created software, the temperature and stress field contours of brake disc can be calculated and the efficiency of the calculation is enhanced.

Abstract: The excessive residual stress induced by quenching in steels will easily result in distortion and failure of parts. In order to obtain the more suitable quenchant, quenching process of Cr12MoV steel with different mediums involving water and oil are simulated, respectively. In present paper, the influence of nonlinear surface heat transfer coefficient, thermodynamic parameters and latent heat are considered comprehensively. The distribution of temperature, microstructure, hardness and residual stress after quenching for Cr12MoV steel are simulated by DEFORM finite element software. According to the results mentioned above, the variations of each field of the steel are analyzed.

Abstract: When crossing difficult terrain or extreme regional geological conditions encountered, there are difficulties in laying road routes, the spacing between two adjacent tunnels is limited. Neighborhood tunnel is a form of tunnel structure between separate and arch ones, less affected by the topography. It is more conveniently and easier to control the cost. Surrounding rock deformation mechanism with construction of three-step method is more complex, and therefore a reasonable means of construction technology and support is essential. Taking a certain neighborhood tunnel highway engineering background, aimed to provide guidance for follow-up monitoring and support, we use numerical simulation software FLAC^3D on three-step method excavation construction. Rational creep analysis of geotechnical model and calculation parameters is selected. It helps to calculation and analysis the mechanical response of tunnel surrounding rock characteristics and clarify the tendency of displacement and stress fields.

Abstract: This paper analyzed the temperature field of one large mining machinery disc brake during normal braking conditions in ANSYS. Basing on the sequential coupling methods, analyzed the brake disc's thermal stress distribution and changes. According to the analysis results, estimated its thermal fatigue life.

Abstract: Most bones are anisotropically loaded and seem to be adapted to the anisotropic stress or strain field by changing the anisotropy in their microstructure. Osteocyte (OCY) is believed to play an important role as a mechanosensor and regulator of modeling and/or remodeling orchestrating osteoblast and osteoclast activity to make bone suitable to resist the mechanical environment. In general, osteocytes sense magnitude of stress (strain) applied upon the bone and then work as a trigger to change bone mass to adjust bone’s mechanical function to the stress field. This structural optimization is an important aspect of the bone functional adaptation; another inevitable optimization might be achieved through the change in intrinsic material anisotropy including the preferential c-axis orientation of biological apatite (BAp) crystal. To achieve this adaptation through material anisotropy, osteocyte needs to be a mechanosensor which can detect anisotropic stress field. In the present study, osteocyte lacunae and canaliculi in the mid-diaphysis and the distal part of the rat femur were stained by a fluorescein dye for visualization and analysis. The mid-diaphysis shows greater degree of the preferential c-axis orientation of BAp crystal than the distal part in relation to the magnitude of uni-axial stress field. It was found that the osteocytes in long bone preferentially align along the bone long axis and the degree of alignment is greater in the mid-diaphysis than in the distal region, which seems to be effective for the sensation of the site-dependent specific stress field applied on the long bone.

Abstract: In rock and soil media, seepage and stress fields are interacting and interrelated system. Analyzing on mechanism of seepage field acting on stress field and on mechanism of stress field acting on seepage field in rock and soil media, it established mathematical model of seepage field with stress field acting on and mathematical model of stress field with seepage field acting on. According to coupling mechanism, it gave mathematical model of coupling seepage field and stress field and corresponding steps of FEM

Abstract: The present study evaluate the stress field during the cracking caused by applying pressure loading to this ends of material. Our problem formulated by using the brittle material (concrete, ceramic, glass,...) having; elasticity modulus E and Poissons ratio (υ).The fundamental idea of this work rests on the determination of the influence of the dislocation presented near of the main crack on this cracking. This problem can be treated by finite element method while using Software (ABAQUS). One uses a square plate from element fissured at his end (semi-infinite) and a dislocation in the vicinity of the main crack, with various distances between the two cracks (main crack-dislocation), for each distance we have stresses can be found at the end of the main crack. After the determination of these latter, we deduced that the presence of dislocation influences largely on the propagation of cracking by amplification or reduction of this propagation.

Abstract: In order to investigate the effect of microscopic structure on fatigue behavior of nanoscale components, a resonant fatigue experiment is conducted using a nanocomponents specimen where the test section is composed of a single crystalline Si substrate, a 200 nm thickness Cu polycrystalline film and a SiN amorphous layer. In the specimen, only the Cu portion plastically deforms because the yield stress is lower than those of other materials. The shape and the crystalline orientation of each grain on the surface of Cu portion are specified by means of EBSD. Although crystallographic slip bands with a width of a few tens of nanometers appear only in a grain of Cu portion, the grain is different from that expected by the Schmid factor. A FEM analysis, which takes into account the deformation anisotropy of grains, reveals that shear stress to generate slip bands is concentrated on the grain owing to the deformation constraint by neighboring crystals and components.

Abstract: The present study evaluates stress fields, the stress intensity factor and energy release rates at the time of the cracking in a composite material. Our problems are formulated using two materials having different parameters such as the shearing modulus and the Poissons ratio. After having determined the displacement and stress fields, one homogenized the latter in order to allow comparing the results with those of other researchers. During the propagation of the main crack, the surrounding dislocation induces two effects: amplification effect which increases the stress at the main crack-tip and a shielding effect which reduces the propagation of the main crack. Finally, Energy Release Rates (ERR) associated to the different transformation inside the damage zone is evaluated on the basis of the superposition of all energies: the energy due to the main crack, the energy due to the existing dislocation and the energy due to the interaction.