Abstract: Based on the heterogeneity of rock, by using the RFPA2D, influene of the horizontal in-situ stresses on the distributions of plastic zones is discussed. The deformation and nonlinear gradual failure characteristics of circular roadway in deep rock mass as well as the displacement and the stress variation of the key position in the periphery of the roadway were analyzed, When λ>1, the plastic area was large-scale, but deflection more little , when λ<1, the plastic area was little-scale, but deflection increase. The study indicates that the stress concentration occurs in the periphery of the roadway after evacuation and plastic deformation zone engenders under the persisting stress of the surrounding rock, then the cracks appears and expands continuously, the broken rock zone appears at last and the intensity of the stress concentration decreases as well as the stress field shifts beyond.
Abstract: In this paper, according to the structure of warships, the equivalence method of the protective structure with reinforcing ribs is presented abided by the principal of equivalence in rigidity. The minimized model and the equivalence model of the protective structure with reinforcing ribs penetrated by projectiles are investigated in experiment and numerical simulations, and the results show that the equivalence method of the protective structure is reasonable. The reinforcing ribs are extensively used in protective structures, especially in ship structures. The reinforcing ribs are characterized in extensive distribution range and little weight of unit length, and have the main effect that the rigidity requirement of the structure is satisfied so that the structure has enough rigidity stability. However, the big and the small reinforcing ribs in actual structures originally have small size of the cross sectional area (CSA). According to a usual model research method, after an original structure is proportionally reduced according to the minimized proportion of one to four , the size of the CSA of the big and the small reinforcing ribs becomes smaller, and the shape of the cross sectional area is shown in Figure1. Under such circumstances, an experimental research on the dynamic response of the reinforcing ribs under the impact load has the characteristics of great difficulty and bad feasibility, and in addition, the reliability of reflecting target characteristic by a proportionally reduced model is very low. In order to study the action of the reinforcing ribs more objectively, the T-shaped cross section of the reinforcing ribs is converted to a rectangular cross section according to the principle of rigidity equivalence, and then, the action can be researched actually. The study method is given as follows.
Abstract: Nowadays in the market, there are many kinds of warm retention materials. Although each material has its own heat loss reduction, there should be methods for evaluating the warmth properties and giving out reliable results. In this paper, the warmth retention properties of three typical non-woven wadding were studied. On the basis of four warming related tests and analyses, the conclusions were got that after filming, because of existence of motionless air, their warmth retention properties increase obviously. In the same time, the air permeability of the three non-woven wadding decrease clearly because of the film on the wadding surface which obstructs air from flowing easily.
Abstract: Dynamic propagation of mode Ⅲ crack under variable moving loads on the crack surface is investigated using the theory of complex functions. Using the approaches of self-similar functions, the problems are readily transformed into Riemann-Hilbert problems. The paper presents a new mechanical model for dynamic crack propagation, in which the crack is under the conditions that the variable concentrated loads Pt3/x2 and Px/t move along x-axial with velocity β. At last, analytical solutions of stress, displacement and stress intensity factor are attained, respectively.
Abstract: In this paper, a crack analysis model based on finite element method and virtual crack extension technique was proposed to investigate the occurrence of surface fracture of polyethylene acetabular cup under gait loadings. To this, a simplified hip joint model was created for facture analysis. The stress intensity factor (SIF) at crack site was estimated and used to evaluate the propagation of the surface crack. Current results show that under normal gait loading, the SIF at crack tip within polyethylene cup was predicted to be lower than the fatigue threshold of polyethylene material. However, under the heel strike instant, the crack tip SIF exceeds the fracture strength of polyethylene subject to gamma radiation, which may drive the crack to propagate to final fracture. Overall, the presented analysis model has demonstrated the probability of severe surface damage occurring in polyethylene cup under impact walking conditions. This provides a valuable reference to the improvement of the mechanical properties or design of bearing materials in clinical orthopedic application.
Abstract: The effects of HCO3- concentration on CO2 corrosion for Q235 steel were investigated by weight loss tests and potentiodynamic polarization curve and EIS (Electrochemical Impedance Spectroscopy) techniques. The results showed that the corrosion rate of Q235 steel decreased wih on increase of HCO3- concentration when [HCO3-] was lower than 600mg/L. An evident active-passive behavior exhibited in anodic process at 1000mg/L·HCO3- .The cathodic reactions were promoted by increasing [HCO3-] when it reached 1000mg/L, H2CO3 and HCO3- become the most important cathodic reaction. Anodic behavior was an active process at higher [HCO3-] concentration and the anodic current density increased with the increase of [HCO3-] concentration.
Abstract: By the theory of complex functions, dynamic propagation problems on symmetrical mode Ⅲ interface crack were researched. The problems considered can be very facilely transformed into Riemann-Hilbert problem by the methods of self-similar functions, and the general expressions of analytical solutions for the surfaces of mode Ⅲ symmetrical interface crack subjected to motive variable loadings Px2/t2 and Pt3/x2 were obtained, respectively. After those solutions were utilized by superposition theorem, the solutions of arbitrary complex problems could be attained.
Abstract: The thin films of copper 2, 9, 16, 23-tetra-iso-propoxy phthalocyanine (i-pro-CuPc) were prepared by spin-coating technique. The surface morphology and spectroscopy property of the thin films were characterized by AFM, UV-Vis and FT-IR spectra. The results show that good films can be obtained under certain spinning speed. The gas-sensing properties of the multilayers to three alcohols gas were measured at room temperature. The spin-coating thin films exhibited high sensitivity and rapid response- recovery characteristics to these gases. The response and recovery time of the thin films to 30*10-6 v/v of C2H5OH vapor is only 28 s and 55 s, respectively.
Abstract: Transparent conducting Ti-Al co-doped zinc oxide films (TAZO) with high transparency and relatively low resistivity have been successfully prepared by direct current magnetron sputtering. The effect of sputtering power on the structural, optical, and electrical properties of Ti-Al co-doped films were investigated. The XRD patterns show that the thin films were highly textured along the c-axis and perpendicular to the surface of the substrate. The electrical resistivity decreases when the sputtering power increases from 40W to 120W. When the sputtering power is 120w and the target-substrate distance is 60mm, it is obtained that the lowest resistivity is 3.23×10-4Ω·cm.The lowest stress is 0.864Gpa in all the deposited films. All the films present a high transmittance of above 91% in the visible range.
Abstract: After studying the slab of the CSP, the composition segregation and the finished products, we drew the conclusion that the low magnification of CSP thin slab is denser, columnar grain more developed; Loose and segregation exist while the segregation is smaller than traditional one. From the surface to the center, obvious carbon segregation exists: nearby the center is negative segregation and in the center is positive segregation. With the increase of carbon content, carbon segregation also increases. The carbon content of tundish is different from that of rolled steel coil --namely, the carbon content of the rolled coil is significantly lower.