Papers by Keyword: Loading Mode

Abstract: Metal/polymer joints as well as metal/metal joints bonded by epoxy adhesive have been widely used for automotive, electrical device and others. In the present study, the adhesion strength of a stainless-steel/epoxy joint was evaluated by using of the shear test and the 4-point bending test. Three kind of the surface finishing condition of the stainless steel were selected, and the effect of the surface morphologies of the interface on the adhesion strength in the metal/epoxy joint was investigated. The relationship between the interface morphology and the loading mode in the metal/epoxy joint was discussed.

Abstract: The aim of this study is to discuss an effect of stress ratio and loading mode on high cycle fatigue performances of extruded magnesium alloys. Axial loading fatigue tests under three conditions of stress ratio, R, of 0, -1 and-1.5, and also rotating bending fatigue tests have been performed in laboratory air at room temperature using hourglass shaped specimens of AZ31, AZ61, AZ80 and T5-treated AZ80 alloy. From the experimental results, some materials showed a specific stepwise S-N curve on which two knees appear. The shape of S-N diagram depended on a kind of tested materials, applied stress ratio and loading mode. It was suggested from the detail observation of fracture surface that fatigue crack initiation mechanism changed from a twin-induced failure mode at high stress amplitude level to a slip-induced one at low stress amplitude level. This transition was determined with the relation between the minimum stress during a fatigue cycle and the compressive yield stress at which deformation twin occurs.

Abstract: Based on the solution of one-dimensional consolidation model of T-shaped bidirectional soil-cement deep mixing column composite foundation and its calculating program deduced by the separation of variables and Laplace method. This paper discussed the consolidation and settlement characteristics of composite foundation under the conditions of different loading modes, foundation reinforcement modes, diameter of enlarged pile head and pile spacing. The results indicate, the soil layer in the region of enlarged pile head hardly be influenced by above factors, the lower soil layer and soft substratum soil are influenced greatly. Loading mode has a large effect on the consolidation, when loading instantaneously, the rate of consolidation is faster than that of loading constantly. The consolidation and settlement behavior of composite foundation reinforced by T-shaped bidirectional soil-cement deep mixing column and traditional bidirectional deep mixing column is much better than the original natural foundation. When the other parameters stay the same, consolidation degree and total settlement decrease with the increase of enlarged pile head diameter. With the increase of pile spacing, consolidation rate of the composite foundation decreases significantly, but the settlement value increases rapidly on the contrary.

Abstract: A bio-robot treats the living animal itself as the robot-moving carrier, which possesses good mobility and adaptability even in complicated non-structured environments. As one of the flyable bio-robots, pigeon-robots have been studied for several years. However, how to arrange the equipments on board effectively to minimize the impact to pigeons natural flight has not been considered. In this study, we estimated the bearing capacity of a pigeon during takeoff by increasing the weight gradually. Different loading modes have also been compared to find a rational way to reduce the influence of the loading to flyability. These results are expected to be helpful to the design of pigeon-robots.

Abstract: This work aims to investigate parameterized modeling and a different mode of loading with finite element analysis for flat end mill. A loading mode is chosen according to the cutting force model of overall end mills. Normal and shear stresses which calculate from the cutting force experiments are loaded on the rack face of flat end mill. The stress distribution of end mill in high-speed cutting is obtained by finite element analysis. It is shown that the maximum stress is located at major flank face near the tool tip, rather than the nose of tool and the chisel edge. It shows the tool breakage mechanism in the local region. In the end, we compared the finite element analysis results with the experiment ones. It indicates that the analysis results agree well with the experimental data. Therefore, the proposed loading mode is available.

Abstract: This document deals with the whole process compression model test on 12 short columns of separation concrete-filled steel tubes (CFST) which are subjected to eccentric compression on the non-separation side. The experimental parameters include the separation ratio and the eccentricity ratio. The results show that the separation ratio and the eccentricity ratio will influence CFST components’ mechanical properties which contain the relationship of load-strain amd load-deformation, that especially embodied in the nonlinear stage. When compressed on non-separation side, the confinement of steel tubes to core concrete will be continuously weakened and the ultimate load capacity of the components will be decreased obviously with both the separation ratio and the eccentricity ratio increasing gradually. But it less serious which compare with that compressed on separation side.

Abstract: Abstract. Based on the concept of energy design, pushover analysis and elastoplastic dynamic response have been made under the earthquake. It is seen that the loading mode plays an important role in the pushover analysis. The loads in the pushover analysis distribute along the height of the structure that should reflect the distribution of the inertial forces under the earthquake so that the calculated displacements have a good accuracy in contrast to the real displacements. Only in such a way, the result by pushover analysis method is credible. On the other hand, it is found that the high order vibration modes can not be neglected in the pushover analysis for a continuous rigid frame bridges with long span and high piers. However, the bridge design codes have not told how to consider the effect of high order vibration modes. A simplified loading mode is then proposed in this work. A contribution ratio of vibration mode is defined to indicate whether the vibration mode should be considered or not in the pushover analysis. The proposed loading mode is applied to a real continuous rigid frame bridge with large span and high piers. The dynamic response and aseismatic property are evaluated and discussed. In addition, the results by pushover analysis are compared to the results by non-linear time-history analysis. The result shows that the high order vibrational modes indeed have a pronounced influence on the result. The proposed loading mode can give a reasonable result.

Abstract: Reactive Powder Concrete(RPC) is a cementitious material that exhibits high performance properties. Brittle failure mode usually appears when it is subjected to high or complicated stress. The fragility performance of RPC can be great improved if efficient confinement is provided. In this paper, four RPC-filled steel tube stub columns under axial loads were analyzed using the finite element program ABAQUS. Two different axially loading modes were considered. The analysis results were compared with the results of the tests. It was found that the FEM models can predict the force-displacement relationship of such columns with acceptable accuracy.

Abstract: A thermo-mechanical coupling model for the rough surface is established. The model considers friction contact between a rigid flat plane and a rough surface based on 3D fractal theory and allows the analysis of the effects of elastic-plastic deformation of rough body and the interplay among asperities. The contact pressure distribution for the static state beneath different loading mode and for the dynamic state in the presence of the frictional heat flux is found. The results show the fluctuation of the average contact pressure during the process of loading is related to the velocity of loading. The synthetical function of multiple factors such as the thermal deformation, the rising temperature, the interaction between asperities makes the complicated relationships among the maximum temperature, the maximum contact pressure and the real contact area.

Abstract: A typical mechanical character of rock is that the tensile strength is far less than the compressive strength. Meanwhile, the test data of tensile strength is very dispersive. Because the direct tensile tests always result in failure due to the difficulty in clamping the rock sample, the splitting test is used to determine the tensile strength of rock. There are four kinds of loading modes in the splitting test in actual laboratory test: angle pad splitting, round pad splitting, aclinic loading platen splitting, arc loading platen splitting. In this paper, the direct tensile test, the splitting test and the influence of different loading modes on rock tensile strength were studied. In order to study the stress distribution, the progressive splitting failure process was numerically modeled under the four kinds of loading cases by the Realistic Failure Process Analysis code (RFPA2D). Results show that the stress states under angle pad splitting, round pad splitting are similar to the stress states under diametrical compressive state. Regarding that the round pad splitting test is easy to implement, and its numerical results are also stable relatively, the round pad loading mode was suggested to be adopted.