Papers by Keyword: Bending Deformation

Abstract: Experimental studies of bending deformation of carbon - and fiberglass samples after 8-month exposure in full-scale conditions were performed and the modulus of transverse elasticity was determined. It was found that the influence of the external environment on fiberglass samples is more significant. For carbon fiber, there was an average decrease of 7.1%, and for fiberglass-by 14%. Modification of samples in ultrahigh frequencies (UHF) electromagnetic field reduces the negative influence of the environment: the values of the transverse elastic modulus of carbon fiber and fiberglass samples are reduced by 5% and 11%, respectively. It is shown that the UHF electromagnetic field in rational modes can increase the modulus of transverse elasticity of carbon fiber by (27-30)%, fiberglass – by (20.8-25.6)% with a significant increase in the uniformity of this parameter. Experimental studies of the bending deformation of carbon-and fiberglass specimens after 8-month exposure in natural conditions have been carried out, and the shear elastic modulus has been determined. It has been established that the influence of the external environment on fiberglass samples is more significant. For carbon fiber reinforced plastic, a decrease was noted on average by 7.1%, for fiberglass - by 14%. Modification of samples in a microwave electromagnetic field helps to reduce the negative influence of the external environment: the values ​​of the shear modulus of the prototypes of carbon fiber reinforced plastic and fiberglass are reduced by 5% and 11%, respectively. It is shown that the microwave electromagnetic field in rational modes allows increasing the transverse elastic modulus of carbon fiber reinforced plastic by (27-30)%, fiberglass - by (20.8-25.6)% with a significant increase in the uniformity of this parameter.

Abstract: TC4 titanium alloy plate was processed under multiple laser shocks and bending deformation was studied. A method was proposed to determine the curvature radius of bending deformation of metal plate under multiple laser shocks based on the theoretical model of curvature radius of bending deformation and the eigenstrain field was calculated by a modified finite element analysis method. Effect of shock wave peak pressure and the number of impacts on the curvature radius was studied. Results show that bending deformation increases rapidly at the beginning and then it stops growing. Bending deformation increases rapidly with the increase of the number of impacts and it cannot increase after three impacts.

Abstract: In a previous study, we showed the anisotropy of plastic strain due to the pearlitic transformation and proposed a hydrostatic pressure-dependent constitutive equation to describe this phenomenon. In the present study, we assess the validity of this model using a bending-tensile loading system to experimentally and numerically analyze and characterize the pearlitic transformation plasticity. First, the maximum bending deflections due to the austenite-pearlite transformation were measured under different loadings and then transformation-plasticity coefficients were determined. Furthermore, as was done for bending-tensile loading tests, the pearlitic transformation plasticity was simulated using Abaqus Standard under the same austenitization and loading conditions as in experiments, and the calculated results for pearlitic-transformation plastic deformation are compared with the experimental results. The results show that the transformation plastic deflection due to the pearlitic transformation decreases with increasing applied tensile stress. In addition, this behavior can be described by a hydrostatic pressure-dependent model in large-deformation theory.

Abstract: In various kinds of shape memory alloy (SMA), Fe-based SMA (Fe-SMA) shows smaller shape memory effect compared with the other SMAs. However, Fe-SMA shows huge advantages on the excellent formability, machinability, etc. Moreover, its production cost is cheaper than other SMAs; therefore, the alloy is attempted to be applied to structural members such as joints and dampers. Since bending deformation at higher deformation rate is generated in the members, especially the joints, due to impact force such as earthquake or wind, a clarification on the bending strength of the joints at various deformation rate is strongly required. In this study, at first, it is attempted that the bending strength and its rate sensitivity of the joints which consist of Fe-based SMA are experimentally estimated by the three-point bending test at various deformation rate. Then, the force balance equation is challenged to be derived to predict the bending strength.

Abstract: Three-point bending system with one end simple support and the other end fix support has been proposed to analyze the transformation plasticity (TP) behavior and obtain transformation plasticity coefficient. In this investigation two types of materials SCM440 steel and S45C steel have been studied. The specimens were heated to austenite temperature and the temperature kept constant for several minutes, then cooling and loading processes were performed. Austenite to martensite phase transformation with forced cooling for SCM440 steel and austenite to pearlite phase transformation with natural cooling for S45C steel due to bending stresses have been occurred. The deflections of specimen were measured during loading process. By obtaining the maximum deflection due to transformation plasticity, the transformation plasticity coefficient was determined.

Abstract: In this study, three-point bending test is conducted at various deformation rate by using a thin plate of Fe-based alloy. The rate sensitivity of its bending deformation during loading and shape memory effect by heating after unloading are investigated experimentally. The results obtained are summarized as bellows. (1) In the case where the quasi-static loading was applied, the positive rate sensitivity, which means the stress level increases with increasing the deflection rate, can be observed slightly. (2) It is hard to observe that recovery of deflection by SME depends on deflection rate under quasi-static loading. (3) In the case where the impact loading was applied, the positive rate sensitivity can be observed clearly.

Abstract: The newly proposed rotating bending process of metal tubes is a novel kind of Severe Plastic Deformation (SPD) process, which is expected to refine and control the microstructure of metallic tubular materials. The stress distribution and accumulated equivalent plastic strain of deformation part have a significant influence on the microstructure refinement and control of metal tubes during the rotating bending process. The present study focused on the analysis of stress and strain of deformation part during rotating bending process of metal tubes. The model of the deforming metal tubes was proposed. The formulas for determining the stress and accumulated equivalent plastic strain were successfully achieved by analyzing the deformation of metal tubes during rotating bending process.

Abstract: In this paper, with the thermal mechanical coupled method and the whole rolling process simulation result using as the initial thermal field, the thermal field and deformation of rail during cooling have been simulated, then rail pre-bending process is proposed according rail bending deformation curve during cooling The results show that the bending curve formula fitting by rail cooling deformation curve is accurate comparing with the actual situation. Moreover, pre-bending process is set by fitting formula, and the rail recovers straightly after cooling.

Abstract: To South-to-north water transfer project as the background, and based on the Peck formula, this paper educes the formula of settlement and internal force which caused by disturbance of the tunnel of the buried pipeline. Considering the different depths of the buried pipelines, the different diameter of the tunnel, the spacing interval between different tunnels and the depth of different tunnels and so on, this paper analyzes the effect of the twin-parallel-tunnels passing through construction on buried oil & gas pipeline. The research shows that the tunnel diameter has no effect on the width of surface subsider and the deflection of buried oil & gas pipelines, but it has great influence on pipeline internal forces. The spacing interval of tunnel has almost no influence on pipe deflection but has effect on the maximum internal force. Different depths of the tunnel contributes much to the rule of pipeline settlement and the distribution of internal forces, and it has greater influence on the internal force than on the pipe deflection . The relationship between the effect and the depth of the tunnels is non-linear. With the tunnel depth increasing, the hazardous conditions of the pipelines show significant improvement.

Abstract: The cooling process of heavy rail is the important step to the output, that the preflexed rail is cooled on the stepping-type cold bed which has been carried by the chain transmission device. We employed the finite element method to analyze the bending deformation of the U75V rail through natural cooling process, the effected factors including the rail side-laying on the cold bed, the latent heat of phase change, and the thermal radiation are considered in the analysis. In the paper, we discussed the establishment of the heavy rail cooling model, the cooling parameters and the boundary condition, and emphatically analyzed the rail bending deformation changes and its principles through the cooling process. The study of the hundred-meter high speed heavy rail can provide the theoretical foundation and reference value to the formulation of cooling technical parameters and preflex technical schedule.