Papers by Keyword: Pre-Stress

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Authors: Heng Sheng Lin, Sheng Chi Tsai, Yuan Chuan Hsu, Ming Che Hsiao, Chia Chou Ke, Bean Yin Lee
Abstract: The manifolds of airbag inflator were used to be produced by sheet-metal forming. It comprised at least eleven forming stages to achieve its final shape. Uneven wall thickness and poor dimensional accuracy were the common defects because the planar anisotropy of sheet-metal caused earing on the cup rim. In this study, the cup-shape workpiece is obtained from backward-extrusion of billets, followed by two stages of end-forming of tube and three stages of hole-piercing. During the end-forming production, the tool life of the first forming stage was the most severe because it applies close-die forging to increase its rim thickness. Therefore, in addition to the design of prestressed die insert, special attendance is paid to the partition of the die insert to further alleviate the stress level. The optimization of die insert was aided by the finite element analysis of DEFORM software. The results show that by lowering the parting line, the stress level can be minimized. The tool life can therefore be improved.
Authors: Petr Fajman, Jiří Máca
Abstract: One of the most impressive membrane structures in our country is the roofing of the K Barrandovu tram stop in Prague. Cable and membrane structures must permanently be kept under tensile prestress. The stress magnitude at zero load depends on the structural design, the final shape of the structure and its shape in production. The measurements of 2009 and 2012 pointed out the problem that some cables showed zero prestress.
Authors: Wei Yue, Minehiro Nishiyama
Abstract: This paper presents experimental results of cyclic loading tests carried out on three L-shaped prestressed concrete beam-column corner joints. Three types of reinforcing methods to enhance the anchorage performance of beam and column longitudinal reinforcing bars were studied based on the experimental results such as the load-displacement relation curves, deformation capacity, prestressing force variation, and strain measurements of the beam and column reinforcing bars. The test specimens were KPCL1 with the column longitudinal reinforcement with 180-degree hooks at their ends, KPCL2 with the column longitudinal reinforcement bent in a U-shape, and KPCL3 with U-shaped column longitudinal reinforcement and additional transverse reinforcement on the beam longitudinal reinforcement. It can be concluded that the anchorage performance was somehow enhanced by the three reinforcing methods in the positive direction of loading (closing direction), while in the negative direction of loading (opening direction) there was no remarkable improvement.
Authors: Hua Cai, Feng Shuo Li, Xin Li
Abstract: ABAQUS software is adopted. And the three-dimensional finite element models, respectively oblique and vertical reinforcements, are used for the calculation of the prestressed concrete pavement structure. The prestress is imposed on pavement by changing the temperature of reinforcements. Then through the analysis of mechanical behavior of the two kinds of prestressed reinforcement concrete pavements under the standard load. The results show that the oblique reinforcement pavement is flatter and the range of influnence is smaller. These data of the two kinds of pavements are provided for engineering design and construction.
Authors: Jian Feng Ye, Chun Long Zheng, Xue Shi Yao
Abstract: Aiming at a rotor model, the coupled bending-axial vibration is being analyzed.Calculation results show that the prestress relative to rotational centrifugal load may influence bending vibration frequencies of a rotor.The bending vibration frequencies will increase when the prestress increases.The axial vibration frequency has not an influence because the direction of the spinning prestress is perpendicular to axis.When a rotor is applies axial force, a compressional force will tend to increase the axial vibration frequencies while a tensile force will decrease the axial vibration frequencies.The effects of the prestress(centrifugal load )of the spinning rotor and the axial prestress can be accounted by an adjustment of the stiffness matrix for analysis.By use of the stiffness matrix,the changed axial and bending vibration frequencies can be explained.The coupled bending-axial vibration may take place when the bending vibration frequencies have increased in the state of the changed prestress.In the end, the coupled bending-axial vibration frequency can be calculated.On the basis of prestress, the coupled lateral-torsional vibration and the coupled torsional-axial vibration frequency can be analysed,similarly.
Authors: Li Jiao Pan, Zi Tang Yu, Yong Ming He
Abstract: The application of computer simulation technology in engineering design and analysis fields can effectively reduce product production cost, and improve the design efficiency. Through the computer simulation analysis of the key structure of gilling machine, the maximum stress value and its position of the working screw can be obtained in the working condition when roller’s linear velocity are at 1st and 2nd gear ratio, respectively, about 66.0m/min and 57.0m/min. In addition, in the assembly model simulation analysis of gilling machine structure, the influence of prestress simulation is considered and obtained the first 4 order’s natural frequencies and mode shapes in two kinds of gear ratios in those working conditions. It provides some suggestions that can be used to research the effect factors of gilling machine design, the gilling machine structure optimization and operating mode control.
Authors: Jian Yang, Zhi Fang
Abstract: An experimental program was formulated to investigate the characteristics of complete stress-strain curve of UHPC in uniaxial compression and flexural behaviors of prestressed UHPC beams. The particular focus was the influence of the partial prestress ratio and jacking stress on the flexural response of UHPC beams. The tests of beams demonstrated that the UHPC beams have an excellent behavior in load carrying capacity, crack distribution and deformability; their ultimate deflection can reach 1/34~1/42 of the span. Based on this investigation, theoretical correlations for the prediction structure response of UHPC beams are proposed.
Authors: Wen Yu Hou, Lian Guang Wang, Peng Liu
Abstract: The prestressed composite T beam with concrete-filled steel tube is made through welding with half I-beam to connect the concrete-filled circular steel tube. The prestressed reinforcement was equipped on the T-beam. The load-bearing capacity and rigidity of the composite beam was enhanced by using prestressed force. In consideration of applying prestress, the corresponding parts stress and strain from the beginning of applying prestress to the phase of elimination of the pressure is calculated through the process of applying prestress; establish the equation of elastic flexural capacity with different location of neutral axis according to the theoretical analyses. Also use the superposition method to build the equation of the deflection. The computational results show that applying prestress reduces the deformation of the composite structure and the mechanic performance has improved which provide important theoretical basis with practical application in engineering.
Authors: Hao Yang, Na Li, Bing Shuang Xu
Abstract: When establishing the prestressed bridge model with the entity unit, the simulation of prestress bar has very big limitation. The paper takes 20 nodes isoparametric element as an example and puts forward a kind of numerical method combined with the Newton iterative algorithm and Gauss integral algorithm to calculate equivalent loads of prestress in body element. This method can be used to calculate the equivalent loads of prestress in the various complex steel in bundle shapes and suits the computer programming. Through the final regular inspection, this method has been proved to have very high precision.
Authors: Jun Zhang, Lang Ni Deng, Ling Liao
Abstract: Existing experimental studies showed that the reinforced concrete (RC) beams strengthened with prestressed carbon fiber-reinforced polymer (CFRP) plates had two possible flexural failure modes (including the compression failure and tension failure) according to the CFRP reinforcement ratio. Theoretical formulas based on the compatibility of strains and equilibrium of forces were presented to predict the nominal flexural strength of strengthened beams under the two failure modes, respectively. It can provide a reference for engineering application of strengthening design.
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