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Influence of confining prestress on the transition from interface defeat topenetration in ceramic targets

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Defence Technology（防务技术） 2016年第3期12卷 263-271页

作者： Patrik LUNDBERG RenéRENSTROM Olof ANDERSSON FOI Swedish Defence Research AgencySE-164 90 StockholmSweden

Replica scaled impact experiments with unconfined ceramic targets have shown that the transition velocity,i.e.,the impact velocity at which interface defeat ceases and ceramic penetration occurs,decreased as the length scale increased.A possible explanation of how this scale effect is related to the formation of a cone crack in the ceramic has been presented by the authors in an earlier ***,the influence of confinement and prestress on cone cracking and transition velocity is *** hypothesis is that prestress will suppress the formation and growth of the cone crack by lowering the driving stress.A set of impact experiments has been performed in which the transition velocity for four different levels of prestress has been *** transition velocities as a function of the level of confining prestress is compared to an analytical model for the influence of prestress on the formation and extension of the cone crack in the ceramic *** experiments and model indicate that prestress has a strong influence on the transition from interface defeat to penetration,although the model underestimates the influence of prestress.

关键词： Impact Ceramic Armour Interface defeat Dwell Confinement prestress

Modal analysis of the torque converter in different prestress

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High Technology Letters 2020年第1期26卷 61-67页

作者： Zhang Zeyu Hui Jizhuang Shi Ze Suo Xuefeng Zhang Xuhui Fan Hongwei Key Laboratory of Road Construction Technology and Equipment Ministry of EducationChang'an UniversityXi'an 710064P.R.China Shaanxi Key Laboratory of Mine Electromechanical Equipment Intelligent Monitoring Xi'an University of Science and TechnologyXi'an 710054P.R.China Research Center Tibet Tianlu Co.LtdLhasa 850000P.R.China

In order to study the mechanical properties and the dynamic performance of torque converter,to reduce the vibration and noise during the operation and to improve the stability,a 215 mm hydraulic torque converter is taken as the research object,and modal analyses are performed based on the finite element *** weak parts of the impeller structure are obtained after calculating the models of the impeller and turbine without *** variation of the modal frequency of the turbine and impeller are obtained under different prestress conditions by calculating different rotational speeds of the transmission *** fundamental frequencies of the impeller and the turbine increase by 0.43%and 4.82%respectively when the rotational speed ranges from 100 rpm to 4500 *** results of the present research indicate that the modal frequencies at different speeds are similar to the fundamental frequencies of the ***,it is possible to estimate the vibration characteristics of the structure and optimize the structural design by numerical modal analysis in the static state instead of the dynamic state.

关键词： hydraulic torque converter modal analysis prestress finite element analysis

prestress Design of Stainless Steel Fibers/Zirconia Composite by Tape Casting

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Journal of Wuhan University of Technology(Materials Science) 2010年第4期25卷 565-569页

作者：赵康 School of Materials and Engineering Xi'an University of Technology

prestressed SUS316 fibers/ZrO2 composite was fabricated using tape casting. Causes of cracks were analyzed by classical thermo-elastic theory and finite element method in preparation process. An optimization design was carried out on SUS316 fibers’ arrangement modes by reducing residual thermal stress. Interface topography and element distribution of composite were observed, and bending strengths were tested. Results show that cracks are generated along the direction vertical to SUS316 fibers by axial thermal stress due to different thermal expansion coefficients between SUS316 fibers and zirconia, and the average cracking space is 2 mm. No macroscopic defect is found in composite with SUS316 fibers of sine distribution, and it has better interfacial binding force since interdiffusion between SUS316 and zirconia. Bending strengths of composite with 0°/0°lamination are anisotropic and that are 385.74 MPa and 500.7 MPa respectively, but that with 0°/90°lamination is isotropic and it is 433.92 MPa. Bending strength of composite is increased obviously compared with that of zirconia because the prestress of surface is compressive stress.

关键词： SUS316 fibers/ZrO2 prestress tape casting finite element bending strength

Life cycle detection of prestress in large prestressed reinforcement structures

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Journal of Central South University 2005年第S2期14卷 90-94页

作者：金秀梅杜彦良孙宝臣 School of Mechanical Electronic and Control Engineering Beijing Jiaotong University Beijing 100044 China Structural Health Monitoring and Control Institute Shijiazhuang Railway Institute Shijiazhuang 050043 China

To monitor the stress state of prestressed reinforcement in large reinforcement prestressed structure, two sensing structures, namely the direct spiral-winding structure and sawtooth modulated structure, were designed based on the ordinary communication optical fiber. The sensing theories were analyzed, and the experimental studies were also carried out. The quasi-distributed sensing system based on optical time domain reflective technology was established. The detection wavelength and spatial resolution were analyzed, and the estimation formula of maximal number of sensing point was also given. The results show that the system can realize the quasi-distributed test of measurand with single fiber, which helps to simplify the in-out wires. Moreover it can take on the important task of long-term and continuous monitoring of prestress, which helps to realize the life cycle detection of prestress, and play an important role in the estimating of bridge health state.

关键词： life cycle detection smart structure prestress optical fiber quasi-distribution

A discussion of fatigue properties of notched specimens subjected to prestressing treatment machined from FGH4097

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Chinese Journal of Aeronautics 2024年第4期37卷 508-523页

作者： Rongxi SHI Dasheng WEI Le HAN Shun YANG School of Energy and Power Engineering Beihang UniversityBeijing 100191China Jiangxi Research Institute Beihang UniversityNanchang 330096China Research Institute of Aero-Engine Beihang UniversityBeijing 100191China

Experimental and numerical investigations were performed to reveal the effect of prestress on the fatigue properties of FGH4097 so as to quantitatively evaluate the overspeed benefit of the disc of aeroengine. A corresponding experiment was performed to examine the effect of prestress on the fatigue life of FGH97. A complete model describing the fatigue properties of the prestressed notch specimen was proposed. After the modification of mean stress, stress gradient and prestressing treatment, the model is finally verified by fatigue test of presstressed notch specimens machined from FGH4097 with satisfactory accuracy and good engineering applicability. The new model highlights that for the variable fatigue loads, the introduction of appropriate prestress is expected to benefit to the notch specimens and certainly to the disc of aeroengine regards of their fatigue properties. Both the calculation method of fatigue life parameters and the prestress correction model are proved to have good prediction accuracy.

关键词： Turbine blisk Overspeed test prestress Fatigue life prediction FGH4097

High prestress truss cable support principle and its application in large cross section coal roadway

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Journal of Coal Science & Engineering(China) 2007年第1期13卷 18-21页

作者：姚精明何富连萧潇 State Key Laboratory of High-Efficient Mining and Safety of Metal Mines Ministry of Education University of Science and Technology Beijing Beijing 100083 China

With the enlarge of cross section of roadway, the radius of plastic area and broken area increase, and the tensile stress and shear stress distributing in roof coal-rock layers relevantly increase, which induce support effect not obvious for ordinary bolt（cable）. While bounding point and support structure of the truss cable is in vertex angle of roadway, and supplies coal-rock layers in bounding area with the horizontal and vertical pressure, so it settles the support problems in large cross section coal roadway. From the point of view of mechanics, gave emphasis on the invalid mechanics of ordinary bolt （cable） in large cross section coal roadway and supported mechanics of prestress truss cable. The author successfully used this technique in Wuyang Mine, and had the huge economic efficiency and the social benefit.

关键词： truss cable large cross section roadway ordinary bolt (cable) prestress

Theoretical Analysis on Deflection and Bearing Capacity of prestressed Bamboo-Steel Composite Beams

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Journal of Renewable Materials 2024年第1期12卷 149-166页

作者： Qifeng Shan Ming Mao Yushun Li School of Civil Engineering Zhejiang Industry Polytechnic CollegeShaoxing312000China School of Civil&Environmental Engineering and Geography Science Ningbo UniversityNingbo315211China College of Civil Engineering and Architecture Qingdao Agricultural UniversityQingdao266109China

A theoretical analysis of upward deflection and midspan deflection of prestressed bamboo-steel composite beams is presented in this *** deflection analysis considers the influences of interface slippage and shear ***,the calculation model for flexural capacity is proposed considering the two stages of *** theoretical results are verified with 8 specimens considering different prestressed load levels,load schemes,and prestress *** results indicate that the proposed theoretical analysis provides a feasible prediction of the deflection and bearing capacity of bamboo-steel composite *** deflection analysis,the method considering the slippage and shear deformation provides better *** theoretical method for bearing capacity matches well with the test results,and the relative errors in the serviceability limit state and ultimate limit state are 4.95%and 5.85%,respectively,which meet the accuracy requirements of the engineered application.

关键词： Bamboo scrimber composite beam prestress deflection bearing capacity

EXPERIMENTAL STUDIES OF THE EFFECTS OF prestress

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Chinese Journal of Biomedical Engineering(English Edition) 1996年第4期5卷 163-171页

作者： on intact Chanine Tibia Bone StructureLiu Baowei,Lu Shibi,Wang JifangDept.of Orthop. of General Hospital of PLA China,Beijing 100853,China

Three types of steel plate that have difrerent bending and axial stirrness were applied in the experiment. They are fixed on intact canine tibiae andstudied the effects on biomechanics, circulation and structure or bone. The result isthat tibia fixed with plate with high bending and axial stiffness produced the greaterprestress and stress shielding value and slight circulation disorder in early *** the osteoporosls or tibias bone occurred early;One fixed with low bending andaxial stirrness protluced the less prestress and stress shielding value and sever circulation disorder in bone in early stage, but the osteoporosis occurred late. We considered that local osteoporosity of intact tibias arter plate rixed were caused by prestress initially and stress shielding secondarily, the local circulation disorder notimportant factor.

关键词： plate internal fixation prestress stress shielding CT

Effect of Initial Load on the MechanicalProperties of Concrete Beam Strengthenedwith Extraneous prestress

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Journal of China University of Mining and Technology 2004年第2期14卷 179-183页

作者：殷惠光付修兵赵启林 Department of Civil Engineering Xuzhou Institute of Technology Xuzhou Jiangsu 221008 China Nanjing Institute of Civil Architecture Design Nanjing Jiangsu 210007 China Institute of Engineering PLA University of Science and Technology Nanjing Jiangsu 210007 China

In order to study the effect of initial load on the mechanical properties of concrete beam strengthened with extraneous prestress, contrastive experiments were conducted on three reinforced concrete beams with different initial loads. The results indicate that the mechanical properties of the three beams are different. The cracking of reinforced concrete due to the initial loads badly weakens the rigidity of the reinforced concrete structure. Under the same increment in load, the greater the initial load is, the smaller the rigidity of the reinforced concrete beams becomes. The calculation methods of deflection and split of reinforced concrete beam are proposed.

关键词： extraneous prestress strengthening concrete experiment