Directory of Open Access Journals (Sweden)
Walt Wells
2008-01-01
Full Text Available Our objective in this paper is to solve a second order differential equation for a long, simply supported column member subjected to a lateral axial load using Heun's numerical method. We will use the solution to find the critical load at which the column member will fail due to buckling. We will calculate this load using Euler's derived analytical approach for an exact solution, as well as Euler's Numerical Method. We will then compare the three calculated values to see how much they deviate from one another. During the critical load calculation, it will be necessary to calculate the moment of inertia for the column member.
The failure of axially loaded steel columns
International Nuclear Information System (INIS)
Slender compression steel members fail by elastic bucking, and short compression members may be loaded until the steel yields. In the majority of usual situations, failure occurs by inelastic buckling after a portion of the cross section has yielded. Residual stresses are the primary cause of the nonlinear protion of the average stress strain curve of axially loaded compression members (huber and Beedle, 1954). A number of theories tackled the problem of inelastic bucking. The LRFD Code ended with adopting an empirical parabolic equation that is stitched to the Euler hyperbola at the column slenderness value of λ C =2 square root and is believed to provide a reasonable approximation for column strength curves. The analysis of steel sections used in this paper defines an explicit from of failure to define the failure load of axially loaded columns in the inelastic range. inelastic bucking is defined in terms of the elaSTIC bucking of transformed sections. Two examples are used to clarify the method of analysis that accounts for residual stresses. (author). 9 refs., 5 figs
Axially Loaded Behavior of Driven PC Piles
Hsu, Shih-Tsung
2010-05-01
To obtain a fair load-settlement curve of a driven pile, and to evaluate the ultimate pile capacity more accurately, a numerical model was created to simulate the ground movements during a pile being driven. After the procedure, the axially loaded behaviors of the piles in silty sand were analyzed. The numerical results are compared with those results by full scale pile load tests. It was found, although the loads added on the tested piles are different from those by the numerical analyses which applied displacement increments on piles, the load-settlement behaviors of piles calculated from the numerical model were close to those measured from field tests before the piles stressed to peak. Total load, shaft friction, and point bearing do not reach peak values at the same pile settlement; furthermore, the point bearing slowly increases all the while, with no peak. However, the point bearing only contributes 10˜20% of ultimate pile capacity. No matter which relative density of silty sand, pile diameter, and pile length increased, ultimate pile capacity increased as well.
Test Setup for Axially Loaded Piles in Sand
DEFF Research Database (Denmark)
Thomassen, Kristina
The test setup for testing axially static and cyclic loaded piles in sand is described in the following. The purpose for the tests is to examine the tensile capacity of axially loaded piles in dense fully saturated sand. The pile dimensions are chosen to resemble full scale dimension of piles used...
LOAD CARRYING CAPABILITY OF LIQUID FILLED CYLINDRICAL SHELL STRUCTURES UNDER AXIAL COMPRESSION
Qasim H. Shah; MOHAMMAD MUJAHID; MUSHTAK AL-ATABI; YOUSIF A. ABAKR
2011-01-01
Empty and water filled cylindrical Tin (Sn) coated steel cans were loaded under axial compression at varying loading rates to study their resistance to withstand accidental loads. Compared to empty cans the water filled cans exhibit greater resistance to axially applied compression loads before a complete collapse. The time and load or stroke and load plots showed three significant load peaks related to three stages during loading until the cylinder collapse. First peak corresponds to the ini...
Comparison of design methods for axially loaded buckets in sand
DEFF Research Database (Denmark)
Vaitkunaite, Evelina; Nielsen, Benjaminn Nordahl; Ibsen, Lars Bo
A study of the present knowledge about the bucket resistance for axial loading was performed considering analytical and numerical design methods as well as physical models. A case study was performed with two bucket foundations of equal diameter, but different skirt lengths installed in dense sand....... Itwas found that bearing capacity from the surcharge increases approximately twice if the foundation skirt is two times longer. However, the predicted compressive soil capacity can differ by 3.6 times depending on the chosen bearing capacity parameters. Few methods are available for the estimation of...
Static Tension Tests on Axially Loaded Pile Segments in Sand
DEFF Research Database (Denmark)
Thomassen, Kristina; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo
showed best agreement with the traditional design method given in the American Petroleum Institute (API) design code. When t-z curves obtained from the test results were compared to t-z curve formulations found in the literature, the Zhang formulation gave good predictions of the initial and post......This paper provides laboratory test results of static axially loaded piles in sand. With a newly developed test setup, the pile-soil interface friction was investigated by using an open-ended steel pile segment with a diameter of 0.5 m. Use of a pile length of 1 m enabled the pile-soil interface...... friction to be analyzed at a given soil horizon while increasing the vertical effective stress in the sand. Test results obtained by this approach can be analyzed as single t-z curves and compared to predictions of unit shaft friction from current design methods for offshore foundations. The test results...
Dynamic impedance of piles in visco-elastic material considering axial loads
Institute of Scientific and Technical Information of China (English)
JIANG Jian-guo; ZHOU Xu-hong; ZHANG Jia-sheng
2005-01-01
The dynamic impedance function of pile in visco-elastie material considering axial loads under lateral dynamic force was analyzed, and the beam dynamic differential equation was used to induce the dynamic impedance function. After analyzing the edge conditions, the dynamic impedance functions were deduced. Contrasted with the result that does not consider axial loads, the axial loads have obvious influence on the dynamic impedance function.And the results show that the dimensionless prarmeter of the dynamic impedance will change from 6 % to 9 % when considering axial loads, and dimensionless prarmeter of the dynamic impedance of the coupling horizontal-sway will increase by 31 %.
Self-weight loading of horizontal hydraulic cylinders with axial load
Hale, J. M.; Sim, Ee Yu
2016-05-01
An iterative matrix method is described to determine the deformed shape of a horizontal stepped tube with large axial load, representing a heavy hydraulic cylinder. The method is applicable to both simply supported (pinned-pinned) and clamped-clamped end constraints. The clamped-clamped case is extended to include rotational compliance in the clamps. Using this analysis, radial loads on the piston seals of the cylinder are determined. Comparison is made between the seal loading of a typical large cylinder in pinned-pinned and clamped-clamped configurations, respectively. It is shown that the seal loading can be considerably reduced by the use of the clamped-clamped configuration provided the ends can be well aligned, but that the load is sensitive to angular misalignment.
The Buckling Analysis of Axially Loaded Columns with Artificial Neural Networks
Ülker, Mehmet; CİVALEK, Ömer
2002-01-01
The determination of effective design values in structural analysis is important.Axially loaded columns are designed according to the their buckling load capacity. In this study, a multi-layer artificial neural network is trained to give critical load for axially loaded columns and various support conditions. Back-propagation training algorithms are used considering the circular, square, rectangular, and I cross-sections. The artificial neural network, with is trained for circular and rec...
Design and analysis of a novel mechanical loading machine for dynamic in vivo axial loading
Macione, James; Nesbitt, Sterling; Pandit, Vaibhav; Kotha, Shiva
2012-02-01
This paper describes the construction of a loading machine for performing in vivo, dynamic mechanical loading of the rodent forearm. The loading machine utilizes a unique type of electromagnetic actuator with no mechanically resistive components (servotube), allowing highly accurate loads to be created. A regression analysis of the force created by the actuator with respect to the input voltage demonstrates high linear correlation (R2 = 1). When the linear correlation is used to create dynamic loading waveforms in the frequency (0.5-10 Hz) and load (1-50 N) range used for in vivo loading, less than 1% normalized root mean square error (NRMSE) is computed. Larger NRMSE is found at increased frequencies, with 5%-8% occurring at 40 Hz, and reasons are discussed. Amplifiers (strain gauge, linear voltage displacement transducer (LVDT), and load cell) are constructed, calibrated, and integrated, to allow well-resolved dynamic measurements to be recorded at each program cycle. Each of the amplifiers uses an active filter with cutoff frequency at the maximum in vivo loading frequencies (50 Hz) so that electronic noise generated by the servo drive and actuator are reduced. The LVDT and load cell amplifiers allow evaluation of stress-strain relationships to determine if in vivo bone damage is occurring. The strain gauge amplifier allows dynamic force to strain calibrations to occur for animals of different sex, age, and strain. Unique features are integrated into the loading system, including a weightless mode, which allows the limbs of anesthetized animals to be quickly positioned and removed. Although the device is constructed for in vivo axial bone loading, it can be used within constraints, as a general measurement instrument in a laboratory setting.
Ding, Lan; Zhu, Hong-Ping; Wu, Li
2016-07-01
The propagation and attenuation properties of waves in ordered and disordered periodic composite Timoshenko beams, which consider the effects of axial static load and structural damping, resting on elastic foundations are studied when the system is subjected to moving loads of constant amplitude with a constant velocity. The transfer matrix methodology is adopted to formulate the model in a reference coordinate system moving with the load. The localization factor is calculated to determine the wave velocity pass bands and stop bands. The interactions between the static axial load and moving load, structural damping and disorder on the bands are analyzed.
Institute of Scientific and Technical Information of China (English)
TIAN Zhimin; WU Ping'an; JIA Jianwei
2008-01-01
Experimental investigation into impact-resistant behavior of reactive powder concrete (RPC)-filled steel tubular columns was conducted, and dynamic response of the columns under axial impact loading was studied by means of numerical simulation method.Increase coefficient of load carrying capacity and ratio of load carrying capacity between steel tube and RPC core of columns were obtained.
LOAD CARRYING CAPABILITY OF LIQUID FILLED CYLINDRICAL SHELL STRUCTURES UNDER AXIAL COMPRESSION
Directory of Open Access Journals (Sweden)
QASIM H. SHAH
2011-08-01
Full Text Available Empty and water filled cylindrical Tin (Sn coated steel cans were loaded under axial compression at varying loading rates to study their resistance to withstand accidental loads. Compared to empty cans the water filled cans exhibit greater resistance to axially applied compression loads before a complete collapse. The time and load or stroke and load plots showed three significant load peaks related to three stages during loading until the cylinder collapse. First peak corresponds to the initial structural buckling of can. Second peak occurs when cylindrical can walls gradually come into full contact with water. The third peak shows the maximum load carrying capability of the structure where pressurized water deforms the can walls into curved shape until can walls fail under peak pressure. The collapse process of water filled cylindrical shell was further studied using Smooth Particle Hydrodynamics (SPH technique in LSDYNA. Load peaks observed in the experimental work were successfully simulated which substantiated the experimental work.
Stabilizing effects of ankle bracing under a combination of inversion and axial compression loading.
Tohyama, Harukazu; Yasuda, Kazunori; Beynnon, Bruce D; Renstrom, Per A
2006-04-01
The combined effects of bracing, axial compression and inversion rotation on the ankle-subtalar complexes were evaluated. Ex vivo tests under the load-controlled condition were performed on six cadaver ankle specimens using a six degree-of-freedom fixture. Inversion rotation was measured while subjecting the ankle-subtalar complex to a 2.5 N-m inversion moment and a combination of the testing variables (brace type, no brace, 178 N axial compression load, no compression load, 0 degrees and 20 degrees of plantar flexion) for a total of 16 tests per specimen. Three commercially available braces (two semirigid types and one lace up type) were evaluated. An axial compression load significantly decreased ankle-subtalar motion in unbraced ankles for the tested inversion moment. The contribution of bracing to stabilization of the ankle was smaller in the axial loading condition than in the no axial loading condition. The semirigid braces had greater stabilizing effects in response to the inversion moment than the lace up brace. Stabilizing effects of bracing were significantly greater in 20 degrees of plantar flexion than in 0 degrees of plantar flexion. The most common mechanism for an ankle sprain injury is inversion rotation on a weight-bearing ankle. Therefore, we should not overestimate stabilizing effects of bracing from evaluations of bracing without axial compression loading. PMID:15959767
Akshay P. Mote; H. S. JADHAV
2014-01-01
This paper presents the results of experimental study related to the strengthening of R C short columns strengthened with BFRP wrap under axial loading. For strengthening of reinforced concrete columns, total fourteen columns were cast and tested up to failure of the columns under axial loading. The columns were bonded with BFRP sheets in single layer and double layers with various configurations. Out of the fourteen columns two columns were control columns and remaining colum...
Fire behavior of axially loaded slender high strength concrete-filled tubular columns
Romero, Manuel L.; Moliner, V.; Espinós Capilla, Ana; Ibáñez Usach, Carmen; Hospitaler Pérez, Antonio
2011-01-01
This paper describes sixteen fire tests conducted on slender circular hollow section columns filled with normal and high strength concrete, subjected to concentric axial loads. The test parameters were the nominal strength of concrete (30 and 80 MPa), the infilling type (plain concrete, reinforced concrete and steel fiber reinforced concrete) and the axial load level (20% and 40%). The columns were tested under fixed-pinned boundary conditions and the relative slenderness at room temperature ...
Directory of Open Access Journals (Sweden)
Cojocaru Vasile
2014-06-01
Full Text Available In the thread root area of the threaded bolts submitted to axial loading occur local stresses, higher that nominal stresses calculated for the bolts. These local stresses can generate failure and can reduce the fatigue life of the parts. The paper is focused on the study of the influence of the thread root radius on the maximum local stresses. A large diameter trapezoidal bolt was subjected to a static analysis (axial loading using finite element simulation.
Optimum design of laminated composite under axial compressive load
Indian Academy of Sciences (India)
N G R Iyengar; Nilesh Vyas
2011-02-01
In the present study optimal design of composite laminates, with and without rectangular cut-out, is carried out for maximizing the buckling load. Optimization study is carried out for obtaining the maximum buckling load with design variables as ply thickness, cut-out size and orientation of cut-out with respect to laminate. Buckling load is evaluated using a ‘simple higher order shear deformation theory’ based on four unknown displacements $u,v,w_b$ and $w_s$. A C1 continuous shear flexible finite element based on HSDT model is developed using Hermite cubic polynomial. It is observed that for thick anti-symmetric laminates, the non-dimensional buckling load decreases with increase in aspect ratio and increase in fibre orientation angle. There is a decrease in the non-dimensional buckling load of symmetric laminate in the presence of cut-out.
Directory of Open Access Journals (Sweden)
Belinda Pingguan-Murphy
2012-08-01
Full Text Available OBJECTIVES: The promotion of extracellular matrix synthesis by chondrocytes is a requisite part of an effective cartilage tissue engineering strategy. The aim of this in vitro study was to determine the effect of bi-axial cyclic mechanical loading on cell proliferation and the synthesis of glycosaminoglycans by chondrocytes in threedimensional cultures. METHOD: A strain comprising 10% direct compression and 1% compressive shear was applied to bovine chondrocytes seeded in an agarose gel during two 12-hour conditioning periods separated by a 12-hour resting period. RESULTS: The bi-axial-loaded chondrocytes demonstrated a significant increase in glycosaminoglycan synthesis compared with samples exposed to uni-axial or no loading over the same period (p<0.05. The use of a free-swelling recovery period prior to the loading regime resulted in additional glycosaminoglycan production and a significant increase in DNA content (p<0.05, indicating cell proliferation. CONCLUSIONS: These results demonstrate that the use of a bi-axial loading regime results in increased matrix production compared with uni-axial loading.
Directory of Open Access Journals (Sweden)
Akshay P. Mote
2014-07-01
Full Text Available This paper presents the results of experimental study related to the strengthening of R C short columns strengthened with BFRP wrap under axial loading. For strengthening of reinforced concrete columns, total fourteen columns were cast and tested up to failure of the columns under axial loading. The columns were bonded with BFRP sheets in single layer and double layers with various configurations. Out of the fourteen columns two columns were control columns and remaining columns were strengthened with BFRP. The experimental results show that the columns strengthened with BFRP show high load carrying capacity and ductility index. Keywords:
Stabilizing effects of ankle bracing under a combination of inversion and axial compression loading
Tohyama, Harukazu; Yasuda, Kazunori; Beynnon, Bruce D.; Renstrom, Per A.
2006-01-01
The combined effects of bracing, axial compression and inversion rotation on the ankle-subtalar complexes were evaluated. Ex vivo tests under the load-controlled condition were performed on six cadaver ankle specimens using a six degree-of-freedom fixture. Inversion rotation was measured while subjecting the ankle-subtalar complex to a 2.5 N-m inversion moment and a combination of the testing variables (brace type, no brace, 178 N axial compression load, no compression load, 0° and 20° of pla...
Dávila, A.; Márquez, S.; Landgrave, E.; Vázquez, Z.; Vera, K.; Caudillo, C.
2015-06-01
A computerized system for real-time displacement visualization using carrier fringes in an electronic speckle in-plane sensitive interferometer allows force calibration for micro-displacement analysis of rat bones and verification of axial loading conditions. Once the force has been calibrated and the load is applied along the bone axis, the difference-of-phase method is used to obtain the phase map, which after phase unwrapping, allows the evaluation of the displacements produced by the bone deformation. The proposed method avoids common loading mistakes using first carrier fringes to assure that the loads are within the measuring capabilities of the in-plane interferometer and the Carré phase-stepping method to compensate for linear phase step miscalibration. The experimental results obtained with the calibration of loading forces and axial loading verification show the advantages of the system proposed here over a system which uses a cantilever configuration to make a similar bone deformation analysis.
An exact dynamic stiffness matrix for axially loaded double-beam systems
Indian Academy of Sciences (India)
Li Xiaobin; Xu Shuangxi; Wu Weiguo; Li Jun
2014-06-01
An exact dynamic stiffness method is presented in this paper to determine the natural frequencies and mode shapes of the axially loaded double-beam systems,which consist of two homogeneous and prismatic beams with a distributed spring in parallel between them.The effects of the axial force, shear deformation and rotary inertia are considered, as shown in the theoretical formulation. The dynamic stiffness influence coefficients are formulated from the governing differential equations of the axially loaded double-beam system in free vibration by using the Laplace transform method. An example is given to demonstrate the effectiveness of this method, in which ten boundary conditions are investigated and the effect of the axial force on the natural frequencies and mode shapes of the double-beam system are further discussed.
Directory of Open Access Journals (Sweden)
Ye-Wei Zhang
2013-01-01
Full Text Available Nonlinear targeted energy transfer (TET is applied to suppress the excessive vibration of an axially moving string with transverse wind loads. The coupling dynamic equations used are modeled by a nonlinear energy sink (NES attached to the string to absorb vibrational energy. By a two-term Galerkin procedure, the equations are discretized, and the effects of vibration suppression by numerical methods are demonstrated. Results show that the NES can effectively suppress the vibration of the axially moving string with transverse wind loadings, thereby protecting the string from excessive movement.
BARRERA PUERTO, ANGELA; Bonet Senach, José Luís; Romero, Manuel L.; Miguel Sosa, Pedro
2011-01-01
The use of high strength concrete (HSC) in columns has become more frequent since a substantial reduction of the cross-section is obtained, meaning that slenderness increases for the same axial load and length, producing higher second order effects. However, the experimental tests in the literature of reinforced concrete columns subjected to axial load and lateral force focus on shear span ratios, according to Eurocode 2 (2004), clause 5.6.3., (M/(V·h)) lower than 6.5. This gap in the literat...
Aeroelasticity of Axially Loaded Aerodynamic Structures for Truss-Braced Wing Aircraft
Nguyen, Nhan; Ting, Eric; Lebofsky, Sonia
2015-01-01
This paper presents an aeroelastic finite-element formulation for axially loaded aerodynamic structures. The presence of axial loading causes the bending and torsional sitffnesses to change. For aircraft with axially loaded structures such as the truss-braced wing aircraft, the aeroelastic behaviors of such structures are nonlinear and depend on the aerodynamic loading exerted on these structures. Under axial strain, a tensile force is created which can influence the stiffness of the overall aircraft structure. This tension stiffening is a geometric nonlinear effect that needs to be captured in aeroelastic analyses to better understand the behaviors of these types of aircraft structures. A frequency analysis of a rotating blade structure is performed to demonstrate the analytical method. A flutter analysis of a truss-braced wing aircraft is performed to analyze the effect of geometric nonlinear effect of tension stiffening on the flutter speed. The results show that the geometric nonlinear tension stiffening effect can have a significant impact on the flutter speed prediction. In general, increased wing loading results in an increase in the flutter speed. The study illustrates the importance of accounting for the geometric nonlinear tension stiffening effect in analyzing the truss-braced wing aircraft.
Experimental creep behaviour determination of cladding tube materials under multi-axial loadings
International Nuclear Information System (INIS)
Cladding tubes are structural parts of nuclear plants, submitted to complex thermomechanical loadings. Thus, it is necessary to know and predict their behaviour to preserve their integrity and to enhance their lifetime. Therefore, a new experimental device has been developed to control the load path under multi-axial load conditions. The apparatus is designed to determine the thermomechanical behaviour of zirconium alloys used for cladding tubes. First results are presented. Creep tests with different biaxial loadings were performed. Results are analysed in terms of thermal expansion and of creep strain. The anisotropy of the material is revealed and iso-creep strain curves are given.
Comparison of Design Methods for Axially Loaded Driven Piles in Cohesionless Soil
DEFF Research Database (Denmark)
Thomassen, Kristina; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo
For offshore wind turbines on deeper waters, a jacket sub-structure supported by axially loaded piles is thought to be the most suitable solution. The design method recommended by API and two CPT-based design methods are compared for two uniform sand profiles. The analysis show great difference in...
Axial forces and bending moments in the loaded rabbit tibia in vivo
Directory of Open Access Journals (Sweden)
Reifenrath Janin
2012-03-01
Full Text Available Abstract Background Different animal models are used as fracture models in orthopaedic research prior to implant use in humans, although biomechanical forces can differ to a great extend between species due to variable anatomic conditions, particularly with regard to the gait. The rabbit is an often used fracture model, but biomechanical data are very rare. The objective of the present study was to measure axial forces, bending moments, and bending axis directly in the rabbit tibia in vivo. The following hypothesis was tested: Axial forces and bending moments in the mid-diaphysis of rabbit tibia differ from other experimental animals or indirectly calculated data. Methods A minifixateur system with 4 force sensors was developed and attached to rabbit tibia (n = 4, which were subsequently ostectomised. Axial forces, bending moments and bending angles were calculated telemetrically during weight bearing in motion between 6 and 42 days post operation. Results Highest single values were 201% body weight [% bw] for axial forces and 409% bw cm for bending moments. Whereas there was a continous decrease in axial forces over time after day 10 (P = 0.03 on day 15, a decrease in bending moments was inconsistent (P = 0.03 on day 27. High values for bending moments were frequently, but not consistently, associated with high values for axial forces. Conclusion Axial forces in rabbit tibia exceeded axial forces in sheep, and differed from indirectly calculated data. The rabbit is an appropriate fracture model because axial loads and bending moments in rabbit tibia were more closely to human conditions than in sheep tibia as an animal model.
Influence of axial load on the lateral pile groups response in cohesionless and cohesive soil
Institute of Scientific and Technical Information of China (English)
Jasim M. ABBASA[1; Zamri CHIK[2; Mohd Raihan TAHA[2
2015-01-01
The lateral response of single and group of piles under simultaneous vertical and lateral loads has been analyzed using a 3D finite element approach. The response in this assessment considered lateral pile displacement and lateral soil resistance and corresponding p-y curve. As a result, modified p-y curves for lateral single pile response were improved with respect to the influence of increasing axial load intensities. The improved plots can be used for lateral loaded pile design and to produce the group action design p-multiplier curves and equations. The effect of load combination on the lateral pile group response was performed on three pile group configurations （i.e., 2 × 1, 2 × 2 and 3 × 2） with four pile spacings （i.e., s = 2D, 4D, 6D and 8D）. As a result, design curves were developed and applied on the actual case studies and similar expected cases for assessment of pile group behavior using improved p-multiplier. A design equation was derived from predicted design curves to be used in the evaluation of the lateral pile group action taking into account the effect of axial load intensities. It was found that the group interaction effect led to reduced lateral resistance for the pile in the group relative to that for the single pile in case of pure lateral load. While, in case of simultaneous combined loads, large axial load intensities （i.e., more than 6H, where H is lateral load values） will have an increase inp-multiplier by approximately 100% and will consequently contribute to greater group piles capacities.
Si-coated single-walled carbon nanotubes under axial loads: An atomistic simulation study
International Nuclear Information System (INIS)
The mechanical properties of the Si-coated imperfect (5, 5) single-walled carbon nanotube (SWCNT), the imperfect (5, 5) SWCNT and several perfect armchair SWCNTs under axial loads were investigated using molecular dynamics simulation. The interactions between atoms were modeled using the empirical Tersoff potential and the Tersoff-Brenner potential coupled with the Lennard-Jones potential. We get Young's modulus of the defective (5, 5) nanotube with and without the Si coating under axial tension 1107.92 and 1076.02 GPa, respectively. The results also show that the structure failure of the Si-coated imperfect (5, 5) SWCNT under axial compression occurs at a slightly higher strain than for the perfect (5, 5) SWCNT. Therefore, we can confirm the protective effect of Si as a coating material for defective SWCNTs. We also obtain the critical buckling strains of perfect SWCNTs
Performance of composite I-beams under axial compression and bending load modes
Energy Technology Data Exchange (ETDEWEB)
Khalid, Y.A.; Ali, F.A.; Sahari, B.B.; Saad, E.M.A
2005-04-15
An experimental and finite-element analyses for glass/epoxy composite I-beams have been carried out. Four, six, eight and 10 layers of woven fabric glass/epoxy composite I-beams were fabricated by a hand lay-up (molding) process. Quasi-static axial crushing and bending loading modes were used for this investigation. The load-displacement response was obtained and the energy absorption values were calculated for all the composite I-beams. Three tests were done for each composite I-beams type and each loading case for the results conformation. The second part of this study includes the elastic behavior of composite I-beams of the same dimensions and materials using finite-element analysis. The woven fabric glass/epoxy composite I-beams mechanical properties have been obtained from tensile tests. Results from this investigation show that the load required and the specific energy absorption for composite I-beams under axial compression load were higher than those for three and four point bending. On the other hand, the loads required for composite I-beams under four point bending were higher than those for three point bending, while the specific energy absorption for composite I-beams under three point bending were higher than those for four point bending. The first crushing loads difference between the experimental and finite-element results fell in the 3.6-10.92% range for axial compression tests, while fell in the 1.44-12.99% and 4.94-22.0% range for three and four point bending, respectively.
Bending vibration of axially loaded Timoshenko beams with locally distributed Kelvin-Voigt damping
Chen, Wei-Ren
2011-06-01
Utilizing the Timoshenko beam theory and applying Hamilton's principle, the bending vibration equations of an axially loaded beam with locally distributed internal damping of the Kelvin-Voigt type are established. The partial differential equations of motion are then discretized into linear second-order ordinary differential equations based on a finite element method. A quadratic eigenvalue problem of a damped system is formed to determine the eigenfrequencies of the damped beams. The effects of the internal damping, sizes and locations of damped segment, axial load and restraint types on the damping and oscillating parts of the damped natural frequency are investigated. It is believed that the present study is valuable for better understanding the influence of various parameters of the damped beam on its vibration characteristics.
Second-order FE Analysis of Axial Loaded Concrete Members According to Eurocode 2
Yosef Nezhad Arya, Nessa
2015-01-01
A nonlinear finite element analysis was performed for an axial loaded reinforced concrete column subjected to biaxial bending taking into account second-order effects. According to Eurocode there are two ways to take second-order effects into consideration: nonlinear FE analysis and hand calculation based on the simplified methods explained in Eurocode 2. Since simulating this kind of structures in ABAQUS is difficult, several simulations were made to find the correct model with satisfying ac...
Concrete-Filled-Large Deformable FRP Tubular Columns under Axial Compressive Loading
Omar I. Abdelkarim; Mohamed A. ElGawady
2015-01-01
The behavior of concrete-filled fiber tubes (CFFT) polymers under axial compressive loading was investigated. Unlike the traditional fiber reinforced polymers (FRP) such as carbon, glass, aramid, etc., the FRP tubes in this study were designed using large rupture strains FRP which are made of recycled materials such as plastic bottles; hence, large rupture strain (LRS) FRP composites are environmentally friendly and can be used in the context of green construction. This study performed finite...
Fiber beam model for fire response simulation of axially loaded concrete filled tubular columns
Ibáñez Usach, Carmen; Romero, Manuel L.; Hospitaler Pérez, Antonio
2013-01-01
This paper presents a fiber beam model for the fire response simulation of concrete filled tubular columns of circular section under concentric axial load. The model consists of two parallel components, one with a circular tubular steel section, and the other with a solid circular concrete section. The components interact with nonlinear longitudinal and transverse links at the end nodes. The element is formulated on a system without rigid body modes and accounts for large displacement geometr...
Directory of Open Access Journals (Sweden)
Yijie Huang
2015-01-01
Full Text Available A new mechanical model for analysing the behaviour of axially loaded recycled aggregate concrete filled steel tubes (RACFSTs stub columns is presented in this study. The model is derived from the typical elastoplasticity, the nonlinear elastic mechanics, and the properties of materials. Based on the mechanical model, a novel numerical program is developed. The mechanical model and the numerical program are adopted to study the effect of recycled coarse aggregate (RCA replacement percentage on RACFST mechanical behaviour. The complete load-deformation relationship of specimens, the steel tube axial and circumferential stresses, and the performance of the confined core concrete and the variation of interaction are also investigated. The analytical results indicate that this model is able to capture the mechanical behaviour of RACFST. It is also found that the axial and circumferential stresses of steel tube change nonlinearly during the loading stages. It is concluded that the behaviour of the confined core concrete is significantly influenced by the confining pressure. The steel tube confinement could improve the mechanical behaviour of RAC effectively and the RCA replacement percentage slightly changes the response of core concrete. Finally, the relations between confined core concrete and confining pressure are analysed.
Concrete-Filled-Large Deformable FRP Tubular Columns under Axial Compressive Loading
Directory of Open Access Journals (Sweden)
Omar I. Abdelkarim
2015-10-01
Full Text Available The behavior of concrete-filled fiber tubes (CFFT polymers under axial compressive loading was investigated. Unlike the traditional fiber reinforced polymers (FRP such as carbon, glass, aramid, etc., the FRP tubes in this study were designed using large rupture strains FRP which are made of recycled materials such as plastic bottles; hence, large rupture strain (LRS FRP composites are environmentally friendly and can be used in the context of green construction. This study performed finite element (FE analysis using LS-DYNA software to conduct an extensive parametric study on CFFT. The effects of the FRP confinement ratio, the unconfined concrete compressive strength ( , column size, and column aspect ratio on the behavior of the CFFT under axial compressive loading were investigated during this study. A comparison between the behavior of the CFFTs with LRS-FRP and those with traditional FRP (carbon and glass with a high range of confinement ratios was conducted as well. A new hybrid FRP system combined with traditional and LRS-FRP is proposed. Generally, the CFFTs with LRS-FRP showed remarkable behavior under axial loading in strength and ultimate strain. Equations to estimate the concrete dilation parameter and dilation angle of the CFFTs with LRS-FRP tubes and hybrid FRP tubes are suggested.
Effect of axial loads on implant-supported partial fixed prostheses by strain gauge analysis
Directory of Open Access Journals (Sweden)
Luis Gustavo Oliveira de Vasconcellos
2011-12-01
Full Text Available OBJECTIVES: The present study used strain gauge analysis to perform an in vitro evaluation of the effect of axial loading on 3 elements of implant-supported partial fixed prostheses, varying the type of prosthetic cylinder and the loading points. MATERIAL AND METHODS: Three internal hexagon implants were linearly embedded in a polyurethane block. Microunit abutments were connected to the implants applying a torque of 20 Ncm, and prefabricated Co-Cr cylinders and plastic prosthetic cylinders were screwed onto the abutments, which received standard patterns cast in Co-Cr alloy (n=5. Four strain gauges (SG were bonded onto the surface of the block tangentially to the implants, SG 01 mesially to implant 1, SG 02 and SG 03 mesially and distally to implant 2, respectively, and SG 04 distally to implant 3. Each metallic structure was screwed onto the abutments with a 10 Ncm torque and an axial load of 30 kg was applied at five predetermined points (A, B, C, D, E. The data obtained from the strain gauge analyses were analyzed statistically by RM ANOVA and Tukey's test, with a level of significance of p<0.05. RESULTS: There was a significant difference for the loading point (p=0.0001, with point B generating the smallest microdeformation (239.49 µε and point D the highest (442.77 µε. No significant difference was found for the cylinder type (p=0.748. CONCLUSIONS: It was concluded that the type of cylinder did not affect in the magnitude of microdeformation, but the axial loading location influenced this magnitude.
International Nuclear Information System (INIS)
A new method which can give continuous guidance for controlling axial xenon oscillations in large PWRs has been presented. The method is based on two additional newly defined axial offsets, A Oi and A Ox together with the conventional axial offset of power distribution A Op. A Oi and A Ox are the axial offsets of power distributions which would give the current iodine and xenon distributions under equilibrium conditions, respectively. The information from A Oi, A Ox and A Op are used to display the trajectory of (A Op - A Ox, A Oi - A Ox) in the X-Y plane. The trajectory shows a very characteristic behavior. With the characteristics in mind the xenon oscillation can be controlled quite easily to lead the plot to the origin where three A Os are identical. The method has been proved with the power level constant. However, it is necessary to modify the definition of A Ox so as to apply this method to load following operations. A reasonable way of the modification is described and the results are presented. (author)
Determination of load-transfer parameters of single piles axially loaded
Directory of Open Access Journals (Sweden)
Yaich Achour N
2014-04-01
Full Text Available Modern buildings require more use of the deep foundations including piles. The good perception of the behavior of piles and the knowledge of their bearing capacity is essential for a rational use. The present work focuses on the behavior of single pile under vertical loads in clay and sand soils. Thus, an approach to semi-empirical calculations load transfer as well as finite element modeling are used in order to determine the curve loading / sag at the head of pile and deduce the calculation parameters. This study has allowed predicting the load curves piles, knowing their geometric properties and some test results of in-situ soil (CPT, PMT and SPT.
Reassessing the Plastic Hinge Model for Energy Dissipation of Axially Loaded Columns
Directory of Open Access Journals (Sweden)
R. M. Korol
2014-01-01
Full Text Available This paper investigates the energy dissipation potential of axially loaded columns and evaluates the use of a plastic hinge model for analysis of hi-rise building column collapse under extreme loading conditions. The experimental program considered seven axially loaded H-shaped extruded aluminum structural section columns having slenderness ratios that would be typical of floor-to-ceiling heights in buildings. All seven test specimens initially experienced minor-axis overall buckling followed by formation of a plastic hinge at the mid-height region, leading to local buckling of the flanges on the compression side of the plastic hinge, and eventual folding of the compression flanges. The experimental energy absorption, based on load-displacement relations, was compared to the energy estimates based on section plastic moment resistance based on measured yield stress and based on measured hinge rotations. It was found that the theoretical plastic hinge model underestimates a column’s actual ability to absorb energy by a factor in the range of 3 to 4 below that obtained from tests. It was also noted that the realizable hinge rotation is less than 180°. The above observations are based, of course, on actual columns being able to sustain high tensile strains at hinge locations without fracturing.
Parametric Equation of Stress Concentration Factor for Circular X-Joints Under Axial Loads
Institute of Scientific and Technical Information of China (English)
QU Shu-ying; ZHANG Guo-dong; ZHANG Bao-feng; WANG Xin-jian
2007-01-01
In engineering practice,tubular X-joints have been widely used in offshore structures.The fatigue failure of tubular X-joints in offshore engineering is mainly caused by axial tensile stress.In this study,the stress concentration factor distribution along the weld toe in the hot spot stress region for tubular X-joints subject to axial loads have been analyzed by use of finite element method.Through numerical analysis,it has been found that the peak stress concentration factor is located at the saddle position.Thereafter,80 models have been analyzed,and the effect of the geometric parameters of a tubular X-joint on the stress concentration factor has been investigated.Based on the experimental values of the numerical stress concentration factor,a parametric equation to calculate the stress concentration factor of tubular X-joints has been proposed.The accuracy of this equation has been verified against the requirement of the Fatigue Guidance Review Panel,and the proposed equation is found capable of producing reasonably accurate stress concentration factor values for tubular X-joints subject to axial loads.
Strength and Deformation of Axially Loaded Fiber-Reinforced Polymer Sheet Confined Concrete Columns
Institute of Scientific and Technical Information of China (English)
李静; 钱稼茹; 蒋剑彪
2004-01-01
Experimental results of 29 axially loaded fiber-reinforced polymer sheet (FS) confined concrete columns and two reference plain concrete columns are introduced. Twenty four column specimens were confined with carbon fiber sheet (CFS) and five column specimens were hybrid confined with both CFS and glass fiber sheet (GFS). The influence of aspect ratio, FS material, initial axial force ratio, and FS confinement degree on the strength and deformation of columns were studied. Based on the experimental results, the equations of complete stress-strain curve of CFS confined concrete are proposed. These equations are suitable for the nonlinear analysis of square and rectangular section columns. Suggestions of applying FS to confine concrete columns are presented.
International Nuclear Information System (INIS)
This paper presents the comparison of a reliability technique that employs a Fourier series representation of random axisymmetric and asymmetric imperfections in a cylindrical pressure vessel subjected to an axial end load and external pressure, with evaluations prescribed by the ASME Boiler and Pressure Vessel Code, Section VIII, Division 2 Rules. The ultimate goal of the reliability technique described herein is to predict the critical buckling load associated with the subject cylindrical pressure vessel. Initial geometric imperfections are shown to have a significant effect on the calculated load carrying capacity of the vessel. Fourier decomposition was employed to interpret imperfections as structural features that can be easily related to various other types of defined imperfections. The initial functional description of the imperfections consists of an axisymmetric portion and a deviant portion, which are availed in the form of a double Fourier series. Fifty simulated shells generated by the Monte Carlo technique are employed in the final prediction of the critical buckling load. The representation of initial geometrical imperfections in the cylindrical pressure vessel requires the determination of respective Fourier coefficients. Multi-mode analyses are expanded to evaluate a large number of potential buckling modes for both predefined geometries in combination with asymmetric imperfections as a function of position within the given cylindrical shell. The probability of the ultimate buckling stress exceeding a predefined threshold stress is also calculated. The method and results described herein are in stark contrast to the “knockdown factor” approach as applied to compressive stress evaluations currently utilized in industry. Further effort is needed to improve on the current design rules regarding column buckling of large diameter pressure vessels subjected to an axial end load and external pressure designed in accordance with ASME Boiler and
Experimental Tests on the Composite Foam Sandwich Pipes Subjected to Axial Load
Li, Feng; Zhao, QiLin; Xu, Kang; Zhang, DongDong
2015-12-01
Compared to the composite thin-walled tube, the composite foam sandwich pipe has better local flexural rigidity, which can take full advantage of the high strength of composite materials. In this paper, a series of composite foam sandwich pipes with different parameters were designed and manufactured using the prefabricated polyurethane foam core-skin co-curing molding technique with E-glass fabric prepreg. The corresponding axial-load compressive tests were conducted to investigate the influence factors that experimentally determine the axial compressive performances of the tubes. In the tests, the detailed failure process and the corresponding load-displacement characteristics were obtained; the influence rules of the foam core density, surface layer thickness, fiber ply combination and end restraint on the failure modes and ultimate bearing capacity were studied. Results indicated that: (1) the fiber ply combination, surface layer thickness and end restraint have a great influence on the ultimate load bearing capacity; (2) a reasonable fiber ply combination and reliable interfacial adhesion not only optimize the strength but also transform the failure mode from brittle failure to ductile failure, which is vital to the fully utilization of the composite strength of these composite foam sandwich pipes.
Tan, J L Y; Deshpande, V S; Fleck, N A
2016-07-13
A damage-based finite-element model is used to predict the fracture behaviour of centre-notched quasi-isotropic carbon-fibre-reinforced-polymer laminates under multi-axial loading. Damage within each ply is associated with fibre tension, fibre compression, matrix tension and matrix compression. Inter-ply delamination is modelled by cohesive interfaces using a traction-separation law. Failure envelopes for a notch and a circular hole are predicted for in-plane multi-axial loading and are in good agreement with the observed failure envelopes from a parallel experimental study. The ply-by-ply (and inter-ply) damage evolution and the critical mechanisms of ultimate failure also agree with the observed damage evolution. It is demonstrated that accurate predictions of notched compressive strength are obtained upon employing the band broadening stress for microbuckling, highlighting the importance of this damage mode in compression. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'. PMID:27242302
Analytical investigation of pile-soil interaction in sand under axial and lateral loads
Abdel-Mohti, Ahmed; Khodair, Yasser
2014-03-01
This paper presents a numerical study of pile-soil interaction due to application of axial and lateral loads to piles in sand. The pile-soil interaction was analyzed using the finite difference (FD) software LPILE and two finite element (FE) software. The three-dimensional (3D) FE models of pile-soil interaction have been created using Abaqus/Cae and SAP2000. Various types of soft soil were studied, such as loose, medium, and dense sand. A lateral displacement of 2 cm was applied to the top of the pile while maintaining a zero slope in a guided fixation. A combined lateral and axial load of 300 kN was also studied. The paper compared between the bending moments and lateral displacements along the depth of the pile obtained from the FD solutions and FE analyses. A parametric study was conducted to study the effect of crucial design parameters such as the modulus of elasticity of soil and the number of nonlinear soil springs that can be used to model the soil. A good agreement between the results obtained by the FE models and the FD solution was observed. Also, the FE models were capable of predicting the pile-soil interaction for all types of soft soil.
Effect of Axial Pre-Compression on Lateral Performance of Masonry Under Cyclic Loading
Directory of Open Access Journals (Sweden)
Syed HassanFarooq
2011-10-01
Full Text Available Strengthening of masonry against seismic events is very essential and getting maximum attention of researchers around the globe. An extensive experimental program was carried out to study the in-plane lateral performance of un-reinforced masonry, strengthened and retrofitted masonry wall panels under lateral cyclic loading. Twenty tests were carried out; four tests under monotonic lateral loading, twelve tests under static cyclic loading and four tests under pure compression. The test results were analyzed in five groups and this paper presents the analysis of group 4, which deals with effect of axial pre-compression on masonry seismic performance. Three single leaf panels with aspect ratio of 0.67 having size 1.65x1.1m were constructed using same material and workmanship. All the three un-reinforced walls were tested under 0, 0.5 and 1.0MPa vertical pre-compression and displacement controlled static cyclic loading. The wall tested under 0.5MPa pre-compression was reference specimen. The key parameters studied were hysterics behavior, peak lateral load, ultimate lateral displacement, energy dissipation, ductility, response factor and damping ratio. It was observed that level of axial pre-compression has significant effect on lateral capacity, failure mode and performance of masonry. In case of zero pre-compression the lateral capacity was very less and wall went into rocking failure at early stages of loading. Increase in pre-compression to 1.0MPa enhanced the lateral capacity by a factor of 1.92 times. After analysis of test results, it is found that pre-compression has significant effect on lateral capacity, failure mode and performance of masonry. In case of zero pre-compression the lateral capacity was very less and wall went into rocking failure at early stages of loading. Increase in pre-compression to 1.0MPa enhanced the lateral capacity by a factor of 1.92 times. After analysis of test results, it is found that pre-compression has very
Multi-axial load application and DIC measurement of advanced composite beam deformation behavior
Directory of Open Access Journals (Sweden)
Berggreen C.
2010-06-01
Full Text Available For the validation of a new beam element formulation, a wide set of experimental data consisting of deformation patterns obtained for a number of specially designed composite beam elements, have been obtained. The composite materials applied in the beams consist of glass-fiber reinforced plastic with specially designed layup configurations promoting advanced coupling behavior. Furthermore, the beams are designed with different cross-section shapes. The data obtained from the experiments are also used in order to improve the general understanding related to practical implementation of mechanisms of elastic couplings due to anisotropic properties of composite materials. The knowledge gained from these experiments is therefore essential in order to facilitate an implementation of passive control in future large wind turbine blades. A test setup based on a four-column MTS servo-hydraulic testing machine with a maximum capacity of 100 kN was developed, see Figure 1. The setup allows installing and testing beams of different cross-sections applying load cases such as axial extension, shear force bending, pure bending in two principal directions as well as pure torsion, see Figure 2. In order to apply multi-axial loading, a load application system consisting of three hydraulic actuators were mounted in two planes using multi-axial servo-hydraulic control. The actuator setup consists of the main actuator on the servo-hydraulic test machine working in the vertical axis (depicted on Figure 1 placed at the testing machine crosshead and used for application of vertical forces to the specimens. Two extra actuators are placed in a horizontal plane on the T-slot table of the test machine in different positions in order to apply loading at the tip of the specimen in various configurations. In order to precisely characterize the global as well as surface deformations of the beam specimens tested, a combination of different measurement systems were used during
Remote monitoring of bi-axial loads on a lifting surface moving unsteadily in water
International Nuclear Information System (INIS)
A system of measuring the bi-axial load on a lifting surface (blade) which is freely moving and operates submerged in water at the laboratory scale is described. A blade with a span of 500 mm, a chord of 60 mm and a thickness of 9 mm (15% of the chord) was employed and the lift/drag forces were measured using a bespoke strain-gauge based load cell located at the mid-span of the blade, measuring bending moments in two independent directions. The requirement to move freely dictated that the load cell was encapsulated within the blade, along with signal conditioning circuitry, power supply and a data logger with wireless transmission. Submerged operation in water resulted in very short transmission distances, meaning that data were recorded and subsequently transferred using an aerial placed close to the blade while it was stationary. Assumptions based on Euler–Bernoulli beam bending theory were used to infer the total load from measurements of the bending moment at the mid-span and example data from a freely moving aerofoil on a Darrieus-type tidal energy extraction device are presented. The novelty of this system lies in its combination of free movement, submerged operation and small scale. (paper)
Claus, Andrew P; Verrel, Julius; Pounds, Paul E I; Shaw, Renee C; Brady, Niamh; Chew, Min T; Dekkers, Thomas A; Hodges, Paul W
2016-05-01
Sudden application of load along a sagittal or coronal axis has been used to study trunk stiffness, but not axial (vertical) load. This study introduces a new method for sudden-release axial load perturbation. Prima facie validity was supported by comparison with standard mechanical systems. We report the response of the human body to axial perturbation in sitting and standing and within-day repeatability of measures. Load of 20% of body weight was released from light contact onto the shoulders of 22 healthy participants (10 males). Force input was measured via force transducers at shoulders, output via a force plate below the participant, and kinematics via 3-D motion capture. System identification was used to fit data from the time of load release to time of peak load-displacement, fitting with a 2nd-order mass-spring-damper system with a delay term. At peak load-displacement, the mean (SD) effective stiffness measured with this device for participants in sitting was 12.0(3.4)N/mm, and in standing was 13.3(4.2)N/mm. Peak force output exceeded input by 44.8 (10.0)% in sitting and by 30.4(7.9)% in standing. Intra-class correlation coefficients for within-day repeatability of axial stiffness were 0.58 (CI: -0.03 to 0.83) in sitting and 0.82(0.57-0.93) in standing. Despite greater degrees of freedom in standing than sitting, standing involved lesser time, downward displacement, peak output force and was more repeatable in defending upright postural control against the same axial loads. This method provides a foundation for future studies of neuromuscular control with axial perturbation. PMID:26968087
The effect of variable stator on performance of a highly loaded tandem axial flow compressor stage
Eshraghi, Hamzeh; Boroomand, Masoud; Tousi, Abolghasem M.; Fallah, Mohammad Toude; Mohammadi, Ali
2016-06-01
Increasing the aerodynamic load on compressor blades helps to obtain a higher pressure ratio in lower rotational speeds. Considering the high aerodynamic load effects and structural concerns in the design process, it is possible to obtain higher pressure ratios compared to conventional compressors. However, it must be noted that imposing higher aerodynamic loads results in higher loss coefficients and deteriorates the overall performance. To avoid the loss increase, the boundary layer quality must be studied carefully over the blade suction surface. Employment of advanced shaped airfoils (like CDAs), slotted blades or other boundary layer control methods has helped the designers to use higher aerodynamic loads on compressor blades. Tandem cascade is a passive boundary layer control method, which is based on using the flow momentum to control the boundary layer on the suction surface and also to avoid the probable separation caused by higher aerodynamic loads. In fact, the front pressure side flow momentum helps to compensate the positive pressure gradient over the aft blade's suction side. Also, in comparison to the single blade stators, tandem variable stators have more degrees of freedom, and this issue increases the possibility of finding enhanced conditions in the compressor off-design performance. In the current study, a 3D design procedure for an axial flow tandem compressor stage has been applied to design a highly loaded stage. Following, this design is numerically investigated using a CFD code and the stage characteristic map is reported. Also, the effect of various stator stagger angles on the compressor performance and especially on the compressor surge margin has been discussed. To validate the CFD method, another known compressor stage is presented and its performance is numerically investigated and the results are compared with available experimental results.
The Effect of Variable Stator on Performance of a Highly Loaded Tandem Axial Flow Compressor Stage
Institute of Scientific and Technical Information of China (English)
Hamzeh Eshraghi; Masoud Boroomand; Abolghasem M.Tousi; Mohammad Toude Fallah; Ali Mohammadi
2016-01-01
Increasing the aerodynamic load on compressor blades helps to obtain a higher pressure ratio in lower rotational speeds.Considering the high aerodynamic load effects and structural concerns in the design process,it is possible to obtain higher pressure ratios compared to conventional compressors.However,it must be noted that imposing higher aerodynamic loads results in higher loss coefficients and deteriorates the overall performance.To avoid the loss increase,the boundary layer quality must be studied carefully over the blade suction surface.Employment of advanced shaped airfoils (like CDAs),slotted blades or other boundary layer control methods has helped the designers to use higher aerodynamic loads on compressor blades.Tandem cascade is a passive boundary layer control method,which is based on using the flow momentum to control the boundary layer on the suction surface and also to avoid the probable separation caused by higher aerodynamic loads.In fact,the front pressure side flow momentum helps to compensate the positive pressure gradient over the aft blade's suction side.Also,in comparison to the single blade stators,tandem variable stators have more degrees of freedom,and this issue increases the possibility of finding enhanced conditions in the compressor off-design performance.In the current study,a 3D design procedure for an axial flow tandem compressor stage has been applied to design a highly loaded stage.Following,this design is numerically investigated using a CFD code and the stage characteristic map is reported.Also,the effect of various stator stagger angles on the compressor performance and especially on the compressor surge margin has been discussed.To validate the CFD method,another known compressor stage is presented and its performance is numerically investigated and the results are compared with available experimental results.
Comparison of Methods to Predict Lower Bound Buckling Loads of Cylinders Under Axial Compression
Haynie, Waddy T.; Hilburger, Mark W.
2010-01-01
Results from a numerical study of the buckling response of two different orthogrid stiffened circular cylindrical shells with initial imperfections and subjected to axial compression are used to compare three different lower bound buckling load prediction techniques. These lower bound prediction techniques assume different imperfection types and include an imperfection based on a mode shape from an eigenvalue analysis, an imperfection caused by a lateral perturbation load, and an imperfection in the shape of a single stress-free dimple. The STAGS finite element code is used for the analyses. Responses of the cylinders for ranges of imperfection amplitudes are considered, and the effect of each imperfection is compared to the response of a geometrically perfect cylinder. Similar behavior was observed for shells that include a lateral perturbation load and a single dimple imperfection, and the results indicate that the predicted lower bounds are much less conservative than the corresponding results for the cylinders with the mode shape imperfection considered herein. In addition, the lateral perturbation technique and the single dimple imperfection produce response characteristics that are physically meaningful and can be validated via testing.
Multisized Inert Particle Loading for Solid Rocket Axial Combustion Instability Suppression
Directory of Open Access Journals (Sweden)
David R. Greatrix
2012-01-01
Full Text Available In the present investigation, various factors and trends, related to the usage of two or more sets of inert particles comprised of the same material (nominally aluminum but at different diameters for the suppression of axial shock wave development, are numerically predicted for a composite-propellant cylindrical-grain solid rocket motor. The limit pressure wave magnitudes at a later reference time in a given pulsed firing simulation run are collected for a series of runs at different particle sizes and loading distributions and mapped onto corresponding attenuation trend charts. The inert particles’ presence in the central core flow is demonstrated to be an effective means of instability symptom suppression, in correlating with past experimental successes in the usage of particles. However, the predicted results of this study suggest that one needs to be careful when selecting more than one size of particle for a given motor application.
Modelling of stiffness degradation due to cracking in laminates subjected to multi-axial loading.
Kashtalyan, M; Soutis, C
2016-07-13
The paper presents an analytical approach to predicting the effect of intra- and interlaminar cracking on residual stiffness properties of the laminate, which can be used in the post-initial failure analysis, taking full account of damage mode interaction. The approach is based on a two-dimensional shear lag stress analysis and the equivalent constraint model of the laminate with multiple damaged plies. The application of the approach to predicting degraded stiffness properties of multidirectional laminates under multi-axial loading is demonstrated on cross-ply glass/epoxy and carbon/epoxy laminates with transverse and longitudinal matrix cracks and crack-induced transverse and longitudinal delaminations.This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'. PMID:27242290
Simulating of marble subjected to uni-axial loading using index-parabola damage model
Institute of Scientific and Technical Information of China (English)
温世游; 李夕兵; 骆达成
2001-01-01
The limitations of several existing classical rock damage models were critically appraised. Thereafter, a description of a new model to estimate the response of rock was provided. The results of an investigation lead to the development and confirmation of a new index-parabola damage model. The new model is divided into two parts, fictitious damage and real damage and bordered by the critical damage point. In fictitious damage, the damage variable follows the index distribution, while in the real damage a parabolic distribution is used. Thus, the so-called index-parabola damage model is derived. The proposed damage model is applied to simulate the damage procedure of marble under uni-axial loading. The results of the tests show that the proposed model is in excellent agreement with experimental data, in particular the nonlinear characteristic of rock deformation is adequately represented.
DEFF Research Database (Denmark)
Madsen, Rasmus; Jensen, Tue Secher; Pope, Malcolm;
2007-01-01
STUDY DESIGN: A method comparison study. OBJECTIVE: To investigate the effect of body position and axial load of the lumbar spine on disc height, lumbar lordosis, and dural sac cross-sectional area (DCSA). SUMMARY OF BACKGROUND DATA.: The effects of flexion and extension on spinal canal diameters...... position with applied axial loading. Disc height, lumbar lordosis, and DCSA were measured and the different positions were compared. RESULTS: In section 1, the only significant difference between positions was a reduced lumbar lordosis during standing when compared with lying (P = 0.04), most probably a...... and DCSA are well documented. However, the effects of axial loading, achieved by upright standing or by a compression device, are still unclear. METHODS: Patients with lumbar spinal stenosis were examined in 2 separate studies, including 16 and 20 patients, respectively. In section 1, magnetic...
International Nuclear Information System (INIS)
Given that most applications of shape memory alloys (SMA) are in the wire form, a reduced order model and analysis has been attempted in this paper. It takes into account the fact that the predominant actions are axial (bending inclusive) and torsional. A thermodynamic framework is first developed to simulate the behaviour of the SMA material under thermo-mechanical loading that is a combination of axial and shear stresses arising at a point in a wire due to axial and torsional loads applied to the wire. Since only a few variants relevant to axial-torsion are going to be active in transformation under this kind of loading, a reduced order model that tracks the evolution of four martensite variants and an austenite variant is proposed. It is shown through simulations that these five model parameters amply form a minimal set of model parameters sufficient for simulating response under tension–torsion loading excursions. The model is further applied to the structural member, in this case, a wire of circular cross-section subject to a twist and an axial extension and the capability of the model to simulate the kind of response expected in wires. Incorporation of this model into a large deformation space frame nonlinear analysis will help in the design and analysis of several applications where SMA wire forms are used. (paper)
The effect of axial and transverse loading on the transport properties of ITER Nb3Sn strands
Nijhuis, A.; Pompe van Meerdervoort, R. P.; Krooshoop, H. J. G.; Wessel, W. A. J.; Zhou, C.; Rolando, G.; Sanabria, C.; Lee, P. J.; Larbalestier, D. C.; Devred, A.; Vostner, A.; Mitchell, N.; Takahashi, Y.; Nabara, Y.; Boutboul, T.; Tronza, V.; Park, S.-H.; Yu, W.
2013-08-01
The differences in thermal contraction of the composite materials in a cable in conduit conductor (CICC) for the International Thermonuclear Experimental Reactor (ITER), in combination with electromagnetic charging, cause axial, transverse contact and bending strains in the Nb3Sn filaments. These local loads cause distributed strain alterations, reducing the superconducting transport properties. The sensitivity of ITER strands to different strain loads is experimentally explored with dedicated probes. The starting point of the characterization is measurement of the critical current under axial compressive and tensile strain, determining the strain sensitivity and the irreversibility limit corresponding to the initiation of cracks in the Nb3Sn filaments for axial strain. The influence of spatial periodic bending and contact load is evaluated by using a wavelength of 5 mm. The strand axial tensile stress-strain characteristic is measured for comparison of the axial stiffness of the strands. Cyclic loading is applied for transverse loads following the evolution of the critical current, n-value and deformation. This involves a component representing a permanent (plastic) change and as well as a factor revealing reversible (elastic) behavior as a function of the applied load. The experimental results enable discrimination in performance reduction per specific load type and per strand type, which is in general different for each manufacturer involved. Metallographic filament fracture studies are compared to electromagnetic and mechanical load test results. A detailed multifilament strand model is applied to analyze the quantitative impact of strain sensitivity, intrastrand resistances and filament crack density on the performance reduction of strands and full-size ITER CICCs. Although a full-size conductor test is used for qualification of a strand manufacturer, the results presented here are part of the ITER strand verification program. In this paper, we present an
The effect of axial and transverse loading on the transport properties of ITER Nb3Sn strands
International Nuclear Information System (INIS)
The differences in thermal contraction of the composite materials in a cable in conduit conductor (CICC) for the International Thermonuclear Experimental Reactor (ITER), in combination with electromagnetic charging, cause axial, transverse contact and bending strains in the Nb3Sn filaments. These local loads cause distributed strain alterations, reducing the superconducting transport properties. The sensitivity of ITER strands to different strain loads is experimentally explored with dedicated probes. The starting point of the characterization is measurement of the critical current under axial compressive and tensile strain, determining the strain sensitivity and the irreversibility limit corresponding to the initiation of cracks in the Nb3Sn filaments for axial strain. The influence of spatial periodic bending and contact load is evaluated by using a wavelength of 5 mm. The strand axial tensile stress–strain characteristic is measured for comparison of the axial stiffness of the strands. Cyclic loading is applied for transverse loads following the evolution of the critical current, n-value and deformation. This involves a component representing a permanent (plastic) change and as well as a factor revealing reversible (elastic) behavior as a function of the applied load. The experimental results enable discrimination in performance reduction per specific load type and per strand type, which is in general different for each manufacturer involved. Metallographic filament fracture studies are compared to electromagnetic and mechanical load test results. A detailed multifilament strand model is applied to analyze the quantitative impact of strain sensitivity, intrastrand resistances and filament crack density on the performance reduction of strands and full-size ITER CICCs. Although a full-size conductor test is used for qualification of a strand manufacturer, the results presented here are part of the ITER strand verification program. In this paper, we present an
A Developed Methodology in Design of Highly Loaded Tandem Axial Flow Compressor Stage
Directory of Open Access Journals (Sweden)
Masoud Boroomand
2016-01-01
Full Text Available This study, primarily reports the development of a 3D design procedure for axial flow tandem compressor stages and then the method is used to design a highly loaded tandem stage. In order to investigate the effects of such arrangement, another stage with conventional loading with single blade for both rotor and stator rows is designed with similar specification. In order to ease the comparison of results, chord lengths and hub/shroud geometries are selected with the same dimensions. At the next stage a three dimensional numerical model is developed to predict the characteristic performance of both tandem and conventional stages. The model is validated with the experimental results of NASA-67 stage and the level of the accuracy of the model is presented. Employing the model to simulate the performance of both stages at design and offdesign operating points show that, tandem stage can provide higher pressure ratio with acceptable efficiency. In another word, tandem stage is capable having the same pressure ratio at lower rotational speed. The safe operation domain and loss mechanism in tandem stage are also discussed in this report.
Damped lateral vibrations of straight and curved cables with no axial pre-load
Otrin, Miha; Boltežar, Miha
2007-03-01
This paper presents a study of the lateral vibrations of straight and curved cables with no axial pre-load. For the computation of the vibration transmissibility we used finite elements based on the Euler-Bernoulli theory. The dissipation of energy was studied with viscous- and structural-damping models, where the Rayleigh coefficients and the frequency dependence of the loss factor were identified. By using the equality between the measured and the computed natural frequencies the frequency dependence of the dynamic modulus of elasticity was estimated and used for all the studied types of cable. The excitation was the result of moving the support in a direction perpendicular to the axis of the cable. The mathematical model for the computation of the vibrations of the straight and curved cables was verified with experimental measurements in which the support excitation was achieved with an electrodynamic shaker and the amplitude force was measured at the fixed support with a dynamometer. For the curved cable the mathematical model was verified for in-plane and out-off-plane vibrations. Three straight cables of different lengths were analyzed for the dependence of the Rayleigh coefficients on the length of the cables.
International Nuclear Information System (INIS)
A polycrystal finite element (FE) model describing the temperature evolution of low carbon steel is proposed in order to forecast the local mechanical fields as a function of temperature, for bainitic microstructure submitted to tri-axial loading. The model is designed for finite strains, large lattice rotations and temperatures ranging into the brittle-ductile transition domain. The dislocation densities are the internal variables. At low temperature in Body Centred Cubic (BCC) materials, plasticity is governed by double kink nucleation of screw dislocations, whereas at high temperature, plasticity depends on interactions between mobile dislocations and the forest dislocations. In this paper, the constitutive law and the evolution of the dislocation densities are written as a function of temperature and describe low and high temperature mechanisms. The studied aggregates are built from Electron Back Scattering Diffraction (EBSD) images of real bainitic steel. The aggregate is submitted to a tri-axial loading in order to describe the material at a crack tip. Mechanical parameters are deduced from mechanical tests. The local strain and stress fields, computed for different applied loadings, present local variations which depend on temperature and on tri-axial ratio. The distribution curves of the maximal principal stresses show that heterogeneities respectively increase with temperature and decrease with tri-axial ratio. A direct application of this model provides the evaluation of the rupture probability within the aggregate, which is treated as the elementary volume in the weak link theory. A comparison with the Beremin criterion calibrated on experimental data, shows that the computed fracture probability dispersion induced by the stress heterogeneities is of the same order than the measured dispersion. Temperature and stress tri-axiality ratio effects are also investigated. It is shown that these two parameters have a strong effect on fracture owing to their
International Nuclear Information System (INIS)
In this study, the buckling analysis of the simply supported truncated conical shell made of functionally graded materials (FGMs) is presented. The FGM truncated conical shell subjected to an axial compressive load and resting on Winkler-Pasternak type elastic foundations. The material properties of functionally graded shells are assumed to vary continuously through the thickness. The modified Donnell type stability and compatibility equations are solved by Galerkin's method and the critical axial load of FGM truncated conical shells with and without elastic foundations have been found analytically. The appropriate formulas for homogenous and FGM cylindrical shells with and without elastic foundations are found as a special case. Several examples are presented to show the accuracy and efficiency of the formulation. Finally, parametric studies on the buckling of FGM truncated conical and cylindrical shells on elastic foundations are being investigated. These parameters include; power-law and exponential distributions of FGM, Winkler foundation modulus, Pasternak foundation modulus and aspect ratios of shells.
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During load following operation of PWRs, it is required to control the changes of core power distribution and reactivity effectively. Since occurrence of xenon spatial distribution oscillation following the change of the reactor power can cause oscillation in the power distribution, one strategy for the core power distribution control is by eliminating xenon oscillation as fast as possible. A lot of studies have been done to solve the problem, some of which use complex mathematical treatments. On the other hand, the three axial offsets trajectory method, which uses a simple mathematical treatment based on two points reactor model, has been proved to be effective for xenon oscillation control. In this study, we examined the feasibility of application of the three axial offsets trajectory method as a strategy generator for the reactor control in the load following operation
International Nuclear Information System (INIS)
Metabolic changes induced by axial vibratory load to the spine were investigated based on water metabolism in normal intervertebral discs of rabbits with or without pentobarbital anesthesia. Tritiated water concentration in the intervertebral discs of unanesthetized rabbits was reduced remarkably by axial vibration for 30 minutes using the vibration machine developed for this study. Repeated vibratory load for 18 and 42 hours duration showed the recovery of 3H2O concentration of the intervertebral disc without anesthesia. Computer simulation suggested a reduction of blood flow surrounding the intervertebral disc following the vibration stress. However, no reduction of the 3H2O concentration in the intervertebral disc was noted under anesthesia. Emotional stress cannot be excluded as a factor in water metabolism in the intervertebral disc
Strength Behavior of High Strength R/C Columns under Biaxial Bending-Shear and Varying Axial Load
MIZOGUCHI, Mitsuo; Arakawa, Takashi; ARAI, Yasuyuki
1991-01-01
Twelve short square R/C columns using high-strength concrete were tested to examine the effects of biaxial bending-shear force and varying axial load on the shear and flexural strength behavior. The columns were cyclically deflected either along their transverse principal axis to produce uniaxial bending-shear or along their diagonal to produce biaxial bending-shear. For columns failing in flexure, the experimental results were found to be in close agreement with the computed values given by ...
Frederico Martins Alves da Silva; Augusta Finotti Brazão; Paulo Batista Gonçalves
2015-01-01
This work investigates the influence of Young’s modulus, shells thickness, and geometrical imperfection uncertainties on the parametric instability loads of simply supported axially excited cylindrical shells. The Donnell nonlinear shallow shell theory is used for the displacement field of the cylindrical shell and the parameters under investigation are considered as uncertain parameters with a known probability density function in the equilibrium equation. The uncertainties are discretized a...
International Nuclear Information System (INIS)
This paper presents a novel vibration-based piezoelectric energy harvester capable of passively tuning its resonant frequency to a wide range of frequencies. The device comprises a dual bimorph with a mass at its free end. A novel sliding mechanism, consisting of two oblique springs connected to the tip mass, is proposed to widen the resonance frequency of the device even to very low frequencies. The application of two oblique springs results in an additional stiffness and axial load that are introduced within the system, such that the resonance frequency of the device is now a function of both the stiffness and axial load associated with the spring forces. An operator can manually change the resonance frequency of the harvester just by small adjustments of the sliding mechanism. Further, the device allows one to tune the resonance frequency of the beam to match very low frequencies without the requirement of having a large proof mass. The analytical solution of an axially loaded cantilevered piezoelectric energy harvester with tip stiffness, using Euler–Bernoulli beam assumptions, is presented. A parametric case study is presented to demonstrate the performance of the device. (paper)
Bouzid, T.; Demagh, K.
2011-03-01
Reinforced and concrete-encased composite columns of arbitrarily shaped cross sections subjected to biaxial bending and axial loads are commonly used in many structures. For this purpose, an iterative numerical procedure for the strength analysis and design of short and slender reinforced concrete columns with a square cross section under biaxial bending and an axial load by using an EC2 stress-strain model is presented in this paper. The computational procedure takes into account the nonlinear behavior of the materials (i.e., concrete and reinforcing bars) and includes the second - order effects due to the additional eccentricity of the applied axial load by the Moment Magnification Method. The ability of the proposed method and its formulation has been tested by comparing its results with the experimental ones reported by some authors. This comparison has shown that a good degree of agreement and accuracy between the experimental and theoretical results have been obtained. An average ratio (proposed to test) of 1.06 with a deviation of 9% is achieved.
Cyclic and Rapid Axial Load Tests on Displacement Piles in Soft Clay
Doherty, Paul; Gavin, Kenneth
2012-01-01
Offshore piles are subjected to complex loading regimes, which include both rapidly applied static and cyclic loads. This note describes an experimental investigation conducted in order to assess the factors influencing the response of offshore piles to these loading conditions. The tests were performed using instrumented model piles installed in soft clay. During cyclic loading, the piles demonstrated a transition from stable to unstable behaviour when the applied loads reache...
Directory of Open Access Journals (Sweden)
Achillopoulou Dimitra
2014-12-01
Full Text Available The study deals with the investigation of the effect of casting deficiencies- both experimentally and analytically on axial yield load or reinforced concrete columns. It includes 6 specimens of square section (150x150x500 mm of 24.37 MPa nominal concrete strength with 4 longitudinal steel bars of 8 mm (500 MPa nominal strength with confinement ratio ωc=0.15. Through casting procedure the necessary provisions defined by International Standards were not applied strictly in order to create construction deficiencies. These deficiencies are quantified geometrically without the use of expensive and expertise non-destructive methods and their effect on the axial load capacity of the concrete columns is calibrated trough a novel and simplified prediction model extracted by an experimental and analytical investigation that included 6 specimens. It is concluded that: a even with suitable repair, load reduction up to 22% is the outcome of the initial construction damage presence, b the lower dispersion is noted for the section damage index proposed, c extended damage alters the failure mode to brittle accompanied with longitudinal bars buckling, d the proposed model presents more than satisfying results to the load capacity prediction of repaired columns.
Dynamic stability of slender columns with semi-rigid connections under periodic axial load: theory
Directory of Open Access Journals (Sweden)
Oliver Giraldo-Londoño
2014-01-01
Full Text Available La estabilidad dinámica de una columna elástica prismática esbelta con conexiones semirrígidas en ambos extremos de rigidez idéntica y con desplazamiento lateral entre los dos extremos totalmente inhibido sujetos a cargas axiales paramétricos incluyendo los efectos combinados de inercia rotacional y amortiguación externas se investiga de una manera clásica. Expresiones cerradas que se pueden utilizar para predecir las regiones de inestabilidad dinámica de columnas esbeltas son desarrolladas haciendo uso de la teoría de Floquet. La solución propuesta es capaz de capturar el fenómeno de estabilidad en columnas sometidas a cargas axiales periódicas utilizando un solo elemento de columna. El método propuesto y las ecuaciones correspondientes se pueden utilizar para investigar los efectos del amortiguamiento, la inercia rotacional de la columna, y las conexiones semirrígidas en el análisis de estabilidad de columnas esbeltas sometidas a cargas axiales periódicas. Los efectos producidos por las deformaciones por cizallamiento a lo largo de la columna, así como los producidos por la inercia axial, el acoplamiento entre las deflexiones longitudinales y transversales y la curvatura no se tienen en cuenta. Estudios de sensibilidad que muestran los efectos de la inercia rotacional, el amortiguamiento y las conexiones semi-rígidas en la estabilidad dinámica de columnas sometidas a cargas axiales paramétricas son presentados en una publicación adjunta.
Jing, C.; Chang, C.; Gold, S. H.; Konecny, R.; Antipov, S.; Schoessow, P.; Kanareykin, A.; Gai, W.
2013-11-01
Efforts by a number of institutions to develop a Dielectric-Loaded Accelerating (DLA) structure capable of supporting high gradient acceleration when driven by an external radio frequency source have been ongoing over the past decade. Single surface resonant multipactor has been previously identified as one of the major limitations on the practical application of DLA structures in electron accelerators. In this paper, we report the results of an experiment that demonstrated suppression of multipactor growth in an X-band DLA structure through the use of an applied axial magnetic field. This represents an advance toward the practical use of DLA structures in many accelerator applications.
Energy Technology Data Exchange (ETDEWEB)
Jing, C.; Konecny, R.; Antipov, S. [Euclid Techlabs, LLC, 5900 Harper Rd., Solon, Ohio 44139 (United States); High Energy Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Chang, C. [Science and Technology on High Power Microwave Laboratory, Xi' an City 710024 (China); Institute of Energy, Tsinghua University, Beijing 100084 (China); Gold, S. H. [Naval Research Laboratory, Plasma Physics Division, Washington, DC 20375 (United States); Schoessow, P.; Kanareykin, A. [Euclid Techlabs, LLC, 5900 Harper Rd., Solon, Ohio 44139 (United States); Gai, W. [High Energy Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
2013-11-18
Efforts by a number of institutions to develop a Dielectric-Loaded Accelerating (DLA) structure capable of supporting high gradient acceleration when driven by an external radio frequency source have been ongoing over the past decade. Single surface resonant multipactor has been previously identified as one of the major limitations on the practical application of DLA structures in electron accelerators. In this paper, we report the results of an experiment that demonstrated suppression of multipactor growth in an X-band DLA structure through the use of an applied axial magnetic field. This represents an advance toward the practical use of DLA structures in many accelerator applications.
International Nuclear Information System (INIS)
The existence of a large damping increase under axial flow is clearly demonstrated by test results. Therefore this phenomenon concerns not only isolated tubes, but also rod bundles with multiple support such as fuel assemblies, and it may represent a large conservatism margin when not allowed for in their modelling. Test results also demonstrate that the mock-up behaviour is representative of that of a full-scale assembly, and that actual confinement conditions are not of much concern since their influence remains small. However, applying test results under axial flow to a core model can be envisaged only with caution, since no clear physical interpretation of this phenomenon has been found (at least for such large damping values). Further studies will comprise a complementary experimental program, in order to specify the physical nature and the application range of this effect, and to provide hints for a theoretical interpretation. (author)
A cylindrical shell with an axial crack under skew-symmetric loading.
Yuceoglu, U.; Erdogan, F.
1973-01-01
The skew-symmetric problem for a cylindrical shell containing an axial crack is considered. It is assumed that the material has a special orthotropy - namely, that the shear modulus may be evaluated from the measured Young's moduli and Poisson ratios and is not an independent material constant. The problem is solved within the confines of an eighth-order linearized shallow shell theory. As numerical examples, the torsion of an isotropic cylinder and that of a specially orthotropic cylinder (titanium) are considered. The membrane and bending components of the stress intensity factor are calculated and are given as functions of a dimensionless shell parameter. In the torsion problem for the axially cracked cylinder the bending effects appear to be much more significant than that found for the circumferentially cracked cylindrical shell. Also, as the shell parameter increases, unlike the results found in the pressurized shell, the bending stresses around crack ends do not change sign.
Axial forces and bending moments in the loaded rabbit tibia in vivo
Reifenrath Janin; Gottschalk Daniel; Angrisani Nina; Besdo Silke; Meyer-Lindenberg Andrea
2012-01-01
Abstract Background Different animal models are used as fracture models in orthopaedic research prior to implant use in humans, although biomechanical forces can differ to a great extend between species due to variable anatomic conditions, particularly with regard to the gait. The rabbit is an often used fracture model, but biomechanical data are very rare. The objective of the present study was to measure axial forces, bending moments, and bending axis directly in the rabbit tibia in vivo. T...
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Sofiyev, A.H., E-mail: asofiyev@mmf.sdu.edu.t [Department of Civil Engineering, Suleyman Demirel University, 32260 Isparta (Turkey)
2010-12-15
In this study, the buckling analysis of the simply supported truncated conical shell made of functionally graded materials (FGMs) is presented. The FGM truncated conical shell subjected to an axial compressive load and resting on Winkler-Pasternak type elastic foundations. The material properties of functionally graded shells are assumed to vary continuously through the thickness. The modified Donnell type stability and compatibility equations are solved by Galerkin's method and the critical axial load of FGM truncated conical shells with and without elastic foundations have been found analytically. The appropriate formulas for homogenous and FGM cylindrical shells with and without elastic foundations are found as a special case. Several examples are presented to show the accuracy and efficiency of the formulation. Finally, parametric studies on the buckling of FGM truncated conical and cylindrical shells on elastic foundations are being investigated. These parameters include; power-law and exponential distributions of FGM, Winkler foundation modulus, Pasternak foundation modulus and aspect ratios of shells.
Dynamic stability of slender columns with semi-rigid connections under periodic axial load: theory
Oliver Giraldo-Londoño; J. DARÍO ARISTIZÁBAL-OCHOA
2014-01-01
La estabilidad dinámica de una columna elástica prismática esbelta con conexiones semirrígidas en ambos extremos de rigidez idéntica y con desplazamiento lateral entre los dos extremos totalmente inhibido sujetos a cargas axiales paramétricos incluyendo los efectos combinados de inercia rotacional y amortiguación externas se investiga de una manera clásica. Expresiones cerradas que se pueden utilizar para predecir las regiones de inestabilidad dinámica de columnas esbeltas son desarrolladas h...
Analysis of the axial electric field in a plasma-loaded-helix travelling wave tube
Institute of Scientific and Technical Information of China (English)
Xie Hong-Quan; Liu Pu-Kun
2006-01-01
A helix type slow wave structure filled with plasma is immersed in a strong longitudinal magnetic field. Taking into account the effect of the plasma and the dielectric, the system is separated radially into three regions. By means of the sheath model and Maxwell equation, the distribution of the electromagnetic field is established. Using the boundary conditions of each region, the dispersion relation of the slow wave structure is derived. The trend of change for the radial profile of the axial electric field is analysed respectively in different plasma densities, plasma column radius and dielectric constant by numerical computation. Some useful results are obtained on the basis of the discussion.
Dynamic stability of simply supported composite cylindrical shells under partial axial loading
Dey, Tanish; Ramachandra, L. S.
2015-09-01
The parametric vibration of a simply supported composite circular cylindrical shell under periodic partial edge loadings is discussed in this article. Donnell's nonlinear shallow shell theory considering first order shear deformation theory is used to model the shell. The applied partial edge loading is represented in terms of a Fourier series and stress distributions within the cylindrical shell are determined by prebuckling analysis. The governing equations of the dynamic instability of shells are derived in terms of displacements (u-v-w) and rotations (φx, φθ). Employing the Galerkin and Bolotin methods the dynamic instability regions are computed. Using the expression for the stress function derived in this paper, the pre-buckling stresses in the cylindrical shell due to partial loading can be calculated explicitly. Numerical results are presented to show the influence of radius-to-thickness ratio, different partial edge loading distributions and shear deformation on the dynamic instability regions. The linear and nonlinear responses in the stable and unstable regions are presented to bring out the characteristic features of the dynamic instability regions, such as the existence of beats, its dependence on forcing frequency and effect of nonlinearity on the response. The effect of dynamic load amplitude on the nonlinear response is also studied. It is found that for higher values of dynamic loading, the shell exhibits chaotic behavior.
Testing and Analysis of Composite Skin/Stringer Debonding Under Multi-Axial Loading
Krueger, Ronald; Cvitkovich, Michael K.; O'Brien, T. Kevin; Minguet, Pierre J.
2000-01-01
A consistent step-wise approach is presented to investigate the damage mechanism in composite bonded skin/stringer constructions under uniaxial and biaxial (in-plane/out-of-plane) loading conditions. The approach uses experiments to detect the failure mechanism, computational stress analysis to determine the location of first matrix cracking and computational fracture mechanics to investigate the potential for delamination growth. In a first step, tests were performed on specimens, which consisted of a tapered composite flange, representing a stringer or frame, bonded onto a composite skin. Tests were performed under monotonic loading conditions in tension, three-point bending, and combined tension/bending to evaluate the debonding mechanisms between the skin and the bonded stringer. For combined tension/bending testing, a unique servohydraulic load frame was used that was capable of applying both in-plane tension and out-of-plane bending loads simultaneously. Specimen edges were examined on the microscope to document the damage occurrence and to identify typical damage patterns. For all three load cases, observed failure initiated in the flange, near the flange tip, causing the flange to almost fully debond from skin. In a second step, a two dimensional plane-strain finite element model was developed to analyze the different test cases using a geometrically nonlinear solution. For all three loading conditions, computed principal stresses exceeded the transverse strength of the material in those areas of the flange where the matrix cracks had developed during the tests. In a third step, delaminations of various lengths were simulated in two locations where delaminations were observed during the tests. The analyses showed that at the loads corresponding to matrix ply crack initiation computed strain energy release rates exceeded the values obtained from a mixed mode failure criterion in one location, Hence. Unstable delamination propagation is likely to occur as
Fraternali, Fernando; Carpentieri, Gerardo; Amendola, Ada
2015-01-01
We study the geometrically nonlinear behavior of uniformly compressed tensegrity prisms through fully elastic and rigid-elastic models. The given models predict a variety of mechanical behaviors in the regime of large displacements, including an extreme stiffening-type response, already known in the literature, and a newly discovered, extreme softening behavior. The latter may lead to a snap buckling event producing an axial collapse of the structure. The switching from one mechanical regime to another depends on the aspect ratio of the structure, the magnitude of the applied prestress, and the material properties of the constituent elements. We discuss potential mechanical and acoustic applications of such behaviors, which are related to the design and manufacture of tensegrity lattices and innovative metamaterials.
International Nuclear Information System (INIS)
Reliability based structural design insures a uniformly designed structure, in terms of safety. By considering an adequate reliability index (or probability of failure) for different parts of a structure, a reasonable balance between cost and safety of the structure can be achieved. In this study, the reliability of steel tension and compression members designed with AASHTO LRFD bridge design specifications (2007) is evaluated. These members are prevalent in different types of truss or arch bridges. Various conditions such as redundancy, ductility and importance of the bridge are taken into account by changing the load modification factor, η. To include the effect of the span length, a variable ratio of dead load to total load is considered. Current load factors in AASHTO LRFD code are accepted due to their verification in a comprehensive study for reliability of girder-type bridges. Furthermore, load and resistance distribution models are chosen based on the latest existing experimental data. The Monte Carlo simulation technique with randomly generated samples is applied in numerical calculations. For tension members, analysis results show relatively high reliability indices in yielding design, while having slightly low reliabilities for the fracture mode. For fracture design of steel tension members, an increase in vehicular dynamic load allowance (IM) from 33% to 75% is suggested to insure a safer behavior. Also, it is shown that the resistance factor for yielding of gross section, φy, can be increased from 0.95 to 1.00 while maintaining enough safety for designed tension members. In addition, obtained reliability curves for steel compression members show a safe behavior of designed compression members with conservative response in some cases. More results and plotted curves are discussed in detail and possible adjustments in code criteria are presented in this paper
Energy Technology Data Exchange (ETDEWEB)
Singh, Punit; Nestmann, Franz [Institute for Water and River Basin Management (IWG), University of Karlsruhe, Kaiser Str. 12, D 76128 Karlsruhe (Germany)
2010-09-15
A detailed experimental investigation of the effects of exit blade geometry on the part-load performance of low-head, axial flow propeller turbines is presented. Even as these turbines find important applications in small-scale energy generation using micro-hydro, the relationship between the layout of blade profile, geometry and turbine performance continues to be poorly characterized. The experimental results presented here help understand the relationship between exit tip angle, discharge through the turbine, shaft power, and efficiency. The modification was implemented on two different propeller runners and it was found that the power and efficiency gains from decreasing the exit tip angle could be explained by a theoretical model presented here based on classical theory of turbomachines. In particular, the focus is on the behaviour of internal parameters like the runner loss coefficient, relative flow angle at exit, mean axial flow velocity and net tangential flow velocity. The study concluded that the effects of exit tip modification were significant. The introspective discussion on the theoretical model's limitation and test facility suggests wider and continued experimentation pertaining to the internal parameters like inlet vortex profile and exit swirl profile. It also recommends thorough validation of the model and its improvement so that it can be made capable for accurate characterization of blade geometric effects. (author)
Directory of Open Access Journals (Sweden)
Gianfranco De Matteis
2014-05-01
Full Text Available The component method for aluminium joints has been recently introduced in some codes and guidelines. Nevertheless, it is still in need of some development and improvement, as in some cases it was obtained by adapting the existing formulations that are valid for steel. The current paper presents the main outcomes of a parametric analysis carried out by means of finite element (FE numerical models for determining the influence of both column axial load and heat affected zone—in the case of welded details—on the structural response of the column web in a tension component. The proposed study integrates previous research carried out by the authors, where the influence of the assumed alloy was investigated and interpreted by corrective parameters expressed as a function of both the material strain hardening and ductility.
A rotational and axial motion system load frame insert for in situ high energy x-ray studies
International Nuclear Information System (INIS)
High energy x-ray characterization methods hold great potential for gaining insight into the behavior of materials and providing comparison datasets for the validation and development of mesoscale modeling tools. A suite of techniques have been developed by the x-ray community for characterizing the 3D structure and micromechanical state of polycrystalline materials; however, combining these techniques with in situ mechanical testing under well characterized and controlled boundary conditions has been challenging due to experimental design requirements, which demand new high-precision hardware as well as access to high-energy x-ray beamlines. We describe the design and performance of a load frame insert with a rotational and axial motion system that has been developed to meet these requirements. An example dataset from a deforming titanium alloy demonstrates the new capability
Pellicano, F.; Amabili, M.
2006-05-01
In the present paper the dynamic stability of circular cylindrical shells subjected to static and dynamic axial loads is investigated. Both Donnell's nonlinear shallow shell and Sanders-Koiter shell theories have been applied to model finite-amplitude static and dynamic deformations. Results are compared in order to evaluate the accuracy of these theories in predicting instability onset and post-critical nonlinear response. The effect of a contained fluid on the stability and the post-critical behaviour is analyzed in detail. Geometric imperfections are considered and their influence on the dynamic instability and post-critical behaviour is investigated. Chaotic dynamics of pre-compressed shells is investigated by means of nonlinear time-series techniques, extracting correlation dimension and Lyapunov exponents.
Pullout strength of axially loaded steel rods bonded in glulam at a 45º angle to the grain
Directory of Open Access Journals (Sweden)
Julio Cesar Molina
2009-01-01
Full Text Available This paper presents an experimental analysis of the pullout strength of bonded and axially loaded steel rods used as connector elements in log-concrete composite bridge decks. Static and cyclic tests were carried out to evaluate the fatigue of the connectors using two species of reforested wood, three types of commercial adhesives and three levels of wood moisture content. It was found that six failure modes (rod interface failure, timber interface failure, combined timber interface/rod interface failure, combined rod interface/timber substrate failure, rod failure, and adhesive failure can occur in the geometry of a single test specimen. The results indicate the good performance of epoxy glued steel rod connectors for use in log-concrete composite bridge decks.
Deformation Behavior and TExture Evolution of Steel Alloys under Axial-Torsional Loading
Energy Technology Data Exchange (ETDEWEB)
Siriruk, A.; Kant, M.; Penumadu, D.; Garlea, E.; Vogel, S.
2011-06-01
Using hollow cylinder samples with suitable geometry obtained from round bar stock, the deformation behavior of bcc Fe based 12L14 steel alloy is evaluated under multi-axial conditions. A stacked strain gage rosette and extensometer mounted on the cylindrical surface at the mid height of the specimen provided strain tensor as a function of applied stress for pure tensile and torsion tests prior to yielding. This study examines elastic and yield behavior and effects of these with respect to texture evolution. Hollow cylinder specimen geometry (tubes) with small wall thickness and relatively (to its thickness) large inner diameter is used. The variation of observed yield surface in deviatoric plane and the effect on mode of deformation (tension versus torsion versus its combination) on stress-strain behavior is discussed. Bulk texture was studied using neutron time-of-flight diffractometer at High-Pressure-Preferred Orientation (HIPPO) - Los Alamos Neutron Science Center (LANSCE) instrument and the evolution of texture and related anisotropy for pure tension versus torsion are also included.
Yangwei Liu; Jinjing Sun; Lipeng Lu
2014-01-01
Control of corner separation has attracted much interest due to its improvement of performance and energy utilization in turbomachinery. Numerical studies have been performed under both design and off-design flow conditions to investigate the effects of boundary layer suction (BLS) on corner separation in a highly loaded compressor cascade. Two new BLS slot configurations are proposed and a total of five suction slot configurations were studied and compared. Averaged static pressure rise, exi...
Eigenvalues of an axially loaded cantilever beam with an eccentric end rigid body
Lajimi, S Amir Mousavi
2014-01-01
An analytical form of the characteristic equation for a vertically mounted cantilever beam with an end rigid body is obtained and solved for the eigenvalues of the structure. The effect of the weight of the structure is taken into consideration by estimating the load as a function of the length of the beam. The mass, rotary inertia and eccentricity of the end rigid body are demonstrated to considerably affect the eigenvalues of the structure.
Institute of Scientific and Technical Information of China (English)
沈惠申
2004-01-01
A compressive postbuckling analysis is presented for a laminated cylinderical panel with piezoelectric actuators subjected to the combined action of mechanical, electrical and thermal loads. The temperature field considered is assumed to be a uniform distribution over the panel surface and through the panel thickness and the electric field is assumed to be the transverse component Ez only. The material properties are assumed to be independent of the temperature and the electric field. The governing equations are based on the classicalshell theory with von Ka rman-Donnell-type of kinematic nonlinearity. The nonlinear prebuckling deformations and initial geometric imperfections of the panel are both taken into account. A boundary layer theory of shell buckling, which includes the effects of nonlinearprebuckling deformations, large deflections in the postbuckling range, and initial geometric imperfections of the shell, is extended to the case of hybrid laminated cylindrical panels of finite length. A singular perturbation technique is employed to determine the buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the compressive postbuckling behavior of perfect and imperfect, cross-ply laminated cylindrical thin panels with fully covered or embedded piezoelectric actuators under different sets of thermal and electrical loading conditions. The effects played by temperature rise, applied voltage,stacking sequence, the character of in-plane boundary conditions, as well as initial geometric imperfections are studied.
The Axial and Radial Solid Loadings up the CFB-Riser
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
@@1 INTRODUCTION The determination of the solids hold-up and local solid fluxes is of paramount importance in the study of the hydrodynamics of a two-phase flow. Several tech-niques have been used during the past decades (Table1). These methods can be classified in two groups,depending on their possible disturbance of the two-phase flow. During a detailed investigation of the hy-drodynamics of circulating fiuidized beds (CFBs), the authors studied the solid loading profiles using several above mentioned techniques. The text below sum-marises the important findings and data treatment.
Directory of Open Access Journals (Sweden)
Yangwei Liu
2014-11-01
Full Text Available Control of corner separation has attracted much interest due to its improvement of performance and energy utilization in turbomachinery. Numerical studies have been performed under both design and off-design flow conditions to investigate the effects of boundary layer suction (BLS on corner separation in a highly loaded compressor cascade. Two new BLS slot configurations are proposed and a total of five suction slot configurations were studied and compared. Averaged static pressure rise, exit loss coefficient, passage blockage and flow turning angle have been given and compared systematically over a range of operation incidence angles. Distributions of significant loss removal, blade loading, exit deviation and total pressure loss at 3 degree and 7 degree incidence have also been studied. Under the same suction mass flows of 0.7% of the inlet mass flows, the pitchwise suction slot on the endwall shows a better optimal performance over the whole operation incidence among single suction slots. By using of the new proposed compound slot configuration with one spanwise slot on the blade suction side and one pitchwise slot on the endwall, the maximum reduction of total pressure loss at 7 degree incidence can be 39.4%.
Directory of Open Access Journals (Sweden)
Muhammad Abid
2010-11-01
Full Text Available In this paper result of an extensive comparative experimental study of a gasketed and non-gasketed flange joint with different assemblies with different combined load combinations is carried out to investigate joint performance i.e. joint strength and sealing capability. Actual joint load capacities are determined under both the design and proof test pressure with maximum additional external loading (axial and bending that can be applied for safe joint performance. In addition, application of combined load is also discussed in the light of equivalent pressure approach.
Institute of Scientific and Technical Information of China (English)
卢亦焱; 李娜; 李杉; 梁鸿骏
2015-01-01
An experimental study on the compressive behavior of steel fiber reinforced concrete-filled steel tube columns is presented. Specimens were tested to investigate the effects of the concrete strength, the thickness of steel tube and the steel fiber volume fraction on the ultimate strength and the ductility. The experimental results indicate that the addition of steel fibers in concrete can significantly improve the ductility and the energy dissipation capacity of the concrete-filled steel tube columns and delay the local buckling of the steel tube, but has no obvious effect on the failure mode. It has also been found that the addition of steel fibers is a more effective method than using thicker steel tube in enhancing the ductility, and more advantageous in the case of higher strength concrete. An analytical model to estimate the load capacity is proposed for steel tube columns filled with both plain concrete and steel fiber reinforced concrete. The predicted results are in good agreement with the experimental ones obtained in this work and literatures.
Seismic vulnerability evaluation of axially loaded steel built-up laced members Ⅱ: evaluations
Institute of Scientific and Technical Information of China (English)
Kangmin Lee; Michel Bruneau
2008-01-01
The test results described in Part 1 of this paper (Lee and Bruneau, 2008) on twelve steel built-up laced members(BLMs) subjected to quasi-static loading are analyzed to provide better knowledge on their seismic behavior. Strengthcapacity of the BLM specimens is correlated with the strength predicted by the AISC LRFD Specifications. Assessmentsof hysteretic properties such as ductility capacity, energy dissipation capacity, and strength degradation after buckling of thespecimen are performed. The compressive strength of BLMs is found to be relatively well predicted by the AISC LRFDSpecifications. BLMs with smaller kl/r were ductile but failed to reach the target ductility of 3.0 before starting to fracture,while those with larger kl/r could meet the ductility demand in most cases. The normalized energy dissipation ratio, ECETand the normalized compressive strength degradation, Cr"/Cr of BLMs typically decrease as normalized displacements δ/δbexpincrease, and the ratios for specimens with larger kl/r dropped more rapidly than for specimens with smaller kl/r; similartrends were observed for the monolithic braces. The BLMs with a smaller slenderness ratio, kl/r, and width-to-thickness ratio,b/t, experienced a larger number of inelastic cycles than those with larger ratios.
Directory of Open Access Journals (Sweden)
Wenbin SUN
2014-12-01
Full Text Available Comparing with the circular concrete columns confined with fiber reinforced polymer (FRP wrap or tube, the rectilinear confined columns were reported much less. Due to the non-uniform distribution of confining pressure in the rectilinear confined columns, the FRP confinement effectiveness was significant reduced. This paper presents findings of an experimental program where nine prefabricated rectangular cross-section CFRP tubes with CFRP integrated crossties filled concrete to form concrete-filled FRP tube (CFFT short columns and three plain concrete control specimens were tested. All specimens were axially loaded until failure. The rest results showed that the stress-strain curves of CFFTs consisted of two distinct branches, an ascending branch before the concrete peak stress was reaches and a second branch that terminated when the tube ruptured, and that the CFFTs with integrated crossties experienced most uniform confinement pressure distribution. Test research also found that the stress-strain curves of CFFTs indicated an increase in ductility. These demonstrate that this confinement system can produce higher lateral confinement stiffness. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6035
Energy Technology Data Exchange (ETDEWEB)
Ehlers, R.
1986-01-01
For a linear-elastic cylinder with an axial through crack subject to internal pressure loading, stress intensity factors and crack opening areas were calculated by the finite element method. Wall thickness and crack length were varied for constant mean radius of the cylinder, thus varying the shell parameter lambda with 2.5
Directory of Open Access Journals (Sweden)
Frederico Martins Alves da Silva
2015-01-01
Full Text Available This work investigates the influence of Young’s modulus, shells thickness, and geometrical imperfection uncertainties on the parametric instability loads of simply supported axially excited cylindrical shells. The Donnell nonlinear shallow shell theory is used for the displacement field of the cylindrical shell and the parameters under investigation are considered as uncertain parameters with a known probability density function in the equilibrium equation. The uncertainties are discretized as Hermite-Chaos polynomials together with the Galerkin stochastic procedure that discretizes the stochastic equation in a set of deterministic equations of motion. Then, a general expression for the transversal displacement is obtained by a perturbation procedure which identifies all nonlinear modes that couple with the linear modes. So, a particular solution is selected which ensures the convergence of the response up to very large deflections. Applying the standard Galerkin method, a discrete system in time domain that considers the uncertainties is obtained and solved by fourth-order Runge-Kutta method. Several numerical strategies are used to study the nonlinear behavior of the shell considering the uncertainties in the parameters. Special attention is given to the influence of the uncertainties on the parametric instability and time response, showing that the Hermite-Chaos polynomial is a good numerical tool.
International Nuclear Information System (INIS)
For a linear-elastic cylinder with an axial through crack subject to internal pressure loading, stress intensity factors and crack opening areas were calculated by the finite element method. Wall thickness and crack length were varied for constant mean radius of the cylinder, thus varying the shell parameter lambda with 2.5 <= lambda <= 23. The computed stress intensity factors depend on lambda as well as on R/t and show considerable differences to solutions based on shallow shell theory even for very short cracks. The range of validity of these solutions is discussed. Starting from the observation that the energy release rate for a semi-infinite crack is finite, a simple interpolation formula is given that retains the proper asymptotic behaviour for very long and very short cracks. Crack opening areas are given and compared to an approximate analytical formula from the literature. Some general limitations of the validity of the present results, particularly the required minimum lengths of the cylinder, are discussed. (author)
关节轴承轴向极限载荷分析%Analysis of axial limit load of spherical plain bearing
Institute of Scientific and Technical Information of China (English)
王弘慧; 栾佳园; 陈立萍
2012-01-01
利用ANSYS自带APDL程序语言，建立了关节轴承的参数化模型，分析了在不同径向载荷时轴向载荷的变化情况及对应力的影响，得到了与最大应力对应的轴向极限载荷，为关节轴承的设计提供了理论基础% Parameterized mold has been established in use of AYSY with APDL programming language, analyzing variation of axial load with different radial load and influence on the stress, so as to obtain axial limit load relative to maximum stress and lay theoretical foundation for the design of spherical plain bearings.
Singer, Ellen; Garcia, Tanya; Stover, Susan
2013-02-22
The biomechanical circumstances that promote sagittal fracture of the equine proximal phalanx (P1) are poorly understood. In order to improve our understanding of equine metacarpophalangeal joint (MCPJ) biomechanics and potential aetiologies of sagittal P1 fractures, the study objectives were to quantify P1 bone strains, collateromotion and axial rotation during MCPJ extension under controlled loading circumstances. Unilateral limbs from six cadavers were instrumented with bone reference markers for measurement of P1 movement relative to third metacarpal bone positions during axial limb loading to 10,500N. Bone reference markers recorded by video were digitized and the movement analyzed during MCPJ extension. Concurrently, dorsoproximal P1 surface strains were measured with one uniaxial and one rosette strain gauge. Strain gauge data was reduced to determine principal and shear strain magnitude and direction. External axial rotation and collateromotion increased with increasing MCPJ extension. Maximum principal strain increased linearly as load increased from 2000 to 10,500N. Minimum principal and maximum shear strains had curvilinear relationships with limb loading, with negligible strain magnitude until approximately 6000N load, after which strain increased rapidly. The direction of P1 minimum principal strain shifted approximately 30-40° as load increased from 5400N to 10,000N, moving from proximolateral-distomedial to a nearly proximodistal direction. At near maximal MCPJ extension, with concurrent axial rotation and collateromotion, a rapid increase in dorsoproximal P1 bone strain and a change in principal strain direction occurred. The alterations in principal strain magnitude and direction associated with maximal MCPJ extension may support a biomechanical theory for sagittal P1 fracture occurrence in horses. PMID:23246042
Joshi, A.; Suryanarayan, S.
1989-03-01
The problem of free vibration of beams having different end conditions and subjected to static initial loads has been studied with the aim of arriving at good closed-form analytical solutions. Elementary beam theory is used as a starting point to obtain the transverse vibration frequencies for various cases of classical homogeneous end conditions and for various values of the static axial load and end moment. These results indicate that it is possible to identify simple algebraic expressions which accurately represent the solution for various boundary conditions. It is also found that reasonably accurate estimates of the predominantly flexural frequency of coupled flexural-torsional vibration can be obtained from the uncoupled flexural vibration frequency of beam-columns. This is achieved by defining an effective axial load parameter, which is a combination of the axial load, the end moment and the slenderness parameter. Finally, the study also brings out that the various expressions, corresponding to different end conditions, can be combined together into a single expression for the predominantly flexural frequency. This expression is common for the boundary conditions considered here and use is made of various normalizing factors which depend on the boundary conditions, and are obtainable from the corresponding free vibration and stability analyses of beam-columns.
Espinós Capilla, Ana; Ibáñez Usach, Carmen; Romero, Manuel L.; Hospitaler Pérez, Antonio
2011-01-01
[EN] In this paper, the behaviour of slender axially loaded square and circular CFT columns exposed to fire is modelled using the finite element analysis package ABAQUS. A realistic sequentially coupled nonlinear thermal-stress analysis is conducted for a series of columns available in the literature. By means of this model, a comparison between fire resistance simulations results and experimental tests found in literature is made. Similarly, simulations results are compared to...
International Nuclear Information System (INIS)
Procedures are described for maintaining the axial offset value of the core, as an indicia of the axial power distribution, substantially equal to a target value, which is modified periodically to account for core burnup. In one embodiment a neutron absorbing element within the core coolant, or moderator, is employed to assist control of reactivity changes associated with changes in power with the full length control rods mainly employed to adjust variations in the axial power distribution, while the part length rods remain completely withdrawn from the fuel region of the core. In a second embodiment reactivity changes associated with changes in power are controlled by the full length rods, while the part length rods are used to adjust the axial power distribution and the neutron absorbing element within the core coolant or moderator is used to compensate for xenon buildup or depletion. (author)
Directory of Open Access Journals (Sweden)
Mehrdad Nasirshoaibi
2015-01-01
Full Text Available Based on the Rayleigh beam theory, the forced transverse vibrations of a closed double single-walled carbon nanotube (SWCNT system containing a fluid with a Pasternak layer in-between are investigated. It is assumed that the two single-walled carbon nanotubes of the system are continuously joined by a Pasternak layer and both sides of SWCNTs containing a fluid are closed. The dynamic responses of the system caused by arbitrarily distributed continuous loads are obtained. The effect of compressive axial load on the forced vibrations of the double single-walled carbon nanotube system is discussed for one case of particular excitation loading. The properties of the forced transverse vibrations of the system are found to be significantly dependent on the compressive axial load. The steady-state vibration amplitudes of the SWCNT decrease with increasing of length of SWCNT. Vibrations caused by the harmonic exciting forces are discussed, and conditions of resonance and dynamic vibration absorption are formulated. The SWCNT-type dynamic absorber is a new concept of a dynamic vibration absorber (DVA, which can be applied to suppress excessive vibrations of corresponding SWCNT systems.
Kimura, S.; Steinbach, G. C.; Watenpaugh, D. E.; Hargens, A. R.
2001-01-01
STUDY DESIGN: Axial load-dependent changes in the lumbar spine of supine healthy volunteers were examined using a compression device compatible with magnetic resonance imaging. OBJECTIVE: To test two hypotheses: Axial loading of 50% body weight from shoulder to feet in supine posture 1) simulates the upright lumbar spine alignment and 2) decreases disc height significantly. SUMMARY OF BACKGROUND DATA: Axial compression on the lumbar spine has significantly narrowed the lumbar dural sac in patients with sciatica, neurogenic claudication or both. METHODS: Using a device compatible with magnetic resonance imaging, the lumbar spine of eight young volunteers, ages 22 to 36 years, was axially compressed with a force equivalent to 50% of body weight, approximating the normal load on the lumbar spine in upright posture. Sagittal lumbar magnetic resonance imaging was performed to measure intervertebral angle and disc height before and during compression. RESULTS: Each intervertebral angle before and during compression was as follows: T12-L1 (-0.8 degrees +/- 2.5 degrees and -1.5 degrees +/- 2.6 degrees ), L1-L2 (0.7 degrees +/- 1.4 degrees and 3.3 degrees +/- 2.9 degrees ), L2-L3 (4.7 degrees +/- 3.5 degrees and 7.3 degrees +/- 6 degrees ), L3-L4 (7.9 degrees +/- 2.4 degrees and 11.1 degrees +/- 4.6 degrees ), L4-L5 (14.3 degrees +/- 3.3 degrees and 14.9 degrees +/- 1.7 degrees ), L5-S1 (25.8 degrees +/- 5.2 degrees and 20.8 degrees +/- 6 degrees ), and L1-S1 (53.4 degrees +/- 11.9 degrees and 57.3 degrees +/- 16.7 degrees ). Negative values reflect kyphosis, and positive values reflect lordosis. A significant difference between values before and during compression was obtained at L3-L4 and L5-S1. There was a significant decrease in disc height only at L4-L5 during compression. CONCLUSIONS: The axial force of 50% body weight in supine posture simulates the upright lumbar spine morphologically. No change in intervertebral angle occurred at L4-L5. However, disc height at L4-L
Directory of Open Access Journals (Sweden)
Oliver Giraldo-Londoño
2014-01-01
Full Text Available La estabilidad dinámica de una columna elástica prismática esbelta con conexiones semirrígidas en ambos extremos de rigidez idéntica y con desplazamiento lateral entre los dos extremos totalmente inhibido sujetos a cargas axiales paramétricas incluyendo los efectos combinados de inercia rotacional y amortiguación externas fue presentada en una publicación adjunta. Expresiones cerradas que se pueden utilizar para predecir las regiones inestabilidad dinámica de columnas esbeltas se desarrollan haciendo uso de la teoría de Floquet. Las ecuaciones propuestas son sencillas y fáciles de aplicar. La solución propuesta es capaz de capturar el fenómeno de estabilidad en columnas sometidas a cargas axiales periódicas utilizando un solo elemento de columna. El método propuesto y las ecuaciones correspondientes se pueden utilizar para investigar los efectos del amortiguamiento, la inercia rotacional de la columna, y las conexiones semirrígidas en el análisis de estabilidad de columnas esbeltas sometidas a cargas axiales periódicas. Estudios de sensibilidad presentados en esta publicación muestran los efectos de la inercia rotacional, el amortiguamiento y las conexiones semi-rígidas en la estabilidad dinámica de columnas sometidas a cargas axiales paramétricas. Los estudios analíticos indican que el comportamiento dinámico de columnas bajo carga periódica está fuertemente afectado por la rigidez a la flexión de las conexiones de los dos apoyos y por el amortiguamiento externo, pero no tanto por la inercia rotacional. Tres ejemplos se presentan en detalle y los resultados calculados se comparan con los reportados por otros investigadores.
Gil, Christopher M.
1998-01-01
An experimental program to determine flow surfaces has been established and implemented for solution annealed and aged IN718. The procedure involved subjecting tubular specimens to various ratios of axial-torsional stress at temperatures between 23 and 649 C and measuring strain with a biaxial extensometer. Each stress probe corresponds to a different direction in stress space, and unloading occurs when a 30 microstrain (1 micro eplison = 10(exp -6) mm/mm) offset is detected. This technique was used to map out yield loci in axial-torsional stress space. Flow surfaces were determined by post-processing the experimental data to determine the inelastic strain rate components. Surfaces of constant inelastic strain rate (SCISRS) and surfaces of constant inelastic power (SCIPS) were mapped out in the axial-shear stress plane. The von Mises yield criterion appeared to closely fit the initial loci for solutioned IN718 at 23 C. However, the initial loci for solutioned IN718 at 371 and 454 C, and all of the initial loci for aged IN718 were offset in the compression direction. Subsequent loci showed translation, distortion, and for the case of solutioned IN718, a slight cross effect. Aged IN718 showed significantly more hardening behavior than solutioned IN718.
Su, RKL; Wang, L.
2015-01-01
In this study, the behaviour of the preloaded reinforced concrete columns under large eccentric compression loading and strengthened with flat and precambered steel plates was investigated. An original analytical model considering the effects of stress-lagging induced by eccentric pre-compressed loading was developed to predict the ultimate load capacity of plate-strengthened columns. Then, 10 specimens with different eccentricities, plate thicknesses and initial precamber displacements were ...
Oliver Giraldo-Londoño; J. DARÍO ARISTIZÁBAL-OCHOA
2014-01-01
La estabilidad dinámica de una columna elástica prismática esbelta con conexiones semirrígidas en ambos extremos de rigidez idéntica y con desplazamiento lateral entre los dos extremos totalmente inhibido sujetos a cargas axiales paramétricas incluyendo los efectos combinados de inercia rotacional y amortiguación externas fue presentada en una publicación adjunta. Expresiones cerradas que se pueden utilizar para predecir las regiones inestabilidad dinámica de columnas esbeltas se desarrollan ...
International Nuclear Information System (INIS)
A limit load solution for an edge cracked plate that includes any combination of biaxial bending and membrane loading is developed in the study. This solution will then be compared to the solution within the Miller Compendium and that obtained from Finite Element (FE) analyses. The solutions applicability to a cylinder will also be considered through the use of FE modeling. Through these comparisons it is hoped that the derived limit load solution can be validated and guidance for its applicability to a cylinder provided
Covey-Crump, S. J.; Xiao, W. F.; Mecklenburgh, J.; Rutter, E. H.; May, S. E.
2016-07-01
For technical reasons, virtually all plastic deformation experiments on geological materials have been performed in either pure shear or simple shear. These special case loading geometries are rather restrictive for those seeking insight into how microstructure evolves under the more general loading geometries that occur during natural deformation. Moreover, they are insufficient to establish how plastic flow properties might vary with the 3rd invariant of the deviatoric stress tensor (J3) which describes the stress configuration, and so applications that use those flow properties (e.g. glaciological and geodynamical modelling) may be correspondingly compromised. We describe an inexpensive and relatively straightforward modification to the widely used Paterson rock deformation apparatus that allows torsion experiments to be performed under simultaneously applied axial loads. We illustrate the performance of this modification with the results of combined stress experiments performed on Carrara marble and Solnhofen limestone at 500°-600 °C and confining pressures of 300 MPa. The flow stresses are best described by the Drucker yield function which includes J3-dependence. However, that J3-dependence is small. Hence for these initially approximately isotropic calcite rocks, flow stresses are adequately described by the J3-independent von Mises yield criterion that is widely used in deformation modelling. Loading geometry does, however, have a profound influence on the type and rate of development of crystallographic preferred orientation, and hence of mechanical anisotropy. The apparatus modification extends the range of loading geometries that can be used to investigate microstructural evolution, as well as providing greater scope for determining the shape of the yield surface in plastically anisotropic materials.
International Nuclear Information System (INIS)
In this study, the technique of seismic strengthening existing reinforced concrete columns and beams using additional concrete layers and jackets is examined. The finite element method and the finite element program ATENA is used in this investigation. When a reinforced jacket or layer is being constructed around a column it is already preloaded due to existing service loads. This effect has been examined for different values of the axial load normalized to the strengthened column. The techniques of strengthening with a concrete jacket or a reinforced concrete layer on the compressive side of the column are examined. Another phenomenon that is examined in this study is the shrinkage of the new concrete of an additional layer used to strengthen an existing member. For this investigation, a simply supported beam with an additional reinforced concrete layer on the tensile side is examined. The results demonstrate that the effect of preloading is important when a reinforced concrete layer is being used with shear connectors between the old and the new reinforcement. It was also found that the shrinkage of the new concrete reduces the strength of the strengthened beam and induces an initial sliding between the old and the new concrete
Institute of Scientific and Technical Information of China (English)
Zhen-zhen PENG; Xin-min CHEN; Jun WANG; Ai-jie LI; Zu-jie XU
2013-01-01
Objective:This study investigated the effect of proximal contact strength on the three-dimensional displacements of cantilever fixed partial denture (CFPD) under vertically concentrated loading with digital laser speckle (DLS) technique.Methods:Fresh mandible of beagle dog was used to establish the implant-supported CFPD for specimen.DLS technique was employed for measuring the three-dimensional displacement of the prosthesis under vertically concentrated loading ranging from 200 to 3000 g.The effect of the contact tightness on the displacement of CFPD was investigated by means of changing the contact tightness.Results:When an axial concentrated loading was exerted on the pontic of the implant-supported CFPD,the displacement of the CFPD was the greatest.The displacement of the prosthesis decreased with the increase of contact strength.When the contact strength was 0,0.95,and 3.25 N,the displacement of the buccolingual direction was smaller than that of the mesiodistal direction but greater than that of the occlusogingival direction.When the force on the contact area was 6.50 N,the mesiodistal displacement of the prosthesis was the biggest while the buccolingual displacement was the smallest.Conclusions:The implantsupported CFPD is an effective therapy for fully or partially edentulous patients.The restoration of the contact area and the selection of the appropriate contact strength can reduce the displacement of the CFPD,and get a better stress distribution.The most appropriate force value is 3.25 N in this study.
Indian Academy of Sciences (India)
Cengiz Erdonmez; C Erdem Imrak
2011-12-01
Due to the complex geometry of wires within a wire rope, it is difﬁcult to model and analyse independent wire rope core accurately (IWRC). In this paper, a more realistic three-dimensional modelling approach and ﬁnite element analysis of wire ropes are explained. Single helical geometry is enough to model simple straight strand while IWRC has a more complex geometry by inclusion of double helical wires in outer strands. Taking the advantage of the double helical wires, three-dimensional IWRCs modelling is applied for both right regular lay and lang lay IWRCs. Wire-by-wire based results are gathered by using the proposed modelling and analysis method under various loading conditions. Illustrative examples are given for those show the accuracy and the robustness of the present FE analysis scheme with considering frictional properties and contact interactions between wires. FE analysis results are compared with the analytical and available test results and show reasonable agreement with a simpler and more practical approach.
Directory of Open Access Journals (Sweden)
Dr. Nitin Jain
2012-02-01
Full Text Available Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} A comprehensive plane stress finite element study is made for reduction of stress concentration factor (SCF in a uni-axially loaded infinite width rectangular isotropic/orthotropic plate with central circular hole. The finite element formulation was carried out by the analysis section of the package ANSYS. With the help of present work, stress concentration can be reduced up to 24.4 % in an isotropic and 31 % in an orthotropic plate by introducing four coaxial auxiliary holes on either side of main hole. The study reveals that the introduction of these holes helps to smooth flow of the tensile stress past the main hole and result a reduction in stress concentration factor. With such reduction in maximum stress levels, the improvement in fatigue life of a component can be significant.
Institute of Scientific and Technical Information of China (English)
李明; 陈扬骥; 钱若军; 姚念亮
2001-01-01
Stability for I-Section aluminium alloy bars of disparate slenderness,loaded by axial compressive force,is studied by experiments in this paper.Stability parameters are calculated from experimental data and compared with the results of several formulas by other researchers.Practical formula for engineering utilization is derived for the stability parameters of I-Section aluminium alloy bars loaded by axial compressive force.%通过对不同长细比铝合金工字形轴心压杆稳定性的试验研究，计算得出了相应的稳定系数，并与几种公式的计算结果对比，得出了可用于我国铝合金轴心压杆设计的稳定系数计算公式。
Mahadev, Sthanu
Continued research and development efforts devoted in recent years have generated novel avenues towards the advancement of efficient and effective, slender laminated fiber-reinforced composite members. Numerous studies have focused on the modeling and response characterization of composite structures with particular relevance to thin-walled cylindrical composite shells. This class of shell configurations is being actively explored to fully determine their mechanical efficacy as primary aerospace structural members. The proposed research is targeted towards formulating a composite shell theory based prognosis methodology that entails an elaborate analysis and investigation of thin-walled cylindrical shell type laminated composite configurations that are highly desirable in increasing number of mechanical and aerospace applications. The prime motivation to adopt this theory arises from its superior ability to generate simple yet viable closed-form analytical solution procedure to numerous geometrically intense, inherent curvature possessing composite structures. This analytical evaluative routine offers to acquire a first-hand insight on the primary mechanical characteristics that essentially govern the behavior of slender composite shells under typical static loading conditions. Current work exposes the robustness of this mathematical framework via demonstrating its potential towards the prediction of structural properties such as axial stiffness and bending stiffness respectively. Longitudinal ply-stress computations are investigated upon deriving the global stiffness matrix model for composite cylindrical tubes with circular cross-sections. Additionally, this work employs a finite element based numerical technique to substantiate the analytical results reported for cylindrically shaped circular composite tubes. Furthermore, this concept development is extended to the study of thin-walled, open cross-sectioned, curved laminated shells that are geometrically
Institute of Scientific and Technical Information of China (English)
吴炎海; 方映平; 冯文贤; 蔡杨
2015-01-01
Axial static loading test was carried out on 6 recycled aggregate concrete filled circular steel tubular long columns. The whole loading process and failure modes were observed,and the curves of specimens about load-deformation and load-strain were plotted. The influences of the test parameters namely slenderness ratio and confine-ment index on deformation and the bearing capacities of specimens were analyzed. By domestic and foreign relevant specifications,the ultimate bearing capacity of the specimens were calculated and compared with the measured val-ues. The results indicated that the failure process of recycled aggregate concrete filled steel tubular long columns un-der axial compression includes elastic stage,elastic-plastic stage and plastic stage,and all the failure modes are elas-tic-plastic instability;Both the slenderness ratio and confinement index affect the mechanical performance of recy-cled aggregate concrete filled steel tubular long columns under axial loading,and the confinement index is more ob-vious;Finally,the calculation and design method of recycled aggregate filled steel tubular long columns under axial loading were proposed.%进行6根圆钢管再生混凝土长柱轴压的静力加载试验，观察试件受力的全过程和破坏形态，绘制出各试件的荷载-变形和荷载-应变关系曲线，分析长径比和套箍系数2个变化参数对试件变形和承载力的影响规律，采用国内外相关规程计算各试件的极限承载力并与实测值进行对比。结果表明：钢管再生混凝土轴压长柱受力过程经历了弹性阶段、弹塑性阶段和塑性下降阶段，均为弹塑性失稳破坏；长径比和套箍系数对钢管再生混凝土轴压长柱的受力性能均有影响，其中套箍系数影响较大；最后对于钢管再生混凝土长柱轴压的承载力计算及构件的设计提出建议。
Directory of Open Access Journals (Sweden)
Achoura D.
2012-09-01
Full Text Available Dans cette étude, on présente les résultats expérimentaux obtenus sur des poteaux mixtes béton-acier mince réalisés par soudures. Un total de 24 profilés en acier, et en forme de I a été testé sous charge de compression uni-axiale à l’âge de 28 jours. les spécimens ont été réparties comme suit: 4 à vides, 4 partiellement remplies avec un béton ordinaire sans l’addition des connecteurs, 4 renforcés par des connecteurs de cisaillements de type cornière en U, 4 autres l’ont été avec des connecteurs de cisaillements type goujons et 8 restants ont été renforcés avec des liens transversaux d’espacement 100mm, 50mm, soudés aux bouts des ailes opposées. Les principaux paramètres étudiés sont: l’élancement du profilé, le type de connecteur de renforcement. A partir des résultats d’essais obtenus, il est confirmé que les parois minces sont plus sensibles de l’apparition au voilement et la longueur des profilés a un effet considérable sur la capacité portante et le mode de rupture. L’addition des connecteurs de renforcement a confirmé l’augmentation de la charge ultime par rapport aux profilés sans connecteurs. In the present work, results of tests conducted on thin welded steel-concrete stubs are presented. A total of 24 stubs an I steel section were tested under axial compression at 28 days after the date of casting, 4 were empty, 4 filled with normal concrete, 8 columns had shear connecters welded along the centreline of the web, and 8 columns had steel rods welded between the tips of opposing flanges on both sides of the spacing of the transverse link 100 mm and 50 mm. The main parameters studied were: the heel height, and type of connector strengthening. From the test results, it is confirmed that the thin walls are more sensitive to the appearance local buckling and the length of the profiles has a significant effect on the bearing capacity and failure mode. The bearing capacity was increased
Institute of Scientific and Technical Information of China (English)
龚金科; 李靖; 胡辽平; 余明果; 颜胜; 陈韬
2014-01-01
In this paper, the working states of turbocharger in exhaust braking condition are analyzed for the vehicles concurrently adopting exhaust braking and turbocharging. Through a linked test with both exhaust bra-king and turbocharging functioning, the boundary conditions required for numerical calculation are obtained, and based on which the axial forces of turbine in both steady and transitional conditions are calculated. The results show that in exhaust braking condition, the axial force of turbine reverses its direction, and the higher the exhaust back-pressure the larger the axial force. In the process of working condition switching, the turbine is subjected to high shock load with a highest value up to 221N, and the shorter switching time and higher back pressure will lead to a greater impact load. Hence selecting a reasonable backpressure and an appropriate witching strategy can effectively reduce the axial load of turbine.%本文中针对同时采用排气制动和涡轮增压的车辆,分析其在排气制动工况下增压器的工作状态。通过排气制动与增压器联动试验得出数值计算所需的边界条件,并据此计算涡轮转子在稳态工况和过渡工况的轴向受力。结果表明,在排气制动工况下,增压器涡轮转子的轴向受力反向,且排气背压越高,涡轮转子所受轴向力越大；在工况切换过程中,涡轮转子所受突变载荷较大,最高值达221N,工况切换时间越短、背压越高,轴向冲击载荷越大。因此确定合理的排气背压和工况切换策略可有效降低涡轮转子所承受的轴向载荷。
International Nuclear Information System (INIS)
This report is a continuation of the thesis [23], devoted to the onset of necking plastic instabilities during tension tests on metallic plates bi-axially loaded in their plane. We are also interested here in compression tests, and in the development of antisymmetric defects with respect to the median plane of the plate. As in the thesis, we search for the dominant mode, i.e. the most unstable pair of wavelengths (λ1, λ2) in the loading plane. An approximate analytical formulation for the growth rate is proposed, especially for plane-strain tests in the absence of viscous effects, and for static tests in tension in the x1 and x2 loading directions. In that latter case, we retrieve published results [14][15]. For plane-strain tests, we show that infinitely dense networks of shear bands inclined at 45 deg. with respect to the loading direction instantaneously occur when heat softening prevails over work-hardening. (author)
A. Espinós; A. Hospitaler; M. L. Romero
2009-01-01
In recent years, concrete filled tubular (CFT) columns have become popular among designers and structural engineers, due to a series of highly appreciated advantages: high load-bearing capacity, high seismic resistance, attractive appearance, reduced column footing, fast construction technology and high fire resistance without external protection. In a fire, the degradation of the material properties will cause CFT columns to become highly nonlinear and inelastic, which makes it quite difficu...
International Nuclear Information System (INIS)
SiC/SiC composites are candidate materials for in-core components of future nuclear reactors. The analysis of these structures using numerical simulations requires material constitutive laws. The present work focuses on understanding the deformation mechanisms of these materials in order to build a constitutive model able to predict their stress-strain response under complex loadings. An extensive characterization of the mechanical behaviour of SiC/SiC multi-layered tubes - similar to fuel cladding concepts - was carried out, using tension internal pressure, tension-torsion and bending tests, that allowed to build an important experimental basis for the understanding of the mechanisms and the identification of constitutive laws. In-situ and post-failure observations have allowed quantifying the orientation of surface matrix cracks as a function of the loading type. Full-field measurements using Digital Image Correlation at the tow scale brought precise information on the composite surface kinematics, such as the crack opening or the deformation of the matrix fragments. These measurements also evidence the importance of the tow reorientation, that could explain specific features of the macroscopic behaviour because of its coupling with matrix cracking. Finally, these experimental data allowed to build a constitutive model, identified on only four uniaxial tests, able to predict satisfactorily the macroscopic behaviour under several biaxial loadings. The correct prediction of local quantities, such as the characteristics of the matrix cracking in tension, has also been verified. (author)
Nagpal, Shubhrata; Jain, Nitin Kumar; Sanyal, Shubhashis
2016-01-01
The problem of finding the stress concentration factor of a loaded rectangular plate has offered considerably analytical difficulty. The present work focused on understanding of behavior of isotropic and orthotropic plate subjected to static in-plane loading using finite element method. The complete plate model configuration has been analyzed using finite element method based software ANSYS. In the present work two parameters: thickness to width of plate (T/A) and diameter of hole to width of plate (D/A) have been varied for analysis of stress concentration factor (SCF) and its mitigation. Plates of five different materials have been considered for complete analysis to find out the sensitivity of stress concentration factor. The D/A ratio varied from 0.1 to 0.7 for analysis of SCF and varied from 0.1 to 0.5 for analyzing the mitigation of SCF. 0.01, 0.05 and 0.1 are considered as T/A ratio for all the cases. The results are presented in graphical form and discussed. The mitigation in SCF reported is very encouraging. The SCF is more sensitive to D/A ratio as compared to T/A.
Institute of Scientific and Technical Information of China (English)
钟大虎; 夏辉; 窦益华; 曹银萍
2014-01-01
为校核螺旋屈曲管柱的强度安全性，基于弹簧理论与第四强度理论，推导出螺旋屈曲状态下管柱内、外侧相当应力的计算公式，并以油田常用规格油套管为例，探讨了轴向压力对管柱内、外侧最大相当应力的影响。算例结果表明，螺旋屈曲管柱内侧最大相当应力恒大于外侧；管柱内、外侧最大相当应力随轴向压力的增大而增大。轴向压力由200KN 增大至800KN 时，管柱内、外侧最大相当应力分别增大170%和413.8%。研究弥补了传统管柱力学分析的不足，提供了螺旋屈曲管柱安全性研究新方法，同时也可为现场安全施工提供参考。%To make clear stress distribution and variation of helical buckling tubing string, the formulas of equivalent stresses inside and outside of the tubing string were deduced based on the spring theory and the fourth strength theory. Taking tubing string and casing commonly used in oilfield as object, stress calculation programs were compiled to explore the influence of axial compression load on equivalent VonMises stress. From the analysis, we can see that the equivalent VonMises stresses inside of the helical buckling tubing string were higher than that outside. The equivalent VonMises stress increased with the axial compression load, and the increase is 170 percent and 413.8 percent respectively for stress inside and outside of the tubing string with compression load increased from 200KN to 800KN. The proposed method used for the helical buckling tubing string covered the shortage of traditional tubular mechanics effectively and can also provide reference for the field application.
Institute of Scientific and Technical Information of China (English)
李俊华; 赵银海; 唐跃锋; 刘明哲
2012-01-01
进行了5个火灾后型钢混凝土柱轴心压力作用下的试验,研究长细比、混凝土强度对构件破坏形态和剩余承载能力的影响.试验结果表明,火灾后型钢混凝土轴心受压柱在荷载作用下的破坏形态与常温下基本相同,试件破坏时其内部核心型钢依然完好,不会发生局部屈曲现象.混凝土强度和长细比是影响型钢混凝土轴心受压柱火灾后承载能力的两个重要因素,当长细比相差不太大的情况下,混凝土强度高的试件,其火灾后极限承载力相对较高;在混凝土强度大致相当的情况下,随着长细比的增大,火灾后试件的极限承载力降低.利用YB规程和JGJ规程方法,对所有试件常温下的极限承载力进行了计算,结果表明在该文的试验条件下得到的火灾后型钢混凝土轴心受压柱承载能力的试验值与常温下承载力计算结果的比值在62%～71％之间,经历火灾作用后型钢混凝土轴心受压柱承载能力显著降低,火灾后的剩余承载力水平平均为常温下承载力水平的67％.%This paper provided five test data pertaining to the residual load bearing capacity of steel reinforced concrete (SRC) columns after exposure to fire. Two parameters, that is, slenderness ratio and concrete strength are mainly taken into consideration. Test results show that the failure pattern of SRC columns under an axial pressure force after exposure to fire is basically the same with that at room temperature. When the specimens are destroyed, the internal core steels are still fine, having no local buckling phenomena. Concrete strength and the slendemess ratio are two important factors that affect the strength of SRC columns under an axial pressure force after exposure to fire. For the specimens of about the same slenderness ratios, the higher concrete strength they are, the higher ultimate bearing capacity they have. In the condition of roughly the same concrete strength, the ultimate
Lajnef, N.; Burgueño, R.; Borchani, W.; Sun, Y.
2014-05-01
A major obstacle limiting the development of deployable sensing and actuation solutions is the scarcity of power. Converted energy from ambient loading using piezoelectric scavengers is a possible solution. Most of the previously developed research focused on vibration-based piezoelectric harvesters which are typically characterized by a response with a narrow natural frequency range. Several techniques were used to improve their effectiveness. These methods focus only on the transducer’s properties and configurations, but do little to improve the stimuli from the source. In contrast, this work proposes to focus on the input deformations generated within the structure, and the induction of an amplified amplitude and up-converted frequency toward the harvesters’ natural spectrum. This paper introduces the concept of using mechanically-equivalent energy converters and frequency modulators that can transform low-amplitude and low-rate service deformations into an amplified vibration input to the piezoelectric transducer. The introduced concept allows energy conversion within the unexplored quasi-static frequency range (≪1 Hz). The post-buckling behavior of bilaterally constrained columns is used as the mechanism for frequency up-conversion. A bimorph cantilever polyvinylidene fluoride (PVDF) piezoelectric beam is used for energy conversion. Experimental prototypes were built and tested to validate the introduced concept and the levels of extractable power were evaluated for different cases under varying input frequencies. Finally, finite element simulations are reported to provide insight into the scalability and performance of the developed concept.
Directory of Open Access Journals (Sweden)
A. Espinós
2009-01-01
Full Text Available In recent years, concrete filled tubular (CFT columns have become popular among designers and structural engineers, due to a series of highly appreciated advantages: high load-bearing capacity, high seismic resistance, attractive appearance, reduced column footing, fast construction technology and high fire resistance without external protection. In a fire, the degradation of the material properties will cause CFT columns to become highly nonlinear and inelastic, which makes it quite difficult to predict their failure. In fact, it is still not possible for analytical methods to predict with enough accuracy the behaviour of columns of this kind when exposed to fire. Numerical models are therefore widely sought. Many numerical simulations have been carried out worldwide, without obtaining satisfactory results. This work proposes a three-dimensional numerical model for studying the actual fire behaviour of columns of this kind. This model was validated by comparing the simulation results with fire resistance tests carried out by other researchers, as well as with the predictions of the Eurocode 4 simplified calculation model.
Energy Technology Data Exchange (ETDEWEB)
Nascimento, J.L.; Irmao, M.A.S.; Araujo, A.L.; Silva, A.A. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Dept. de Engenharia Mecanica
2004-07-01
Structures and mechanical components, subjects to conditions of loading in operation, accumulate faults during your useful lives. The detection and condition monitoring of the faults is essential of the point of view of the efficiency and safety. Efforts have been accomplished, in the sense of constituting models and methodologies that indicate the most opportune moment for the shut down industrial plant, seeking your maintenance. In the present work, it intends an alternative method for the detection and the condition monitoring of faults in a cantilever bar by the analysis of your longitudinal displacement. The methodology is constituted basically in simulating the computational model of the bar for Finite Element Method (FEM), where the faults are characterized by one of the elements with reduced transverse section. The existence of two classes of angular coefficients is noticed, that will be the analysis parameters, where the first tells respect the intact element and the second the damaged element, both different ones for each position and depth of simulated faults. The same ones are thrown as input in a Artificial Neural Networks, that once trained is capable to identify the position and the depth efficiently in that meets the faults. (author)
International Nuclear Information System (INIS)
A major obstacle limiting the development of deployable sensing and actuation solutions is the scarcity of power. Converted energy from ambient loading using piezoelectric scavengers is a possible solution. Most of the previously developed research focused on vibration-based piezoelectric harvesters which are typically characterized by a response with a narrow natural frequency range. Several techniques were used to improve their effectiveness. These methods focus only on the transducer’s properties and configurations, but do little to improve the stimuli from the source. In contrast, this work proposes to focus on the input deformations generated within the structure, and the induction of an amplified amplitude and up-converted frequency toward the harvesters’ natural spectrum. This paper introduces the concept of using mechanically-equivalent energy converters and frequency modulators that can transform low-amplitude and low-rate service deformations into an amplified vibration input to the piezoelectric transducer. The introduced concept allows energy conversion within the unexplored quasi-static frequency range (≪1 Hz). The post-buckling behavior of bilaterally constrained columns is used as the mechanism for frequency up-conversion. A bimorph cantilever polyvinylidene fluoride (PVDF) piezoelectric beam is used for energy conversion. Experimental prototypes were built and tested to validate the introduced concept and the levels of extractable power were evaluated for different cases under varying input frequencies. Finally, finite element simulations are reported to provide insight into the scalability and performance of the developed concept. (paper)
Institute of Scientific and Technical Information of China (English)
施连会; 王安稳
2011-01-01
The axial disturbance to the head of supercavitation vehicles was considered, and the governing equations for dynamic stability of a submarine vehicle were derived.Then, the numerical calculation for the dynamic instability of the submarine vehicle was performed with Bolotin method, the corresponding curves of the critical frequency were obtained and the effects of the load parameters and the vehicle parameters on the primary unstable region were analyzed.The results provided a certain theoretical foundation for the security evaluation of supercavitation vehicles.%考虑超空泡航行体头部受到的轴向扰动载倚作用,推导了水下航行体动力失稳控制方程,进而利用Bolotin方法对水下航行体的动力稳定性问题进行了数值计算,得到了相应的临界频率曲线,并分析了载倚参数和航行体参数变化对主动力不稳定区域的影响规律,计算结果可为水下航行体的安全评估提供一定的理论依据.
Directory of Open Access Journals (Sweden)
Anamaria Siriani de Oliveira
2006-02-01
extremidad libre con la carga rotacional externa (ELCR. Se seleccionaron 20 voluntarias (23,2 años ± 0,9 sedentarias. Ellos estimaron el grosor en mm. de los tríceps del brazo, los bíceps del brazo, pectoral mayor, trapecio y deltoides. El registro electromiográfico de superficie se hizo, durante la realización de los ejercicios con EFCA y de los con ELCR, usando 100% de la resistencia máxima establecidos previamente. Se compararon los valores de RMS normalizados por la reducción máxima voluntaria a través de modelo de efectos mixtos con un nivel de significancia de 5%. En estas condiciones experimentales, los resultados del estudio presente mostraron que ejercicios similares, clasificados por la condición de la extremidad y la dirección de la carga aplicada al miembro superior, promoven niveles similares de electromiografía con actividad en sólo parte de los músculos estudiados. Estos descubrimientos cuestionan la capacidad del sistema de la clasificación usada en este estudio para predecir el tipo de respuesta muscular esperada en el logro de tareas diferentes de misma clasificación.The knowledge of the electromyographic activity produced during shoulder exercises can help in determining its clinical applicability. The purpose of this study was to assess the influence of the load direction and the extremity condition on the electrical activity of the shoulder girdle and upper limb muscles during exercises with fixed distal extremity and external axial load (FEAL and mobile extremity with rotational external load (MERL. Twenty 23.2 ± 0.9 years old female sedentary volunteers were selected. The triceps brachii, biceps brachii, major pectoral, trapezium and deltoid muscles were assessed. The surface electromyography was recorded during two FEAL and two MERL exercises using 100% of the previously established maximal resistance. The RMS values normalized by the maximal voluntary contraction were compared by a mixed effect model with 5% significance level. In
Institute of Scientific and Technical Information of China (English)
郭彦林; 王永海
2011-01-01
The multi-storey and multi-span plane frame was no obvious out-plane support because of some floors removed, and this lead to a multi-column buckle in the out-plane direction of the frame due to lack of lateral supports. The out-plane buckling behavior of two storey plane multi-columns subjected an axial load was investigated theoretically and its design criterion was presented in this study. Firstly, the out-plane bracing stiffness of columns in a multi-column model was obtained by theoretical derivation, so that an up-down column with a mid spring support could be treated as an equivalent analytical model which can reflect the behavior of the two storey multi-column model. Afterwards, the elastic buckling load and the corresponding effective slenderness of the multi-column was obtained by using the conclusion of the equivalent model. In the end, the ultimate load-carrying capacity of multi-columns was conducted by using the finite element numerical analysis, in which the random out-plane imperfections distribution of different columns in the multi-column model was taken account. From the study above, it was proved to be available that the design approach of the equivalent model could be used in a two storey multi-column model.%在高层筒中筒结构中由于某一层楼板抽空,导致两层通高区中外筒框架柱无明确面外支撑,此时通高区群柱面外失稳往往成为结构设计的控制因素之一.该文针对等轴压的两层多跨平面群柱模型,首先通过理论推导得出各柱面外等效支撑刚度的表达式,将两层群柱的面外稳定性研究模型简化柱跨中带侧向弹簧支撑的轴压单柱模型;然后,运用既有单柱简化模型的研究成果得到柱子弹性屈曲荷载和计算长度系数与等效支撑刚度的关系,并通过弹性屈曲有限元分析验证了该文提出的等效支撑刚度和屈曲荷载简化计算公式的准确性:最后,考虑群柱中各柱平面外几何初
International Nuclear Information System (INIS)
The purpose of this calculation is to develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips. Thus, accounting for axially varying burnup in criticality analyses is also referred to as accounting for the ''end effect'' reactivity. The magnitude of the reactivity change due to ''end effect'' is dependent on the initial assembly enrichment, the assembly average burnup, and the particular axial profile characterizing the burnup distribution. The set of bounding axial profiles should incorporate multiple BWR core designs and provide statistical confidence (95 percent confidence that 95 percent of the population is bound by the profile) that end nodes are conservatively represented. The profiles should also conserve the overall burnup of the fuel assembly. More background on BWR axial profiles is provided in Attachment I
Energy Technology Data Exchange (ETDEWEB)
J. Huffer
2004-09-28
The purpose of this calculation is to develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips. Thus, accounting for axially varying burnup in criticality analyses is also referred to as accounting for the ''end effect'' reactivity. The magnitude of the reactivity change due to ''end effect'' is dependent on the initial assembly enrichment, the assembly average burnup, and the particular axial profile characterizing the burnup distribution. The set of bounding axial profiles should incorporate multiple BWR core designs and provide statistical confidence (95 percent confidence that 95 percent of the population is bound by the profile) that end nodes are conservatively represented. The profiles should also conserve the overall burnup of the fuel assembly. More background on BWR axial profiles is provided in Attachment I.
Energy Technology Data Exchange (ETDEWEB)
Theobald, K. [RWTH Aachen (Germany). Inst. fuer Strahlenantriebe und Turboarbeitsmaschinen; Michel, A. [MTU Aero Engines GmbH, Muenchen (Germany)
2003-07-01
For investigating 3D flow phenomena in turbomachinery, a 3.5-stage axial compressor with CDA blading was constructed at the Institute of Jet Propulsion Systems and Turbo-Engines, and vibrations in the guide blades were investigated on selected guide blades of all four guide wheels on which semiconductor straing gauges had been attached in positions calculated according to a NASTRAN calculation. The data provided by the strain gauges were recorded digitally. The harmonics of the rotor wheels were clearly identified as the main influencing factors of guide blade vibration. The effects of flow indentations in the wake was more pronounced than the effects of potential-theoretic flow effects. The vibration characteristics of the guide blades are first of all determined by the rotational speed of the compressor; the throttle state has hardly any effect. Within one guide blade row, differences in their intrinsic frequencies were observed. As the measuring system had not been calibrated, mechanical stress in the strain gauges and material stress in the blades were estimated only, using the known basic equations and assuming worst case. The estimates showed that the values are safely below the limiting load. (orig.) [German] Zur Untersuchung der dreidimensionalen Stroemungsvorgaenge in Turbomaschinen wurde am Institut fuer Strahlantriebe und Turboarbeitsmaschinen ein 3,5 stufiger Axialverdichter mit CDA-Beschaufelung aufgebaut. Anliegen des hier vorgestellten Kurzprojektes war die schwingungsmechanische Untersuchung der Leitschaufeln der Maschine. Dazu wurden ausgewaehlte Leitschaufeln aus allen vier Leitraedern mit Halbleiter-Dehnungsmessstreifen bestueckt. Die HL-DMS wurden an durch eine NASTRAN-Rechnung ermittelte Positionen auf die Schaufeln geklebt. Die gemessenen Spannungen der DMS wurden nach Verstaerkung mit einem digitalen Bandgeraet aufgezeichnet. Die Harmonischen der Laufraeder zeichneten sich klar als der Haupteinflussfaktor fuer die Schwingungen der
Signatures for axial chromodynamics
International Nuclear Information System (INIS)
Within the context of basic left-right symmetry and the hypothesis of unification of weak, electromagnetic and strong forces at a mass level approximately equal to 104-106 GeV, relatively light ''mass'' axial gluons, confined or liberated, must be postulated. The authors remark that the existence of such ''light'' axial gluons supplementing the familiar vector octet preserves the successes of QCD, both for deep inelastic processes and charmonium physics. Through the characteristic spin-spin force, generated by their exchange, they may even help resolve some of the discrepancies between vector QCD predictions and charmonium physics. The main remark of this note is that if colour is liberated, not only vector but also axial-vector gluons are produced in high-energy e-e+ experiments, e.g. at PETRA and PEP, with fairly large cross-section. Distinctive decay modes of such liberated axial gluons are noted
Surface nanoscale axial photonics
Sumetsky, M.; Fini, J. M.
2011-01-01
Dense photonic integration promises to revolutionize optical computing and communications. However, efforts towards this goal face unacceptable attenuation of light caused by surface roughness in microscopic devices. Here we address this problem by introducing Surface Nanoscale Axial Photonics (SNAP). The SNAP platform is based on whispering gallery modes circulating around the optical fiber surface and undergoing slow axial propagation readily described by the one-dimensional Schr\\"odinger e...
Axial Non-linear Dynamic Soil-Pile Interaction - Keynote
Holeyman A.; Whenham V.
2014-01-01
This keynote lecture describes recent analytical and numerical advances in the modeling of the axial nonlinear dynamic interaction between a single pile and its embedding soil. On one hand, analytical solutions are developed for assessing the nonlinear axial dynamic response of the shaft of a pile subjected to dynamic loads, and in particular to vibratory loads. Radial inhomogeneity arising from shear modulus degradation is evaluated over a range of parameters and compared with those obtained...
PWR AXIAL BURNUP PROFILE ANALYSIS
International Nuclear Information System (INIS)
The purpose of this activity is to develop a representative ''limiting'' axial burnup profile for pressurized water reactors (PWRs), which would encompass the isotopic axial variations caused by different assembly irradiation histories, and produce conservative isotopics with respect to criticality. The effect that the low burnup regions near the ends of spent fuel have on system reactivity is termed the ''end-effect''. This calculation will quantify the end-effects associated with Pressurized Water Reactor (PWR) fuel assemblies emplaced in a hypothetical 21 PWR waste package. The scope of this calculation covers an initial enrichment range of 3.0 through 5.0 wt% U-235 and a burnup range of 10 through 50 GWd/MTU. This activity supports the validation of the process for ensuring conservative generation of spent fuel isotopics with respect to criticality safety applications, and the use of burnup credit for commercial spent nuclear fuel. The intended use of these results will be in the development of PWR waste package loading curves, and applications involving burnup credit. Limitations of this evaluation are that the limiting profiles are only confirmed for use with the B andW 15 x 15 fuel assembly design. However, this assembly design is considered bounding of all other typical commercial PWR fuel assembly designs. This calculation is subject to the Quality Assurance Requirements and Description (QARD) because this activity supports investigations of items or barriers on the Q-list (YMP 2001)
PWR AXIAL BURNUP PROFILE ANALYSIS
Energy Technology Data Exchange (ETDEWEB)
J.M. Acaglione
2003-09-17
The purpose of this activity is to develop a representative ''limiting'' axial burnup profile for pressurized water reactors (PWRs), which would encompass the isotopic axial variations caused by different assembly irradiation histories, and produce conservative isotopics with respect to criticality. The effect that the low burnup regions near the ends of spent fuel have on system reactivity is termed the ''end-effect''. This calculation will quantify the end-effects associated with Pressurized Water Reactor (PWR) fuel assemblies emplaced in a hypothetical 21 PWR waste package. The scope of this calculation covers an initial enrichment range of 3.0 through 5.0 wt% U-235 and a burnup range of 10 through 50 GWd/MTU. This activity supports the validation of the process for ensuring conservative generation of spent fuel isotopics with respect to criticality safety applications, and the use of burnup credit for commercial spent nuclear fuel. The intended use of these results will be in the development of PWR waste package loading curves, and applications involving burnup credit. Limitations of this evaluation are that the limiting profiles are only confirmed for use with the B&W 15 x 15 fuel assembly design. However, this assembly design is considered bounding of all other typical commercial PWR fuel assembly designs. This calculation is subject to the Quality Assurance Requirements and Description (QARD) because this activity supports investigations of items or barriers on the Q-list (YMP 2001).
Behavior of Composite Columns Subjected to Lateral Cyclic Loading
AL-Bdoor, Mazen
2013-01-01
ABSTRACT: Nonlinear 3-D finite element models were developed to investigate the cumulative damage of composite columns subjected to cyclic loading by comparing the effects of different levels of axial loads on the cyclic capacity of steel, reinforced concrete, and composite beam-columns. The beam-column specimens were modeled as fixed cantilever beam-columns with an axial load level of 10%, 15%, and 20% of their axial load capacity as well as cyclic loading similar to that suggested ...
A new strategy of axial power distribution control based on three axial offsets concept
International Nuclear Information System (INIS)
We have proposed a very simple control procedure for axial xenon oscillation control based on a characteristic trajectory. The trajectory is drawn by three offsets of power distributions, namely, AOp, AOi and AOx. They are defined as the offset of axial power distribution, the offset of the power distribution under which the current iodine distribution is obtained as the equilibrium and that for xenon distribution, respectively. When these offsets are plotted on X-Y plane for (AOp-AOx, AOi-AOx) the trajectory draws a quite characteristic ellipse (or an elliptic spiral). On the other hands, Constant Axial Offset Control (CAOC) procedure is adopted as axial power distribution control strategy during both base load and load following operations in domestic PWRs. In the previous paper, we have presented an innovative procedure of axial power distribution control during load following in PWRs based on this trajectory such that the AOp-AOx is to be controlled to zero when the value deviates the pre-determined limiting values. In this paper we propose a modified control strategy to get more stability of axial power distributions. In this strategy, we control the trajectory to be close to the major axis of the ellipse when the power distribution reaches the limiting values. In other words, the plot is not controlled only to reduce AOp-AOx but also AOi-AOx is taken into account at the same time. It is known that when the plot is controlled to the major axis, it means that the point gives the peak position of axial xenon oscillation. Therefore xenon oscillation will not increase its amplitude any more. Thus more stable axial power distribution control is attained. This kind of design concept is quite important especially for the future PWRs with elongated fuel length and longer core life. Because in a longer effective core and also the longer core life, it has been known that the stability of axial xenon oscillation becomes more unstable. In this paper, some simulation
On renormalization of axial anomaly
International Nuclear Information System (INIS)
It is shown that multiplicative renormalization of the axial singlet current results in renormalization of the axial anomaly in all orders of perturbation theory. It is a necessary condition for the Adler - Bardeen theorem being valid. 10 refs.; 2 figs
Axial compressor stability enhancement
Houghton, Timothy Oliver.
2010-01-01
Aircraft jet engines must operate in a stable manner at all times. One source of instability is compressor stall. Stall problems can be reduced by machining cavities into the compressor casing adjacent to the rotor blades. This ?casing treatment? is the focus of the present work. Two treatment configurations are tested: circumferential grooves cut into the casing above the rotor blades, and axial slots cut into the casing adjacent to the rotor blade leading edges. The performance of a single ...
Axial flow heat exchanger devices and methods for heat transfer using axial flow devices
Koplow, Jeffrey P.
2016-02-16
Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.
Effect of weld reinforcement on axial plastic buckling of welded steel cylindrical shells
Institute of Scientific and Technical Information of China (English)
Chu-lin YU; Zhi-ping CHEN; Ji WANG; Shun-juan YAN; Li-cai YANG
2012-01-01
The effect of weld reinforcement on axial plastic buckling of welded steel cylindrical shells is investigated through experimental and numerical buckling analysis using six welded steel cylindrical shell specimens.The relationship between the amplitude of weld reinforcement and the axial plastic buckling critical load is explored.The effect of the material yield strength and the number of circumferential welds on the axial plastic buckling is studied.Results show that circumferential weld reinforcement represents a severe imperfect form of axially compressed welded steel cylindrical shells and the axial plastic buckling critical load decreases with the increment of the mean amplitude of circumferential weld reinforcement.The material yield strength and the number of circumferential welds are found to have no significant effect on buckling waveforms; however,the axial plastic buckling critical load can be decreased to some extent with the increase of the number of circumferential welds.
Dynamic calibration of tri-axial piezoelectric force transducers
International Nuclear Information System (INIS)
Applied dynamic loads are often difficult to measure accurately due to the dynamic response of the sensor used and the dependence of the sensor's sensitivity on the mounting and loading details. For tri-axial force transducers, which are capable of measuring forces along the axial direction and along both directions of the transducer's face, dynamic calibration is further complicated by the coupling of the sensor's measurement directions. For this reason, a new apparatus for dynamic calibration of normal and tangential directions of a tri-axial piezoelectric force transducer has been constructed and tested. The calibration force is provided from a spring loaded uni-axial impulse hammer. The apparatus allows for calibration at a variety of calibration angles and speeds; the loading for all cases of a nonzero calibration angle is oblique, with the point of force application being eccentric to the centerline of the force transducer's normal axis. As such, tangential loads are always accompanied by a normal load. The calibration results show that the normal direction correction factors have a systematic dependence on the calibration angle; the tangential correction factors show some scatter but do not appear to be dependent on the calibration angle
An Assessment of Cumulative Axial and Torsional Fatigue in a Cobalt-Base Superalloy
Kalluri, Sreeramesh; Bonacuse, Peter J.
2010-01-01
Cumulative fatigue under axial and torsional loading conditions can include both load-order (higMow and low/high) as well as load-type sequence (axial/torsional and torsional/axial) effects. Previously reported experimental studies on a cobalt-base superalloy, Haynes 188 at 538 C, addressed these effects. These studies characterized the cumulative axial and torsional fatigue behavior under high amplitude followed by low amplitude (Kalluri, S. and Bonacuse, P. J., "Cumulative Axial and Torsional Fatigue: An Investigation of Load-Type Sequance Effects," in Multiaxial Fatigue and Deformation: Testing and Prediction, ASTM STP 1387, S. Kalluri, and P. J. Bonacuse, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2000, pp. 281-301) and low amplitude followed by high amplitude (Bonacuse, P. and Kalluri, S. "Sequenced Axial and Torsional Cumulative Fatigue: Low Amplitude Followed by High Amplitude Loading," Biaxial/Multiaxial Fatigue and Fracture, ESIS Publication 31, A. Carpinteri, M. De Freitas, and A. Spagnoli, Eds., Elsevier, New York, 2003, pp. 165-182) conditions. In both studies, experiments with the following four load-type sequences were performed: (a) axial/axial, (b) torsional/torsional, (c) axial/torsional, and (d) torsional/axial. In this paper, the cumulative axial and torsional fatigue data generated in the two previous studies are combined to generate a comprehensive cumulative fatigue database on both the load-order and load-type sequence effects. This comprehensive database is used to examine applicability of the Palmgren-langer-Miner linear damage rule and a nonlinear damage curve approach for Haynes 188 subjected to the load-order and load-type sequencing described above. Summations of life fractions from the experiments are compared to the predictions from both the linear and nonlinear cumulative fatigue damage approaches. The significance of load-order versus load-type sequence effects for axial and torsional loading conditions
Buckling localization in a cylindrical panel under axial compression
DEFF Research Database (Denmark)
Tvergaard, Viggo; Needleman, A.
2000-01-01
Localization of an initially periodic buckling pattern is investigated for an axially compressed elastic-plastic cylindrical panel of the type occurring between axial stiffeners on cylindrical shells. The phenomenon of buckling localization and its analogy with plastic flow localization in tensile......, but where subsequently the load starts to increase again, it is found that near the local load minimum, the buckling pattern switches back to a periodic type of pattern. The inelastic material behavior of the panel is described in terms of J(2) corner theory, which avoids the sometimes unrealistically...
Axial skeletal CT densitometry
International Nuclear Information System (INIS)
Since the discovery of the Roentgen ray a precise and accurate assessment of bone mineral content has been a challenge to many investigators. A number of methods have been developed but no one satisfied. Considering its technical possibilities computed tomography is very promising in determination of bone mineral content (BMC). The new modality enables BMC estimations in the axial skeletal trabecular bone. CT densitometry can be performed on a normal commercially available third generation whole body CT scanner. No dedicated device in a special clinical set-up is necessary. In this study 106 patients, most of them clinically suspected of osteoporosis, were examined. The new method CT densitometry has been evaluated. The results have been correlated to alternative BMC determination methods. (Auth.)
Energy Technology Data Exchange (ETDEWEB)
Schmidt-Hurtienne, B.
2000-07-01
According to experimental results the dynamic fracturing of concrete exhibits a transient dynamic strength increase that grows unproportional with the strain rate. The dynamic stress-strain relation for concrete is not governed by the current strain rate exclusively, but by the complete load history instead. Inspite of these acknowledged results the rate effect is still being defined in most hydrocodes by including simple strength increase factors in constitutive models, that depend only on the actual strain rate. Dynamic load histories including loading and unloading e.g. from recordings in a split Hopkinson bar test setup cannot be simulated with this simplified approach. The development of a new phenomenological constitutive law taking into account the load history is motivated by the lack of physical embedment in most dynamic material laws. A coupled damage-plasticity model is derived for the time independent part of the constitutive law. The damage formulation takes care of the anisotropic elastic degradation due to microcracking, whereas the internal friction of the microcrack surfaces especially during compressive loading states is described by the plastic part of the mode. The strain rate influence on the dynamic strength of concrete can physically be attributed to inertia effect and viscous retardation during the opening and development of microcracks as well as the mesostructural scale effects due to the heterogeneous composition of concrete. The time dependent opening of microcracks and thereby the retarded activation of damage is described by a rheological model. The solution of the differential equation leads to a history function displaying the relaxation of elasticity around newly developed damage as a function of the load history. To reduce computational costs the history function can be replaced by simpler relaxation functions. Therefore an exponential function with variable relaxation time is chosen. The dynamic continuum damage constitutive law
Reactivity effects of nonuniform axial burnup distributions on spent fuel
International Nuclear Information System (INIS)
When conducting future criticality safety analyses on spent fuel shipping casks, burnup credit may play a significant role in determining the number of fuel assemblies that can be safely loaded into each cask. An important area in burnup credit analysis is the burnup variation along the length of the fuel assembly, which is determined by the location of the assembly in the reactor core and its residence time. A study of the effects of axial burnup distributions on reactivity has been conducted, using data from existing power plant fuel. Utilizing a one-dimensional, two-group diffusion code, named REALAX, the reactivity effects of axial burnup profiles have been calculated for various PWR fuel assemblies. The reactivity effects calculated by the code are defined in terms of k for the axially dependent burnup distribution minus k for a uniform axial burnup distribution at the assembly average burnup divided by k for a uniform axial burnup distribution at the assembly average burnup. Criticality safety specialists can take advantage of the quick-running code to determine axial effects of different assembly burnup profiles. In general, the positive reactivity effects of axial burnup distributions increase as burnup increases, though they do not increase faster than the overall decrease in reactivity due to burnup
Reactivity effects of nonuniform axial burnup distributions on spent fuel
Energy Technology Data Exchange (ETDEWEB)
Leary, R.W. II; Parish, T.A. [Texas A & M Univ., College Station, TX (United States)
1995-12-01
When conducting future criticality safety analyses on spent fuel shipping casks, burnup credit may play a significant role in determining the number of fuel assemblies that can be safely loaded into each cask. An important area in burnup credit analysis is the burnup variation along the length of the fuel assembly, which is determined by the location of the assembly in the reactor core and its residence time. A study of the effects of axial burnup distributions on reactivity has been conducted, using data from existing power plant fuel. Utilizing a one-dimensional, two-group diffusion code, named REALAX, the reactivity effects of axial burnup profiles have been calculated for various PWR fuel assemblies. The reactivity effects calculated by the code are defined in terms of k for the axially dependent burnup distribution minus k for a uniform axial burnup distribution at the assembly average burnup divided by k for a uniform axial burnup distribution at the assembly average burnup. Criticality safety specialists can take advantage of the quick-running code to determine axial effects of different assembly burnup profiles. In general, the positive reactivity effects of axial burnup distributions increase as burnup increases, though they do not increase faster than the overall decrease in reactivity due to burnup.
Energy Dissipation in Sandwich Structures During Axial Compression
DEFF Research Database (Denmark)
Urban, Jesper
2002-01-01
The purpose of this paper is to investigate the energy dissipation in sandwich structures during axial crushing. Axial crushing tests on six sandwich elements are described. The sandwich elements consist of a polyurethane core and E-glass/Polyester skin. The elements compare to full......-scale structural elements in fast sandwich vessels. Two of the crushing tests are simulated with the explicit finite element software LS-DYNA3D. The key results are load-end shortening relationship and the energy dissipation. Good agreement between the numerical predictions and the experiments are obtained. A...... simple analytical model for the energy dissipation during axial crushing is proposed. Keywords: Sandwich, Energy Dissipation, Axial Crushing, LS-DYNA, Analytical crushing models, Crashworthiness....
Study on Asphalt Pavement Fatigue-Damage with Forecasting Axial Load Spectrum%按预测轴载谱分析沥青路面的疲劳损伤
Institute of Scientific and Technical Information of China (English)
马林; 葛折圣; 胡晓倩; 黄明波
2011-01-01
现行《公路沥青路面设计规范》(JTGG D50-2006)轴载等效换算方法难以反映超载、重载交通对路面结构的影响.结构层参数取值未考虑结构层在疲劳过程中的材料损伤,是重载交通沥青路面出现早期破坏的原因之一.采用预测轴载谱和Miner法则,计算分析了路面结构的疲劳损伤累积过程,并考虑不同使用阶段路面基层模量衰减对路面结构损伤进程的影响.结果表明,半刚性基层厚沥青面层路面结构的疲劳损伤累积进程明显优于目前国内较典型的半刚性基层沥青路面结构.研究结果为重载交通沥青路面结构设计指明了方向.%In Specifications for Design of Highway Asphalt Pavement (JTG D50-2006), the method of Equivalent Axle Loads could not reflect the influence on pavement structure by overload and heavy-load transportation. And the parameter of structural layers was no considering the material damage in the process of fatigue. It is one of the reasons why asphalt pavement is damaged early. The fatigue-damage accumulation in pavement structure was analyzed by using the forecasting axle load spectrum and Miner law. And the parameter of structural layers attenuated while the material damage in the process of fatigue. The results show that the fatigue damage accumulation process of semi-rigid base total thickness asphalt pavement structure is significantly better than the current domestic typical semi-rigid bituminous pavement structure. So this research results can help the development of structure design of heave-load asphalt pavement.
Axial anomaly in nonrenormalizable theories
International Nuclear Information System (INIS)
The anomaly for the axial current in nonrenormalizable theories with electromagnetic coupling is considered. The spinor electrodynamics with Pauli term is examined in detail using the Feynman graph technique and the point-splitting method. The same finite value for the axial anomaly emerges. (author)
Rapalino, Otto; Smirniotopoulos, James G
2016-01-01
Extra-axial brain tumors are the most common adult intracranial neoplasms and encompass a broad spectrum of pathologic subtypes. Meningiomas are the most common extra-axial brain tumor (approximately one-third of all intracranial neoplasms) and typically present as slowly growing dural-based masses. Benign meningiomas are very common, and may occasionally be difficult to differentiate from more aggressive subtypes (i.e., atypical or malignant varieties) or other dural-based masses with more aggressive biologic behavior (e.g., hemangiopericytoma or dural-based metastases). Many neoplasms that typically affect the brain parenchyma (intra-axial), such as gliomas, may also present with primary or secondary extra-axial involvement. This chapter provides a general and concise overview of the common types of extra-axial tumors and their typical imaging features. PMID:27432671
Axial Compressor Stall and Surge Prediction by Measurements
Hönen, H.
1999-01-01
The paper deals with experimental investigations and analyses of unsteady pressure distributions in different axial compressors. Based on measurements in a single stage research compressor the influence of increasing aerodynamic load onto the pressure and velocity fluctuations is demonstrated. Detailed measurements in a 14-stage and a 17-stage gas turbine compressor are reported. For both compressors parameters could be found which are clearly influenced by the aerodynamic load.For the 14-sta...
Build Axial Gradient Field by Using Axial Magnetized Permanent Rings
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
Axial magnetic field produced by an axial magnetized permanent ring was studied. For two permanent rings, if they are magnetized in the same directions, a nearly uniform axial field can be produced. If they are magnetized in opposite direction,an axial gradient magnetic field can be generated, with the field range changing from -B0 to B0. A permanent magnet with a high axial gradient field was fabricated, the measured results agree with the PANDIRA calculation very well. For wider usage,it is desirable for the field gradient to be changed. Some methods to produce the variable gradient field are presented. These kinds of axial gradient magnetic field can also be used as a beam focusing for linear accelerator if the periodic field can be produced along the beam trajectory. The axial magnetic field is something like a solenoid, large stray field will leak to the outside environment if no method is taken to control them. In this paper, one method is illustrated to shield off the outside leakage field.
Institute of Scientific and Technical Information of China (English)
赵楠; 李正良; 刘红军
2013-01-01
进行了19个长细比λ=30～90的Q420 L220 mm×20 mm角钢试件的轴压试验研究.结果表明:此类构件在长细比λ＞45时,以弯曲失稳破坏为主；长细比λ≤45时,以弯扭失稳为主.研究了现行钢结构规范中防止局部屈曲宽厚比限值公式和计算弯扭失稳的换算长细比取值公式的适用性.采用逆算单元长度法得到了大规格等边角钢的柱子曲线,研究了此类构件与普通规格等边角钢的差异以及肢厚、肢宽和钢材强度等对柱子曲线的影响.提出了高强大规格等边角钢轴压构件的承载力计算方法.并且研究了高强大规格等边角钢两端偏心受压的柱子曲线,给出了长细比修正系数的建议公式.%The axial compression member test was conducted to investigate the stability performance of these members, including nineteen Q420 L220×20 specimens which slenderness ratio(λ) ranged from 30~90. The test results showed that when slendemess is λ > 45, flexural buckling was observed and when slenderness is λ ≤45, local or flexural-torsion or torsion buckling was observed. The applicability of local buckling wide thickness ratio formula and flexural-torsional buckling conversion slenderness ratio formula was researched. By means of inverse calculation segment length method, the column curve of the large size equal angle was got. The comparison with common size angle and parameter analysis was made. Calculation method of bearing capacity of large size equal angle was given. Two ends eccentric compression column curve was also researched, and a suggestion formula of slenderness ratio correction coefficient was given.
Notari, Alessio
2016-01-01
We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term $\\frac{\\phi}{f_\\gamma} F \\tilde{F}$, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density $\\rho_R$, which which can lead to inflation without the need of a flat potential. We analyze the system, for momenta $k$ smaller than the cutoff $f_\\gamma$, including numerically the backreaction. We consider the evolution from a given static initial condition and explicitly show that, if $f_\\gamma$ is smaller than the field excursion $\\phi_0$ by about a factor of at least ${\\cal O} (20)$, there is a friction effect which turns on before that the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of...
Bode, Hans R.
2009-01-01
Morphogen gradients play an important role in pattern formation during early stages of embryonic development in many bilaterians. In an adult hydra, axial patterning processes are constantly active because of the tissue dynamics in the adult. These processes include an organizer region in the head, which continuously produces and transmits two signals that are distributed in gradients down the body column. One signal sets up and maintains the head activation gradient, which is a morphogenetic gradient. This gradient confers the capacity of head formation on tissue of the body column, which takes place during bud formation, hydra's mode of asexual reproduction, as well as during head regeneration following bisection of the animal anywhere along the body column. The other signal sets up the head inhibition gradient, which prevents head formation, thereby restricting bud formation to the lower part of the body column in an adult hydra. Little is known about the molecular basis of the two gradients. In contrast, the canonical Wnt pathway plays a central role in setting up and maintaining the head organizer. PMID:20066073
Nonlinear Model and Qualitative Analysis for Coupled Axial/Torsional Vibrations of Drill String
Fushen Ren; Baojin Wang; Suli Chen; Zhigang Yao; Baojun Bai
2016-01-01
A nonlinear dynamics model and qualitative analysis are presented to study the key effective factors for coupled axial/torsional vibrations of a drill string, which is described as a simplified, equivalent, flexible shell under axial rotation. Here, after dimensionless processing, the mathematical models are obtained accounting for the coupling of axial and torsional vibrations using the nonlinear dynamics qualitative method, in which excitation loads and boundary conditions of the drill stri...
Shear Behavior of Reinforced Concrete Shear Walls under Tensile Axial Force with Eccentricity
MIZOGUCHI, Mitsuo; ARAI, Yasuyuki; KUCHIJI, Hideki
2000-01-01
A lateral loading test of six reinforced concrete shear walls subjected to an eccentric tensile axial force was carried out to examine their shear behavior. Next facts ware confirmed on the shear strength of the walls subjected to an eccentric tensile axial force. The test results can be evaluat by the shear strength equation [2] considering axial tensile stress. The calculated values given by the (AIJ "Design Guidelines for Earthquake Resistant Reinforced Concrete Buildings Based on Inelasti...
FINITE ELEMENT ANALYSIS OF AXIAL FEED BAR ROLLING
Institute of Scientific and Technical Information of China (English)
C.G. Xu; G.H. Liu; G.S. Ren; Z. Shen; C.P. Ma; W. W. Ren
2007-01-01
A flexible technique of hot working of bars by axial feed rolling was introduced. The processdeformation, strain field, stress field, and temperature field of the parts are analyzed by finite elementmethod (FEM)-simulation software DEFORM-3D. The material flow rule and tool load have beeninvestigated.
Institute of Scientific and Technical Information of China (English)
郭彦林; 王永海
2011-01-01
The buckling behavior of a compressed column braced with two spring supports, as the equivalent model of three-storey multi-column frame, was investigated systemically in the previous study. It was observed that, with the bracing stiffness increasing, the buckling mode of the column changed from symmetric single wave to antisymmetric double waves before the fully fixed supported reaction was reached. Obviously, two lateral supports in the equivalent model were independent, and the stiffness of the supports was the same even under different buckling mode. However, the two lateral supports of the column were not independent in three-storey multi-column frame subjected to different buckling modes, and the interaction between lateral bracing stiffness of columns and different buckling modes needs to be taken account. In this study , the out-plane lateral bracing stiffness of the columns under different buckling modes in three-storey multi-column frame was obtained via theoretical derivation, so that the column braced with two lateral spring supports could be treated as an equivalent model where the column has different lateral brace stiffness under corresponding buckling mode. The elastic buckling load and effective slenderness of the multi-column were obtained by using the results obtained from the equivalent model. The ultimate load-carrying capacity of three-storey multi-column frame with imperfections was analyzed by using finite element method. The random out-plane imperfection distributions of different columns in the frame were considered in the study above. It was proved that the design approach of the equivalent model could be used to estimate the load-carrying capacity of three-storey multi-column frame.%对带两个等跨布置侧向弹簧支撑的轴压柱（三层通高群柱的面外稳定性等效模型）的研究表明，随着柱子受到支撑作用的增强，柱子最低阶屈曲模态会依次经历单波、双波及三波（完全支撑）三种
Study of axial magnetic effect
International Nuclear Information System (INIS)
The Axial Magnetic Effect manifests itself as an equilibrium energy flow of massless fermions induced by the axial (chiral) magnetic field. Here we study the Axial Magnetic Effect in the quenched SU(2) lattice gauge theory with massless overlap fermions at finite temperature. We numerically observe that in the low-temperature hadron phase the effect is absent due to the quark confinement. In the high-temperature deconfinement phase the energy flow is an increasing function of the temperature which reaches the predicted asymptotic T2 behavior at high temperatures. We find, however, that energy flow is about one order of magnitude lower compared to a theoretical prediction
Characterization of Multiflux Axial Compressors
International Nuclear Information System (INIS)
In the present work the results of analytical models of performance are compared with experimental data acquired in the multi flux axial compressor test facility, built in The Pilcaniyeu Technological Complex for the SIGMA project.We describe the experimental circuit and the data of the dispersion inside the axial compressor obtained using a tracer gas through one of the annular inlets.The attained results can be used to validate the design code for the multi flux axial compressors and SIGMA industrial plant
Axial gap rotating electrical machine
Energy Technology Data Exchange (ETDEWEB)
None
2016-02-23
Direct drive rotating electrical machines with axial air gaps are disclosed. In these machines, a rotor ring and stator ring define an axial air gap between them. Sets of gap-maintaining rolling supports bear between the rotor ring and the stator ring at their peripheries to maintain the axial air gap. Also disclosed are wind turbines using these generators, and structures and methods for mounting direct drive rotating electrical generators to the hubs of wind turbines. In particular, the rotor ring of the generator may be carried directly by the hub of a wind turbine to rotate relative to a shaft without being mounted directly to the shaft.
Institute of Scientific and Technical Information of China (English)
邵永波; 杜之富; Lie Seng Tjhen
2011-01-01
应用分区产生网格的方法产生了K型节点的有限元模型,计算了在轴向荷载作用下K型节点焊缝周围的热点应力分布情况,并与相关试验结果进行对比分析,验证了所提出的有限元模型的可行性和准确性.通过对1 152个K节点模型分析,研究了几何参数对K型节点焊缝周围热点应力分布的影响,发现在几何参数取不同值时热点应力的分布随几何参数的变化发生改变,而且热点应力的位置也随着几何参数的变化在冠点和鞍点之间移动.并在此几何参数分析的基础上,提出了K型节点焊缝周围应力集中系数分布的参数公式,并对参数公式进行了误差分析.对于绝大多数K节点模型,拟合得到的参数公式所计算的焊缝周围应力分布结果是精确可靠的,所以提出的参数公式为工程中K节点疲劳设计和分析提供了参考方法.%The finite element model of tubular K-joint is presented using sub-zone mesh generation method. The distribution of hot spot stress (HSS) along weld toe of a tubular K-joint under axial loads is analyzed,and the results obtained by means of the finite element model were compared with experimental measurements. It is shown that the finite element model proposed in this study is feasible and accurate for estimating the stress distribution of the K-joint.Through the parametric study on 1 152 K-joint models, the effect of geometrical parameters on the distribution of hot spot stress along the weld of tubular K-joints subjected to axial loads is investigated, and it is found that the distribution of hot spot stress is varied with different geometrical parameters values. Furthermore, the position of the hot spot stress shifts between the crown and the saddle when some geometrical parameters are different.Based on the parametric study, parametric equations of stress concentration factor distribution along the weld toe of tubular K-joints under axial loads are proposed,and the
Ratchetting experiments on thin cylinders subject to axially moving temperature fronts
International Nuclear Information System (INIS)
This presentation includes figures describing apparatus for cold front experiments, and experimental data obtained under different experimental conditions (axial load, very thin cylinder, large number of cycles, hot fronts): increase in diameter; profile development; decrease in length
Failure Processes in Embedded Monolayer Graphene under Axial Compression
Androulidakis, Charalampos; Koukaras, Emmanuel N.; Frank, Otakar; Tsoukleri, Georgia; Sfyris, Dimitris; Parthenios, John; Pugno, Nicola; Papagelis, Konstantinos; Novoselov, Kostya S.; Galiotis, Costas
2014-01-01
Exfoliated monolayer graphene flakes were embedded in a polymer matrix and loaded under axial compression. By monitoring the shifts of the 2D Raman phonons of rectangular flakes of various sizes under load, the critical strain to failure was determined. Prior to loading care was taken for the examined area of the flake to be free of residual stresses. The critical strain values for first failure were found to be independent of flake size at a mean value of –0.60% corresponding to a yield stre...
Analysis and testing of axial compression in imperfect slender truss struts
Lake, Mark S.; Georgiadis, Nicholas
1990-01-01
The axial compression of imperfect slender struts for large space structures is addressed. The load-shortening behavior of struts with initially imperfect shapes and eccentric compressive end loading is analyzed using linear beam-column theory and results are compared with geometrically nonlinear solutions to determine the applicability of linear analysis. A set of developmental aluminum clad graphite/epoxy struts sized for application to the Space Station Freedom truss are measured to determine their initial imperfection magnitude, load eccentricity, and cross sectional area and moment of inertia. Load-shortening curves are determined from axial compression tests of these specimens and are correlated with theoretical curves generated using linear analysis.
Vectorial versus axial goldstone bosons
International Nuclear Information System (INIS)
The Yukawa interactions of fermions with Goldstone bosons are given in closed form for an arbitrary renormalizable field theory to all orders of perturbation theory or for a general effective Lagrangian. Although the diagonal couplings are always pseudoscalar there is an important difference between spontaneously broken vector and axial-vector global symmetries. Compared to the axial case, the diagonal douplings of 'vectorial' Goldstone bosons to charged fermions are suppressed by mixing angles or appear only via radiative corrections involving gauge fields. This general result may be relevant for the problem of flavour symmetry breaking in composite models. (Author)
Simulation of an Axial Vircator
Tikhomirov, V V
2013-01-01
An algorithm of particle-in-cell simulations is described and tested to aid further the actual design of simple vircators working on axially symmetric modes. The methods of correction of the numerical solution, have been chosen and jointly tested, allow the stable simulation of the fast nonlinear multiflow dynamics of virtual cathode formation and evolution, as well as the fields generated by the virtual cathode. The selected combination of the correction methods can be straightforwardly generalized to the case of axially nonsymmetric modes, while the parameters of these correction methods can be widely used to improve an agreement between the simulation predictions and the experimental data.
Vibrations and Stability of Axially and Transversely Loaded Structures
Piana, Gianfranco
2013-01-01
Modern lightweight and long-span structures are becoming increasingly slender and flexible thanks to continuous improvements in structural analysis techniques, construction methods, and the use of lighter and stronger materials. Modern airplanes, large roofs, and long-span bridges are just some examples of structures for which a design based on vibration and stability is of primary importance. The thesis aims to investigate into the interplay between vibration and stability phenomena in elast...
Axial structure of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Veronique Bernard; Latifa Elouadrhiri; Ulf-G Meissner
2002-01-01
We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton.
Axial field permanent magnet DC motor with powder iron armature
Sharkh, Suleiman M.A.; Mohammad, Mohammad T.
2007-01-01
The paper describes a double-gap axial field permanent magnet (PM) dc motor whose double-layer armature wave winding is constructed of copper strips. It investigates the performance of two machines using powder iron and lamination steel materials as armature teeth. Tests are conducted to evaluate the motor torque and speed curves as well as their efficiency under different loads. Finite element analysis (FEA) and equivalent circuit models are used to determine the levels of the magnetic satur...
Improvement of the axial buckling capability of elliptical cylindrical shells
Paschero, Maurizio
2008-01-01
A rather thorough and novel buckling analysis of an axially-loaded orthotropic circular cylindrical shell is formulated. The analysis assumes prebuckling rotations are negligible and uses a unique re-defining of the orthotropic material properties in terms of a so-called geometric mean isotropic (GMI) material. Closed-form expressions for the buckling stress in terms of cylinder geometry and orthotropic material properties are presented, the particular closed form depending on ...
Axial Non-linear Dynamic Soil-Pile Interaction - Keynote
Directory of Open Access Journals (Sweden)
Holeyman A.
2014-01-01
Full Text Available This keynote lecture describes recent analytical and numerical advances in the modeling of the axial nonlinear dynamic interaction between a single pile and its embedding soil. On one hand, analytical solutions are developed for assessing the nonlinear axial dynamic response of the shaft of a pile subjected to dynamic loads, and in particular to vibratory loads. Radial inhomogeneity arising from shear modulus degradation is evaluated over a range of parameters and compared with those obtained by other authors and by a numerical radial discrete model simulating the pile and soil movements from integration of the laws of motion. New approximate non linear solutions for axial pile shaft behaviour developed from general elastodynamic equations are presented and compared to existing linear solutions. The soil non linear behaviour and its ability to dissipate mechanical energy upon cyclic loading are shown to have a significant influence on the mechanical impedance provided by the surrounding soil against pile shaft movement. The limitations of over-simplified modelling of pile response are highlighted.
Axially symmetric rotating traversable wormholes
Kuhfittig, P K F
2003-01-01
This paper generalizes the static and spherically symmetric traversable wormhole geometry to a rotating axially symmetric one with a time-dependent angular velocity by means of an exact solution. It was found that the violation of the weak energy condition, although unavoidable, is considerably less severe than in the static spherically symmetric case. The radial tidal constraint is more easily met due to the rotation. Similar improvements are seen in one of the lateral tidal constraints. The magnitude of the angular velocity may have little effect on the weak energy condition violation for an axially symmetric wormhole. For a spherically symmetric one, however, the violation becomes less severe with increasing angular velocity. The time rate of change of the angular velocity, on the other hand, was found to have no effect at all. Finally, the angular velocity must depend only on the radial coordinate, confirming an earlier result.
View of the Axial Field Spectrometer
1980-01-01
The Axial Field Spectrometer, with the vertical uranium/scintillator calorimeter and the central drift chamber retracted for service. One coil of the Open Axial Field Magnet is just visible to the right.
Simulation of an Axial Vircator
Tikhomirov, V. V.; Siahlo, S. E.
2013-01-01
An algorithm of particle-in-cell simulations is described and tested to aid further the actual design of simple vircators working on axially symmetric modes. The methods of correction of the numerical solution, have been chosen and jointly tested, allow the stable simulation of the fast nonlinear multiflow dynamics of virtual cathode formation and evolution, as well as the fields generated by the virtual cathode. The selected combination of the correction methods can be straightforwardly gene...
Dynamic and failure properties of high damping rubber bearing under high axial stress
Energy Technology Data Exchange (ETDEWEB)
Ishizuka, Hidetake; Murota, Nobuo [Bridgestone Corp., Yokohama (Japan). Yokohama Plant; Fukumori, Takeshi [Bridgestone Corp., Tokyo (Japan). Technical Center
1995-12-01
Seismic isolation bearings have been used under axial stresses less than 100(kgf/cm{sup 2}) for many years. If higher axial loads can be applied, however, a larger period shift will be achieved and the size of the isolation devices may be reduced resulting in a cost reduction of the bearing. This paper describes experimental studies of dynamic and failure properties of high damping rubber bearings (HDR) under high axial stress of over 120(kgf/cm{sup 2}) compared with the conventional stress of 65(kgf/cm{sup 2}). The results show that HDR continues to have stable performance under high axial stress with high shear strain. It indicates that high axial stress over 100(kgf/cm{sup 2}) is within the capability of the BDR isolation bearing.
Shear Strength of Reinforced Concrete Shear Walls under Eccentric Tensile Axial Force
MIZOGUCHI, Mitsuo; ARAI, Yasuyuki; Hosoya, Koji
2002-01-01
Six reinforced concrete shear wall models were built and tested to investigate effects of cyclic lateral loading and an eccentric tensile axial force on their shear strength behavior. The following are confirmed from this test result. When the elongation at the bottom of the boundary column on the compression side for a lateral force is small, the shear strength of shear walls subjected to a tensile axial force at the boundary column can be evaluated by conventional shear strenght equations, ...
Axial Force at the Vessel Bottom Induced by Axial Impellers
I. Fořt; P. Hasal; A. Paglianti; F. Magelli
2008-01-01
This paper deals with the axial force affecting the flat bottom of a cylindrical stirred vessel. The vessel is equipped with four radial baffles and is stirred with a four 45° pitched blade impeller pumping downwards. The set of pressure transducers is located along the whole radius of the flat bottom between two radial baffles. The radial distribution of the dynamic pressures indicated by the transducers is measured in dependence on the impeller off-bottom clearance and impeller speed.It fol...
Stability of axially restrained steel columns under temperature action
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
The in-plane elastic buckling of a steel column under thermal loading is investigated. The column is pinned at its ends, with two linear elastic springs that model the restraint provided by adjacent members in a structural assemblage or an elastic foundation. Across a section, the temperature is assumed to be linearly distributed. Based on a nonlinear strain-displacement relationship, the energy method is used to obtain the equilibrium and buckling equations. Then the buckling of columns with three different thermal loading cases is studied. The results show that the analytical formulas can be used to evaluate the critical temperature for elastic buckling. The thermal gradient plays a positive role in improving the stability of columns. Comparing these predictions with uniform temperature distribution over cross section, it can be shown that the buckling load is seriously underestimated. It can also be found that axial restraints can significantly affect the column elastic buckling loads. The critical temperature decreases with an increase of restraint stiffness. Furthermore, the effect of axial stiffness increases when increasing the thermal gradients and decreasing the slenderness ratio of columns.
Axial and Centrifugal Compressor Mean Line Flow Analysis Method
Veres, Joseph P.
2009-01-01
This paper describes a method to estimate key aerodynamic parameters of single and multistage axial and centrifugal compressors. This mean-line compressor code COMDES provides the capability of sizing single and multistage compressors quickly during the conceptual design process. Based on the compressible fluid flow equations and the Euler equation, the code can estimate rotor inlet and exit blade angles when run in the design mode. The design point rotor efficiency and stator losses are inputs to the code, and are modeled at off design. When run in the off-design analysis mode, it can be used to generate performance maps based on simple models for losses due to rotor incidence and inlet guide vane reset angle. The code can provide an improved understanding of basic aerodynamic parameters such as diffusion factor, loading levels and incidence, when matching multistage compressor blade rows at design and at part-speed operation. Rotor loading levels and relative velocity ratio are correlated to the onset of compressor surge. NASA Stage 37 and the three-stage NASA 74-A axial compressors were analyzed and the results compared to test data. The code has been used to generate the performance map for the NASA 76-B three-stage axial compressor featuring variable geometry. The compressor stages were aerodynamically matched at off-design speeds by adjusting the variable inlet guide vane and variable stator geometry angles to control the rotor diffusion factor and incidence angles.
International Nuclear Information System (INIS)
The strange axial-vector mesons K1 (1270) and K1 (1400) are reanalyzed in the light of the updated experimental information and compared with the recent result on the Kππ production in τ decay. The mixing angle between the strange mesons of 3P1 and 1P1 is determined by the partial decay rates, and, independently, by the masses. They lead to θK∼33 degree or 57 degree. The observed K1 (1400) production dominance in the τ decay favors θK∼33 degree. Flavor-SU(3) breaking of 20% or so in the production amplitudes can explain quantitatively the observed production ratio
NUMERICAL PREDICTION OF COMPOSITE BEAM SUBJECTED TO COMBINED NEGATIVE BENDING AND AXIAL TENSION
Directory of Open Access Journals (Sweden)
MAHESAN BAVAN
2013-08-01
Full Text Available The present study has investigated the finite element method (FEM techniques of composite beam subjected to combined axial tension and negative bending. The negative bending regions of composite beams are influenced by worsen failures due to various levels of axial tensile loads on steel section especially in the regions near internal supports. Three dimensional solid FEM model was developed to accurately predict the unfavourable phenomenon of cracking of concrete and compression of steel in the negative bending regions of composite beam due to axial tensile loads. The prediction of quasi-static solution was extensively analysed with various deformation speeds and energy stabilities. The FEM model was then validated with existing experimental data. Reasonable agreements were observed between the results of FEM model and experimental analysis in the combination of vertical-axial forces and failure modes on ultimate limit state behaviour. The local failure modes known as shear studs failure, excess yielding on steel beam and crushing on concrete were completely verified by extensive similarity between the numerical and experimental results. Finally, a proper way of modelling techniques for large FEM models by considering uncertainties of material behaviour due to biaxial loadings and complex contact interactions is discussed. Further, the model is suggested for the limit state prediction of composite beam with calibrating necessary degree of the combined axial loads.
Buckling Imperfection Sensitivity of Axially Compressed Orthotropic Cylinders
Schultz, Marc R.; Nemeth, Michael P.
2010-01-01
Structural stability is a major consideration in the design of lightweight shell structures. However, the theoretical predictions of geometrically perfect structures often considerably over predict the buckling loads of inherently imperfect real structures. It is reasonably well understood how the shell geometry affects the imperfection sensitivity of axially compressed cylindrical shells; however, the effects of shell anisotropy on the imperfection sensitivity is less well understood. In the present paper, the development of an analytical model for assessing the imperfection sensitivity of axially compressed orthotropic cylinders is discussed. Results from the analytical model for four shell designs are compared with those from a general-purpose finite-element code, and good qualitative agreement is found. Reasons for discrepancies are discussed, and potential design implications of this line of research are discussed.
Mass Effect on Axial Charge Dynamics
Guo, Er-dong
2016-01-01
We studied effect of finite quark mass on the dynamics of axial charge using the D3/D7 model in holography. The mass term in axial anomaly equation affects both the fluctuation (generation) and dissipation of axial charge. We studied the dependence of the effect on quark mass and external magnetic field. For axial charge generation, we calculated the mass diffusion rate, which characterizes the helicity flipping rate. The rate is a non-monotonous function of mass and can be significantly enhanced by the magnetic field. The diffusive behavior is also related to a divergent susceptibility of axial charge. For axial charge dissipation, we found that in the long time limit, the mass term dissipates all the charge effectively generated by parallel electric and magnetic fields. The result is consistent with a relaxation time approximation. The rate of dissipation through mass term is a monotonous increasing function of both quark mass and magnetic field.
Axial Vector $Z'$ and Anomaly Cancellation
Ismail, Ahmed; Tsao, Kuo-Hsing; Unwin, James
2016-01-01
Whilst the prospect of new $Z'$ gauge bosons with only axial couplings to the Standard Model (SM) fermions is widely discussed, examples of anomaly-free renormalisable models are lacking in the literature. We look to remedy this by constructing several motivated examples. Specifically, we consider axial vectors which couple universally to all SM fermions, as well as those which are generation-specific, leptophilic, and leptophobic. Anomaly cancellation typically requires the presence of new coloured and charged chiral fermions, and we argue that the masses of these new states must generally be comparable to that of the axial vector. Finally, an axial vector mediator could provide a portal between SM and hidden sector states, and we also consider the possibility that the axial vector couples to dark matter. If the dark matter relic density is set due to freeze-out via the axial vector, this strongly constrains the parameter space.
Axial velocity in decaying swirl flow
Algifri, A. H.; Bhardwaj, R. K.; Rao, Y. V. N.
1988-09-01
Experiments were carried out on turbulent swirling flow with variable initial swirl at different flow rates to study the effect of swirl on axial velocity. A correlation was made between the defect in the swirling flow axial velocity and the swirl number which locally defines the swirl intensity. An expression which can be used to predict the axial velocity distribution of turbulent swirling flow in a pipe is presented.
Sensorless Control of Axial Magnetic Bearings
Atsumo, Daichi; Yoshida, Toshiya; Ohniwa, Katsumi
This paper describes a sensorless control method of axial active magnetic bearings (AMBs). At high frequencies, inductance of the axial electromagnets is hardly dependent on the airgap because of the eddy current effects of the non-laminated core. Therefore the carrier frequency should be 3 kHz below to improve the sensitivity to the airgap. In the experiment, Sensorless controll of the axial AMBs have been achieved.
International Nuclear Information System (INIS)
The dynamical symmetry limit of the two-fluid Interacting Vector Boson Model (IVBM), defined through the chain Sp(12,R) contains U(3,3) contains Up(3) x Un(3) contains SU*(3) contains SO(3), is considered and applied for the description of nuclear collective spectra exhibiting axially asymmetric features. The effect of the introduction of a Majorana interaction to the SU*(3) model Hamiltonian on the γ-band energies is studied. The theoretical predictions are compared with the experimental data for 192Os, 190Os, and 112Ru isotopes. It is shown that by taking into account the full symplectic structures in the considered dynamical symmetry of the IVBM, the proper description of the energy spectra and the γ-band energy staggering of the nuclei under considerations can be achieved. The obtained results show that the potential energy surfaces for the following two nuclei 192Os and 112Ru, possess almost γ-flat potentials with very shallow triaxial minima, suggesting a more complex and intermediate situation between γ-rigid and γ-unstable structures. Additionally, the absolute B(E2) intraband transition probabilities between the states of the ground-state band and γ band, as well as the B(M1) interband transition probabilities between the states of the ground and γ bands for the two nuclei 192Os and 190Os are calculated and compared with experiment and for the B(E2) values with the predictions of some other collective models incorporating the γ-rigid or γ-unstable structures. The obtained results agree well with the experimental data and reveal the relevance of the used dynamical symmetry of IVBM in the description of nuclei exhibiting axially asymmetric features in their spectra. (orig.)
Indian Academy of Sciences (India)
K Athiannan; R Palaninathan
2004-02-01
This paper presents experimental studies on buckling of cylindrical shell models under axial and transverse shear loads. Tests are carried out using an experimental facility specially designed, fabricated and installed, with provision for in-situ measurement of the initial geometric imperfections. The shell models are made by rolling and seam welding process and hence are expected to have imperfections more or less of a kind similar to that of real shell structures. The present work thus differs from most of the earlier investigations. The measured maximum imperfections $\\delta_{\\text{max}}$ are of the order of $\\pm 3t$ (t = thickness). The buckling loads obtained experimentally are compared with the numerical buckling values obtained through ﬁnite element method (FEM). In the case of axial buckling, the imperfect geometry is obtained in four ways and in the case of transverse shear buckling, the FE modelling of imperfect geometry is done in two ways. The initial geometric imperfections affect the load carrying capacity. The load reduction is considerable in the case of axial compression and is marginal in the case of transverse shear buckling. Comparisons between experimental buckling loads under axial compression, reveal that the extent of imperfection, rather than its maximum value, in a specimen inﬂuences the failure load. Buckling tests under transverse shear are conducted with and without axial constraints. While differences in experimental loads are seen to exist between the two conditions, the numerical values are almost equal. The buckling modes are different, and the experimentally observed and numerically predicted values are in complete disagreement.
Effective quantum number for axially symmetric problems
Trunov, N. N.
2014-01-01
We generalize the universal effective quantum number introduced earlier for centrally symmetric problems. The proposed number determines the semiclassical quantization condition for axially symmetric potentials.
Origin of axial current in scyllac
International Nuclear Information System (INIS)
The origin of the axial current observed in Scyllac (a high beta stellarator experiment) is discussed. A shaped coil and/or helical winding produce rotational transform which links magnetic lines of force to the plasma column and the axial current is induced electromagnetically. This phenomenon is inherent in a pulsed high-beta stellarator. The rotational transform produced by the induced axial current is much smaller than that associated with the l = 1, 0 equilibrium fields. The effect of the axial current on the equilibrium and stability of the plasma column is thus small. It is also shown that the magnetic field shear near a plasma surface is very strong
Nonlinear vibrations and imperfection sensitivity of a cylindrical shell containing axial fluid flow
del Prado, Z.; Gonçalves, P. B.; Païdoussis, M. P.
2009-10-01
The high imperfection sensitivity of cylindrical shells under static compressive axial loads is a well-known phenomenon in structural stability. On the other hand, less is known of the influence of imperfections on the nonlinear vibrations of these shells under harmonic axial loads. The aim of this work is to study the simultaneous influence of geometric imperfections and an axial fluid flow on the nonlinear vibrations and instabilities of simply supported circular cylindrical shells under axial load. The fluid is assumed to be non-viscous and incompressible and the flow to be isentropic and irrotational. The behavior of the thin-walled shell is modeled by Donnell's nonlinear shallow-shell equations. It is subjected to a static uniform compressive axial pre-load plus a harmonic axial load. A low-dimensional modal expansion, which satisfies the relevant boundary and continuity conditions, and takes into account all relevant nonlinear modal interactions observed in the past in the nonlinear vibrations of cylindrical shells with and without flow is used together with the Galerkin method to derive a set of eight coupled nonlinear ordinary differential equations of motion which are, in turn, solved by the Runge-Kutta method. The shell is considered to be initially at rest, in a position corresponding to a pre-buckling configuration. Then, a harmonic excitation is applied and conditions for parametric instability and dynamic snap-through are sought. The results clarify the marked influence of geometric imperfections and fluid flow on the dynamic stability boundaries, bifurcations and basins of attraction.
International Nuclear Information System (INIS)
The present paper provides the elastic stress intensity factors (SIFs) and the crack opening displacements (CODs) of a thick walled pipe with a slanted axial through wall crack. For estimating these elastic fracture mechanics parameters, systematic three dimensional elastic finite element (FE) analyses were performed by considering geometric variables, i. e., thickness of pipe, reference crack length, and crack length ratio, affecting the SIFs and CODs. As for loading condition, the internal pressure was considered. Based on the FE results, the SIFs and CODs of slanted axial through wall cracks in a thick-walled pipe along the crack front and the wall thickness were calculated. In particular, to calculate the SIFs of a thick walled pipe with a slanted axial through wall crack from those of a thick walled pipe with an idealized axial through wall crack, a slant correction factor representing the effect of the slant crack on the SIFs was proposed
Bounding axial profile analysis for the topical report database
International Nuclear Information System (INIS)
Quantifying the open-quotes end effectsclose quotes reactivities of realistic end-of-cycle burnup distributions is important in performing criticality safety analyses for spent fuel shipping containers. Yankee Atomic Electric Company has compiled an axial burnup profile database (ABPD) for a large number of PWR fuel types. The profiles for fuel types with initially uniform axial loadings of U-235 and burnable poisons were collected from the ABPD to form the topical report database (TRD). Based on the TRD, a strategy was set up to find bounding profiles which conservatively estimate the maximum open-quotes end effectsclose quotes reactivities in different burnup ranges. A two-group, one-dimensional diffusion code, REALAX, was used to calculate the k-effectives and open-quotes end effectsclose quotes reactivities for each of the axially varying burnup distributions in the TRD. REALAX was also proven to have consistency with the well-known three-dimensional, multi-group diffusion code, DIF3D
International Nuclear Information System (INIS)
The influence of an induced axial magnetic field on plasma dynamics and radiative characteristics of Z pinches is investigated. An axial magnetic field was induced in a novel Z-pinch load: a double planar wire array with skewed wires (DPWAsk), which represents a planar wire array in an open magnetic configuration. The induced axial magnetic field suppressed magneto-Rayleigh-Taylor (MRT) instabilities (with m = 0 and m = 1 instability modes) in the Z-pinch plasma. The influence of the initial axial magnetic field on the structure of the plasma column at stagnation was manifested through the formation of a more uniform plasma column compared to a standard double planar wire array (DPWA) load [V. L. Kantsyrev et al., Phys. Plasmas 15, 030704 (2008)]. The DPWAsk load is characterized by suppression of MRT instabilities and by the formation of the sub-keV radiation pulse that occurs before the main x-ray peak. Gradients in plasma parameters along the cathode-anode gap were observed and analyzed for DPWAsk loads made from low atomic number Z (Al) and mid-Z (brass) wires.
Finite Element Analysis of Ultimate Load Capacity of Slender Concrete-Filled Steel Composite Columns
Directory of Open Access Journals (Sweden)
Alireza Bahrami
2011-01-01
Full Text Available Ultimate load capacity of slender concrete-filled steel composite columns is investigated in this paper. Nonlinear analyses are done by the use of finite element software, LUSAS, to study the ultimate axial load behaviour of the columns. Verification of the finite element modelling is done by comparing the result with the corresponding experimental result reported by other researchers. Analyses are carried out to assess different shapes and number of cold-formed steel sheeting stiffeners with various thicknesses of cold-formed steel sheets and their effects on the behaviour and ultimate axial load capacity of the columns. The results are presented in the form of axial load-normalized axial shortening plots. It is demonstrated that the ultimate axial load capacity of the slender concrete-filled steel composite columns can be accurately predicted by proposed finite element modelling. Obtained results from the study show that various thicknesses of cold-formed steel sheets, and different shapes and number of stiffeners influence the ultimate axial load capacity and behaviour of the columns. Also, the ultimate axial load capacity of the columns is improved by increase of number of stiffeners. Moreover, increase of thickness of cold-formed steel sheet enhances the ultimate axial load capacity.
Axial force measurement for esophageal function testing.
Gravesen, Flemming H; Funch-Jensen, Peter; Gregersen, Hans; Drewes, Asbjørn Mohr
2009-01-14
The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method. PMID:19132762
Axial force measurement for esophageal function testing
Institute of Scientific and Technical Information of China (English)
Flemming H Gravesen; Peter Funch-Jensen; Hans Gregersen; Asbjφrn Mohr Drewes
2009-01-01
The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.
Axial length variability in cataract surgery
International Nuclear Information System (INIS)
To determine the mean axial length and biometric measures in patients undergoing cataract surgery and further compare the variability of axial length between the gender and with age. Study Design: Cross-sectional observational study. Place and Duration of Study: Eye Unit I, Department of Ophthalmology, Liaquat University of Medical and Health Sciences, Hyderabad, Pakistan from January 2010 to December 2012. Methodology: All patients referred for cataract surgery were assessed. The study included 886 eyes which were straightforward cataract cases with no other ocular problem. The data was collected for axial length, keratometric values and Intra-Ocular Lens (IOL) power prior to cataract surgery. The collected data was then analyzed using SPSS version 19 for windows software. Results: Gender based comparison showed significant difference in age, axial length, keratometric values and IOL power between the two groups (p=0.000). 86% of the eyes had an axial length between 21.00 mm and 23.99 mm. In univariate analysis there was significant (p=0.000) relation between overall age and axial length. The keratometric values ranged between 36.75 D and 52.50 D. Majority of the IOL powers ranged between 20.00 D and 23.00 D. Conclusion: The mean axial length of patients undergoing cataract surgery was 22.96 +- 1.04 mm, was comparable to Indian and Chinese population but shorter than the Western population. Females had shorter axial lengths, similar to other studies. Axial length was positively associated with age among the females, the cause of which is yet to be determined. (author)
New Anomaly of the Axial-Vector Current
Institute of Scientific and Technical Information of China (English)
HE Han-Xin
2001-01-01
By computing the axial-vector current operator equation, we find the anomalous axial-vector curl equation besides the well-known anomalous axial-vector divergence equation (the Adler-Bell-Jackiw anomaly) and discuss its implication.``
Study on axial offset oscillation for WWER-1000 reactor by using WWER-1000 simulator
International Nuclear Information System (INIS)
In the operation of thermal neutron reactors, it is known that the spatial xenon oscillations arise frequently. The nature of these oscillations is that almost of power concentrate just at a small region in the reactor core volume. The characteristic parameter for the axial power distribution is axial offset. In this subject, the cause of axial offset oscillation and its characteristics are studied. We investigate axial offset oscillation in begin of fuel cycle (BOC) and end of fuel cycle (EOC) of loading 1 enrichment and loading 5 enrichment for WWER-1000 reactor, using WWER-1000 reactor simulation program that was originally developed by IAEA. The results are: (1) the formation of axial offset oscillation is due to periodic deviation from an equilibrium distribution of iodine, xenon and neutron flux density between the upper half and the lower half of the reactor core, when the control group number 1 is inserted into the bottom of reactor core; (2) regarding the same fuel enrichment, in BOC, offset oscillates with larger amplitude and slower damping than in EOC. On the other hand, in higher fuel enrichment, offset oscillates with smaller amplitude and quicker damping than in lower fuel enrichment. (author)
Yunqiang Liu; Jiuping Xu; Shize Wang; Bin Qi
2013-01-01
The axial stress and deformation of high temperature high pressure deviated gas wells are studied. A new model is multiple nonlinear equation systems by comprehensive consideration of axial load of tubular string, internal and external fluid pressure, normal pressure between the tubular and well wall, and friction and viscous friction of fluid flowing. The varied temperature and pressure fields were researched by the coupled differential equations concerning mass, momentum, and energy equatio...
Axial Thermal Rotation of Slender Rods
Li, Dichuan; Fakhri, Nikta; Pasquali, Matteo; Biswal, Sibani Lisa
2011-05-01
Axial rotational diffusion of rodlike polymers is important in processes such as microtubule filament sliding and flagella beating. By imaging the motion of small kinks along the backbone of chains of DNA-linked colloids, we produce a direct and systematic measurement of axial rotational diffusivity of rods both in bulk solution and near a wall. The measured diffusivities decrease linearly with the chain length, irrespective of the distance from a wall, in agreement with slender-body hydrodynamics theory. Moreover, the presence of small kinks does not affect the chain’s axial diffusivity. Our system and measurements provide insights into fundamental axial diffusion processes of slender objects, which encompass a wide range of entities including biological filaments and linear polymer chains.
Nonlinear Model and Qualitative Analysis for Coupled Axial/Torsional Vibrations of Drill String
Directory of Open Access Journals (Sweden)
Fushen Ren
2016-01-01
Full Text Available A nonlinear dynamics model and qualitative analysis are presented to study the key effective factors for coupled axial/torsional vibrations of a drill string, which is described as a simplified, equivalent, flexible shell under axial rotation. Here, after dimensionless processing, the mathematical models are obtained accounting for the coupling of axial and torsional vibrations using the nonlinear dynamics qualitative method, in which excitation loads and boundary conditions of the drill string are simplified to a rotating, flexible shell. The analysis of dynamics responses is performed by means of the Runge-Kutta-Fehlberg method, in which the rules that govern the changing of the torsional and axial excitation are revealed, and suggestions for engineering applications are also given. The simulation analysis shows that when the drill string is in a lower-speed rotation zone, the torsional excitation is the key factor in the coupling vibration, and increasing the torsional stress of the drill string more easily leads to the coupling vibration; however, when the drill string is in a higher-speed rotating zone, the axial excitation is a key factor in the coupling vibration, and the axial stress in a particular interval more easily leads to the coupling vibration of the drill string.
Recommendations for Addressing Axial Burnup in the PWR Burnup Credit Analyses
Energy Technology Data Exchange (ETDEWEB)
Wagner, J.C.
2002-10-23
This report presents studies performed to support the development of a technically justifiable approach for addressing the axial-burnup distribution in pressurized-water reactor (PWR) burnup-credit criticality safety analyses. The effect of the axial-burnup distribution on reactivity and proposed approaches for addressing the axial-burnup distribution are briefly reviewed. A publicly available database of profiles is examined in detail to identify profiles that maximize the neutron multiplication factor, k{sub eff}, assess its adequacy for PWR burnup credit analyses, and investigate the existence of trends with fuel type and/or reactor operations. A statistical evaluation of the k{sub eff} values associated with the profiles in the axial-burnup-profile database was performed, and the most reactive (bounding) profiles were identified as statistical outliers. The impact of these bounding profiles on k{sub eff} is quantified for a high-density burnup credit cask. Analyses are also presented to quantify the potential reactivity consequence of loading assemblies with axial-burnup profiles that are not bounded by the database. The report concludes with a discussion on the issues for consideration and recommendations for addressing axial burnup in criticality safety analyses using burnup credit for dry cask storage and transportation.
Computer axial tomography in geosciences
International Nuclear Information System (INIS)
Computer Axial Tomography (CAT) is one of the most adequate non-invasive techniques for the investigation of the internal structure of a large category of objects. Initially designed for medical investigations, this technique, based on the attenuation of X- or gamma-ray (and in some cases neutrons), generates digital images which map the numerical values of the linear attenuation coefficient of a section or of the entire volume of the investigated sample. Shortly after its application in medicine, CAT has been successfully used in archaeology, life sciences, and geosciences as well as for the industrial materials non-destructive testing. Depending on the energy of the utilized radiation as well as on the effective atomic number of the sample, CAT can provide with a spatial resolution of 0.01 - 0.5 mm, quantitative as well as qualitative information concerning local density, porosity or chemical composition of the sample. At present two types of axial Computer Tomographs (CT) are in use. One category, consisting of medical as well as industrial CT is equipped with X-ray tubes while the other uses isotopic gamma-ray sources. CT provided with intense X-ray sources (equivalent to 12-15 kCi or 450-550 TBq) has the advantage of an extremely short running time (a few seconds and even less) but presents some disadvantages known as beam hardening and absorption edge effects. These effects, intrinsically related to the polychromatic nature of the X-rays generated by classical tubes, need special mathematical or physical corrections. A polychromatic X-ray beam can be made almost monochromatic by means of crystal diffraction or by using adequate multicomponent filters, but these devices are costly and considerably diminish the output of X-ray generators. In the case of CT of the second type, monochromatic gamma-rays generated by radioisotopic sources, such as 169 Yb (50.4 keV), 241 Am (59 keV), 192 Ir (310.5 and 469.1 keV ) or 137 Cs (662.7 keV), are used in combination with
Nonperturbative features of the axial current
Kopeliovich, B Z; Siddikov, M
2013-01-01
In this paper we study the nonperturbative structure of the axial current and evaluate the two-point distribution amplitudes $\\int d\\xi\\, e^{-iq...\\xi}$ in the framework of the instanton vacuum model in the leading order in $\\mathcal{O}(N_{c})$. We perform a direct numerical test of the relations between the axial current and the pion distribution amplitudes, imposed by PCAC, and found excellent agreement.
Axial Vircator for Electronic Warfare Applications
L. Drazan; R. Vrana
2009-01-01
This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM) is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered b...
Nonperturbative Aspects of Axial Vector Vertex
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; CHEN Xiang-Song; WANG Fan; CHANG Chao-Hsi; ZHAO En-Guang
2002-01-01
It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model.Gluon dressing of the axial vector vertex and the quark self-energy functions are described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger Dyson equation in the rainbow approximation,respectively.
DEFF Research Database (Denmark)
Kock, Carsten Weber; Vesth, Allan
The report describes Load measurements carried out on a given wind turbine. The aim of the measurement program regarding the loads on the turbine is to verify the basic characteristics of the wind turbine and loads on the blades, the rotor and the tower, using [Ref 1], [Ref2] and [Ref 3]. Regarding...
An Unbroken Axial Vector Current Conservation Law
Sharafiddinov, Rasulkhozha S
2015-01-01
The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space i...
MULTIAXIAL CREEP-FATIGUE LIFE EVALUATION UNDER PROPORTIONAL LOADING
Institute of Scientific and Technical Information of China (English)
Y.Noguchi; M.Miyahara
2004-01-01
A new method was proposed for the multiaxial creep-fatigue life evaluation under proportional loadings. Because this method was derived from the strain range partitioning method with a multiaxiality factor, it was possible to consider the influence of both creep-fatigue interaction and multiaxial stress state on fatigue life. In order to predict the combined axial-torsional fatigue life the damage under combined loading was defined as linear summation of the damages under axial loading and torsional loading.Axial-torsional creep-fatigue tests were carried out using tubular specimens of 316LC austenitic stainless steel and the ferritic rotor steel. This rotor steel was developed for the permanent magnet type eddy current retarder in heavy trucks. Experimentally obtained lives of both steels were well corresponded with the lives predicted by the proposed method. It was found that the proposed method was effective in multiaxial fatigue life evaluation under proportional creep-fatigue loadings.
Improvement of the axial power distribution control capabilities in WWER-1000 reactors
International Nuclear Information System (INIS)
This article describes an automatic reactor power control system for WWER-1000 reactor and reports simulation analysis results for a typical daily load follow operation. The associated reactor control algorithm is called 'mode G' that uses a heavy-worth bank (H-bank) dedicated to axial power shape control and the light-gray banks (G-banks) for reactor power change and reactivity compensation. The simulation results for daily load follow operation in three burnup states of first cycle illustrate that the load follow capability of WWER-1000 reactors using this algorithm will be improved
Buckling of Cracked Laminated Composite Cylindrical Shells Subjected to Combined Loading
Allahbakhsh, Hamidreza; Shariati, Mahmoud
2013-10-01
A series of finite element analysis on the cracked composite cylindrical shells under combined loading is carried out to study the effect of loading condition, crack size and orientation on the buckling behavior of laminated composite cylindrical shells. The interaction buckling curves of cracked laminated composite cylinders subject to different combinations of axial compression, bending, internal pressure and external pressure are obtained, using the finite element method. Results show that the internal pressure increases the critical buckling load of the CFRP cylindrical shells and bending and external pressure decrease it. Numerical analysis show that axial crack has the most detrimental effect on the buckling load of a cylindrical shell and results show that for lower values of the axial compressive load and higher values of the external pressure, the buckling is usually in the global mode and for higher values of axial compressive load and lower levels of external pressure the buckling mode is mostly in the local mode.
International Nuclear Information System (INIS)
The axial buckling behavior of magnetically affected current-carrying nanowires is studied accounting for the surface energy effect. Using Euler–Bernoulli beam theory, the Lorentz force on the nanowire is determined and the governing equations are established. By application of the Galerkin approach and assumed mode method, the critical axial compressive load of the nanostructure is evaluated in the cases of simply supported and fully clamped ends. The effects of surface energy, electric current, strength of the magnetic field, slenderness ratio, and nanowire’s radius on the axial buckling loads are comprehensively discussed. The obtained results reveal that both the electric current and exerted magnetic field endanger the axial stability of the nanowire. For high levels of electric current or magnetic field strength, the surface effect becomes significant in the axial buckling performance of the nanostructure. (paper)
International Nuclear Information System (INIS)
Slides used in a presentation at The Power of Change Conference in Vancouver, BC in April 1995 about the changing needs for load forecasting were presented. Technological innovations and population increase were said to be the prime driving forces behind the changing needs in load forecasting. Structural changes, market place changes, electricity supply planning changes, and changes in planning objectives were other factors discussed. It was concluded that load forecasting was a form of information gathering, that provided important market intelligence
Optimization of residual heat removal pump axial thrust and axial bearing
Energy Technology Data Exchange (ETDEWEB)
Schubert, F.
1996-12-01
The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies.
American Society for Testing and Materials. Philadelphia
2007-01-01
1.1 This practice covers the procedure for the performance of axial force controlled fatigue tests to obtain the fatigue strength of metallic materials in the fatigue regime where the strains are predominately elastic, both upon initial loading and throughout the test. This practice is limited to the fatigue testing of axial unnotched and notched specimens subjected to a constant amplitude, periodic forcing function in air at room temperature. This practice is not intended for application in axial fatigue tests of components or parts. Note 1-The following documents, although not directly referenced in the text, are considered important enough to be listed in this practice: E 739 Practice for Statistical Analysis of Linear or Linearized Stress-Life (S-N) and Strain-Life (-N) Fatigue Data STP 566 Handbook of Fatigue Testing STP 588 Manual on Statistical Planning and Analysis for Fatigue Experiments STP 731 Tables for Estimating Median Fatigue Limits
Low-pressure reversible axial fan designed with different specific work of elementary stages
Directory of Open Access Journals (Sweden)
Bogdanović Božidar P.
2012-01-01
Full Text Available Low-pressure axial fan impellers designed according to the principle of equal specific work of all elementary stages have blades whose profile near the fan hub is under a significantly larger inclination angle than at the impeller periphery. In order to minimize the spatial curvature of the fan blades and the fan hub length, impeller blades of low-pressure axial fans can be designed with different specific work of elementary stages, so that the specific work of elementary stages is smaller at the hub than at the periphery. This paper presents the operating characteristics of a low-pressure reversible axial fan with straight blade profiles, designed with different specific work of elementary stages. The fan was tested on a standard test rig, with air intake loading on the suction side of the fan.
Multiaxial fatigue criterion based on parameters from torsion and axial S-N curve
Directory of Open Access Journals (Sweden)
M. Margetin
2016-07-01
Full Text Available Multiaxial high cycle fatigue is a topic that concerns nearly all industrial domains. In recent years, a great deal of recommendations how to address problems with multiaxial fatigue life time estimation have been made and a huge progress in the field has been achieved. Until now, however, no universal criterion for multiaxial fatigue has been proposed. Addressing this situation, this paper offers a design of a new multiaxial criterion for high cycle fatigue. This criterion is based on critical plane search. Damage parameter consists of a combination of normal and shear stresses on a critical plane (which is a plane with maximal shear stress amplitude. Material parameters used in proposed criterion are obtained from torsion and axial S-N curves. Proposed criterion correctly calculates life time for boundary loading condition (pure torsion and pure axial loading. Application of proposed model is demonstrated on biaxial loading and the results are verified with testing program using specimens made from S355 steel. Fatigue material parameters for proposed criterion and multiple sets of data for different combination of axial and torsional loading have been obtained during the experiment.
Polarization converters based on axially symmetric twisted nematic liquid crystal.
Ko, Shih-Wei; Ting, Chi-Lun; Fuh, Andy Y-G; Lin, Tsung-Hsien
2010-02-15
An axially symmetric twisted nematic liquid crystal (ASTNLC) device, based on axially symmetric photoalignment, was demonstrated. Such an ASTNLC device can convert axial (azimuthal) to azimuthal (axial) polarization. The optical properties of the ASTNLC device are analyzed and found to agree with simulation results. The ASTNLC device with a specific device can be adopted as an arbitrary axial symmetric polarization converter or waveplate for axially, azimuthally or vertically polarized light. A design for converting linear polarized light to axially symmetric circular polarized light is also demonstrated. PMID:20389369
Observations of impeller tip cavitation in an axial flow pump
International Nuclear Information System (INIS)
As the suction head of an axial-flow pump is reduced its performance is degraded by cavitation phenomena. Cavitation may occur in the inlet region or, in some instances, in the stator blades, however the most usual source is the impeller blading, specifically the tip section. Practical difficulties in cavitation testing and in obtaining data from the vicinity of rotating impeller have reduced the availability of consistent information on cavitation effects. The state of knowledge is such that quite fundamental effects may still be overlooked. Furthermore, even if the suction head is not reduced, cavitation resulting from increased blade loading may jeopardize performance. As the pump is throttled up its characteristic the pressures in the suction peak region may drop below the vapor pressure resulting in strong local cavitation. It is usual in the testing of axial pumps to discriminate between the effects of inlet and discharge throttling by plotting performance characteristics as a function of both of these variables. The purpose of the present investigation is not the systematic study of these variables over the whole range but rather the detailed photographic investigation of cavitation patterns in order to elucidate physical phenomena not previously observed or understood
Load-shortening behavior of an initially curved eccentrically loaded column
Fichter, W. B.; Pinson, Mark W.
1989-01-01
To explore the feasibility of using buckled columns to provide a soft support system for simulating a free-free boundary condition in dynamic testing, the nonlinear load-shortening behavior of initially imperfect, eccentrically loaded slender columns is analyzed. Load-shortening curves are obtained for various combinations of load eccentricity and uniform initial curvature and are compared, for reference purposes, with the limiting case of the classical elastica. Results for numerous combinations of initial curvature and load eccentricity show that, over a wide range of shortening, an axially loaded slender column exhibits load-deflection compliance which is of the same order as that of a straight but otherwise identical cantilever beam under lateral tip loading.
Improving the lattice axial vector current
Horsley, R; Perlt, H; Rakow, P E L; Schierholz, G; Schiller, A; Zanotti, J M
2015-01-01
For Wilson and clover fermions traditional formulations of the axial vector current do not respect the continuum Ward identity which relates the divergence of that current to the pseudoscalar density. Here we propose to use a point-split or one-link axial vector current whose divergence exactly satisfies a lattice Ward identity, involving the pseudoscalar density and a number of irrelevant operators. We check in one-loop lattice perturbation theory with SLiNC fermion and gauge plaquette action that this is indeed the case including order $O(a)$ effects. Including these operators the axial Ward identity remains renormalisation invariant. First preliminary results of a nonperturbative check of the Ward identity are also presented.
Axial instability of rotating relativistic stars
Friedman, J L; Friedman, John L.; Morsink, Sharon M.
1998-01-01
Perturbations of rotating relativistic stars can be classified by their behavior under parity. For axial perturbations (r-modes), initial data with negative canonical energy is found with angular dependence $e^{im\\phi}$ for all values of $m\\geq 2$ and for arbitrarily slow rotation. This implies instability (or marginal stability) of such perturbations for rotating perfect fluids. This low $m$-instability is strikingly different from the instability to polar perturbations, which sets in first for large values of $m$. The timescale for the axial instability appears, for small angular velocity $\\Omega$, to be proportional to a high power of $\\Omega$. As in the case of polar modes, viscosity will again presumably enforce stability except for hot, rapidly rotating neutron stars. This work complements Andersson's numerical investigation of axial modes in slowly rotating stars.
The axial distribution of reactivity coefficients
International Nuclear Information System (INIS)
The purpose of the present work is to investigate the correlation of the axial distributions of the different reactivity coefficients with the neutron flux and the neutron flux squared. Calculations were carried out for the Zion Unit 2 PWR. Reactivity coefficients, forward fluxes and adjoint fluxes were all computed and correlations obtained. The core length was divided into 7 axial regions in order to obtain the effect on reactivity in the reactor as a whole of changing the cross sections in each axial region in turn. The parameters chosen for change were coolant density, coolant temperature and fuel temperature. The results appear to bear out our original hypothesis that the reactivity coefficient profiles have a higher positive correlation with the total flux squared profile than with the linear flux profile. (authors). 5 refs., 2 figs
Energy harvesting efficiency of piezoelectric flags in axial flows
Michelin, Sebastien
2012-01-01
Self-sustained oscillations resulting from fluid-solid instabilities, such as the flutter of a flexible flag in axial flow, can be used to harvest energy if one is able to convert the solid energy into electricity. Here, this is achieved using piezoelectric patches attached to the surface of the flag that convert the solid deformation into an electric current powering purely resistive output circuits. Nonlinear numerical simulations in the slender-body limit, based on an explicit description of the coupling between the fluid-solid and electric systems, are used to determine the harvesting efficiency of the system, namely the fraction of the flow kinetic energy flux effectively used to power the output circuit, and its evolution with the system's parameters. The role of the tuning between the characteristic frequencies of the fluid-solid and electric systems is emphasized, as well as the critical impact of the piezoelectric coupling intensity. High fluid loading, classically associated with destabilization by ...
Nonlinear flap-lag axial equations of a rotating beam
Kaza, K. R. V.; Kvaternik, R. G.
1977-01-01
It is possible to identify essentially four approaches by which analysts have established either the linear or nonlinear governing equations of motion for a particular problem related to the dynamics of rotating elastic bodies. The approaches include the effective applied load artifice in combination with a variational principle and the use of Newton's second law, written as D'Alembert's principle, applied to the deformed configuration. A third approach is a variational method in which nonlinear strain-displacement relations and a first-degree displacement field are used. The method introduced by Vigneron (1975) for deriving the linear flap-lag equations of a rotating beam constitutes the fourth approach. The reported investigation shows that all four approaches make use of the geometric nonlinear theory of elasticity. An alternative method for deriving the nonlinear coupled flap-lag-axial equations of motion is also discussed.
Institute of Scientific and Technical Information of China (English)
李长宝; 韩万金
2015-01-01
Numerical simulation method was used to study the unsteady flow characteristics and the effect of warp end wall on the end wall flow.The upstream wakes of rotor blades were simulated with a rotating cylinder.Two cascades with the non-axial symmetry end wall and the flap end wall respectively were simulated in the baseline conditions.Results show that periodic pulsations of boundary layer parameters are mainly focused on the suction side under the effect of the upstream wake.Compared to the flap end wall,the non-axial symmetry end wall is able to decrease the end wall channel vortices,and further reduces the end wall channel energy loss with the unsteady upstream wake.%采用数值模拟的方法研究了在上游尾迹干扰下大焓降叶片流场的非定常性以及端壁翘曲对端壁区流动的控制效果.上游动叶尾迹用转动的圆柱模拟,在基准工况下计算了具有平坦端壁和翘曲端壁的两套大焓降叶栅.结果表明:在上游尾迹的周期干扰下,叶片表面附面层,主要是吸力面附面层参数表现出周期性脉动.在上游尾迹周期作用的非定常环境下,相对平坦端壁,端壁翘曲降低了端壁通道涡量,降低了端区流动损失.
Selection rules and ratios for axial couplings
Buccella, F; Pugliese, A; Sorace, E
1972-01-01
The predictions for the axial couplings following from the use of the mixing operator U(Z), previously introduced to tilt the axial charges of SU/sub 6/ in the physical ones, are studied. The quantum number (-1)/sup L+L3/, where L and L/sub 3/ are the O/sub 3/ angular momentum and its third component, is shown to be conserved. From the properties of Z further predictions can be achieved as the D/F= /sup 3///sub 2/ for the /sup 1///sub 2//sup +/ baryon octet in general agreement with experiment. (14 refs).
Axial Stiffness of Multiwalled Carbon Nanotubes
Zavalniuk, Vladimir
2011-01-01
The axial stiffness of MWCNTs is demonstrated to be determined only by several external shells (usually 3-5 and up to 15 for the extremely large nanotubes and high elongations) what is in a good agreement with experimentally observed inverse relation between the radius and Young modulus (i.e., stiffness) of MWCNTs. This result is a consequence of the van der Waals intershell interaction. The interpolating formula is obtained for the actual axial stiffness of MWCNT as a function of the tube ex...
Axial Vircator for Electronic Warfare Applications
Directory of Open Access Journals (Sweden)
L. Drazan
2009-12-01
Full Text Available This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered by magneto-cumulative generator and in weapons for defense of objects (WDO, it is powered by Marx generator. The possible applications of a vircator in the DEWM area are discussed.
Growth-induced axial buckling of a slender elastic filament embedded in an isotropic elastic matrix
O'Keeffe, Stephen G.
2013-11-01
We investigate the problem of an axially loaded, isotropic, slender cylinder embedded in a soft, isotropic, outer elastic matrix. The cylinder undergoes uniform axial growth, whilst both the cylinder and the surrounding elastic matrix are confined between two rigid plates, so that this growth results in axial compression of the cylinder. We use two different modelling approaches to estimate the critical axial growth (that is, the amount of axial growth the cylinder is able to sustain before it buckles) and buckling wavelength of the cylinder. The first approach treats the filament and surrounding matrix as a single 3-dimensional elastic body undergoing large deformations, whilst the second approach treats the filament as a planar, elastic rod embedded in an infinite elastic foundation. By comparing the results of these two approaches, we obtain an estimate of the foundation modulus parameter, which characterises the strength of the foundation, in terms of the geometric and material properties of the system. © 2013 Elsevier Ltd. All rights reserved.
Low-Friction, High-Stiffness Joint for Uniaxial Load Cell
Lewis, James L.; Le, Thang; Carroll, Monty B.
2007-01-01
A universal-joint assembly has been devised for transferring axial tension or compression to a load cell. To maximize measurement accuracy, the assembly is required to minimize any moments and non-axial forces on the load cell and to exhibit little or no hysteresis. The requirement to minimize hysteresis translates to a requirement to maximize axial stiffness (including minimizing backlash) and a simultaneous requirement to minimize friction. In practice, these are competing requirements, encountered repeatedly in efforts to design universal joints. Often, universal-joint designs represent compromises between these requirements. The improved universal-joint assembly contains two universal joints, each containing two adjustable pairs of angular-contact ball bearings. One might be tempted to ask why one could not use simple ball-and-socket joints rather than something as complex as universal joints containing adjustable pairs of angularcontact ball bearings. The answer is that ball-and-socket joints do not offer sufficient latitude to trade stiffness versus friction: the inevitable result of an attempt to make such a trade in a ball-and-socket joint is either too much backlash or too much friction. The universal joints are located at opposite ends of an axial subassembly that contains the load cell. The axial subassembly includes an axial shaft, an axial housing, and a fifth adjustable pair of angular-contact ball bearings that allows rotation of the axial housing relative to the shaft. The preload on each pair of angular-contact ball bearings can be adjusted to obtain the required stiffness with minimal friction, tailored for a specific application. The universal joint at each end affords two degrees of freedom, allowing only axial force to reach the load cell regardless of application of moments and non-axial forces. The rotational joint on the axial subassembly affords a fifth degree of freedom, preventing application of a torsion load to the load cell.
Classical and numerical approaches to determining V-section band clamp axial stiffness
Barrans, Simon M.; Khodabakhshi, Goodarz; Muller, Matthias
2014-12-01
V-band clamp joints are used in a wide range of applications to connect circular flanges, for ducts, pipes and the turbocharger housing. Previous studies and research on V-bands are either purely empirical or analytical with limited applicability on the variety of V-band design and working conditions. In this paper models of the V-band are developed based on the classical theory of solid mechanics and the finite element method to study the behaviour of theV-bands under axial loading conditions. The good agreement between results from the developed FEA and the classical model support the suitability of the latter to modelV-band joints with diameters greater than 110mm under axial loading. The results from both models suggest that the axial stiffness for thisV-band cross section reaches a peak value for V-bands with radius of approximately 150 mmacross a wide range of coefficients of friction. Also, it is shown that the coefficient of friction and the wedge angle have a significant effect on the axial stiffness of V-bands.
Static Load Distribution in Ball Bearings
Ricci, Mario
2010-01-01
A numerical procedure for computing the internal loading distribution in statically loaded, single-row, angular-contact ball bearings when subjected to a known combined radial and thrust load is presented. The combined radial and thrust load must be applied in order to avoid tilting between inner and outer rings. The numerical procedure requires the iterative solution of Z + 2 simultaneous nonlinear equations - where Z is the number of the balls - to yield an exact solution for axial and radial deflections, and contact angles. Numerical results for a 218 angular-contact ball bearing have been compared with those from the literature and show significant differences in the magnitudes of the ball loads, contact angles, and the extent of the loading zone.
Behavior of Three Metallic Alloys under Combined Axial-Shear Stresses at Elevated Temperature
Colaiuta, J. F.; Lissenden, C. J.; Lerch, B. A.
2003-01-01
Type 316 stainless steel, Haynes 188, and Inconel 718 samples were subjected to an axial-shear strain controlled loading history while the specimen temperature was held at 650 C to quantify the evolution of material state under a complex biaxial load path when the material is in the viscoplastic domain. Yield surfaces were constructed in the axial-shear stress plane using a sensitive, 30 x 10(exp -6)m/m, equivalent offset strain definition for the yield strain. Subsequent yield surfaces were constructed at various points along the strain path to define the material evolution. These subsequent yield surface translated, expanded, and distorted relative to the initial yield surface. Each of these very different materials exhibited components of isotropic, kinematic and distortional hardening. Furthermore, subsequent yield surfaces for each material have a very well defined front face and a poorly defined, flattened, back side.
Directory of Open Access Journals (Sweden)
Rajeev Kumar
2014-07-01
Full Text Available A finite element model of fractured tibia with Joshi’s External Stabilizing System (JESS mounted on it was developed using 3D beam elements in the ANSYS software. The model was loaded in axial compression and the average axial stiffness of the model was calculated. The analytical value of axial stiffness was compared with reported experimental value to validate the finite element model. The validated model was used to carry out parametric studies on the model to determine the axial properties of JESS. It was observed that axial stiffness of JESS increased by 58% when k-wire diameter was varied from 2 mm to 4 mm while keeping other geometric configurations of the device constant; however, the axial stiffness of the device does not show any significant improvement when the diameter of medio-lateral pins in diaphyseal hold were increased. The findings should help in understanding the axial properties of JESS so that it can be used judiciously in clinical applications.
Knowledge Based Design of Axial Flow Compressor
Directory of Open Access Journals (Sweden)
Dinesh kumar.R
2015-05-01
Full Text Available In the aerospace industry with highly competitive market the time to design and delivery is shortening every day. Pressure on delivering robust product with cost economy is in demand in each development. Even though technology is older, it is new for each customer requirement and highly non-liner to fit one in another place. Gas turbine is considered one of a complex design in the aircraft system. It involves experts to be grouped with designers of various segments to arrive the best output. The time is crucial to achieve a best design and it needs knowledge automation incorporated with CAD/CAE tools. In the present work an innovative idea in the form of Knowledge Based Engineering for axial compressor is proposed, this includes the fundamental design of axial compressor integrated with artificial intelligence in the form of knowledge capturing and programmed with high level language (Visual Basis.Net and embedded into CATIA v5. This KBE frame work eases out the design and modeling of axial compressor design and produces 3D modeling for further flow simulation with fluid dynamic in Ansys-Fluent. Most of the aerospace components are developed through simulation driven product development and in this case it is established for axial compressor.
The Axial Current in Electromagnetic Interaction
Cheoun, M K; Cheon, I T; Cheoun, Myung Ki; Cheon, Il-Tong
1998-01-01
We discussed the possibility that the charged axial currents of matter fields could be non-conserved in electromagnetic interaction at $O(e) $ order. It means that chiral symmetry is broken explicitly by electromagnetic interaction. This explicit symmetry breaking of chiral symmetry is shown to lead the mass differences between the charged and neutral particles of matter fields.
Constant-axial-intensity nondiffracting beam.
Cox, A J; D'Anna, J
1992-02-15
Numerical solutions of the Fresnel diffraction integral with various apodizing filter functions are used to indicate that a so-called nondiffracting beam can be produced that maintains a constant spot size and constant axial intensity over a considerable range, approximately 30 m in our example. PMID:19784285
Axially symmetric SU(3) gravitating skyrmions
Energy Technology Data Exchange (ETDEWEB)
Ioannidou, Theodora [Maths Division, School of Technology, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece)]. E-mail: ti3@auth.gr; Kleihaus, Burkhard [Institut fuer Physik, Universitaet Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany)]. E-mail: kleihaus@theorie.physik.uni-oldenburg.de; Zakrzewski, Wojtek [Department of Mathematical Sciences, University of Durham, Durham DH1 3LE (United Kingdom)]. E-mail: w.j.zakrzewski@durham.ac.uk
2004-10-21
Axially symmetric gravitating multi-skyrmion configurations are obtained using the harmonic map ansatz introduced in [J. Math. Phys. 40 (1999) 6353]. In particular, the effect of gravity on the energy and baryon densities of the SU(3) non-gravitating multi-skyrmion configurations is studied in detail.
Axially symmetric SU(3) Gravitating Skyrmions
Ioannidou, T A; Zakrzewski, W J; Ioannidou, Theodora; Kleihaus, Burkhard; Zakrzewski, Wojtek
2004-01-01
Axially symmetric gravitating multi-skyrmion configurations are obtained using the harmonic map ansatz introduced in [1]. In particular, the effect of gravity on the energy and baryon densities of the SU(3) non-gravitating multi-skyrmion configurations is studied in detail.
Axially symmetric SU(3) gravitating skyrmions
International Nuclear Information System (INIS)
Axially symmetric gravitating multi-skyrmion configurations are obtained using the harmonic map ansatz introduced in [J. Math. Phys. 40 (1999) 6353]. In particular, the effect of gravity on the energy and baryon densities of the SU(3) non-gravitating multi-skyrmion configurations is studied in detail
Primitive axial algebras of Jordan type
Hall, J I; Rehren, F; Shpectorov, S.
2014-01-01
An axial algebra over the field $\\mathbb F$ is a commutative algebra generated by idempotents whose adjoint action has multiplicity-free minimal polynomial. For semisimple associative algebras this leads to sums of copies of $\\mathbb F$. Here we consider the first nonassociative case, where adjoint minimal polynomials divide $(x-1)x(x-\\eta)$ for fixed $0\
The effect of non-uniform damping on flutter in axial flow and energy harvesting strategies
Singh, Kiran; Michelin, Sebastien; de Langre, Emmanuel
2012-01-01
The problem of energy harvesting from flutter instabilities in flexible slender structures in axial flows is considered. In a recent study, we used a reduced order theoretical model of such a system to demonstrate the feasibility for harvesting energy from these structures. Following this preliminary study, we now consider a continuous fluid-structure system. Energy harvesting is modelled as strain-based damping and the slender structure under investigation lies in a moderate fluid loading ra...
Comparison of ISO Standard and TKR Patient Axial Force Profiles during the Stance Phase of Gait
Lundberg, Hannah J.; Ngai, Valentina; Markus A. Wimmer
2012-01-01
Preclinical endurance testing of total knee replacements (TKRs) is performed using International Organization for Standardization (ISO) load and motion protocols. The standards are based on data from normal subjects and may not sufficiently mimic in vivo implant conditions. In this study, a mathematical model was used to calculate the axial force profile of 30 TKR patients with two current implant types, 22 with NexGen and eight with Miller-Galante II Cruciate-Retaining TKRs, and statisticall...
Modeling particulate self-healing materials and application to uni-axial compression
Herbst, Olaf; Luding, Stefan
2008-01-01
Using an advanced history dependent contact model for DEM simulations, including elasto-plasticity, viscosity, adhesion, and friction, pressure-sintered tablets are formed from primary particles. These tablets are subjected to unconfined uni-axial compression until and beyond failure. For fast and slow deformation we observe ductile-like and brittle softening, respectively. We propose a model for local self-healing that allows damage to heal during loading such that the material strength of t...
Directory of Open Access Journals (Sweden)
Filippo Cassarà
2013-03-01
Full Text Available Recent research addressed the main role of hepcidin in the regulation of iron metabolism. However, while this mechanism could be relevant in causing iron load in Thalassemia Intermedia and Sickle-Cell Anemia, its role in Thalassemia Major (TM is marginal. This is mainly due to the high impact of transfusional requirement into the severe increase of body iron. Moreover, the damage of iron load may be worsened by infections, as HCV hepatitis, or liver and endocrinological damage. One of the most relevant associations was found between splenectomy and increase of risk for mortality due,probably, to more severe iron load. These issues suggest as morbidity and mortality of this group of patients they do not depend only by our ability in controlling heart damage but even in preventing or treating particular infections and complications. This finding is supported by the impairment of survival curves in patients with complications different from heart damage. However, because, during recent years different direct and indirect methods to detect iron overload in patients affected by secondary hemochromatosis have been implemented, our ability to maintain under control iron load is significantly improved. Anyway, the future in iron load management remains to be able to have an iron load map of our body for targeting chelation and other medical treatment according to the single organ damage.
Reverse loading tests of steel tube under biaxial stress states
Yanaga, Daisaku; Kuroda, Kouichi; Yaita, Satoshi; Kuwabara, Toshihiko
2015-01-01
Biaxial loading and reverse loading tests were performed using seamless carbon steel tubes. Biaxial stress components in the axial and circumferential directions were applied to the tubular specimens using a servo-controlled multiaxial tube expansion testing machine developed by Kuwabara and Sugawara (2013). The tubular specimens were loaded under linear tensile stress paths. Contours of plastic work were measured in the principal stress space, and the differential hardening (DH) behavior was...
Dynamics and statics of flexible axially symmetric shallow shells
Directory of Open Access Journals (Sweden)
2006-01-01
Full Text Available In this work, we propose the method for the investigation of stochastic vibrations of deterministic mechanical systems represented by axially symmetric spherical shells. These structure members are widely used as sensitive elements of pressure measuring devices in various branches of measuring and control industry, machine design, and so forth. The proposed method can be easily extended for the investigation of shallow spherical shells, goffer-type membranes, and so on. The so-called charts of control parameters for a shell subjected to a transversal uniformly distributed and local harmonic loading force and resistance moment are constructed. The scenarios of the transition of vibration of shallow-type system into chaotic state are investigated with the use of the theory of differential equations and the theory of nonlinear dynamics. The method of the control of chaotic vibrations of flexible spherical shells subjected to a transversal harmonic load through a synchronized action of either harmonic resistance moment or force is proposed, illustrated, and discussed.
International Nuclear Information System (INIS)
The axial stability of PWRs [pressurized water reactors] is rather poor. Power transients can introduce large oscillations which are sometimes difficult to handle. An axial model has been developed to study the controllability of a PWR in different power transients. After investigation with the XENOPT code, a new code PLATO [Program for Load And Transient Operation] with a user friendly interface and life reactor data, has been successfully implemented at the Doel power station
Limit load assessment of centre cracked plates under biaxial loading
International Nuclear Information System (INIS)
Fitness-for-service of equipment and components containing defects is generally assessed using procedures such as BS 7910, API 579 and R6. There is currently little detailed advice in these procedures on the effects of biaxial and triaxial loading on fracture. This poster shows some theoretical bounding solutions of the plastic limit load for centre cracked plates under a variety of biaxial loading ratios and compares the estimates with those found by numerical methods using finite element (FE) analysis using Abacus CAE modelling software. The limit load of a structure is the maximum load that it can carry before plastic collapse occurs; this is often when the plastic zone has become large enough to spread from the crack tip to a remote boundary. For an elastic-perfectly plastic material, the irreversible deformation will continue at stresses no higher than the yield stress. The model for these limit load solutions is a bi-axially loaded plate of width 2W and height 2H, a centre crack of width 2a, acted on by remotely applied uniform stresses σ2 perpendicular to the crack and Bσ2 parallel to the crack, where B is the biaxial loading ratio, it means the ratio of the parallel to the perpendicular stress. A quarter plate of an elastic-perfectly plastic material has been modelled. The results show that an exact solution has been found for negative and low positive values of B. For B > 1, the lower bound solution is conservative for all values of a/W and B
Axial flow positive displacement worm compressor
Murrow, Kurt David (Inventor); Giffin, Rollin George (Inventor); Fakunle, Oladapo (Inventor)
2010-01-01
An axial flow positive displacement compressor has an inlet axially spaced apart and upstream from an outlet. Inner and outer bodies have offset inner and outer axes extend from the inlet to the outlet through first and second sections of a compressor assembly in serial downstream flow relationship. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes respectively. The inner and outer helical blades extend radially outwardly and inwardly respectively. The helical blades have first and second twist slopes in the first and second sections respectively. The first twist slopes are less than the second twist slopes. An engine including the compressor has in downstream serial flow relationship from the compressor a combustor and a high pressure turbine drivingly connected to the compressor by a high pressure shaft.
Proto-I axial-focusing experiments
International Nuclear Information System (INIS)
The time-integrated axial (z) focus of the 4.5-cm-radius Proto I (1.5 MV, 500 kA) radial proton diode is presently limited to approx. 3 mm FWHM. This result is obtained with current neutralized beam transport in a gas cell with 6 Torr argon. If the vertical local divergence were the same (10 or less) as the horizontal divergence, the local divergence alone would produce a 1.5 mm FWHM focus. The axial focal size is evidently limited by time-dependent effects. These are studied by observing the beam incident upon various targets with two time-resolved pinhole cameras. The first camera observes Rutherford-scattered protons from gold targets with an array of 11 siicon PIN detectors. The second camera observes K/sub α/-fluorescence from aluminum targets with 4 independently-gated microchannel plates imaging tubes
Microwave axial dielectric properties of carbon fiber
Hong, Wen; Xiao, Peng; Luo, Heng; Li, Zhuan
2015-10-01
Randomly distributed carbon fibers (CFs) reinforced epoxy resin composites are prepared by the pouring method, the dielectric properties of CF composites with different fiber content and length have been performed in the frequency range from 8.2 to 12.4 GHz. The complex permittivity of the composite increases with the fiber length, which is attributed to the decrease of depolarization field, and increases with the volume fraction, which is attributed to the increase of polarization. A formula, based on the theory of Reynolds-Hugh, is proposed to calculate the effective permittivity of CF composites, and validated by the experiments. The proposed formula is further applied to derive the axial permittivity of CF and analyze the effect of fiber length on the axial permittivity.
Direct optical nanoscopy with axially localized detection
Bourg, N; Dupuis, G; Barroca, T; Bon, P; Lécart, S; Fort, E; Lévêque-Fort, S
2014-01-01
Evanescent light excitation is widely used in super-resolution fluorescence microscopy to confine light and reduce background noise. Herein we propose a method of exploiting evanescent light in the context of emission. When a fluorophore is located in close proximity to a medium with a higher refractive index, its near-field component is converted into light that propagates beyond the critical angle. This so-called Supercritical Angle Fluorescence (SAF) can be captured using a hig-NA objective and used to determine the axial position of the fluorophore with nanometer precision. We introduce a new technique for 3D nanoscopy that combines direct STochastic Optical Reconstruction Microscopy (dSTORM) imaging with dedicated detection of SAF emission. We demonstrate that our approach of a Direct Optical Nanoscopy with Axially Localized Detection (DONALD) yields a typical isotropic 3D localization precision of 20 nm.
Review of Axial Burnup Distribution Considerations for Burnup Credit Calculations
International Nuclear Information System (INIS)
This report attempts to summarize and consolidate the existing knowledge on axial burnup distribution issues that are important to burnup credit criticality safety calculations. Recently released Nuclear Regulatory Commission (NRC) staff guidance permits limited burnup credit, and thus, has prompted resolution of the axial burnup distribution issue. The reactivity difference between the neutron multiplication factor (keff) calculated with explicit representation of the axial burnup distribution and keff calculated assuming a uniform axial burnup is referred to as the ''end effect.'' This end effect is shown to be dependent on many factors, including the axial-burnup profile, total accumulated burnup, cooling time, initial enrichment, assembly design, and the isotopics considered (i.e., actinide-only or actinides plus fission products). Axial modeling studies, efforts related to the development of axial-profile databases, and the determination of bounding axial profiles are also discussed. Finally, areas that could benefit from further efforts are identified
Review of Axial Burnup Distribution Considerations for Burnup Credit Calculations
Energy Technology Data Exchange (ETDEWEB)
Wagner, J.C.; DeHart, M.D.
2000-03-01
This report attempts to summarize and consolidate the existing knowledge on axial burnup distribution issues that are important to burnup credit criticality safety calculations. Recently released Nuclear Regulatory Commission (NRC) staff guidance permits limited burnup credit, and thus, has prompted resolution of the axial burnup distribution issue. The reactivity difference between the neutron multiplication factor (keff) calculated with explicit representation of the axial burnup distribution and keff calculated assuming a uniform axial burnup is referred to as the ``end effect.'' This end effect is shown to be dependent on many factors, including the axial-burnup profile, total accumulated burnup, cooling time, initial enrichment, assembly design, and the isotopics considered (i.e., actinide-only or actinides plus fission products). Axial modeling studies, efforts related to the development of axial-profile databases, and the determination of bounding axial profiles are also discussed. Finally, areas that could benefit from further efforts are identified.
On the problem of axial anomaly in supersymmetric gauge theories
International Nuclear Information System (INIS)
The explicit relation is found between the axial current obeying the Adler-Bardeen theorem and the supersymmetric one belonging to a supermultiplet. It is shown that the axial and superconformal anomalies are consistent in all orders of perturbation theory
Multimode interaction in axially excited cylindrical shells
Silva F. M. A.; Rodrigues L.; Gonçalves P. B.; Del Prado Z. J. G. N
2014-01-01
Cylindrical shells exhibit a dense frequency spectrum, especially near the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to a complex dynamic behavior. So, the aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under axial forcing with multiple equal or nearly equal natural fr...
Axial flux permanent magnet brushless machines
Gieras, Jacek F; Kamper, Maarten J
2008-01-01
Axial Flux Permanent Magnet (AFPM) brushless machines are modern electrical machines with a lot of advantages over their conventional counterparts. They are being increasingly used in consumer electronics, public life, instrumentation and automation system, clinical engineering, industrial electromechanical drives, automobile manufacturing industry, electric and hybrid electric vehicles, marine vessels and toys. They are also used in more electric aircrafts and many other applications on larger scale. New applications have also emerged in distributed generation systems (wind turbine generators
Axial Flow Characteristics within a Screw Compressor
Nouri, J. M.; Guerrato, D.; Stosic, N.; Arcoumanis, C.
2008-01-01
Angle-resolved axial mean flow and turbulence characteristics were measured inside the working chamber of the male rotor of a screw compressor with high spatial and temporal resolution using laser Doppler velocimetry at two rotor speeds, 750 and 1000 rpm. Measurements were performed through a transparent window near the discharge port to allow the application of various laser techniques. The results showed that an angular resolution up to 2° could fully describe the flow variation inside the ...
Axial force measurement for esophageal function testing
Gravesen, Flemming H; Funch-Jensen, Peter; Gregersen, Hans; Drewes, Asbjørn Mohr
2009-01-01
The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the “golden standard” for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure o...
Axially evoked postural reflexes: influence of task
Govender, Sendhil; Dennis, Danielle L.; Colebatch, James G.
2014-01-01
Postural reflexes were recorded in healthy subjects (n = 17) using brief axial accelerations and tap stimuli applied at the vertebra prominens (C7) and manubrium sterni. Short latency (SL) responses were recorded from the soleus, hamstrings and tibialis anterior muscles and expressed as a percentage of the background EMG prior to stimulus onset. In the majority of postural conditions tested, subjects were recorded standing erect and leaning forward with their feet together. The SL response wa...
Numerical simulation of an axial blood pump.
Chua, Leok Poh; Su, Boyang; Lim, Tau Meng; Zhou, Tongming
2007-07-01
The axial blood pump with a magnetically suspended impeller is superior to other artificial blood pumps because of its small size. In this article, the distributions of velocity, path line, pressure, and shear stress in the straightener, the rotor, and the diffuser of the axial blood pump, as well as the gap zone were obtained using the commercial software, Fluent (version 6.2). The main focus was on the flow field of the blood pump. The numerical results showed that the axial blood pump could produce 5.14 L/min of blood at 100 mm Hg through the outlet when rotating at 11,000 rpm. However, there was a leakage flow of 1.06 L/min in the gap between the rotor cylinder and the pump housing, and thus the overall flow rate the impeller could generate was 6.2 L/min. The numerical results showed that 75% of the scalar shear stresses (SSs) were less than 250 Pa, and 10% were higher than 500 Pa within the whole pump. The high SS region appeared around the blade tip where a large variation of velocity direction and magnitude was found, which might be due to the steep angle variation at the blade tip. Because the exposure time of the blood cell at the high SS region within the pump was relatively short, it might not cause serious damage to the blood cells, but the improvement of blade profile should be considered in the future design of the axial pump. PMID:17584481
Axially heterogeneous thorium fuel designs for transuranic burning in reduced-moderation BWRs
International Nuclear Information System (INIS)
Reduced-moderation Boiling Water Reactors (RBWRs) can allow sustained burning of transuranics (TRU), such that full actinide recycle can be achieved. However, the void coefficient (VC) tends to become positive with reduced moderation and high TRU loading, which can severely limit the design feasibility and performance. This motivates use of thorium (Th) as an alternative feed to uranium (U), as this tends to result in a more negative VC, leading to much improved neutronic performance. While axially homogeneous fuel design is preferable for ease of fuel fabrication, it is valuable to evaluate axially heterogeneous fuel designs to see if improved neutronic performance can be realised, which could lead to a reduction in fuel reprocessing and fabrication throughput. Multi-recycled Th-TRU fuel contains Th, U, Pu and MAs, leading to a wide range of possible fuel designs. Axially heterogeneous designs are considered using 3D pincell calculations using the Monte Carlo code Serpent. Radially heterogeneous assembly designs are considered in a companion paper. Spatial separation of Th-TRU and Th-U3 into regions of the order of a few thermal neutron diffusion lengths greatly improves neutronic performance. This can be accomplished radially or axially, but radial separation results in significantly easier fuel fabrication. Axial seed-blanket heterogeneity improves neutron economy at the expense of high power peaking, such that the radially heterogeneous assembly design is preferred. Separation of Th-TRU and Th-U3 into larger regions is not effective, due to increased power density in the Th-TRU region with voiding and with burn-up, leading to a more positive VC. It is therefore concluded that there is no motivation to pursue axially heterogeneous Th-TRU RBWR burner designs. (author)
DYNAMIC RESPONSES OF VISCOELASTIC AXIALLY MOVING BELT
Institute of Scientific and Technical Information of China (English)
李映辉; 高庆; 蹇开林; 殷学纲
2003-01-01
Based on the Kelvin viscoelastic differential constitutive law and the motion equation of the axially moving belt, the nonlinear dynamic model of the viscoelastic axial moving belt was established. And then it was reduced to be a linear differential system which the analytical solutions with a constant transport velocity and with a harmonically varying transport velocity were obtained by applying Lie group transformations. According to the nonlinear dynamic model, the effects of material parameters and the steady-state velocity and the perturbed axial velocity of the belt on the dynamic responses of the belts were investigated by the research of digital simulation. The result shows: 1 ) The nonlinear vibration frequency of the belt will become small when the relocity of the belt increases. 2 ) Increasing the value of viscosity or decreasing the value of elasticity leads to a deceasing in vibration frequencies. 3 ) The most effects of the transverse amplitudes come from the frequency of the perturbed velocity when the belt moves with harmonic velocity.
The window of opportunity: a relevant concept for axial spondyloarthritis
Robinson, Philip C.; Brown, Matthew A.
2014-01-01
The window of opportunity is a concept critical to rheumatoid arthritis treatment. Early treatment changes the outcome of rheumatoid arthritis treatment, in that response rates are higher with earlier disease-modifying anti-rheumatic drug treatment and damage is substantially reduced. Axial spondyloarthritis is an inflammatory axial disease encompassing both nonradiographic axial spondyloarthritis and established ankylosing spondylitis. In axial spondyloarthritis, studies of magnetic resonanc...
Extra-Axial Medulloblastoma in the Cerebellar Hemisphere
Chung, Eui Jin; Jeun, Sin Soo
2014-01-01
Extra-axial medulloblastoma is a rare phenomenon. We report a case in a 5-year-old boy who presented with nausea, vomiting, and gait disturbance. He was treated with total removal of the tumor. This is the first case of an extra-axially located medulloblastoma occurring in the cerebellar hemisphere posteriolateral to the cerebellopontine angle in Korea. Although the extra-axial occurrence of medulloblastoma is rare, it should be considered in the differential diagnosis of extra-axial lesions ...
Buckling and postbuckling analysis of stiffened composite panels in axial compression
Park, Oung
The major objective of this study is to analyze buckling and delamination behavior of composite stiffened panels subjected to axial compression. First, a combined analytical and experimental study of a blade stiffened composite panel subjected to axial compression was conducted. The effects of the differences between a simple model used to design the panel and the actual experimental conditions were examined. It was found that in spite of many simplifying assumptions the design model did reasonably well in that the experimental failure load was only 10% higher than the design load. Several structural analysis programs, including PANDA2, STAGS, and ABAQUS, were used to obtain high fidelity analysis results. The buckling loads from STAGS agreed well with the experimental failure loads. However, substantial differences were found in the out-of-plane displacements of the panel. Efforts were made to identify the source of these differences. Implementing non-uniform load introduction with general contact definition in the STAGS finite element model improved correlation between the measured and predicted out-of-plane deformations. Next, a new method called Crack Tip Force Method (CTFM) is derived for computing point-wise energy release rate along the delamination front in delaminated plates. The CTFM is computationally simple as the G is computed using the forces transmitted at the crack-tip between the top and bottom sub-laminates and the sub-laminate properties. Finally, buckling and postbuckling of a blade-stiffened composite panel under axial compression with a partial skin-stiffener debond are investigated. Two different finite element models, where nodes of the panel skin and the stiffener flange are located on the mid-plane or at the interface between skin and flange, are used. Linear buckling analysis is conducted using both STAGS and ABAQUS. Postbuckling analysis is conducted with STAGS. Comparison between the present results and previous buckling analysis
Gamp, Alexander
2013-01-01
We begin by giving a description of the radio-frequency generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, radio-frequency feedback and feedforward are described. Examples of digital radio-frequency phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed.
Experimental and analytical investigation of low-solidity axial turbines
Energy Technology Data Exchange (ETDEWEB)
Irdmusa, J.Z.
1990-01-01
This study redesigned the blade leading edges of a small low-solidity axial turbine to obtain operational flexibility. Further flexibility was gained by using a low-solidity cascade, which allowed the leading edges to have a higher radius of curvature. The cascade also allowed larger flow deflections, which resulted in higher utilization factors. Because of the smaller frictional surfaces associated with the low-solidity cascade, the losses were minimized and higher performance achieved. Two small low-solidity axial turbines, one with a high profile ratio and the other with a low profile ratio, were tested. Their performances were evaluated by the temperature drop across them and also by measuring their power output in a specially design test rig. The internal flow in the nozzles was visualized by water flow simulation with dye injection. The internal fluid dynamics were stimulated by computer. The inviscid flow computer programs MERIDL and TSONIC from NASA were used to predict the flow field in both turbines. The location of stagnation points at the leading edge, streamline patterns, pressure distributions, and loading coefficients were determined. Findings showed that the turbine with conventional leading edges (low profile ratio) was very susceptible to changes in the operating condition, while the turbine with newly designed blades (high profile ratio) had very high operational flexibility, complemented by high performance for a wide range of speeds. Findings also showed that high performance can be achieved with low-solidity cascades without being penalized for the losses due to flow separation. Inviscid computer codes MERIDL and TSONIC were effective in investigating the internal aerodynamics of the turbine rotors.
Experimental and Analytical Investigation of Low - Axial Turbines
Irdmusa, Jamshid Zakizadeh
This study redesigned the blade leading edges of a small low-solidity axial turbine to obtain operational flexibility. Further flexibility was gained by using a low-solidity cascade, which allowed the leading edges to have a higher radius of curvature. The cascade also allowed larger flow deflections, which resulted in higher utilization factors. Because of the smaller frictional surfaces associated with the low-solidity cascade, the losses were minimized and higher performance achieved. Two small low-solidity axial turbines, one with a high profile ratio and the other with a low profile ratio, were tested. Their performances were evaluated by the temperature drop across them and also by measuring their power output in a specially design test rig. The velocity fields at the exit of both turbines were mapped out by a one-component Laser Doppler Velocimeter. The internal flow in the nozzles was visualized by water flow simulation with dye injection. The internal fluid dynamics were stimulated by computer. The inviscid flow computer programs MERIDL and TSONIC from NASA were used to predict the flow field in both turbines. The location of stagnation points at the leading edge, streamline patterns, pressure distributions, and loading coefficients were determined. The Hele-Shaw apparatus was used to verify the computer program predictions. Observed streamline patterns were found to agree with predicted ones. Findings showed that the turbine with conventional leading edges (low profile ratio) was very susceptible to changes in the operating condition, while the turbine with newly designed blades (high profile ratio) had very high operational flexibility, complemented by high performance for a wide range of speeds. Findings also showed that high performance can be achieved with low-solidity cascades without being penalized for the losses due to flow separation. Inviscid computer codes MERIDL and TSONIC were effective in investigating the internal aerodynamics of the
Resolution of axial anomaly problem in supersymmetric gauge theories
International Nuclear Information System (INIS)
The explicit form of transformation is found which converters the operators, involved in axial anomaly, from the renormalization scheme obeying the Adler-BaAdeen theorem to a supersymmetric one. It is shown that there is no contradiction between axial current and superconformal anomalies. In supersymmetric scheme the axial current and its anomaly belong to the corresponding supermultiplets
Analysis of PWR cladding transient load under LOCA quench conditions
International Nuclear Information System (INIS)
LOCA is a classical design basis accident needed to be considered in all LWR safety analyses. The thermal shock induced by quench during LOCA may cause fracture in the claddings which could lead to core damage. Therefore it is necessary to study the cladding behavior during quench. This paper reports the results of LOCA quench experiments and simulations using the RANNS code for evaluating local mechanical and thermal states of axial load on the cladding. The experimental measurements suggest the rate of load gain decreases with an increasing of the ECR value due to the thicker zirconia layer which serves as a thermal barrier. In addition, the temperature-induced stress on the cladding along the axial direction appears uneven. Therefore, it is found that the LOCA simulation needs multiple elements in the axial direction for obtaining a fairly good prediction of the axial load gain. Finally, the RANNS simulation of the pellet center temperature is validated, and the RANNS code shows the capability in predicting the axial load generated during quench for ECR of lower or equal to 15%. (author)
Torki, Mohammad Ebrahim; Kazemi, Mohammad Taghi; Reddy, Junuthula N.; Haddadpoud, Hassan; Mahmoudkhani, Saeid
2014-02-01
In this paper, flutter of functionally graded material (FGM) cylindrical shells under distributed axial follower forces is addressed. The first-order shear deformation theory is used to model the shell, and the material properties are assumed to be graded in the thickness direction according to a power law distribution using the properties of two base material phases. The solution is obtained by using the extended Galerkin's method, which accounts for the natural boundary conditions that are not satisfied by the assumed displacement functions. The effect of changing the concentrated (Beck's) follower force into the uniform (Leipholz's) and linear (Hauger's) distributed follower loads on the critical circumferential mode number and the minimum flutter load is investigated. As expected, the flutter load increases as the follower force changes from the so-called Beck's load into the so-called Leipholz's and Hauger's loadings. The increased flutter load was calculated for homogeneous shell with different mechanical properties, and it was found that the difference in elasticity moduli bears the most significant effect on the flutter load increase in short, thick shells. Also, for an FGM shell, the increase in the flutter load was calculated directly, and it was found that it can be derived from the simple power law when the corresponding increase for the two base phases are known.
Directory of Open Access Journals (Sweden)
F. Paredes
2012-01-01
Full Text Available It is shown that printed antennas loaded with metamaterial resonators can be designed to exhibit multiband functionality. Two different antenna types and metamaterial loading are considered: (i printed dipoles or monopoles loaded with open complementary split ring resonators (OCSRRs and (ii meander line or folded dipole antennas loaded with split ring resonators (SRRs or spiral resonators (SRs. In the first case, multiband operation is achieved by series connecting one or more OCSRRs within the dipole/monopole. Such resonators force opens at their positions, and by locating them at a quarter wavelength (at the required operating frequencies from the feeding point, it is possible to achieve multiple radiation bands. In the second case, dual-band functionality is achieved through the perturbation of the antenna characteristics caused by the presence of the metamaterial resonators. This latter strategy is specially suited to achieve conjugate matching between the antenna and the chip in radiofrequency identification (RFID tags at two of the regulated UHF-RFID bands.
Lei, Xiao; Narsu, B.; Yun, Guohong; Li, Jiangang; Yao, Haiyan
2016-05-01
Surface effects play a deterministic role in the physical and mechanical properties of nanosized materials and structures. In this paper, we present a self-consistent theoretical scheme for describing the elasticity of nanowires. The natural frequency and the critical compression force of axial buckling are obtained analytically, taking into consideration the influences of lower symmetry, additional elastic parameters, surface reconstruction, surface elasticity, and residual surface stress. Applications of the present theory to elastic systems for the axially oriented Si and Cu nanowires and Ag axially oriented nanowires yield good agreement with experimental data and calculated results. The larger positive value of the new elastic parameter c12α taken into account for Si oriented nanowires drives the curves of natural frequency and critical compression force versus thickness towards the results obtained from density functional theory simulation. Negative surface stress decreases the critical load for axial buckling, thus making the nanowires very easy to bend into various structures. The present study is envisaged to provide useful insights for the design and application of nanowire-based devices.
Estimation of maximum axial force of anchor bolts in consideration of random bolt failures
International Nuclear Information System (INIS)
This paper proposes a method for structural reliability analysis of anchor bolts used in the support skirt of a reactor vessel. The method is based on the conservative assumption that a few anchor bolts within the skirt's inner-wall may fail in a random nature. Under the assumption, the maximum axial forces in the intact bolts are estimated. To reflect the uncertainty, random numbers are generated to simulate the possible failed bolts among a total of 60 bolts, which are circumferentially arranged along the inner side of the wall. Then the outcome of failed bolts together with their locations for every 60 bolts is defined as an experiment of a sample. The locations of failed bolt can significantly affect the stress analysis and its random outcomes require an efficient calculation scheme. In this paper we propose a rapid calculation algorithm, thus the direction of bending moment that causes the worst scenario in the stress analysis of bolts for each experiment can be rapidly found. Taking into consideration of design loads, the finite element method is further employed to calculate the maximum axial bolt force of each experiment. After statistical analysis of maximum axial forces from all experiments, the average maximum axial-force interval that the remaining bolts can withstand under a given random condition is estimated with a 95% confidence level. This interval can be used in conjunction with various results of structural integrity assessment to ensure the structural safety and reliability of a nuclear power plant component
Fire behavior of eccentrically loaded slender high strength concrete-filled tubular columns
Moliner, Vicente; Espinós Capilla, Ana; Romero, Manuel L.; Hospitaler Pérez, Antonio
2013-01-01
This paper describes sixteen fire tests conducted on slender circular hollow section columns filled with normal and high strength concrete, subjected to concentric axial loads. The test parameters were the nominal strength of concrete (30 and 80 MPa), the infilling type (plain concrete, reinforced concrete and steel fiber reinforced concrete) and the axial load level (20% and 40%). The columns were tested under fixed-pinned boundary conditions and the relative slenderness at room temperature ...
CFD Simulation of Casing Treatment of Axial Flow Compressors
DeWitt, Kenneth
2005-01-01
A computational study is carried out to understand the physical mechanism responsible for the improvement in stall margin of an axial flow rotor due to the circumferential casing grooves. It is shown that the computational tool used predicts an increase in operating range of the rotor when casing grooves are present. A budget of the axial momentum equation is carried out at the rotor casing in the tip gap in order to uncover the physical process behind this stall margin improvement. It is shown that for the smooth casing the net axial pressure force . However in the presence of casing grooves the net axial shear stress force acting at the casing is augmented by the axial force due to the radial transport of axial momentum, which occurs across the grooves and power stream interface. This additional force adds to the net axial viscous sheer force and thus leads to an increase in the stall margin of the rotor.
Strength and stability analysis of a single-walled black phosphorus tube under axial compression.
Cai, Kun; Wan, Jing; Wei, Ning; Qin, Qing H
2016-07-01
Few-layered black phosphorus materials currently attract much attention due to their special electronic properties. As a consequence, a single-layer black phosphorus (SLBP) nanotube has been theoretically built. The corresponding electronic properties of such a black phosphorus nanotube (BPNT) were also evaluated numerically. However, unlike graphene formed with 2sp(2) covalent carbon atoms, SLBP is formed with 3sp(3) bonded atoms. It means that the structure from SLBP will possess lower Young's modulus and mechanical strength than those of carbon nanotubes. In this study, molecular dynamics simulation is performed to investigate the strength and stability of BPNTs affected by the factors of diameter, length, loading speed and temperature. Results are fundamental for investigating the other physical properties of a BPNT acting as a component in a nanodevice. For example, buckling of the BPNT happens earlier than fracture, before which the nanostructure has very small axial strain. For the same BPNT, a higher load speed results in lower critical axial strain and a nanotube with lower axial strain can still be stable at a higher temperature. PMID:27211804
Strength and stability analysis of a single-walled black phosphorus tube under axial compression
Cai, Kun; Wan, Jing; Wei, Ning; Qin, Qing H.
2016-07-01
Few-layered black phosphorus materials currently attract much attention due to their special electronic properties. As a consequence, a single-layer black phosphorus (SLBP) nanotube has been theoretically built. The corresponding electronic properties of such a black phosphorus nanotube (BPNT) were also evaluated numerically. However, unlike graphene formed with 2sp2 covalent carbon atoms, SLBP is formed with 3sp3 bonded atoms. It means that the structure from SLBP will possess lower Young’s modulus and mechanical strength than those of carbon nanotubes. In this study, molecular dynamics simulation is performed to investigate the strength and stability of BPNTs affected by the factors of diameter, length, loading speed and temperature. Results are fundamental for investigating the other physical properties of a BPNT acting as a component in a nanodevice. For example, buckling of the BPNT happens earlier than fracture, before which the nanostructure has very small axial strain. For the same BPNT, a higher load speed results in lower critical axial strain and a nanotube with lower axial strain can still be stable at a higher temperature.
Drop size selection in axially heated co-axial fiber capillary instability
Mowlavi, Saviz; Brun, Pierre-Thomas; Gallaire, Francois
2015-11-01
We analyze the sphere size selection mechanism in silicon-in-silica sphere formation through the application of an external axial thermal gradient to a co-axial silicon-in-silica fiber (Gumennik et al., Nature Com., 2013). We first apply a convective/absolute stability analysis to the in-fibre capillary instability governing the sphere formation and demonstrate that the resulting wavelength selection predicts a finite but still too large wavelength. A global stability analysis is then pursued, which accounts for the spatial inhomogeneity of the base flow. F.G. acknowledges funding from ERC SimCoMiCs 280117.
Axial electron-channelling analysis of perovskite
International Nuclear Information System (INIS)
The orientation dependence of characteristic X-ray emission (the Borrmann effect) under near-zone-axis diffraction conditions has been used to identify the site preferences of strontium, zirconium and uranium impurities within a CaTiO3 (perovskite) host structure. As characteristic emission lines from these impurities occur at both higher and lower energies than the calcium or titanium K-shell excitations, effects of delocalization are clearly measureable, and are used as a tool in axial electron channeling or ALCHEMI analysis. It is found that strontium and uranium strongly partition into calcium sites, whereas zirconium occupies titanium sites. (author)
Single Band Helical Antenna in Axial Mode
Directory of Open Access Journals (Sweden)
Parminder Singh
2012-11-01
Full Text Available Helical antennas have been widely used in a various useful applications, due to their low weight and low profile conformability, easy and cheap realization.Radiation properties of this antenna are examined both theoretically and experimentally. In this paper, an attempt has been made to investigate new helical antenna structure for Applications. CST MWS Software is used for the simulation and design calculations of the helical antennas. The axial ratio, return loss, VSWR, Directivity, gain, radiation pattern is evaluated. Using CST MWS simulation software proposed antenna is designed/simulated and optimized. The antenna exhibits a single band from 0 GHz to 3 GHz for GPS and several satellite applications
Resonances in axially symmetric dielectric objects
Helsing, Johan
2016-01-01
A high-order convergent and robust numerical solver is constructed and used to find complex eigenwavenumbers and electromagnetic eigenfields of dielectric objects with axial symmetry. The solver is based on Fourier--Nystr\\"om discretization of M\\"uller's combined integral equations for the transmission problem and can be applied to demanding resonance problems at microwave, terahertz, and optical wavelengths. High achievable accuracy, even at very high wavenumbers, makes the solver ideal for benchmarking and for assessing the performance of general purpose commercial software.
Cervical Spine Axial Rotation Goniometer Design
Directory of Open Access Journals (Sweden)
Emin Ulaş Erdem
2012-06-01
Full Text Available To evaluate the cervical spine rotation movement is quiet harder than other joints. Configuration and arrangement of current goniometers and devices is not always practic in clinics and some methods are quiet expensive. The cervical axial rotation goniometer designed by the authors is consists of five pieces (head apparatus, chair, goniometric platform, eye pads and camera. With this goniometer design a detailed evaluation of cervical spine range of motion can be obtained. Besides, measurement of "joint position sense" which is recently has rising interest in researches can be made practically with this goniometer.
Thermophoretic motion of bodies with axial symmetry
International Nuclear Information System (INIS)
Thermophoresis of axially symmetric bodies is investigated to first order in the Knudsen number, K n. The study is made in the limit where the typical length of the immersed body is small compared with the mean free path. It is shown that in this case, in contrast to what is the case for spherical bodies, the arising thermal force on the body is not in general anti-parallel to the temperature gradient. It is also shown that the gas exerts a torque on the body, which in magnitude and direction depends on the body geometry. Equations of motion describing the body movement are derived. Stationary solutions are studied
van den Ende, D.; Almeida, P.M.R.; Dingemans, T.J.; Van der Zwaag, S.
2007-01-01
The invention relates to a load sensor comprising a polymer matrix and a piezo-ceramic material such as PZT, em not bedded in the polymer matrix, which together form a compos not ite, wherein the polymer matrix is a liquid crystalline resin, and wherein the piezo-ceramic material is a PZT powder forming 30-60% by volume of the composite, and wherein the PZT powder forms 40-50% by volume of the composite.
Modeling of thermo-mechanical fatigue and damage in shape memory alloy axial actuators
Wheeler, Robert W.; Hartl, Darren J.; Chemisky, Yves; Lagoudas, Dimitris C.
2015-04-01
The aerospace, automotive, and energy industries have seen the potential benefits of using shape memory alloys (SMAs) as solid state actuators. Thus far, however, these actuators are generally limited to non-critical components or over-designed due to a lack of understanding regarding how SMAs undergo thermomechanical or actuation fatigue and the inability to accurately predict failure in an actuator during use. The purpose of this study was to characterize the actuation fatigue response of Nickel-Titanium-Hafnium (NiTiHf) axial actuators and, in turn, use this characterization to predict failure and monitor damage in dogbone actuators undergoing various thermomechanical loading paths. Calibration data was collected from constant load, full cycle tests ranging from 200-600MPa. Subsequently, actuator lifetimes were predicted for four additional loading paths. These loading paths consisted of linearly varying load with full transformation (300-500MPa) and step loads which transition from zero stress to 300-400MPa at various martensitic volume fractions. Thermal cycling was achieved via resistive heating and convective cooling and was controlled via a state machine developed in LabVIEW. A previously developed fatigue damage model, which is formulated such that the damage accumulation rate is general in terms of its dependence on current and local stress and actuation strain states, was utilized. This form allows the model to be utilized for specimens undergoing complex loading paths. Agreement between experiments and simulations is discussed.
Axial preloading of a 20 TESLA prototype of a single turn Tokamak toroidal field coil
International Nuclear Information System (INIS)
An axial preloading system has been designed and built as part of the 0.06 scale prototype toroidal field (TF) magnet for the IGNITEX experiment. In the prototype TF coil, as in the full size IGNITEX tokamak, the peak stresses in the inner leg during discharge are made more isotropic (hence the von Mises stress intensity is lowered) through axial preloading. Although preliminary (nonpreloaded) tests of the TF magnet should produce fields as high as 15 T, preloading will permit demonstration of the high (20 T) on-axis magnetic field to be achieved in the IGNITEX device. The preloading system for the prototype is a hydraulic press capable of a load of 580 tons. The press is designed with a short stroke which takes the press from a condition of noncontact to full preloading. During the magnet's pulse and subsequent thermal growth, the hydraulic system of the press maintains the preload force
Nonlinear Models for Transverse Forced Vibration of Axially Moving Viscoelastic Beams
Directory of Open Access Journals (Sweden)
Hu Ding
2011-01-01
Full Text Available Nonlinear models of transverse vibration of axially moving viscoelastic beams subjected external transverse loads via steady-state periodical response are numerically investigated. An integro-partial-differential equation and a partial-differential equation of transverse motion can be derived respectively from a model of the coupled planar vibration for an axially moving beam. The finite difference scheme is developed to calculate steady-state response for the model of coupled planar and the two models of transverse motion under the simple support boundary. Numerical results indicate that the amplitude of the steady-state response for the model of coupled vibration and two models of transverse vibration predict qualitatively the same tendencies with the changing parameters and the integro-partial-differential equation gives results more closely to the coupled planar vibration.
Miller, D. P.; Prahst, P. S.
1994-01-01
An axial compressor test rig has been designed for the operation of small turbomachines. The inlet region consisted of a long flowpath region with two series of support struts and a flapped inlet guide vane. A flow test was run to calibrate and determine the source and magnitudes of the loss mechanisms in the inlet for a highly loaded two-stage axial compressor test. Several flow conditions and IGV angle settings were established in which detailed surveys were completed. Boundary layer bleed was also provided along the casing of the inlet behind the support struts and ahead of the IGV. A detailed discussion of the flowpath design along with a summary of the experimental results are provided in Part 1.
Aerodynamic Design and Analysis of a Low-reaction Axial Compressor Stage
Institute of Scientific and Technical Information of China (English)
Qiang Xiaoqing; Wang Songtao; Feng Guotai; Wang Zhongqi
2008-01-01
There is introduced a new low-reaction, highly-loaded axial compressor design concept which is coupled with boundary layer suction method. The characteristic features of the concept are made clear through its comparison with the MIT boundary layer suction compressor. Also are pointed out the potential applications of this concept as well as its key technological problems. Based on this concept, asingle-stage, low-reaction and low-speed axial compressor is constructed in association with analysis and computation of boundary layersuction on vanes with the aid of a three-dimensional numerical approach. The results attest to the effectiveness of this way to control separation in blade cascades by the boundary layer suction and the feasibility of this proposed design concept.
Plate fin heat exchanger model with axial conduction and variable properites
Hansen, Benjamin Jacob; White, Michael Joseph; Klebaner, Arkadiy
2012-06-01
Future superconduction radio frequency (SRF) cavities, as part of Project X at Fermilab,will be cooled to superfluid helium temperatures by a cryogenic distribution system supplying cold supercritical helium. To reduce vapor fraction during the final Joule Thomson (J-T) expansion into the superfluid helium cooling bath, counter-flow, plate-fin heat exchanger are an effective option. However, at liquid helium temperatures requires consideration of axial heat conduction along the direction of flow, in addition to variable fluid properties. Here we present a numberical model that includes the effects of axial guide design decisions on heat exhanger material choice and geometry. In addition, the J-T expansion process is modeled with the heat exchanger to analyze the effect of heat load and cryogenic supply parameters.
Axial vessel widening in arborescent monocots.
Petit, Giai; DeClerck, Fabrice A J; Carrer, Marco; Anfodillo, Tommaso
2014-02-01
Dicotyledons have evolved a strategy to compensate for the increase in hydraulic resistance to water transport with height growth by widening xylem conduits downwards. In monocots, the accumulation of hydraulic resistance with height should be similar, but the absence of secondary growth represents a strong limitation for the maintenance of xylem hydraulic efficiency during ontogeny. The hydraulic architecture of monocots has been studied but it is unclear how monocots arrange their axial vascular structure during ontogeny to compensate for increases in height. We measured the vessel lumina and estimated the hydraulic diameter (Dh) at different heights along the stem of two arborescent monocots, Bactris gasipaes (Kunth) and Guadua angustifolia (Kunth). For the former, we also estimated the variation in Dh along the leaf rachis. Hydraulic diameter increased basally from the stem apex to the base with a scaling exponent (b) in the range of those reported for dicot trees (b = 0.22 in B. gasipaes; b = 0.31 and 0.23 in G. angustifolia). In B. gasipaes, vessels decrease in Dh from the stem's centre towards the periphery, an opposite pattern compared with dicot trees. Along the leaf rachis, a pattern of increasing Dh basally was also found (b = 0.13). The hydraulic design of the monocots studied revealed an axial pattern of xylem conduits similar to those evolved by dicots to compensate and minimize the negative effect of root-to-leaf length on hydrodynamic resistance to water flow. PMID:24488857
Atroposelective Synthesis of Axially Chiral Thiohydantoin Derivatives.
Sarigul, Sevgi; Dogan, Ilknur
2016-07-15
Nonracemic axially chiral thiohydantoins were synthesized atroposelectively by the reaction of o-aryl isothiocyanates with amino acid ester salts in the presence of triethylamine (TEA). The synthesis of the nonaxially chiral derivatives, however, gave thiohydantoins racemized at C-5 of the heterocyclic ring. The micropreparatively resolved enantiomers of the nonaxially chiral derivatives from the racemic products were found to be optically stable under neutral conditions. On formation of the 5-methyl-3-arylthiohydantoin ring, bulky o-aryl substituents at N3 were found to suppress the C-5 racemization and in this way enabled the transfer of chirality from the α-amino acid to the products. The corresponding 5-isopropylthiohydantoins turned out to be more prone to racemization at C-5 during the ring formation. The isomer compositions of the synthesized axially chiral thiohydantoins have been determined through HPLC analyses with chiral stationary phases. In most cases a high prevalence of the P isomers over the M isomers has been obtained. The barriers to rotation determined around the Nsp(2)-Caryl chiral axis were found to be dependent upon the size of the o-halo aryl substituents. PMID:27322739
Proton spin and baryon octet axial couplings
International Nuclear Information System (INIS)
Peripheral spin structure of the nucelon generated by the soft mesonic radiative corrections is studied within the light-cone perturbation theory. Starting with the tree-level SU(6) symmetry, we find a good description of the axial-vector couplings in β-decay of hyperons. We study the proton helicity flow from the baryonic core to the angular momentum of the pionic cloud. It is found that in the relativistic light-cone approach the spin-flip pattern is different from that in the coventional non-relativistic models. The axial-vector current matrix elements are shown to receive large corrections from beyond the conventional static limit. The important virtue of using the light-cone vertex functions of the meson-baryon Fock components of the proton is that the local gauge invariance and the energy-momentum sum rule are satisfied automatically. We infer the radius of the light-cone form factor from an analysis of the experimental data on the fragmentation of high-energy protons into nucleons and hyperons-the process dominated by stripping off the mesons of the meson-baryon Fock states. (orig.)
Finite element analysis of tooth load distribution on P-110S conic threaded connections
International Nuclear Information System (INIS)
Based on elastic mechanics and by use of thick cylinder theory, this paper presents a finite element analysis model with interference fit and axial load on P-110S conic threaded connections and the tooth load distributions on contact threaded surfaces were investigated. A 2D finite element model with elastic-plastic axisymmetric contact threaded surfaces was established and the tooth load distributions on its thread teeth were analyzed under different interference fit and axial load. Results for the loads on every engaged tooth are obtained. These indicate that the load distribution on the engaged teeth is not uniform, with the maximum tooth load concentrated on the first three pairs or the farthest two pairs of engaged teeth from the pin end and the middle teeth only bear a very small load. Such results are identical to the practical situation and indicate that the finite element model proposed in this paper is reasonable.
High temperature superconducting axial field magnetic coupler: realization and test
Belguerras, L.; Mezani, S.; Lubin, T.; Lévêque, J.; Rezzoug, A.
2015-09-01
Contactless torque transmission through a large airgap is required in some industrial applications in which hermetic isolation is necessary. This torque transmission usually uses magnetic couplers, whose dimension strongly depends on the airgap flux density. The use of high temperature superconducting (HTS) coils to create a strong magnetic field may constitute a solution to reduce the size of the coupler. It is also possible to use this coupler to replace a torque tube in transmitting the torque produced by a HTS motor to its load. This paper presents the detailed construction and tests of an axial field HTS magnetic coupler. Pancake coils have been manufactured from BSCCO tape and used in one rotor of the coupler. The second rotor is mainly composed of NdFeB permanent magnets. Several tests have been carried out showing that the constructed coupler is working properly. A 3D finite element (FE) model of the studied coupler has been developed. Airgap magnetic field and torque measurements have been carried out and compared to the FE results. It has been shown that the measured and the computed quantities are in satisfactory agreement.
Investigation of unsteady flow in axial turbine stage
Directory of Open Access Journals (Sweden)
Němec Martin
2012-04-01
Full Text Available The never ending process to increase the efficiency of turbine stages introduced an idea to create an axial turbine stage test rig as part of closed loop transonic wind tunnel at Vyzkumny a zkusebni letecky ustav (VZLU. Studying of unsteady flow field behaviours in turbine stages is nowadays essential in the development process. Therefore, the test rig was designed with focusing on possibility of detailed studying of unsteady flow fields in turbine stages. New methodologies and new instrumentations were developed at VZLU and successfully integrated to gain valuable information from experiments with turbine stages. Two different turbine stages were tested during the facility introduction process. The measurement of these two models demonstrated how flexible the test rig is. One of them was an enlarged model of small gas turbine stage. The other was scaled-down model of stage of intermediate-pressure steam turbine. The external characteristics of both models were acquired during experiments as well as the detailed unsteady flow field measurement. Turbine stages were tested in various regimes in order to check the capabilities of the facility, methodology and instrumentation together. The paper presents results of unsteady flow field investigation in the enlarged turbine stage with unshrouded rotor. The interaction of structures developed in a stator with the rotor flow field is depicted and the influence of turbine load on evolution of secondary flows in rotor is analysed.
Enzalutamide Reduces the Bone Mass in the Axial But Not the Appendicular Skeleton in Male Mice.
Wu, Jianyao; Movérare-Skrtic, Sofia; Börjesson, Anna E; Lagerquist, Marie K; Sjögren, Klara; Windahl, Sara H; Koskela, Antti; Grahnemo, Louise; Islander, Ulrika; Wilhelmson, Anna S; Tivesten, Åsa; Tuukkanen, Juha; Ohlsson, Claes
2016-02-01
Testosterone is a crucial regulator of the skeleton, but the role of the androgen receptor (AR) for the maintenance of the adult male skeleton is unclear. In the present study, the role of the AR for bone metabolism and skeletal growth after sexual maturation was evaluated by means of the drug enzalutamide, which is a new AR antagonist used in the treatment of prostate cancer patients. Nine-week-old male mice were treated with 10, 30, or 100 mg/kg·d of enzalutamide for 21 days or were surgically castrated and were compared with vehicle-treated gonadal intact mice. Although orchidectomy reduced the cortical bone thickness and trabecular bone volume fraction in the appendicular skeleton, these parameters were unaffected by enzalutamide. In contrast, both enzalutamide and orchidectomy reduced the bone mass in the axial skeleton as demonstrated by a reduced lumbar spine areal bone mineral density (P < .001) and trabecular bone volume fraction in L5 vertebrae (P < .001) compared with vehicle-treated gonadal intact mice. A compression test of the L5 vertebrae revealed that the mechanical strength in the axial skeleton was significantly reduced by enzalutamide (maximal load at failure -15.3% ± 3.5%; P < .01). The effects of enzalutamide in the axial skeleton were associated with a high bone turnover. In conclusion, enzalutamide reduces the bone mass in the axial but not the appendicular skeleton in male mice after sexual maturation. We propose that the effect of testosterone on the axial skeleton in male mice is mainly mediated via the AR. PMID:26587782
LONGER: a computer program for longitudinal ridging and axial collapse assessment of CANDU fuel
International Nuclear Information System (INIS)
CANDU® fuel element sheath is designed to be thin and flexible for the benefit of enhanced heat transfer from the pellet to the coolant through the sheath. The flexibility of the sheath may allow the formation of longitudinal ridges on the sheath or collapse of the sheath into an axial gap under certain conditions. For both cases of deformations, the sheath may experience significant strains, and may result in sheath failure. To ensure the sheath mechanical integrity, the fuel element design needs to be assessed to preclude the conditions for longitudinal ridging and sheath collapse into the axial gap. The AECL developed LONGER computer program is used in fuel design analysis for such purpose. The LONGER code contains a number of models derived based on measurements (empirical models) and based on analytical equations, to predict the following parameters related to the deformations of CANDU nuclear fuel element sheaths. For longitudinal ridging: The critical diametral clearance for sheath longitudinal ridging, and The critical pressure for longitudinal ridging of the sheath. For axial collapse: The critical pressure for instantaneous sheath collapse into an axial gap. For circumferential collapse: The critical pressure for elastic collapse of the sheath, and The effective circumferential collapse pressure of the sheath by taking into account the axial and radial loads and the ovality of the sheath. The LONGER code has been qualified in accordance with the CSA standard N286.7-99 compliant AECL Software Quality Assurance (SQA) program. This paper describes the features and capabilities of the LONGER code that are used in CANDU fuel design analysis. (author)
Beat eMeier; Zimmermann, Thomas D.
2015-01-01
In prospective memory tasks different kinds of load can occur. Adding a prospective memory task can impose a load on ongoing task performance. Adding ongoing task load can affect prospective memory performance. The existence of multiple target events increases prospective load and adding complexity to the to-be-remembered action increases retrospective load. In two experiments, we systematically examined the effects of these different types of load on prospective memory performance. Results s...
Debonding problem of a transversely loaded single lap joint
Energy Technology Data Exchange (ETDEWEB)
Tang, J.H.; Sridhar, I.; Tan, G.E.B. [Nanyang Technological Univ., Singapore (Singapore)
2012-07-01
This paper aims to describe the debonding problem of transversely loaded single lap joint using fracture mechanics approach. This is achieved by first solving the deflection problem of the single lap joint. By evaluating the bending moments at the vicinity of crack tip, non-dimensional energy release rate required for the debonding can be found. The effects of relative position of transverse load and overlap length on the debonding propensity are discussed. As for design consideration, any transverse load moving towards critical side of square edge of the joint should be avoided. Increasing the overlap length improves the joint's strength, particularly when the joint is also axially loaded. (Author)
Axial stress corrosion cracking forming method to metal tube
International Nuclear Information System (INIS)
Generally, it is more difficult in a metal tube, to intentionally cause a stress corrosion cracking in axial direction than in circumferential direction. In the present invention, a bevel is formed on a metal tube and welding is conducted in circumferential direction along the bevel, and welding is conducted in axial direction partially to the portion welded in circumferential direction. Namely, a bevel is formed in circumferential direction to an abutting portion of thick-walled metal tubes with each other, welding is conducted in circumferential direction along the bevel, and welding is conducted in axial direction partially to a portion welded in circumferential direction. With such procedures, since tensile stress in the circumferential direction is increased partially at a portion welded in axial direction, stress corrosion cracking is caused in axial direction at the portion. Then, stress corrosion cracking in axial direction can thus be formed on the thick-walled metal tube. (N.H.)
Universal Axial Algebras and a Theorem of Sakuma
Hall, J I; Rehren, F; Shpectorov, S.
2013-01-01
In the first half of this paper, we define axial algebras: nonassociative commutative algebras generated by axes, that is, semisimple idempotents---the prototypical example of which is Griess' algebra [C85] for the Monster group. When multiplication of eigenspaces of axes is controlled by fusion rules, the structure of the axial algebra is determined to a large degree. We give a construction of the universal Frobenius axial algebra on $n$ generators with a specified fusion rules, of which all...
Vittori, Miloš; Srot, Vesna; Žagar, Kristina; Bussmann, Birgit; van Aken, Peter A; Čeh, Miran; Štrus, Jasna
2016-08-01
Skeletal elements that are exposed to heavy mechanical loads may provide important insights into the evolutionary solutions to mechanical challenges. We analyzed the microscopic architecture of dactylus claws in the woodlice Porcellio scaber and correlated these observations with analyses of the claws' mineral composition with energy dispersive X-ray spectrometry (EDX), electron energy loss spectroscopy (EELS) and selected area electron diffraction (SAED). Extraordinarily, amorphous calcium phosphate is the predominant mineral in the claw endocuticle. Unlike the strongly calcified exocuticle of the dactylus base, the claw exocuticle is devoid of mineral and is highly brominated. The architecture of the dactylus claw cuticle is drastically different from that of other parts of the exoskeleton. In contrast to the quasi-isotropic structure with chitin-protein fibers oriented in multiple directions, characteristic of the arthropod exoskeleton, the chitin-protein fibers and mineral components in the endocuticle of P. scaber claws are exclusively axially oriented. Taken together, these characteristics suggest that the claw cuticle is highly structurally anisotropic and fracture resistant and can be explained as adaptations to predominant axial loading of the thin, elongated claws. The nanoscale architecture of the isopod claw may inspire technological solutions in the design of durable machine elements subjected to heavy loading and wear. PMID:27320700
Fluid pressure response in poroelastic materials subjected to cyclic loading
Kameo, Yoshitaka; Adachi, Taiji; Hojo, Masaki
2009-01-01
When cyclic loading is applied to poroelastic materials, a transient stage of interstitial fluid pressure occurs, preceding a steady state. In each stage, the fluid pressure exhibits a characteristic mechanical behavior. In this study, an analytical solution for fluid pressure in two-dimensional poroelastic materials, which is assumed to be isotropic, under cyclic axial and bending loading is presented, based on poroelasticity. The obtained analytical solution contains transient and steady-st...
True stress and Poisson's ratio of tendons during loading
VERGARI, Claudio; Pourcelot, Philippe; HOLDEN, Laurène; RAVARY-PLUMIOEN, Bérangère; GERARD, Guillaume; Laugier, Pascal; Mitton, David; Crevier-Denoix, Nathalie
2011-01-01
Excessive axial tension is very likely involved in the aetiology of tendon lesions, and the most appropriate indicator of tendon stress state is the true stress, the ratio of instantaneous load to instantaneous cross-sectional area (CSA). Difficulties to measure tendon CSA during tension often led to approximate true stress by assuming that CSA is constant during loading (i.e. by the engineering stress) or that tendon is incompressible, implying a Poisson's ratio of 0.5, although these hypoth...
Composite Axial Flow Propulsor for Small Aircraft
Directory of Open Access Journals (Sweden)
R. Poul
2005-01-01
Full Text Available This work focuses on the design of an axial flow ducted fan driven by a reciprocating engine. The solution minimizes the turbulization of the flow around the aircraft. The fan has a rotor - stator configuration. Due to the need for low weight of the fan, a carbon/epoxy composite material was chosen for the blades and the driving shaft.The fan is designed for optimal isentropic efficiency and free vortex flow. A stress analysis of the rotor blade was performed using the Finite Element Method. The skin of the blade is calculated as a laminate and the foam core as a solid. A static and dynamic analysis were made. The RTM technology is compared with other technologies and is described in detail.
Axially symmetric static sources of gravitational field
Hernandez-Pastora, J L; Martin, J
2016-01-01
A general procedure to find static and axially symmetric, interior solutions to the Einstein equations is presented. All the so obtained solutions, verify the energy conditions for a wide range of values of the parameters, and match smoothly to some exterior solution of the Weyl family, thereby representing globally regular models describing non spherical sources of gravitational field. In the spherically symmetric limit, all our models converge to the well known incompressible perfect fluid solution.The key stone of our approach is based on an ansatz allowing to define the interior metric in terms of the exterior metric functions evaluated at the boundary source. Some particular sources are obtained, and the physical variables of the energy-momentum tensor are calculated explicitly, as well as the geometry of the source in terms of the relativistic multipole moments. The total mass of different configurations is also calculated, it is shown to be equal to the monopole of the exterior solution.
Fragmentation of an axially impacted slender rod
Ji, W.; Waas, A. M.
2010-02-01
Motivated by experimental results on the dynamic buckling and fragmentation of a vertical column impacted by a falling mass, results from an analytical model for dynamic buckling which considers the dynamic interaction between the axial column deformation and the out-of-plane buckling displacements are used to interpret the fragmentation process and the resulting fragment lengths. It is shown that a critical time exists for the rod to undergo fragmentation. At this critical time, the rod deforms in a modulated pattern of waves, setting up the stage for the ensuing fragmentation as a result of induced large curvatures that exceed the critical bending strain of the rod material. The resulting fragment length distributions, which show two characteristics peaks at \\frac{\\lambda}{2} and \\frac{\\lambda}{4} , where λ is a characteristic half-wavelength, are found to compare favorably with the experimental results.
Acoustic horizons in axially symmetric relativistic accretion
Abraham, H; Das, T K; Abraham, Hrvoje; Bilic, Neven; Das, Tapas K.
2006-01-01
Transonic accretion onto astrophysical objects is a unique example of analogue black hole realized in nature. In the framework of acoustic geometry we study axially symmetric accretion and wind of a rotating astrophysical black hole or of a neutron star assuming isentropic flow of a fluid described by a polytropic equation of state. In particular we analyze the causal structure of multitransonic configurations with two sonic points and a shock. Retarded and advanced null curves clearly demonstrate the presence of the acoustic black hole at regular sonic points and of the white hole at the shock. We calculate the analogue surface gravity and the Hawking temperature for the inner and the outer acoustic horizons.
Dynamics of Flapping Flag in Axial Flow
Abderrahmane, Hamid Ait; Fayed, Mohamed; Gunter, Amy-Lee; Paidoussis, Michael P.; Ng, Hoi Dick
2010-11-01
We investigate experimentally the phenomenon of the flapping of a flag, placed within a low turbulent axial flow inside a small scale wind tunnel test section. Flags of different sizes and flexural rigidities were used. Image processing technique was used and the time series of a given point on the edge of the flag was analyzed. The stability condition of the flag was obtained and compared to the recent theoretical models and numerical simulations. Afterwards, the nonlinear dynamics of the flapping was investigated using nonlinear time series method. The nonlinear dynamics is depicted in phase space and the correlation dimension of the attractors is determined. On the basis of observations made in this study, some conclusions on the existing models were drawn.
Collimated trans-axial tomographic scintillation camera
International Nuclear Information System (INIS)
The objects of this invention are first to reduce the time required to obtain statistically significant data in trans-axial tomographic radioisotope scanning using a scintillation camera. Secondly, to provide a scintillation camera system to increase the rate of acceptance of radioactive events to contribute to the positional information obtainable from a known radiation source without sacrificing spatial resolution. Thirdly to reduce the scanning time without loss of image clarity. The system described comprises a scintillation camera detector, means for moving this in orbit about a cranial-caudal axis relative to a patient and a collimator having septa defining apertures such that gamma rays perpendicular to the axis are admitted with high spatial resolution, parallel to the axis with low resolution. The septa may be made of strips of lead. Detailed descriptions are given. (U.K.)
Collimated trans-axial tomographic scintillation camera
International Nuclear Information System (INIS)
The principal problem in trans-axial tomographic radioisotope scanning is the length of time required to obtain meaningful data. Patient movement and radioisotope migration during the scanning period can cause distortion of the image. The object of this invention is to reduce the scanning time without degrading the images obtained. A system is described in which a scintillation camera detector is moved to an orbit about the cranial-caudal axis relative to the patient. A collimator is used in which lead septa are arranged so as to admit gamma rays travelling perpendicular to this axis with high spatial resolution and those travelling in the direction of the axis with low spatial resolution, thus increasing the rate of acceptance of radioactive events to contribute to the positional information obtainable without sacrificing spatial resolution. (author)
Axially symmetric Lorentzian wormholes in general relativity
International Nuclear Information System (INIS)
The field equations of Einstein's theory of general relativity, being local, do not fix the global structure of space-time. They admit topologically non-trivial solutions, including spatially closed universes and the amazing possibility of shortcuts for travel between distant regions in space and time - so-called Lorentzian wormholes. The aim of this thesis is to (mathematically) construct space-times which contain traversal wormholes connecting arbitrary distant regions of an asymptotically flat or asymptotically de Sitter universe. Since the wormhole mouths appear as two separate masses in the exterior space, space-time can at best be axially symmetric. We eliminate the non-staticity caused by the gravitational attraction of the mouths by anchoring them by strings held at infinity or, alternatively, by electric repulsion. The space-times are obtained by surgically grafting together well-known solutions of Einstein's equations along timelike hypersurfaces. This surgery naturally concentrates a non-zero stress-energy tensor on the boundary between the two space-times which can be investigated by using the standard thin shell formalism. It turns out that, when using charged black holes, the provided constructions are possible without violation of any of the energy conditions. In general, observers living in the axially symmetric, asymptotically flat (respectively asymptotically de Sitter) region axe able to send causal signals through the topologically non-trivial region. However, the wormhole space-times contain closed timelike curves. Because of this explicit violation of global hyperbolicity these models do not serve as counterexamples to known topological censorship theorems. (author)
Transverse vibration characteristics of axially moving viscoelastic plate
Institute of Scientific and Technical Information of China (English)
ZHOU Yin-feng; WANG Zhong-min
2007-01-01
The dynamic characteristics and stability of axially moving viscoelastic rectangular thin plate are investigated. Based on the two dimensional viscoelastic differential constitutive relation, the differential equations of motion of the axially moving viscoelastic plate are established. Dimensionless complex frequencies of an axially moving viscoelastic plate with four edges simply supported, two opposite edges simply supported and other two edges clamped are calculated by the differential quadrature method. The effects of the aspect ratio, moving speed and dimensionless delay time of the material on the transverse vibration and stability of the axially moving viscoelastic plate are analyzed.
Imperfection effects on the buckling of hydrostatically loaded cylinders
DEFF Research Database (Denmark)
Pinna, Rodney; Madsen, Søren
2015-01-01
in design has also increased. Practical guidance on how to do this is fairly limited, in particular for geometries or load conditions other than the standard cases. The effect of imperfections on the collapse load of cylinders under axial load has been studied extensively, as such cylinders show the......The presence of geometric and other imperfections in cylinders has been known to result in collapse loads well below those predicted from eigenvalue analysis for a long time. As the designer's ability to routinely employ non-linear FEA has increased, the importance of modelling such imperfections...... largest imperfection sensitivity. Work on cylinders with other loading conditions, such as hydrostatic loading, is more limited. Similarly, there is limited work on cylinders with boundary conditions other than simply-supported ends. This paper looks at the case of cylinders under hydrostatic load, which...
Load-application devices: a comparative strain gauge analysis.
Nishioka, Renato Sussumu; de Vasconcellos, Luis Gustavo Oliveira; Jóias, Renata Pilli; Rode, Sigmar de Mello
2015-01-01
In view of the low loading values commonly employed in dentistry, a load-application device (LAD) was developed as option to the universal testing machine (UTM), using strain gauge analysis. The aim of this study was to develop a load-application device (LAD) and compare the LAD with the UTM apparatus under axial and non-axial loads. An external hexagonal implant was inserted into a polyurethane block and one EsthetiCone abutment was connected to the implant. A plastic prosthetic cylinder was screwed onto the abutment and a conical pattern crown was fabricated using acrylic resin. An impression was made and ten identical standard acrylic resin patterns were obtained from the crown impression, which were cast in nickel-chromium alloy (n=10). Four strain gauges were bonded diametrically around the implant. The specimens were subjected to central (C) and lateral (L) axial loads of 30 kgf, on both devices: G1: LAD/C; G2: LAD/L; G3: UTM/C; G4: UTM/L. The data (με) were statistically analyzed by repeated measures ANOVA and Tukey's test (p<0.05). No statistically significant difference was found between the UTM and LAD devices, regardless of the type of load. It was concluded that the LAD is a reliable alternative, which induces microstrains to implants similar to those obtained with the UTM. PMID:26200149
Load following-up operation method
International Nuclear Information System (INIS)
Purpose: To enable load following-up operation with neither increasing boron density excessively nor distorting axial power distribution at the full power operation. Method: Changes in the reactivity excepting that by the boron density is compensated by control rods. However, since control for the axial power distribution is made difficult if the control rod displaced greatly, the control rod position before the power-up is adjusted and power increase is effected stepwise up to the full power level, to thereby control the axial power distribution with no great distortion. After extraction of control rods and when axial offset approaches about to the stationary value (5 - 10%) at the full power level, boron content is diluted as required and control rod is maintained at that position. For the power-up, the control rods are entirely extracted to increase the power as far as possible, and maintain at that level for several hours, while the compensation for the reactivity due to decrease of xenon is compensated by the insertion of the control rods. (Moriyama, K.)
International Nuclear Information System (INIS)
The oesophagus serves to transport food and fluid from the pharynx to the stomach. Oesophageal function is usually evaluated by means of manometry which is a proxy of the force in the radial direction. However, force measurements in the axial direction will provide a better measure of oesophageal transport function. The aim of this study was to develop a probe based on electrical impedance measurements to quantify the axial force generated by oesophageal contractions, i.e. probe elongation was associated with the axial force. Calibration with weights up to 200 g was done. The dispersion, creep, temperature and bending dependence were studied at the bench. Subsequently, the probe was tested in vivo in a healthy human volunteer. The probe showed good reproducibility and the dispersion was <0.04. Some dependence on temperature, creep and bending was found. Interpolation of the calibration curves made it possible to compensate for temperature fluctuations. The maximum deviation was 6.1 ± 3.7% at loads of 50 g. The influence of creep showed a maximum net creep of 6.1 g after 8 s. The swallowed bolus size correlated with the axial force measurements (P = 0.038) but not with manometric measurements. In conclusion, the new technique measures axial force in the oesophagus and may in the future provide valuable information about oesophageal function
Joglekar, Satish D.
2000-01-01
We summarize the work done in connecting Green's functions in a different classes of gauges and its applications to the problems in the axial gauges.The procedure adopted uses finite field-dependent BRS [FFBRS] transformations to connect axial and the Lorentz type gauges.These transformations preserve the vacuum expectation of gauge-invariant observables explicitly. We discuss the applications of these ideas to the axial gauge pole problem and to the preservation of the Wilson loop and the th...
Bonet Senach, José Luís; Romero, Manuel L.; Miguel Sosa, Pedro
2011-01-01
Most of the design codes (ACI-318-2008 and Euro Code-2-2004) propose the moment magnifier method in order to take into account the second order effect to design slender reinforced concrete columns. The accuracy of this method depends on the effective flexural stiffness of the column. This paper proposes a new equation to obtain the effective stiffness EI of slender reinforced concrete columns. The expression is valid for any shape of cross-section, subjected to combined axial loads and biaxia...
Buckling of un-stiffened cylindrical shell under non-uniform axial conpressive stress
Institute of Scientific and Technical Information of China (English)
宋昌永
2002-01-01
This paper provides a review of recent research advances and trends in the area of stability of un-stiffened circular cylindrical shells subjected to general non-uniform axial compressive stresses. Only the more important and interesting aspects of the research, judged from a personal viewpoint, are discussed. They can be crudely classified into four categories: (1) shells subjected to non-uniform loads; (2) shells on discrete supports; (3) shells with intended cutouts/holes; and (4) shells with non-uniform settlements.
Aerothermal optimization of partially shrouded axial turbines[Dissertation 17138
Energy Technology Data Exchange (ETDEWEB)
Porreca, L.
2007-07-01
This work presents the results of an aerodynamic and thermal study of three different shrouded axial turbine configurations (turbomachinery). The blade geometry of the turbine stages and the tip clearances of the test cases under investigation are identical although the shroud design is different. The first test case (RRD) is representative of a full shroud geometry while the second (CPS) and third (EPS) test cases adopt different partial shroud arrangements. In the EPS case, a shroud platform is added to cover the blade throat. Partial shrouds are sometimes used in industrial application in order to benefit from the aerodynamic advantage of shrouded configuration as well as reducing thermal load and mechanical stress on the blade root. However, the optimal compromise between mechanical issues and aerodynamic performances is still an open issue due to the resulting highly 3-dimensional unsteady flow field, difficulty of achieve an optimal cooling and severe heat load on the shroud sealing fins. An experimental investigation is carried out in order to quantify the effect of the shroud geometry on the aerodynamic performances and to study the resultant flow field in all test cases. The analysis has been conducted in an experimental low-speed axial turbine facility at the Turbomachinery Laboratory at ETH Zurich. Steady and fast response aerodynamic probe technology (FRAP) has been used to characterize the flow field. Moreover, a stereoscopic PIV technique has been design and applied in this experimental facility for the first time. The flow field analysis shows that the effect of the shroud geometry is significant from 60% blade height span to the tip. Tip leakage vortex in the first rotor is originated in the partial shroud test cases while the full shroud case present only a weak indigenous tip passage vortex. Secondary flows development in the following second stator resulted to be greatly affected by the leakage/main flow interaction of the first rotor. The
Simulation of the Load Evolution of an Anchoring System under a Blasting Impulse Load Using FLAC3D
Directory of Open Access Journals (Sweden)
Xigui Zheng
2015-01-01
Full Text Available A limitation in research on bolt anchoring is the unknown relationship between dynamic perturbation and mechanical characteristics. This paper divides dynamic impulse loads into engineering loads and blasting loads and then employs numerical calculation software FLAC3D to analyze the stability of an anchoring system perturbed by an impulse load. The evolution of the dynamic response of the axial force/shear stress in the anchoring system is thus obtained. It is revealed that the corners and middle of the anchoring system are strongly affected by the dynamic load, and the dynamic response of shear stress is distinctly stronger than that of the axial force in the anchoring system. Additionally, the perturbation of the impulse load reduces stress in the anchored rock mass and induces repeated tension and loosening of the rods in the anchoring system, thus reducing the stability of the anchoring system. The oscillation amplitude of the axial force in the anchored segment is mitigated far more than that in the free segment, demonstrating that extended/full-length anchoring is extremely stable and surpasses simple anchors with free ends.
International Nuclear Information System (INIS)
Pipe elbows were important parts frequently used in the pipelines of nuclear power, thermal power and chemical plants, and their integrity needed to be assured under seismic loads and thermal stresses considering local wall thinning or complex stress distribution due to special configuration different from straight pipe. This article investigated in details elastic-plastic stress-strain state of pipe elbow using finite element analysis and clarified there existed high bi-axial stress field at side inner surface of pipe elbow axial cracks initiated. Bi-axial stress factor was around 0.6 for sound elbow and up to 0.95 for local wall thinning at crown. Fracture strain of 1.15 was reduced to around 0.15 for bi-axial stress factor from 0.6 to 0.9. Normalized fatigue life for bi-axial stress field (0.6 - 0.8) was largely reduced to around 15, 19 and 10% of fatigue life of uni-axial state dependent on material strength level. Proposed revised universal slopes taking account of multi-axial stress factor could explain qualitatively effects of strain range, internal pressure and ratchet strain (pre-strain) on low-cycle fatigue life of pipe elbow. (T. Tanaka)
DEFF Research Database (Denmark)
2009-01-01
A load testing circuit a circuit tests the load impedance of a load connected to an amplifier. The load impedance includes a first terminal and a second terminal, the load testing circuit comprising a signal generator providing a test signal of a defined bandwidth to the first terminal of the load...
Polymer-based flexible capacitive sensor for three-axial force measurements
International Nuclear Information System (INIS)
We have developed a flexible-substrate-based three-axial force sensor, composed of finger-shaped electrode capacitors, whose operation is based on the measurement of a capacitance change induced upon applying a three-axial load. The electrode design supports high sensitivity to shear forces. An overall flexibility of the sensor and elasticity of the capacitor's dielectric is obtained by integrating three polymers in the sensor's technology process, namely polyimide, parylene-C, and polydimethylsiloxane, combined with standard metallization processes. We have theoretically modeled the sensor's capacitance and its three-axial force sensitivity. The unit capacitors have static capacitances in the range of 20 pF. The electro-mechanical characterization of the capacitors reveals in the normal direction a sensitivity Sz = 0.024 kPa−1 for pressures <10 kPa, whereas for higher pressures the measured sensitivity Sz = 6.6 × 10−4 kPa−1. Typical measured shear force sensitivity Sx = 2.8 × 10−4 kPa−1. These values give our transducer high potential for use in skin-like sensing applications. (paper)
Investigation on centrifugal impeller in an axial-radial combined compressor with inlet distortion
Li, Du; Yang, Ce; Zhao, Ben; Zhou, Mi; Qi, Mingxu; Zhang, Jizhong
2011-12-01
Assembling an axial rotor and a stator at centrifugal compressor upstream to build an axial-radial combined compressor could achieve high pressure ratio and efficiency by appropriate size augment. Then upstream potential flow and wake effect appear at centrifugal impeller inlet. In this paper, the axial-radial compressor is unsteadily simulated by three-dimensional Reynolds averaged Navier-Stokes equations with uniform and circumferential distorted total pressure inlet condition to investigate upstream effect on radial rotor. The results show that span-wise nonuniform total pressure distribution is generated and radial and circumferential combined distortion is formed at centrifugal rotor inlet. The upstream stator wake deflects to rotor rotation direction and decreases with blade span increases. Circumferential distortion causes different separated flow formations at different pitch positions. The tip leakage vortex is suppressed in centrifugal blade passages. Under distorted inlet condition, flow direction of centrifugal impeller leading edge upstream varies evidently near hub and shroud but varies slightly at mid-span. In addition, compressor stage inlet distortion produces remarkable effect on blade loading of centrifugal blade both along chordwise and pitchwise.
Global design optimization for an axial-flow tandem pump based on surrogate method
Li, D. H.; Zhao, Y.; Y Wang, G.
2013-12-01
Tandem pump, compared with multistage pump, goes without guide vanes between impellers. Better cavitation performance and significant reduction of the axial geometry scale is important for high-speed propulsion. This study presents a global design optimization method based on surrogated method for an axial-flow tandem pump to enhance trade-off performances: energy and cavitation performances. At the same time, interactions between impellers and impacts on the performances are analyzed. Fixed angle of blades in impellers and phase angle are performed as design variables. Efficiency and minimum average pressure coefficient (MAPC) on axial sectional surface in front impeller are the objective function, which can represent energy and cavitation performances well. Different surrogate models are constructed, and Global Sensitivity Analysis and Pareto Front method are used. The results show that, 1) Influence from phase angle on performances can be neglected compared with other two design variables, 2) Impact ratio of fixed angle of blades in two impellers on efficiency are the same as their designed loading distributions, which is 4:6, 3) The optimization results can enhance the trade-off performances well: efficiency is improved by 0.6%, and the MAPC is improved by 4.5%.
Global design optimization for an axial-flow tandem pump based on surrogate method
International Nuclear Information System (INIS)
Tandem pump, compared with multistage pump, goes without guide vanes between impellers. Better cavitation performance and significant reduction of the axial geometry scale is important for high-speed propulsion. This study presents a global design optimization method based on surrogated method for an axial-flow tandem pump to enhance trade-off performances: energy and cavitation performances. At the same time, interactions between impellers and impacts on the performances are analyzed. Fixed angle of blades in impellers and phase angle are performed as design variables. Efficiency and minimum average pressure coefficient (MAPC) on axial sectional surface in front impeller are the objective function, which can represent energy and cavitation performances well. Different surrogate models are constructed, and Global Sensitivity Analysis and Pareto Front method are used. The results show that, 1) Influence from phase angle on performances can be neglected compared with other two design variables, 2) Impact ratio of fixed angle of blades in two impellers on efficiency are the same as their designed loading distributions, which is 4:6, 3) The optimization results can enhance the trade-off performances well: efficiency is improved by 0.6%, and the MAPC is improved by 4.5%
An Unbroken Axial-Vector Current Conservation Law
Sharafiddinov, Rasulkhozha S.
2016-04-01
The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space in which a neutrino is characterized by left as well as by right space-time coordinates. Therefore, it is not surprising that whatever the main purposes experiments about a quasielastic axial-vector mass say in favor of an axial-vector mirror Minkowski space-time.
Improved axial flux shape generator for quick DNB test
International Nuclear Information System (INIS)
Axial power shapes that develop during power maneuvering in pressurized water reactors must be analyzed to ensure that adequate margin to avoid departure from nucleate boiling (DNB) is maintained during these transients. In order to reduce the number of flux shapes that need to be analyzed in detail to determine DNB ratio (DNBR), often generic axial flux shapes are analyzed and Maximum Allowable Peaking (MAP) limits are determined to conservatively filter those actual axial power shapes that are clearly safe. Current generic MAP limits, obtained for axial flux shapes, generated by a two-parameter based axial flux shape generator, are overly conservative for some power shapes and nonconservative for others leading to unnecessary operational restrictions on conservative cases. A penalty is imposed on nonconservative cases. In order to reduce the number of overly conservative and nonconservative cases, the authors have developed a new generic axial power shape generator, that is based on three parameters. Generic MAP limits have been developed for the new axial flux shape generator and tested using real flux shapes by plotting the percent deviation of MAP limits for generic flux shapes from the corresponding value for actual flux shapes. New axial flux shape generator, which is clearly superior as it leads to significantly lower percent deviation, will lead to reduced man-hours for detailed DNBR analyses and remove some of the unnecessary operational restrictions imposed by the old flux shape generator
A new approach to radial and axial gauges
Energy Technology Data Exchange (ETDEWEB)
Weigert, H.; Heinz, U. (Regensburg Univ. (Germany). Inst. fuer Theoretische Physik)
1992-10-01
We develop a new path integral formulation of QCD in radial and axial gauges. This formalism yields free propagators which are free of gauge poles. We find that radial gauges are ghost free. In axial gauges ghosts cannot generally be excluded from the formalism due to the need to fix the residual gauge freedom. (orig.).
Study of a new airfoil used in reversible axial fans
Li, Chaojun; Wei, Baosuo; Gu, Chuangang
1991-01-01
The characteristics of the reverse ventilation of axial flow are analyzed. An s shaped airfoil with a double circular arc was tested in a wind tunnel. The experimental results showed that the characteristics of this new airfoil in reverse ventilation are the same as those in normal ventilation, and that this airfoil is better than the existing airfoils used on reversible axial fans.
Sadowski, Tomasz
2016-01-01
This book discusses complex loadings of turbine blades and protective layer Thermal Barrier Coating (TBC), under real working airplane jet conditions. They obey both multi-axial mechanical loading and sudden temperature variation during starting and landing of the airplanes. In particular, two types of blades are analyzed: stationary and rotating, which are widely applied in turbine engines produced by airplane factories.
Aerothermal optimization of partially shrouded axial turbines[Dissertation 17138
Energy Technology Data Exchange (ETDEWEB)
Porreca, L.
2007-07-01
This work presents the results of an aerodynamic and thermal study of three different shrouded axial turbine configurations (turbomachinery). The blade geometry of the turbine stages and the tip clearances of the test cases under investigation are identical although the shroud design is different. The first test case (RRD) is representative of a full shroud geometry while the second (CPS) and third (EPS) test cases adopt different partial shroud arrangements. In the EPS case, a shroud platform is added to cover the blade throat. Partial shrouds are sometimes used in industrial application in order to benefit from the aerodynamic advantage of shrouded configuration as well as reducing thermal load and mechanical stress on the blade root. However, the optimal compromise between mechanical issues and aerodynamic performances is still an open issue due to the resulting highly 3-dimensional unsteady flow field, difficulty of achieve an optimal cooling and severe heat load on the shroud sealing fins. An experimental investigation is carried out in order to quantify the effect of the shroud geometry on the aerodynamic performances and to study the resultant flow field in all test cases. The analysis has been conducted in an experimental low-speed axial turbine facility at the Turbomachinery Laboratory at ETH Zurich. Steady and fast response aerodynamic probe technology (FRAP) has been used to characterize the flow field. Moreover, a stereoscopic PIV technique has been design and applied in this experimental facility for the first time. The flow field analysis shows that the effect of the shroud geometry is significant from 60% blade height span to the tip. Tip leakage vortex in the first rotor is originated in the partial shroud test cases while the full shroud case present only a weak indigenous tip passage vortex. Secondary flows development in the following second stator resulted to be greatly affected by the leakage/main flow interaction of the first rotor. The
Liu, Yunqiang; Xu, Jiuping; Wang, Shize; Qi, Bin
2013-01-01
The axial stress and deformation of high temperature high pressure deviated gas wells are studied. A new model is multiple nonlinear equation systems by comprehensive consideration of axial load of tubular string, internal and external fluid pressure, normal pressure between the tubular and well wall, and friction and viscous friction of fluid flowing. The varied temperature and pressure fields were researched by the coupled differential equations concerning mass, momentum, and energy equations instead of traditional methods. The axial load, the normal pressure, the friction, and four deformation lengths of tubular string are got ten by means of the dimensionless iterative interpolation algorithm. The basic data of the X Well, 1300 meters deep, are used for case history calculations. The results and some useful conclusions can provide technical reliability in the process of designing well testing in oil or gas wells. PMID:24163623
Directory of Open Access Journals (Sweden)
Yunqiang Liu
2013-01-01
Full Text Available The axial stress and deformation of high temperature high pressure deviated gas wells are studied. A new model is multiple nonlinear equation systems by comprehensive consideration of axial load of tubular string, internal and external fluid pressure, normal pressure between the tubular and well wall, and friction and viscous friction of fluid flowing. The varied temperature and pressure fields were researched by the coupled differential equations concerning mass, momentum, and energy equations instead of traditional methods. The axial load, the normal pressure, the friction, and four deformation lengths of tubular string are got ten by means of the dimensionless iterative interpolation algorithm. The basic data of the X Well, 1300 meters deep, are used for case history calculations. The results and some useful conclusions can provide technical reliability in the process of designing well testing in oil or gas wells.
Load Bearing Innovative Construction from Glass
Kalamar, R.; Eliášová, M.
2015-11-01
Glass plays an exceptional role in the modern architecture due to the optical properties and transparency. Structural elements from glass like beams, facades and roofs are relatively frequent in common practice [1]. Although glass has significantly higher compressive strength in comparison with tensile strength, load bearing glass elements are relatively rare. This opens up new opportunities for application of glass in such structures as transparent columns loaded by the axial force. This paper summarizes the experimental results of the tests on glass columns loaded by centric pressure, which were performed in the laboratories of the CTU in Prague, Faculty of Civil Engineering. The first set of experiments was composed of three specimens in a reduced scale 1:2 to verify real behaviour of the specimens with enclosed hollow cross-section. The main goal of the experiment was to determine force at the first breakage and consequently the maximal force at the collapse of this element.
Multimode interaction in axially excited cylindrical shells
Directory of Open Access Journals (Sweden)
Silva F. M. A.
2014-01-01
Full Text Available Cylindrical shells exhibit a dense frequency spectrum, especially near the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to a complex dynamic behavior. So, the aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under axial forcing with multiple equal or nearly equal natural frequencies. The shell is modelled using the Donnell nonlinear shallow shell theory and the discretized equations of motion are obtained by applying the Galerkin method. For this, a modal solution that takes into account the modal interaction among the relevant modes and the influence of their companion modes (modes with rotational symmetry, which satisfies the boundary and continuity conditions of the shell, is derived. Special attention is given to the 1:1:1:1 internal resonance (four interacting modes. Solving numerically the governing equations of motion and using several tools of nonlinear dynamics, a detailed parametric analysis is conducted to clarify the influence of the internal resonances on the bifurcations, stability boundaries, nonlinear vibration modes and basins of attraction of the structure.
Diagnosis of spondyloarthritis of the axial skeleton
International Nuclear Information System (INIS)
Conventional radiography is used as the first-line imaging test in evaluating the axial skeleton for manifestations of spondyloarthritis, which is a cover term for five entities: ankylosing spondylitis, psoriatric spondyloarthritis, reactive arthritis, enteropathic arthritis, and undifferentiated spondyloarthritis. However, as it often takes many years from the onset of clinical symptoms and the first appearance of radiographic changes, a cross-sectional imaging is warranted (CT and/or MRI) for early diagnosis. MRI sensitively detects early inflammatory stages of spondyloarthritis and can thus fill the gap by markedly reducing the interval between initial symptoms and diagnosis. The aim of this article is to show that all manifestations and forms of spondyloarthritis share the same pathogenetic inflammatory pattern, namely a mixture of bone destruction and bone proliferation: enthesis - enthesitis - enthesiophyte. An enthesis in the true sense is a fibrocartilaginous junction (uncalcified fibrocartilage - tidemark - calcified fibrocartilage) between a tendon, ligament, joint capsule, or fascia and bone. The sacroiliac joint is a special form, a so-called articular fibrocartilaginous enthesis. A wide range of images - including radiographs, CT scans, and MR images - will be presented to provide a comprehensive picture of the entheseal manifestations and inflammatory patterns of the sacroiliac joints, vertebral endplates and ridges, facet joints, costovertebral junctions, and spinal ligaments in spondyloarthritis. (orig.)
Analysis of SONACO axial cooling experiments
International Nuclear Information System (INIS)
The SONACO test rig contained a sodium-cooled, electrically heated 37-pin bundle. On this rig, a series of forced, mixed and natural convection experiments have been performed with the aim of contributing to the understanding of thermal-hydraulic phenomena and providing data for code validation for a subassembly at decay heat power level with low flow or stagnant coolant. The test section and especially the heater pins were equipped with an extensive number of chromel-alumel thermocouples. In addition, special permanent-magnet probes were used for measuring local velocities. In this paper we give a survey of results from axial cooling experiments, where heat was removed by natural convection to a cooling coil situated in the coolant channel (plenum) above the bundle. The experimental conditions led to turbulent convection with a slowly varying, large scale flow pattern. It is shown that a power tilt in the bundle reduces these fluctuations but does not eliminate them. For the uniformly heated bundle, aglebraic expressions for the average turbulent heat flux as well as for temperature and velocity fluctuations are derived from a second-moments model and compared with experimental data. Furthermore, heat transfer in the plenum and the consequences of the SONACO experiments for the coolability of reactor fuel elements under loss-of-flow conditions are discussed. ((orig.))
Axial change in semi-leptonic processes
International Nuclear Information System (INIS)
According to a general argument the time component AOof the axial current should have a large exchange current Aexch0due to a soft-pion exchange diagram the structure and magnitude of which are dictated by current algebra and the low-energy theorem. This implies that Aexch0carries valuable information on the role of chiral symmetry in nuclear medium, and many theoretical and experimental studies have been devoted to Aexch0 in the recent years. My talk surveys the latest developments in these studies. I first review the current status2 of analysis of the relevant Β decay data, paying particular attention to the assessment of nuclear physics uncertainties. I then discuss the observed extra enhancement of Aexch0 over the soft-pion prediction. Two possible explanations to this problem have been reported in the literature: (1) contributions of heavy- meson exchange processes; (2) higher-order terms in chiral perturbation expansion. I review critically these two different approaches and discuss a possible interrelation between them. Finally, I touch upon the relevance of Aexch0 to the in-medium value of the pseudoscalar form factor gp
The Klinger hot gas double axial valve
International Nuclear Information System (INIS)
The Klinger hot gas valve is a medium controlled double axial valve with advanced design features and safety function. It was first proposed by Klinger early in 1976 for the PNP-Project as a containment shut-off for hot helium (918 deg. C and 42 bar), because a market research has shown that such a valve is not state of present techniques. In the first stage of development a feasibility study had to be made by detailed design, calculation and by basic experiments for key components in close collaboration with Interatom/GHT. This was the basis for further design, calculation, construction and experimental work for such a valve prototype within the new development contract. The stage of knowledge to that time revealed the following key priority development areas: Finite element stress analysis for the highly stressed high temperature main components; development of an insulation layout; Detailed experimental tests of functionally important structural components or units of the valve, partly at Klingers (gasstatic bearings, flexible metallic sealing element, aerodynamic and thermohydraulic tests), partly at Interatom (actuator unit and also gasstatic bearings), partly at HRB in Juelich (flexible metallic sealing system, aerodynamic and thermohydraulic tests); Design of a test valve for experimental work in the KVK (test circuit at Interatom) for evaluation of temperature distribution and reliability of operation; Design of a prototype and extensive testing in the KVK
Axial channeling of boron ions into silicon
La Ferla, A.; Galvagno, G.; Raineri, V.; Setola, R.; Rimini, E.; Carbera, A.; Gasparotto, A.
1992-04-01
Channeling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5 × 10 11 and 1 × 10 15 atoms/cm 2. The axial channeling concentration profiles of implanted B + were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, Sc, was extracted from the experimental maximum ranges for the [100] and [110] axis. The energ dependence of the electronic stopping power is given by Sc = KEp with p[100] = 0.469±0.010 and p[110] = 0.554±0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles.
Axial channeling of boron ions into silicon
International Nuclear Information System (INIS)
Channeling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5x1011 and 1x1015 atoms/cm2. The axial channeling concentration profiles of implanted B+ were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, Sc, was extracted from the experimental maximum ranges for the [100] and [110] axis. The energy dependence of the electronic stopping power is given by Se = KEp with p[100] = 0.469±0.010 and p[110] = 0.554±0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles. (orig.)
Axial channeling of boron ions into silicon
Energy Technology Data Exchange (ETDEWEB)
La Ferla, A.; Galvagno, G. (Ist. di Tecnologie e Metodologie per la Microelettronica, CNR, Dipt. di Fisica, Catania (Italy)); Raineri, V.; Setola, R.; Rimini, E. (Dipt. di Fisica, Univ. di Catania (Italy)); Carnera, A.; Gasparotto, A. (Dipt. di Fisica, Univ. di Padova (Italy))
1992-04-01
Channeling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5x10{sup 11} and 1x10{sup 15} atoms/cm{sup 2}. The axial channeling concentration profiles of implanted B{sup +} were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, S{sub c}, was extracted from the experimental maximum ranges for the (100) and (110) axis. The energy dependence of the electronic stopping power is given by S{sub e} = KE{sup p} with p{sub (100)} = 0.469{+-}0.010 and p{sub (110)} = 0.554{+-}0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles. (orig.).
Paraska, Peter J.
1993-01-01
This report documents an analytical study of the response of unsymmetrically laminated cylinders subjected to thermally-induced preloading effects and compressive axial load. Closed-form solutions are obtained for the displacements and intralaminar stresses and recursive relations for the interlaminar shear stress were obtained using the closed-form intralaminar stress solutions. For the cylinder geometries and stacking sequence examples analyzed, several important and as yet undocumented effects of including thermally-induced preloading in the analysis are observed. It should be noted that this work is easily extended to include uniform internal and/or external pressure loadings and the application of strain and stress failure theories.
Directory of Open Access Journals (Sweden)
Beat eMeier
2015-06-01
Full Text Available In prospective memory tasks different kinds of load can occur. Adding a prospective memory task can impose a load on ongoing task performance. Adding ongoing task load can affect prospective memory performance. The existence of multiple target events increases prospective load and adding complexity to the to-be-remembered action increases retrospective load. In two experiments, we systematically examined the effects of these different types of load on prospective memory performance. Results showed an effect of prospective load on costs in the ongoing task for categorical targets (Experiment 2, but not for specific targets (Experiment 1. Retrospective load and ongoing task load both affected remembering the retrospective component of the prospective memory task. We suggest that prospective load can enhance costs in the ongoing task due to additional monitoring requirements. Retrospective load and ongoing task load seem to impact the division of resources between the ongoing task and retrieval of the retrospective component, which may affect disengagement from the ongoing task. In general, the results demonstrate that the different types of load affect prospective memory differentially.
Mechanical loading, damping, and load-driven bone formation in mouse tibiae.
Dodge, Todd; Wanis, Mina; Ayoub, Ramez; Zhao, Liming; Watts, Nelson B; Bhattacharya, Amit; Akkus, Ozan; Robling, Alexander; Yokota, Hiroki
2012-10-01
Mechanical loads play a pivotal role in the growth and maintenance of bone and joints. Although loading can activate anabolic genes and induce bone remodeling, damping is essential for preventing traumatic bone injury and fracture. In this study we investigated the damping capacity of bone, joint tissue, muscle, and skin using a mouse hindlimb model of enhanced loading in conjunction with finite element modeling to model bone curvature. Our hypothesis was that loads were primarily absorbed by the joints and muscle tissue, but that bone also contributed to damping through its compression and natural bending. To test this hypothesis, fresh mouse distal lower limb segments were cyclically loaded in axial compression in sequential bouts, with each subsequent bout having less surrounding tissue. A finite element model was generated to model effects of bone curvature in silico. Two damping-related parameters (phase shift angle and energy loss) were determined from the output of the loading experiments. Interestingly, the experimental results revealed that the knee joint contributed to the largest portion of the damping capacity of the limb, and bone itself accounted for approximately 38% of the total phase shift angle. Computational results showed that normal bone curvature enhanced the damping capacity of the bone by approximately 40%, and the damping effect grew at an accelerated pace as curvature was increased. Although structural curvature reduces critical loads for buckling in beam theory, evolution apparently favors maintaining curvature in the tibia. Histomorphometric analysis of the tibia revealed that in response to axial loading, bone formation was significantly enhanced in the regions that were predicted to receive a curvature-induced bending moment. These results suggest that in addition to bone's compressive damping capacity, surrounding tissues, as well as naturally-occurring bone curvature, also contribute to mechanical damping, which may ultimately affect
Axial electron channeling statistical method of site occupancy determination
Institute of Scientific and Technical Information of China (English)
YE; Jia
2001-01-01
［1］Johnson, W., Sowerby, R., Venter, R. D., Plane Strain Slip Line Fields for Metal Deformation Processes——A Source Book and Bibliography, New York: Pergamon Press, 1982.［2］Hill, R., The Mathematical Theory of Plasticity, Oxford: Oxford University Press, 1950.［3］Sokolovsky, V. V., Theory of Plasticity(in Russia), Moskow: Nat. Tech. Press, 1950.［4］Kachanov, L. M., Foundations Theory of Plasticity, London: North-Holland, 1975.［5］Shield, R. T., On the plastic flow of metal condition of axial symmetry, Proc. Roy. Soc., 1955, 233A: 267.［6］Lippmann, H., IUTAM Symposium on Metal Forming Plasticity, New York: Springer-Verlag, 1979.［7］Spencer, A. J. M., The approximate solution of certain problem of axially-symmetric plastic flow, J. Mech. Phys. Solids, 1964, 12: 231.［8］Wang, R., Xiong, Z. H., Wang, W. B., Foundation of Plasticity (in Chinese), Beijing: Science Press, 1982.［9］Collins, I. E., Dewhurst, P., A slip line field analysis of asymmetrical hot rolling, International Journal of Mechanical Science, 1975, 17: 643.［10］Collins, I. F., Slip line field analysis of forming processes in plane strain and axial symmetry, Advanced Technology of Plasticity, 1984, 11: 1074.［11］Yu, M. H., Yang, S. Y., Liu, C. Y. et al., Unified plane-strain slip line field theory system, J. Civil Engineering (in Chinese), 1997, 30(2): 14［12］Simmons, J. A., Hauser, F., Dorn, E., Mathematical Theories of Plastic Deformation Under Impulsive Loading, Berkeley-Los Angeles: University of California Press, 1962.［13］Lin, C. C., On a perturbation theory based on the method of characteristies, J. Math. Phys., 1954, 33: 117—134.［14］Hopkins, H. G., The method of characteristics and its applications to the theory of stress waver in solids, in Engineering Plasticity, Combridge: Combridge University Press, 1968, 277—315.［15］Shield, R. T., The plastic indentation of a layer by a flat punch, Quart. Appl. Math., 1955, 13: 27.［16］Haar, A., von
Free-edge delamination: Laminate width and loading conditions effects
Murthy, P. L. N.; Chamis, C. C.
1987-01-01
The width and loading conditions effects on free-edge stress fields in composite laminates are investigated using a three-dimensional finite element analysis. This analysis includes a special free-edge region refinement or superelement with progrssive substructuring (mesh refinement) and finite thickness interply layers. The different loading conditions include in-plane and out-of-plane bending, combined axial tension and in-plane shear, twisting, uniform temperature and uniform moisture. Results obtained indicate that: axial tension causes the smallest magnitude of interlaminar free edge stress compared to other loading conditions; free-edge delamination data obtained from laboratory specimens cannot be scaled to structural components; and composite structural components are not likely to delaminate.
Free-edge delamination - Laminate width and loading conditions effects
Murthy, Pappu L. N.; Chamis, Christos C.
1989-01-01
The width and loading conditions effects on free-edge stress fields in composite laminates are investigated using a three-dimensional finite element analysis. This analysis includes a special free-edge region refinement or superelement with progressive substructuring (mesh refinement) and finite thickness interply layers. The different loading conditions include in-plane and out-of-plane bending, combined axial tension and in-plane shear, twisting, uniform temperature and uniform moisture. Results obtained indicate that: axial tension causes the smallest magnitude of interlaminar free edge stress compared to other loading conditions; free-edge delamination data obtained from laboratory specimens cannot be scaled to structural components; and composite structural components are not likely to delaminate.
Refinement of non-synchronous vibrations prediction in axial compressors
Drolet, Martin
2011-12-01
Non-Synchronous Vibrations (NSV), along with classical flutter, are part of the Flow-Induced Vibrations (FIV) family observed in turbomachineries. FIV are typically caused by the interaction of the unsteady aerodynamic loading on a structure and the structure itself and can be generally classified into two categories, which are Forced Responses and Fluid-Elastic Instabilities. The latter regroups NSV and classical flutter. A number of NSV cases have been reported in the industry, in the front stages of axial compressors, and are typically known to cause high-cycle fatigue damages. However, the physical mechanism underlying NSV is not yet fully understood and universally accepted. Previous studies have suggested that the tip clearance flow oscillations, which are more likely to occur at large tip clearances and high aerodynamic blade loading, could explain NSV. It was also suggested that NSV could arise from the impingement of the tip clearance flow leakage on the blade pressure side and that the study of the dynamics of impinging jets could explain NSV. A model to predict the critical speed at which NSV are likely to occur was derived, based on the resonant impinging jet analogy. The model was statistically verified and experimentally demonstrated. Although the proposed model provides a very good approximation of the critical NSV speed, it was found very sensitive to what was defined as the "instability convection coefficient" (k). It was found from experiments that the proposed NSV model can only yield accurate predictions of the critical NSV speed if the k parameter is known. This work investigates NSV based on the proposed model and the resonant impinging jet analogy, mainly using CFD, to improve the critical NSV speed predictions. The results showed that the k parameter is influenced by both the tip clearance size and operating temperature. However, the dominant effect appears to come from the tip clearance size while the effect of temperature on k can be
Shin, Yoon Shik
The objective of this work was to conduct an experimental and numerical investigation of the noise radiated by a small-scale axial fan from two different points-of-view: the development of an inflow treatment to compensate for unfavorable inflow conditions that result in excessive noise, and a consideration of installation effects for the acoustic source type of small axial fans. The effect of disturbed inflow on axial fans was experimentally investigated by intentionally placing a blockage plate at four different locations upstream of a fan. The blocked inflow made the axial fan perform very poorly; the severely decreased pressure performance introduced an overly strong dependence of flow performance on pressure load condition. An inflow diffuser made from aluminum foam was suggested to improve the aerodynamic and acoustic performance of the axial fan under such unfavorable inflow conditions. The inflow diffuser improved the stability of flow performance and reduced the blade passing tone by a small amount, but the levels of the high frequency harmonics of the blade passing tone were increased. A corresponding numerical model was built to model the flow change due to the inflow foam treatment. The inflow foam diffuser was approximated as a homogeneous porous zone to make the computational cost affordable, and it was shown that the model can predict the foam's influence on the pressure and flow performance of the fan. The aeroacoustic analogy model was applied to the solid surfaces of the fan and its housing to simulate the tonal noise at the blade passing frequency. The validity of the homogeneous foam model in terms of aeroacoustic predictions was also confirmed. As for the second aspect of the axial fan noise source, the dipole-like source behavior of an axial fan at the blade passing frequency was verified by directivity measurements. Thus, dipole modeling of an axial fan was justified. This result is associated with the problem of overestimated fan source
Behavior of slender steel concrete composite columns in eccentric loading
Institute of Scientific and Technical Information of China (English)
ZHAO Gen-tian; ZHANG Meng-xi; LI Yong-he
2009-01-01
Ten slender steel reinforced cencrete (SRC) composite columns are tested under eccentric loading conditions.Effects of concrete strength, slenderness of columns and eccentricity of the axial load are studied. The load-carrying capacity is reduced with increased slenderness ratio and eccentricity. Concrete strength has no obvious influence on eccentrically loaded columns. Then, a nonlinear numerical method of pin-ended slender columns is also presented. This method is applicable for determining the material failure load or buckling failure load of a slender steel reinforced concrete composite column. In this method both material and geometric nonlinearities are taken into account. The results of numerical analysis accord well with the test results. The test results are also compared with the results predicted by ACI318-05 and the China Specifications.
Scale effect on wave propagation of double-walled carbon nanotubes with initial axial loading
Energy Technology Data Exchange (ETDEWEB)
Heireche, H; Benzair, A [Departement de physique, Universite de Sidi Bel Abbes, BP 89 Cite Ben M' hidi, 22000 Sidi Bel Abbes (Algeria); Tounsi, A [Laboratoire des Materiaux et Hydrologie, Universite de Sidi Bel Abbes, BP 89 Cite Ben M' hidi, 22000 Sidi Bel Abbes (Algeria)], E-mail: tou_abdel@yahoo.com
2008-05-07
This paper studies the vibrational characteristics of double-walled carbon nanotubes (DWNTs) with initial stress using a nonlocal Euler-Bernoulli beam model. Both the effect of initial stress and the effect of small length scale are discussed in detail. The effect of van der Waals forces is incorporated in the formulation. The corresponding resonant vibrational characteristics are presented in detail; they are shown to be very different from those predicted by classical elasticity theory when nonlocal effects are significant. The influence of initial stress in carbon nanotubes on their flexural vibration modes is dependent on the tension or compression form of the initial stress. The investigation of the effects of initial stress on transverse wave propagation in carbon nanotubes may be used as a useful reference for the application and the design of nanoelectronic and nanodrive devices, nano-oscillators, and nanosensors, in which carbon nanotubes act as basic elements.
Scale effect on wave propagation of double-walled carbon nanotubes with initial axial loading
International Nuclear Information System (INIS)
This paper studies the vibrational characteristics of double-walled carbon nanotubes (DWNTs) with initial stress using a nonlocal Euler-Bernoulli beam model. Both the effect of initial stress and the effect of small length scale are discussed in detail. The effect of van der Waals forces is incorporated in the formulation. The corresponding resonant vibrational characteristics are presented in detail; they are shown to be very different from those predicted by classical elasticity theory when nonlocal effects are significant. The influence of initial stress in carbon nanotubes on their flexural vibration modes is dependent on the tension or compression form of the initial stress. The investigation of the effects of initial stress on transverse wave propagation in carbon nanotubes may be used as a useful reference for the application and the design of nanoelectronic and nanodrive devices, nano-oscillators, and nanosensors, in which carbon nanotubes act as basic elements
International Nuclear Information System (INIS)
One of the most limiting situations for the analysis of the fuel rod integrity under hypothetical transportation accident is the end drop impact of the cask system for the 9 meter free drop. In this situation, fuel rod buckling is produced and its lateral deflection is only limited by adjacent rods or by the wall of the cask basket. The integrity of the fuel rod cladding is usually demonstrated by limiting the maximum stress to the yield stress or by limiting the maximum deformation to that of the ultimate strain. Different approaches based on different assumptions have been followed in order to calculate this integrity, concerning the participation of the fuel mass, about the additional stiffness provided by the fuel column or about the constraints limiting the lateral deflection of the rod. This paper presents an evaluation of the response of an irradiated fuel rod with reduced cladding section to account for waterside corrosion, and placing the focus on the influence of the lateral gap sizes. For that purpose, several FEM models have been developed in ANSYS code. Fuel rod behavior inside the storage basket during a potential accident of a cask system free drop condition has been studied. The relationship between the lateral gap size and the maximum acceleration that the fuel rod can support before yielding is presented, and conclusions on the lateral gap assumptions are drawn. (author)
Time-Dependent Behavior of Reinforced Polymer Concrete Columns under Eccentric Axial Loading
Directory of Open Access Journals (Sweden)
Valentino Paolo Berardi
2012-11-01
Full Text Available Polymer concretes (PCs represent a promising alternative to traditional cementitious materials in the field of new construction. In fact, PCs exhibit high compressive strength and ultimate compressive strain values, as well as good chemical resistance. Within the context of these benefits, this paper presents a study on the time-dependent behavior of polymer concrete columns reinforced with different bar types using a mechanical model recently developed by the authors. Balanced internal reinforcements are considered (i.e., two bars at both the top and bottom of the cross-section. The investigation highlights relevant stress and strain variations over time and, consequently, the emergence of a significant decrease in concrete’s stiffness and strength over time. Therefore, the results indicate that deferred effects due to viscous flow may significantly affect the reliability of reinforced polymer concrete elements over time.
Interaction of bending and axial load for ferritic stainless steel RHS columns
Arrayago Luquin, Itsaso; Picci, F; Mirambell Arrizabalaga, Enrique; Real Saladrigas, Esther
2015-01-01
Stainless steels are ideal for sustainable structural performances due to their excellent corrosion resistance, appropriate mechanical properties, aesthetic appearance and easy maintenance. However, the nonlinear behaviour and strain-hardening effects characterizing these materials make them different from carbon steel and some specific guidance is necessary. Although some investigations regarding the behaviour of stainless steel beam-columns subjected to combined compression and bending mome...
Measuring axial gas loadings acting on the rotor of centrifugal compressor with magnetic bearings
Евгеньев, С. С.; Футин, В. А.
2014-01-01
Точное определение осевых газовых нагрузок, действующих на ротор центробежного компрессора, позволяет повысить надежность и долговечность компрессора. На основе экспериментальных данных и расчетов по известному методу определены осевые газовые нагрузки, действующие на закрытое рабочее колесо. Представлена методика определения осевых газовых нагрузок, действующих на ротор центробежного компрессора, включающая тарировку осевого канала магнитного подвеса и измерение силы тока в осевых электромаг...
Directory of Open Access Journals (Sweden)
Suryani Samsudin
2013-02-01
Full Text Available The development of precast sandwich concrete has gained acceptance worldwide in conjunction with the Industrial Building System (IBS. The advancement and improvement of using wall panel has gone through a lot of achievements through the last decade. The usage of precast lightweight sandwich panel has become the alternative to conventional construction using brick wall. The usage of this panel system contributes to a sustainable and environmental friendly construction. This paper presents an overview of the latest development in precast concrete sandwich panel as an IBS. The purpose of this paper is to provide comprehensive information on latest research development of sandwich panel for building construction purposes. The information on sandwich panel’s composition, material, properties, strength, availability, and its usage as structural element are reported. An innovative concept used in the design of these systems and the use of lightweight materials is also discussed.
International Nuclear Information System (INIS)
This is essentially a revised version of Report GH-15, July 1978. The revision was necessitated by recognition of the fact that the Vaughan-Florence analysis (J. Applied Mechanics, 1970), while correctly stating the governing membrane deflection equation, used, for numerical convenience, a simplified version, omitting a hoop restoring force term. This approach led to excessive deformations. The present report incorporates the hoop restoring term which in GH-15, following in the footsteps of VF, was omitted. The results now come out much more favorably than before
International Nuclear Information System (INIS)
The influence of the choice of flow stress on the plastic collapse estimation of axially cracked steam generator (SG) tubes is considered. The plastic limit and collapse loads of thick-walled tubes with external axial semi-elliptical surface cracks are investigated by three-dimensional non-linear finite element (FE) analyses. The limit pressure solution as a function of the crack depth, length and tube geometry has been developed on the basis of extensive FE limit load analyses employing the elastic-perfectly plastic material behaviour and small strain theory. Unlike the existing solutions, the newly developed analytical approximation of the plastic limit pressure for thick-walled tubes is applicable to a wide range of crack dimensions. Further, the plastic collapse analysis with a real strain-hardening material model and a large deformation theory is performed and an analytical approximation for the estimation of the flow stress is proposed. Numerical results show that the flow stress, defined by some failure assessment diagram (FAD) methods, depends not only on the tube material, but also on the crack geometry. It is shown that the plastic collapse pressure results, in the case of deeper cracks obtained by using the flow stress as the average of the yield stress and the ultimate tensile strength, can become unsafe
THE CONSTITUTIVE RELATION OF CRACK-WEAKENED ROCK MASSES UNDER AXIAL-DIMENSIONAL UNLOADING
Institute of Scientific and Technical Information of China (English)
Xiaoping Zhou; Qihu Qian; Yongxing Zhang
2008-01-01
An accurate and effcient numerical method for solving the crack-crack interaction problem is presented.The method is mainly by means of the dislocation model,stress superposition principle and Chebyshev polynomial expansion of the pseudo-traction.This method can be applied to compute the stress intensity factors of multiple kinked cracks and multiple rows of periodic cracks as well as the overall strains of rock masses containing multiple kinked cracks under complex loads.Many complex computational examples are given.The dependence of the crack-crack interaction on the crack configuration,the geometrical and physical parameters,and loads pattern,is investigated.By comparison with numerical results under confining pressure unloading,it is shown that the crack-crack interaction under axial-dimensional unloading is weaker than those under confining pressure unloading.Numerical results for single faults and crossed faults show that the single faults are more unstable than the crossed faults.It is found from numerical results for different crack lengths and different crack spacing that the interaction among kinked cracks decreases with an increase in length of the kinked cracks and the crack spacing under axial-dimensional unloading.
Performance Evaluation of Axial Flow AG-1 FC and Prototype FM (High Strength) HEPA Filters - 13123
Energy Technology Data Exchange (ETDEWEB)
Giffin, Paxton K.; Parsons, Michael S.; Wilson, John A.; Waggoner, Charles A. [Institute for Clean Energy Technology, Mississippi State University, 205 Research Blvd Starkville, MS 39759 (United States)
2013-07-01
High efficiency particulate air (HEPA) filters are routinely used in DOE nuclear containment activities. The Nuclear Air Cleaning Handbook (NACH) stipulates that air cleaning devices and equipment used in DOE nuclear applications must meet the American Society of Mechanical Engineers (ASME) Code on Nuclear Air and Gas Treatment (AG-1) standard. This testing activity evaluates two different axial flow HEPA filters, those from AG-1 Sections FC and FM. Section FM is under development and has not yet been added to AG-1 due to a lack of qualification data available for these filters. Section FC filters are axial flow units that utilize a fibrous glass filtering medium. The section FM filters utilize a similar fibrous glass medium, but also have scrim backing. The scrim-backed filters have demonstrated the ability to endure pressure impulses capable of completely destroying FC filters. The testing activities presented herein will examine the total lifetime loading for both FC and FM filters under ambient conditions and at elevated conditions of temperature and relative humidity. Results will include loading curves, penetration curves, and testing condition parameters. These testing activities have been developed through collaborations with representatives from the National Nuclear Security Administration (NNSA), DOE Office of Environmental Management (DOE-EM), New Mexico State University, and Mississippi State University. (authors)
Directory of Open Access Journals (Sweden)
F. Aguilar Parés
1999-01-01
Full Text Available Durante el movimiento de un material en un transportador de sinfín surge una fuerza en dirección axial que influye en laselección de uno de los cojinetes de apoyo del equipo. En el artículo aparecen algunas soluciones constructivas que tienen encuentan la fuerza axial. Por otro lado se establece la relación entre la fuerza axial y el empuje axial y se precisa de quiendepende el sentido del empuje axial. Por último se propone un modelo matemático que relaciona la fuerza axial con la potenciarequerida por el equipo.Palabras claves: Transportador de sinf in, fuerza axial , empuje axial ._________________________________________________________________________AbstractDuring the movement of material in a screw conveyor surge a force in axial direction that influence in the selection of one ofthe equipment support bearings. Some constructive solutions appear in the article for considering the axial force. In the otherhand it is established the relation between axial force and axial thurst and it is precised whose direction thurst axial depend of.Finally it is proposed a mathematic model that relates the axial force with the power required by the equipment.Key words: Screw conveyor, axial force, axial thurst .
Neutronal aspects of PWR control for transient load following
International Nuclear Information System (INIS)
The purpose of this thesis is to qualify the CRONOS diffusion code on a load transient in grey mode control. First of all, we have established a general axial calculational model and studied the important physical phenomena: xenon oscillation, grey rods absorption, radial leaks modelling, effect of the initial conditions in Iodine and Xenon. In a second stage, a three dimensional calculation has been performed, the results of which have been compared to a PWR 900 TRICASTIN 3 experiment and have been in good agreement. In the last part, we show that the results of the axial model using one-dimensional CRONOS calculations are quite consistent with the three-dimensional calculation
An update on biomarkers in axial spondyloarthritis.
Prajzlerová, Klára; Grobelná, Kristýna; Pavelka, Karel; Šenolt, Ladislav; Filková, Mária
2016-06-01
Axial spondyloarthritis is a chronic inflammatory disease with the onset at a young age, and, if undiagnosed and untreated, it may result in permanent damage and lifelong disability. Rates of early diagnosis have improved, due in particular to the addition of magnetic resonance imaging into the diagnostic armamentaria; however, it is costly, not widely available, and requires experienced readers to interpret the findings. In addition to clinical measures and imaging techniques, biomarkers that will be described in this review may represent useful tools for diagnosis, monitoring disease activity and outcomes as well as therapeutic responses. Currently, HLA-B27 remains the best genetic biomarker for making a diagnosis, while CRP currently appears to be the best circulating measure for assessing disease activity, predicting structural progression and therapeutic response. Interestingly, key molecules in the pathogenesis of the disease and essential therapeutic targets, such as tumour necrosis factor (TNF)α, interleukin (IL)-17 and IL-23, show only limited association with disease characteristics or disease progression. Some genetic biomarkers and particularly anti-CD74 antibodies, may become a promising tool for the early diagnosis of axSpA. Further biomarkers, such as matrix metalloproteinases (MMP)-3, calprotectin (S100A8/9), vascular endothelial growth factor (VEGF), C-terminal telopeptide of type II collagen (CTX-II) or dickkopf-1 (DKK-1), are not sufficient to reflect disease activity, but may predict spinal structural progression. In addition, recent data have shown that monitoring calprotectin might represent a valuable biomarker of therapeutic response. However, all of these results need to be confirmed in large cohort studies prior to use in daily clinical practice. PMID:26851549
The influence of mechanical loading on osseointegration: an animal study
Institute of Scientific and Technical Information of China (English)
FAN YuBo; XIU KaiHua; DONG Xiang; ZHANG Ming
2009-01-01
Osseointegration of implant provides a stable support for the prosthesis under functional loads. The timing of loading is a critical parameter that can govern the success of the osseointegration of implant. However, it is not clear whether the early loading can affect the success of osseointegration, or whether the no-loading healing period can be shortened. This paper presents an animal study conducted to investigate how external loads influence the osseointegration at the initial stage of healing. Titanium implants were inserted into the goat tibia laterally, and different axial Ioadings were applied to the im-plants in 4 weeks after surgery. After the 2 weeks period of early loading, animals were sacrificed and the tibia bones with the implants were cut off from the bodies. Then mechanical test was employed to find out the differences in the pull-out force, and shear strength at the bone-implant interface between the non-loaded and the loaded implants. The implant-bone interfaces were analyzed by histomor-phometric method, SEM (scanning electron micrograph) and EDS (energy density spectrum). The re-sults indicated that the bone-implant interface did not well integrate 4 weeks after surgery, and the fi-brous tissue could be found at the interfaces of the specimens without Ioadings. While the results of loaded specimens with 10 N axial force showed that that parts of the interface were well integrated, indicating that the early mild loading may play a positive role in the process of the osseointegration. The results support that a certain range of external loading would influence the process of osseointe, gration, and appropriate mechanical loading can be applied to shorten the osseointegration period after surgery.
Gravitational waves from the axial perturbations of hyperon stars
Institute of Scientific and Technical Information of China (English)
Wen De-Hua; Yan Jing; Liu Xue-Mei
2012-01-01
The eigen-frequencies of the axial w-mode oscillations of hyperon stars are examined.It is shown that as the appearance of hyperons softens the equation of state of the super-density matter,the frequency of gravitational waves from the axial w-mode of hyperon star becomes smaller than that of a traditional neutron star at the same stellar mass.Moreover,the eigenfrequencies of hyperon stars also have scaling universality.It is shown that the EURO thirdgeneration gravitational-wave detector has the potential to detect the gravitational-wave signal emitted from the axial w-mode oscillations of a hyperon star.
Tensile Property of Bi-axial Warp Knitted Structure
Institute of Scientific and Technical Information of China (English)
沈为
2003-01-01
The tensile property of bi-axial warp knitted fabrics is tested and compared with that of the plain weave fabric. The results show that there are obvious differences between the tensile property of a bi-axial warp knitted fabric and that of a plain weave fabric.The former can give fuller play to the property of a high modulus yarn than the latter. The tensile strength of a bi-axial warp knitted fabric is linear with the number of yarns in the direction of force.
The axial charges of the hidden-charm pentaquark states
Wang, Guang-Juan; Zhu, Shi-Lin
2016-01-01
With the chiral quark model, we have calculated the axial charges of the pentaquark states with $(I,I_3)=(\\frac{1}{2},\\frac{1}{2})$ and $J^{P}=\\frac{1}{2}^{\\pm},\\frac{3}{2}^{\\pm},\\frac{5}{2}^{\\pm}$. The $P_c$ states with the same $J^P$ quantum numbers but different color-spin-flavor configurations have very different axial charges, which encode important information on their underlying structures. For some of the $J^{P}=\\frac{3}{2}^{\\pm}$ or $\\frac{5}{2}^{\\pm}$ pentaquark states, their axial charges are much smaller than that of the proton.
Effects of external axial magnetic field on fast electron propagation
International Nuclear Information System (INIS)
A scheme employing an external axial magnetic field is proposed to diagnose the intrinsic divergence of laser-generated fast electron beams, and this is studied numerically with hybrid simulations. The maximum beam radius of fast electrons increases with the initial divergence and decreases with the amplitude of the axial magnetic field. It is indicated that the intrinsic divergence of fast electrons can be inferred from measurements of the beam radius at different depth under the axial field. The proposed scheme here may be useful for future fast ignition experiments and in other applications of laser-generated fast electron beams.
Dynamic Analysis of Axial Magnetic Forces for DVD Spindle Motors
Institute of Scientific and Technical Information of China (English)
2000-01-01
The axial magnetic force, induced by the complicated flux linkage distribution from rotor magnet and stator slotted, is constructed by different relative heights and calculated by 3D finite element method (FEM) to analyze the dynamic characteristics for a DVD spindle motor. The axial magnetic force is designed to provide an axial stiffness and govern the natural frequency of the dynamic performance. According to the simulation results and experimental measurements, the dynamic behaviors are significantly improved with a variation of relative height of rotor magnet and stator slotted on a DVD spindle motor.
A non-integral, axial-force measuring element
Ringel, M.; Levin, D.; Seginer, A.
1989-10-01
A new approach to the measurement of the axial force is presented. A nonintegral axial-force measuring element, housed within the wind-tunnel model, avoids the interactions that are caused by nonlinear elastic phenomena characteristic of integral balances. The new design overcomes other problems, such as friction, misalignment and relative motion between metric elements, that plagued previous attempts at separate measurement of the axial force. Calibration and test results prove the ability of the new approach to duplicate and even surpass the results of much more complicated and expensive integral balances. The advantages of the new design make it the best known solution for particular measurement problems.
Electrical load detection aparatus
DEFF Research Database (Denmark)
2010-01-01
A load detection technique for a load comprising multiple frequency-dependant sub-loads comprises measuring a representation of the impedance characteristic of the load; providing stored representations of a multiplicity of impedance characteristics of the load; each one of the stored representat...
AXIAL: a system for boiling water reactor fuel assembly axial optimization using genetic algorithms
International Nuclear Information System (INIS)
A system named AXIAL is developed based on the genetic algorithms (GA) optimization method, using the 3D steady state simulator code Core-Master-PRESTO (CM-PRESTO) to evaluate the objective function. The feasibility of this methodology is investigated for a typical boiling water reactor (BWR) fuel assembly (FA). The axial location of different fuel compositions is found in order to minimize the FA mean enrichment needed to obtain the cycle length under the safety constraints. Thermal limits are evaluated at the end of cycle using the Haling calculation; the hot excess reactivity and the shutdown margin at the beginning of cycle are also evaluated. The implemented objective function is very flexible and complete, incorporating all the thermal and reactivity limits imposed during fuel design analysis; furthermore, additional constraints can be easily introduced in order to obtain an improved solution. The results show a small improvement in the FA average enrichment obtained with the system related to the reference case that has been studied. The results show that the system converge to an optimal solution, it is observed that the mean fuel enrichment decreases while all the constraints are satisfied. A comparison was also performed using one-point and two-points crossover operator and the results of a sensitivity study for different mutation percentage are also showed
Gearbox Reliability Collaborative Investigation of High-Speed-Shaft Bearing Loads
Energy Technology Data Exchange (ETDEWEB)
Keller, Jonathan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Guo, Yi [National Renewable Energy Lab. (NREL), Golden, CO (United States)
2016-06-01
The loads and contact stresses in the bearings of the high speed shaft section of the Gearbox Reliability Collaborative gearbox are examined in this paper. The loads were measured though strain gauges installed on the bearing outer races during dynamometer testing of the gearbox. Loads and stresses were also predicted with a simple analytical model and higher-fidelity commercial models. The experimental data compared favorably to each model, and bearing stresses were below thresholds for contact fatigue and axial cracking.
Enhancement of implant osseointegration by high-frequency low-magnitude loading
Zhang, Xiaolei; A Torcasio; Vandamme, Katleen; Ogawa, Toru; van Lenthe, Harry; Naert, Ignace; Duyck, Joke
2012-01-01
Abstract Background Mechanical loading is known to play an important role in bone remodelling. This study aimed to evaluate the effect of high- and low-frequency axial loading, applied directly to the implant, on peri-implant bone healing and implant osseointegration. Methodology Titanium implants were bilaterally installed in rat tibiae. For every animal, one implant was loaded (test) while the other one was not (control). The test implants were randomly divided into 8 groups ac...
Md. Abu Mowazzem Hossain; Md. Tariqul Hasan; Sung-Tae Hong; Michael Miles; Hoon-Hwe Cho; Heung Nam Han
2014-01-01
Mechanical properties and failure behaviors of friction stir spot welded (FSSW) joints of two dissimilar ferrous alloys, cold-rolled carbon steel (SPCC) and 409L stainless steel (SUS 409L), are investigated under opening-dominant combined loads. The texture of dissimilar FSSW joints depends on the upper sheet material. The failure contours for the FSSW joints under combined loads are constructed in terms of the axial load and shear load by modifying existing failure criteria for resistance sp...
Distribution load estimation (DLE)
Energy Technology Data Exchange (ETDEWEB)
Seppaelae, A.; Lehtonen, M. [VTT Energy, Espoo (Finland)
1998-08-01
The load research has produced customer class load models to convert the customers` annual energy consumption to hourly load values. The reliability of load models applied from a nation-wide sample is limited in any specific network because many local circumstances are different from utility to utility and time to time. Therefore there is a need to find improvements to the load models or, in general, improvements to the load estimates. In Distribution Load Estimation (DLE) the measurements from the network are utilized to improve the customer class load models. The results of DLE will be new load models that better correspond to the loading of the distribution network but are still close to the original load models obtained by load research. The principal data flow of DLE is presented
The Deformation Behavior of TiNi Shape Memory Alloy under Axial Dynamic Compression
Institute of Scientific and Technical Information of China (English)
HUANG Xue-wen; DONG Guang-neng; ZHOU Zhong-rong; XIE You-bai
2004-01-01
The deformation behavior of Ti-50.9at%Ni shape memory alloy under axial compression dynamic loads was investigated by an MTS 858Mini Bionix test machine. The alloy were aged at 500℃ for an hour before being machined into specimens. The compression experiments were conducted at 20℃ and the variety of dynamic loads were controlled by the strain rate, which was 3mm/min, 15mm/min, 30mm/min and 50mm/min, respectively. The experimental results indicate that in the case of 3mm/min, stress-induced martensitic transformation occurs at about 350MPa when loading and reverse transformation at about 200MPa when unloading, during which the aged Ti-50.9at%Ni alloy shows the recoverable nonlinear pseudoelastic strain of 4.3% with the residual strain of 1.2% reserved. With the strain rate increasing, the area encloses by loading-curve and unloading-curve, i.e stress (strain) hysteresis becomes smaller and smaller and the residual strain also decreases, while critical stress for inducing martensitic transformation rises. At a higher strain rate the alloy exhibits linear-like pseudoelasticity, which is up to 4.5%.
Axial strength of cement borehole plugs in granite and basalt. Topical report on rock mass sealing
International Nuclear Information System (INIS)
This report describes experimental and theoretical studies of the axial strength of cement plugs installed in boreholes drilled coaxially in granite and in basalt cylinders. Experimental work has consisted of loading the cement plugs to failure while measuring loads and displacements. Such tests have been performed on borehole plugs with a diameter and a length ranging from 2.5 cm to 10 cm. Results from over one hundred experiments show that the strength is high, sufficient for anticipated loads at repository depths, but very variable, complicating the design of very short plugs. Significant residual strength (thirty to fifty percent of the peak strength) is observed. A frictional model of the interface shear strength, tau = c + sigma(tan phi), in combination with the assumption of an exponential shear stress distribution or plug-rock load transfer, provides the simplest realistic model for plug strength characterization. The integrated strength thus calculated compares moderately well with experimental results. An extensive review is given of more sophisticated analysis procedures that should be of value for general plug design applications. Generic analyses and their implications for plug performance are included. Variability of experimental results complicates the assessment of their direct detailed applicability. 115 references, 70 figures, 19 tables
Time Domain Terahertz Axial Computed Tomography Non Destructive Evaluation Project
National Aeronautics and Space Administration — We propose to demonstrate key elements of feasibility for a high speed automated time domain terahertz computed axial tomography (TD-THz CT) non destructive...
Time Domain Terahertz Axial Computed Tomography Non Destructive Evaluation Project
National Aeronautics and Space Administration — In this Phase 2 project, we propose to develop, construct, and deliver to NASA a computed axial tomography time-domain terahertz (CT TD-THz) non destructive...
Numerical analysis of cocurrent conical and cylindrical axial cyclone separators
Nor, M. A. M.; Al-Kayiem, H. H.; Lemma, T. A.
2015-12-01
Axial concurrent liquid-liquid separator is seen as an alternative unit to the traditional tangential counter current cyclone due to lower droplet break ups, turbulence and pressure drop. This paper presents the numerical analysis of a new conical axial cocurrent design along with a comparison to the cylindrical axial cocurrent type. The simulation was carried out using CFD technique in ANSYS-FLUENT software. The simulation results were validated by comparison with experimental data from literature, and mesh independency and quality were performed. The analysis indicates that the conical version achieves better separation performance compared to the cylindrical type. Simulation results indicate tangential velocity with 8% higher and axial velocity with 80% lower recirculation compared to the cylindrical type. Also, the flow visualization counters shows smaller recirculation region relative to the cylindrical unit. The proposed conical design seems more efficient and suits the crude/water separation in O&G industry.
CT of posterior ocular staphyloma in axial myopia
International Nuclear Information System (INIS)
We present two cases of posterior ocular staphylomas in axial myopia. CT findings of an enlarged globe with focal posterior bulging and scleraluveal rim thinning appear to be specific for this diagnosis. (orig.)
Effect of axial heat flux distribution on CHF
International Nuclear Information System (INIS)
Previous investigations for the effect of axial heat flux distributions on CHF and the prediction methods are reviewed and summarized. A total of 856 CHF data in a tube with a non-uniform axial heat flux distribution has been compiled from the articles and analyzed using the 1995 Groeneveld look-up table. The results showed that two representative correction factors, K5 of the look-up table and Tongs F factor, can be applied to describe the axial heat flux distribution effect on CHF. However, they overpredict slightly the measured CHF, depending on the quality and flux peak shape. Hence, a corrected K5 factor, which accounts for the axial heat flux distribution effect is suggested to correct these trends. It predicted the CHF power for the compiled data with an average error of 1.5% and a standard deviation of 10.3%, and also provides a reasonable prediction of CHF locations
CT of posterior ocular staphyloma in axial myopia
Energy Technology Data Exchange (ETDEWEB)
Swayne, L.C.; Garfinkle, W.B.; Bennett, R.H.
1984-05-01
We present two cases of posterior ocular staphylomas in axial myopia. CT findings of an enlarged globe with focal posterior bulging and scleraluveal rim thinning appear to be specific for this diagnosis.
In-phase and out-of-phase axial-torsional fatigue behavior of Haynes 188 at 760 C
Kalluri, Sreeramesh; Bonacuse, Peter J.
1991-01-01
Isothermal, in-phase and out-of-phase axial-torsional fatigue experiments have been conducted at 760 C on uniform gage section, thin-walled tubular specimens of a wrought cobalt-base superalloy, Haynes 188. Test-control and data acquisition were accomplished with a minicomputer. Fatigue lives of the in- and out-of-phase axial-torsional fatigue tests have been estimated with four different multiaxial fatigue life prediction models that were developed primarly for predicting axial-torsional fatigue lives at room temperature. The models investigated were: (1) the von Mises equivalent strain range; (2) the Modified Multiaxiality Factor Approach; (3) the Modified Smith-Watson-Topper Parameter; and (4) the critical shear plane method of Fatemi, Socie, and Kurath. In general, life predictions by the von Mises equivalent strain range model were within a factor of 2 for a majority of the tests and the predictions by the Modified Multiaxiality Factor Approach were within a factor of 2, while predictions of the Modified Smith-Watson-Topper Parameter and of the critical shear plane method of Fatemi, Socie, and Kurath were unconservative and conservative, respectively, by up to factors of 4. In some of the specimens tested under combined axial-torsional loading conditions, fatigue cracks initiated near extensometer indentations. Two design modifications have been proposed to the thin-walled tubular specimen to overcome this problem.
The development of an axial active magnetic bearing / R. Gouws
Gouws, Rupert
2004-01-01
In this dissertation, the author presents the operation and development of active magnetic bearings (AMBs) , with specific focus on axial M s . The project objective is the development of an axial AMB system. The electromagnetic design, inductive sensor design, dSpace controller model design and actuating amplifier design are aspects discussed in this dissertation. The physical model constitutes two electromagnets positioned above and beneath a 2 kg steel disc with an air gap o...
Design and Simulation of Axial Flow Maglev Blood Pump
Huachun Wu; Ziyan Wang; Xujun Lv
2011-01-01
The axial flow maglev blood pump (AFMBP) has become a global research focus and emphasis for artificial ventricular assist device, which has no mechanical contact, mechanical friction, compact structure and light weight, can effectively solve thrombus and hemolysis. Magnetic suspension and impeller is two of the important parts in the axial flow maglev blood pump, and their structure largely determines the blood pump performance. The research adopts electromagnetic and fluid finite element an...
Radial breathing mode of carbon nanotubes subjected to axial pressure
Lei, Xiao-Wen; Ni, Qing-Qing; Shi, Jin-Xing; Natsuki, Toshiaki
2011-01-01
In this paper, a theoretical analysis of the radial breathing mode (RBM) of carbon nanotubes (CNTs) subjected to axial pressure is presented based on an elastic continuum model. Single-walled carbon nanotubes (SWCNTs) are described as an individual elastic shell and double-walled carbon nanotubes (DWCNTs) are considered to be two shells coupled through the van der Waals force. The effects of axial pressure, wave numbers and nanotube diameter on the RBM frequency are investigated in detail. Th...
Nuclear Axial Currents in Chiral Effective Field Theory
Baroni, A.; Girlanda, L.; Pastore, S.; Schiavilla, R.; Viviani, M
2015-01-01
Two-nucleon axial charge and current operators are derived in chiral effective field theory up to one loop. The derivation is based on time-ordered perturbation theory, and accounts for cancellations between the contributions of irreducible diagrams and the contributions due to non-static corrections from energy denominators of reducible diagrams. Ultraviolet divergencies associated with the loop corrections are isolated in dimensional regularization. The resulting axial current is finite and...
Axial myopia in computed and magnetic resonance tomography
International Nuclear Information System (INIS)
The case of a 44-year old woman suffering from amblyopia on the left eye with unilateral proptosis caused by axial (progressive) myopia is presented. The clinical and radiological findings were discussed in reference to the literature. The diagnosis was established by ruling out neoplastic, inflammatory or endocrine causes for the exophtalmos. CT and MR scans revealed an enlarged left globe without evidence of orbital masses. The findings were regarded as typical for the diagnosis at axial myopia. (orig.)
Watson's theorem and the $N\\Delta(1232)$ axial transition
Alvarez-Ruso, L; Nieves, J; Vacas, M J Vicente
2016-01-01
We present a new determination of the $N\\Delta$ axial form factors from neutrino induced pion production data. For this purpose, the model of Hernandez et al., Phys. Rev. D76, 033005 (2007) is improved by partially restoring unitarity. This is accomplished by imposing Watson's theorem on the dominant vector and axial multipoles. As a consequence, a larger $C_5^A(0)$, in good agreement with the prediction from the off-diagonal Goldberger-Treiman relation, is now obtained.
Volume Dependence of the Axial Charge of the Nucleon
Hall, N. L.; Thomas, A. W.; Young, R.D.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005, Australia); Zanotti, J. M.
2012-01-01
It is shown that the strong volume-dependence of the axial charge of the nucleon seen in lattice QCD calculations can be understood quantitatively in terms of the pion-induced interactions between neighbouring nucleons. The associated wave function renormalization leads to an increased suppression of the axial charge as the strength of the interaction increases, either because of a decrease in lattice size or in pion mass.
Passive axial stabilization of a magnetic radial bearing by superconductors
Energy Technology Data Exchange (ETDEWEB)
Marinescu, M.; Marinescu, N. (Ing.-Buro f. Magnettechnik, Mailander Str.19, D-6000 Frankfurt/M. 70 (DE)); Tenbrink, J.; Krauth, H. (Vacuumschmelze GmbH, Gruner Weg 37, D-6450 Hanau (DE))
1989-09-01
Contactless bearings for high-speed operation can be constructed using passive magnet systems, which inherently need a second, active bearing for their stabilization. Completely passive bearings only can be obtained using diamagnetic materials. This study deals with the axial stabilization of magnetic radial bearings using a permanent magnet/superconductor system. Using finite element calculation procedures it is shown that axial forces of up 3000 N and stiffnesses of up to 400 N/mm may be achieved.
Organo-Axial Volvulus of the Stomach with Diaphragmatic Eventration
Lee, June Sung; Park, Jae Wan; Sohn, Jang Won; Kim, Kyung Chul; Hwang, Seong Gyu; Park, Pil Won; Rim, Kyu Sung; Kim, Hee Jin
2000-01-01
Gastric volvulus occurs when the stomach rotates about its longitudinal axis (organo-axial volvulus), or about an axis joining the lesser and greater curvatures (mesentero-axial volvulus). Primary gastric volvulus, making up one third of cases, occurs when the stabilizing ligaments are too lax as a result of congenital or acquired causes. Secondary gastric volvulus, making up the remainder of cases, occurs in association with a paraesophageal hernia or other congenital or acquired diaphragmat...
Particle simulation of an improved axially extracted vircator
International Nuclear Information System (INIS)
An axially extracted virtual cathode oscillator (vircator) with a feedback annulus is proposed and configured through particle-in-cell (PIC) simulation. In this paper, the effects of the feedback mechanism are studied through PIC method. The simulated results indicate that the improved new vircator can increase the output power twice large than that of the axially-extracted conventional vircator under the same condition. On the other hand, it can narrow the bandwidth and purify the modes
Particle Simulation of an Improved Axially Extracted Vircator
Institute of Scientific and Technical Information of China (English)
刘振祥; 舒挺; 张建德; 钱宝良
2003-01-01
An axially extracted virtual cathode oscillator (vircator) with a feedback annulusis proposed and configured through particle-in-cell (PIC) simulation in Ref. [1]. In this paper,the effects of the feedback mechanism are studied through PIC method. The simulated resultsindicate that the improved new vircator can increase the output power twice large than that ofthe axially-extracted conventional vircator under the same condition. On the other hand, it cannarrow the bandwidth and purify the modes.
The New Performance Calculation Method of Fouled Axial Flow Compressor
Huadong Yang; Hong Xu
2014-01-01
Fouling is the most important performance degradation factor, so it is necessary to accurately predict the effect of fouling on engine performance. In the previous research, it is very difficult to accurately model the fouled axial flow compressor. This paper develops a new performance calculation method of fouled multistage axial flow compressor based on experiment result and operating data. For multistage compressor, the whole compressor is decomposed into two sections. The first section in...
Axial myopia in computed and magnetic resonance tomography
Energy Technology Data Exchange (ETDEWEB)
Beyer-Enke, S.A.; Goerich, J.; Gamroth, A.
1987-08-01
The case of a 44-year old woman suffering from amblyopia on the left eye with unilateral proptosis caused by axial (progressive) myopia is presented. The clinical and radiological findings were discussed in reference to the literature. The diagnosis was established by ruling out neoplastic, inflammatory or endocrine causes for the exophtalmos. CT and MR scans revealed an enlarged left globe without evidence of orbital masses. The findings were regarded as typical for the diagnosis at axial myopia.
Funk, James R; Srinivasan, Sreebala C M; Crandall, Jeff R; Khaewpong, Nopporn; Eppinger, Rolf H; Jaffredo, Anna S; Potier, Pascal; Petit, Philippe Y
2002-11-01
Forced inversion or eversion of the foot is considered a common mechanism of ankle injury in vehicle crashes. The objective of this study was to model empirically the injury tolerance of the human ankle/subtalar joint to dynamic inversion and eversion under three different loading conditions: neutral flexion with no axial preload, neutral flexion with 2 kN axial preload, and 30 degrees of dorsiflexion with 2 kN axial preload. 44 tests were conducted on cadaveric lower limbs, with injury occurring in 30 specimens. Common injuries included malleolar fractures, osteochondral fractures of the talus, fractures of the lateral process of the talus, and collateral ligament tears, depending on the loading configuration. The time of injury was determined either by the peak ankle moment or by a sudden drop in ankle moment that was accompanied by a burst of acoustic emission. Characteristic moment-angle curves to injury were generated for each loading configuration. Neutrally flexed ankles with no applied axial preload sustained injury at 21 +/- 5 Nm and 38 degrees +/- 8 degrees in inversion, and 47 +/- 21 Nm and 28 degrees +/- 4 degrees in eversion. For ankles tested in neutral flexion with 2 kN of axial preload, inversion failure occurred at 77 +/- 27 Nm and 40 degrees +/- 12 degrees , and eversion failure occurred at 142 +/- 100 Nm and 41 degrees +/- 14 degrees . Ankles dorsiflexed 30 degrees and axially preloaded to 2 kN sustained inversion injury at 62 +/- 31 Nm and 33 degrees +/- 4 degrees , and eversion injury at 140 +/- 53 Nm and 40 degrees +/- 6 degrees . Survival analyses were performed to generate injury risk curves in terms of joint moment and rotation angle. PMID:17096228
Distribution load estimation - DLE
Energy Technology Data Exchange (ETDEWEB)
Seppaelae, A. [VTT Energy, Espoo (Finland)
1996-12-31
The load research project has produced statistical information in the form of load models to convert the figures of annual energy consumption to hourly load values. The reliability of load models is limited to a certain network because many local circumstances are different from utility to utility and time to time. Therefore there is a need to make improvements in the load models. Distribution load estimation (DLE) is the method developed here to improve load estimates from the load models. The method is also quite cheap to apply as it utilises information that is already available in SCADA systems
Axial Myopia and its Influence on Diabetic Retinopathy
International Nuclear Information System (INIS)
Objective: To evaluate the correlation between axial myopia and diabetic retinopathy. Study Design: Cross-sectional study. Place and Duration of Study: Eye Department of Postgraduate Medical Institute, Lahore General Hospital, from August 2012 to February 2013. Methodology: A total of 258 participants suffering from type-2 diabetic retinopathy were included. Axial length was measured by two optometrists using contact type ultrasound biometer. Colored retinal photographs, red free retinal photographs and Fundus Fluorescein Angiography (FFA) were performed on all patients using standard fundus camera. All fundus photographs and angiograms were independently reviewed and graded by two qualified vitreoretinal fellows. Results: Out of 258 patients, 163 were males (63.2%) and 95 (36.8%) were females. Average age of patients was 56.30 +- 7.57 years. Average axial length of right and left eyes were 23.16 mm and 23.15 mm respectively. There was statistically significant negative correlation between axial length and severity of diabetic retinopathy in the right eye, (Spearman correlation = -0.511, p = 0.0001) as well as the left eye (Spearman correlation = -0.522, p = 0.0001). Conclusion: There is a protective influence of longer axial length of globe on the stage and severity of diabetic retinopathy. This study may help in modifying the screening protocol for diabetic retinopathy amongst patients of differing axial lengths. (author)
Difference between measured and predicted axial offset at NPP Krsko
International Nuclear Information System (INIS)
At NPP Krsko axial power distribution is monitored through periodic measurements of the AO (axial offset). AO represents the normalized power difference between top and bottom of the core. Within the core design process predicted values of axial offset (P-AO) for the entire core lifetime are calculated. During the core performance surveillance measured AO (M-AO) is compared to the predicted value. Measured vs. predicted axial offset difference (D-AO) of +3% at hot-full-power (HFP) steady-state core conditions is considered to be within measurement and design tolerances. During the last two 18 months cycles increase in the D-AO above 3 % was experienced for limited period of time at NPP Krsko - in cycle 22 for more than 90 EFPD (Effective Full Power Days). For such deviation evaluation has to be performed to confirm that reload safety evaluation and analysis of the core has not been impacted. Root cause analysis was performed afterwards and it was classified as a core design computer code deficiency. Precisely, inadequate axial actinides treatment in the computer code contributed to the observed axial offset difference. (author)
Superfluid phase stability of 3He in axially anisotropic aerogel
International Nuclear Information System (INIS)
Measurements of superfluid 3He in 98% aerogel demonstrate the existence of a metastable A-like phase and a stable B-like phase. It has been suggested that the relative stability of these two phases is controlled by anisotropic quasiparticle scattering in the aerogel. Anisotropic scattering produced by axial compression of the aerogel has been predicted to stabilize the axial state of superfluid 3He. To explore this possibility, we used transverse acoustic impedance to map out the phase diagram of superfluid 3He in a ∼ 98% porous silica aerogel subjected to 17% axial compression. We have previously shown that axial anisotropy in aerogel leads to optical birefringence and that optical cross-polarization studies can be used to characterize such anisotropy. Consequently, we have performed optical cross-polarization experiments to verify the presence and uniformity of the axial anisotropy in our aerogel sample. We find that uniform axial anisotropy introduced by 17% compression does not stabilize the A-like phase. We also find an increase in the supercooling of the A-like phase at lower pressure, indicating a modification to B-like phase nucleation in globally anisotropic aerogels.
International Nuclear Information System (INIS)
Zirconium alloys are widely used in the nuclear industry. Several components, such as cladding or guide tubes, undergo strong mechanical loading during and after their use inside the pressurized water reactors. The current requirements on higher fuel performances lead to the developing on new Zr based alloys exhibiting better mechanical properties. In this framework, creep behaviors of recrystallized Zircaloy-4 and M5™, have been investigated and then compared. In order to give a better understanding of the thermal creep anisotropy of Zr-based alloys, multi-axial creep tests have been carried out at 673 K. Using a specific device, creep conditions have been set using different values of β = σzz/σθθ, σzz and σθθ being respectively the axial and hoop creep stresses. Both axial and hoop strains are measured during each test which is carried out until stationary creep is stabilized. The steady-state strain rates are then used to build isocreep curves. Considering the isocreep curves, the M5™ alloy shows a largely improved creep resistance compared to the recrystallized Zircaloy-4, especially for tubes under high hoop loadings (0 < β < 1). The isocreep curves are then compared with simulations performed using two different mechanical models. Model 1 uses a von Mises yield criterion, the model 2 is based on a Hill yield criterion. For both models, a coefficient derived from Norton law is used to assess the stress dependence
Energy Technology Data Exchange (ETDEWEB)
Rautenberg, M., E-mail: mrautenb@gmail.com [AREVA, AREVA NP, 10 rue Juliette Récamier, 69456 Lyon (France); CIRIMAT, CNRS/UPS/INPT, 4 allée Emile Monso, 31030 Toulouse (France); Poquillon, D. [CIRIMAT, CNRS/UPS/INPT, 4 allée Emile Monso, 31030 Toulouse (France); Pilvin, P. [LIMATB, University Bretagne-Sud, rue de Saint-Maudé, 56321 Lorient (France); Grosjean, C. [AREVA, AREVA NP, 10 rue Juliette Récamier, 69456 Lyon (France); CIRIMAT, CNRS/UPS/INPT, 4 allée Emile Monso, 31030 Toulouse (France); Cloué, J.M. [AREVA, AREVA NP, 10 rue Juliette Récamier, 69456 Lyon (France); Feaugas, X. [LEMMA, Université de La Rochelle, Avenue Michel Crépeau, 17042 La Rochelle (France)
2014-04-01
Zirconium alloys are widely used in the nuclear industry. Several components, such as cladding or guide tubes, undergo strong mechanical loading during and after their use inside the pressurized water reactors. The current requirements on higher fuel performances lead to the developing on new Zr based alloys exhibiting better mechanical properties. In this framework, creep behaviors of recrystallized Zircaloy-4 and M5™, have been investigated and then compared. In order to give a better understanding of the thermal creep anisotropy of Zr-based alloys, multi-axial creep tests have been carried out at 673 K. Using a specific device, creep conditions have been set using different values of β = σ{sub zz}/σ{sub θθ}, σ{sub zz} and σ{sub θθ} being respectively the axial and hoop creep stresses. Both axial and hoop strains are measured during each test which is carried out until stationary creep is stabilized. The steady-state strain rates are then used to build isocreep curves. Considering the isocreep curves, the M5™ alloy shows a largely improved creep resistance compared to the recrystallized Zircaloy-4, especially for tubes under high hoop loadings (0 < β < 1). The isocreep curves are then compared with simulations performed using two different mechanical models. Model 1 uses a von Mises yield criterion, the model 2 is based on a Hill yield criterion. For both models, a coefficient derived from Norton law is used to assess the stress dependence.
Complete multipactor suppression in an X-band dielectric-loaded accelerating structure
Jing, C.; Gold, S. H.; Fischer, Richard; Gai, W.
2016-05-01
Multipactor is a major issue limiting the gradient of rf-driven Dielectric-Loaded Accelerating (DLA) structures. Theoretical models have predicted that an axial magnetic field applied to DLA structures may completely block the multipactor discharge. However, previous attempts to demonstrate this magnetic field effect in an X-band traveling-wave DLA structure were inconclusive, due to the axial variation of the applied magnetic field, and showed only partial suppression of the multipactor loading [Jing et al., Appl. Phys. Lett. 103, 213503 (2013)]. The present experiment has been performed under improved conditions with a uniform axial magnetic field extending along the length of an X-band standing-wave DLA structure. Multipactor loading began to be continuously reduced starting from 3.5 kG applied magnetic field and was completely suppressed at ˜8 kG. Dependence of multipactor suppression on the rf gradient inside the DLA structure was also measured.
Shot loading platform analysis
International Nuclear Information System (INIS)
This document provides the wind/seismic analysis and evaluation for the shot loading platform. Hand calculations were used for the analysis. AISC and UBC load factors were used in this evaluation. The results show that the actual loads are under the allowable loads and all requirements are met
Investigation of axial power gradients near a control rod tip
International Nuclear Information System (INIS)
Highlights: → Pin power gradients near BWR control rod tips have been investigated. → A control rod tip is modeled in MCNP and compared to simplified 2D/3D geometry. → Small nodes increases pin power gradients; standard nodes underestimates gradients. → The MCNP results are validated against axial gamma scan of a controlled fuel pin. - Abstract: Control rod withdrawal in BWRs induces large power steps in the adjacent fuel assemblies. This paper investigates how well a 2D/3D method, e.g., CASMO5/SIMULATE5 computes axial pin power gradients adjacent to an asymmetrical control-rod tip in a BWR. The ability to predict pin power gradients accurately is important for safety considerations whereas large powers steps induced by control rod withdrawal can cause Pellet Cladding Interaction. The computation of axial pin power gradients axially around a control rod tip is a challenging task for any nodal code. On top of that, asymmetrical control rod handles are present in some BWR designs. The lattice code CASMO requires diagonal symmetry of all control rod parts. This introduces an error in computed pin power gradients that has been evaluated by Monte Carlo calculations. The results show that CASMO5/SIMULATE5, despite the asymmetrical control rod handle, is able to predict the axial pin power gradient within 1%/cm for axial nodal sizes of 15-3.68 cm. However, a nodal size of 3.68 cm still causes underestimations of pin power gradients compared with 1 cm nodes. Furthermore, if conventional node sizes are used, ∼15 cm, pin power gradients can be underestimated by over 50% compared with 1 cm nodes. The detailed axial pin power profiles from MCNP are corroborated by measured gamma scan data on fuel rods irradiated adjacent to control rods.
Directory of Open Access Journals (Sweden)
Qingyan Wang
2015-01-01
Full Text Available Thrust bearing is one part with the highest failure rate in hydroturbine generator set, which is primarily due to heavy axial load. Such heavy load often makes oil film destruction, bearing friction, and even burning. It is necessary to study the load and the reduction method. The dynamic thrust is an important factor to influence the axial load and reduction design of electromagnetic device. Therefore, in the paper, combined with the structure features of vertical turbine, the hydraulic thrust is analyzed accurately. Then, take the turbine model HL-220-LT-550, for instance; the electromagnetic levitation load reduction device is designed, and its mathematical model is built, whose purpose is to minimize excitation loss and total quality under the constraints of installation space, connection layout, and heat dissipation. Particle swarm optimization (PSO is employed to search for the optimum solution; finally, the result is verified by finite element method (FEM, which demonstrates that the optimized structure is more effective.
International Nuclear Information System (INIS)
The burst pressure of super duplex stainless steel pipe is measured under combined internal pressure, external axial tension and elevated temperature up to 160 °C. The experimental results are compared with existing burst pressure prediction models. Existing models are found to provide reasonable estimate of the burst pressure at room temperature but significantly over estimate the burst pressure at elevated temperature. Increasing externally applied axial stress and elevated temperature reduces the pressure capacity. - Highlights: • The burst pressure of super duplex steel is measured under combined loading. • Effect of elevated temperature on burst pressure is determined. • Burst pressure decreases with increasing temperature. • Existing models are reliable at room temperature. • Burst strength at elevated temperature is lower than predictions
Static and dynamic response of a sandwich structure under axial compression
Ji, Wooseok
This thesis is concerned with a combined experimental and theoretical investigation of the static and dynamic response of an axially compressed sandwich structure. For the static response problem of sandwich structures, a two-dimensional mechanical model is developed to predict the global and local buckling of a sandwich beam, using classical elasticity. The face sheet and the core are assumed as linear elastic orthotropic continua in a state of planar deformation. General buckling deformation modes (periodic and non-periodic) of the sandwich beam are considered. On the basis of the model developed here, validation and accuracy of several previous theories are discussed for different geometric and material properties of a sandwich beam. The appropriate incremental stress and conjugate incremental finite strain measure for the instability problem of the sandwich beam, and the corresponding constitutive model are addressed. The formulation used in the commercial finite element package is discussed in relation to the formulation adopted in the theoretical derivation. The Dynamic response problem of a sandwich structure subjected to axial impact by a falling mass is also investigated. The dynamic counterpart of the celebrated Euler buckling problem is formulated first and solved by considering the case of a slender column that is impacted by a falling mass. A new notion, that of the time to buckle, "t*" is introduced, which is the corresponding critical quantity analogous to the critical load in static Euler buckling. The dynamic bifurcation buckling analysis is extended to thick sandwich structures using an elastic foundation model. A comprehensive set of impact test results of sandwich columns with various configurations are presented. Failure mechanisms and the temporal history of how a sandwich column responds to axial impact are discussed through the experimental results. The experimental results are compared against analytical dynamic buckling studies and finite
An Axial Vector Photon in a Mirror World
Sharafiddinov, Rasulkhozha S
2015-01-01
The unity of symmetry laws emphasizes, in the case of a mirror CP-even Dirac Lagrangian, the ideas of the left- and right-handed axial-vector photons referring to long- and short-lived bosons of true neutrality, respectively. Such a difference in lifetimes expresses the unidenticality of masses, energies and momenta of axial-vector photons of the different components. They define the unified field theory equation of C-odd particles with an integral spin. Together with a new equation of a theory of truly neutral particles with the half-integral spin, the latter reflects the availability in their nature of the second type of the local axial-vector gauge transformation responsible for origination in the Lagrangian of C-oddity of an interaction Newton component giving an axial-vector mass to all the interacting particles and fields. The mirror axial-vector mass, energy and momentum operators constitute a CP-invariant equation of quantum mechanics, confirming that each of them can individually influence on matter ...
Rotordynamics of Turbine Labyrinth Seals with Rotor Axial Shifting
Directory of Open Access Journals (Sweden)
2006-01-01
Full Text Available Rotors in high-performance steam turbines experience a significant axial shifting during starting and stopping processes due to thermal expansion, for example. This axial shifting could significantly alter the flow pattern and the flow-induced rotordynamic forces in labyrinth seals, which in turn, can considerably affect the rotor-seal system performance. This paper investigates the influence of the rotor axial shifting on leakage rate as well as rotordynamic forces in high-low labyrinth seals over a range of seal clearances and inlet swirl velocities. A well-established CFD-perturbation model was employed to predict the rotordynamic coefficients. A surprisingly large effect was detected for rotordynamic characteristics due to rotor shifting. It was also found that a less destabilizing effect arose from rotor axial shifting in the leakage flow direction, whereas a more destabilizing effect arose from shifting against the leakage flow direction. Further, a tentative explanation was proposed for the large sensitivities of dynamic forces to rotor axial shifting.
Rotordynamics of Turbine Labyrinth Seals with Rotor Axial Shifting
Directory of Open Access Journals (Sweden)
David L. Rhode
2006-03-01
Full Text Available Rotors in high-performance steam turbines experience a significant axial shifting during starting and stopping processes due to thermal expansion, for example. This axial shifting could significantly alter the flow pattern and the flow-induced rotordynamic forces in labyrinth seals, which in turn, can considerably affect the rotor-seal system performance. This paper investigates the influence of the rotor axial shifting on leakage rate as well as rotordynamic forces in high-low labyrinth seals over a range of seal clearances and inlet swirl velocities. A well-established CFD-perturbation model was employed to predict the rotordynamic coefficients. A surprisingly large effect was detected for rotordynamic characteristics due to rotor shifting. It was also found that a less destabilizing effect arose from rotor axial shifting in the leakage flow direction, whereas a more destabilizing effect arose from shifting against the leakage flow direction. Further, a tentative explanation was proposed for the large sensitivities of dynamic forces to rotor axial shifting.
Artery Remodeling Under Axial Twist in Three Days Organ Culture.
Wang, Guo-Liang; Xiao, Yangming; Voorhees, Andrew; Qi, Ying-Xin; Jiang, Zong-Lai; Han, Hai-Chao
2015-08-01
Arteries often endure axial twist due to body movement and surgical procedures, but how arteries remodel under axial twist remains unclear. The objective of this study was to investigate early stage arterial wall remodeling under axial twist. Porcine carotid arteries were twisted axially and maintained for three days in ex vivo organ culture systems while the pressure and flow remained the same as untwisted controls. Cell proliferation, internal elastic lamina (IEL) fenestrae shape and size, endothelial cell (EC) morphology and orientation, as well as the expression of matrix metalloproteinases (MMPs), MMP-2 and MMP-9, and tissue inhibitor of metalloproteinase-2 (TIMP-2) were quantified using immunohistochemistry staining and immunoblotting. Our results demonstrated that cell proliferation in both the intima and media were significantly higher in the twisted arteries compared to the controls. The cell proliferation in the intima increased from 1.33 ± 0.21% to 7.63 ± 1.89%, and in the media from 1.93 ± 0.84% to 8.27 ± 2.92% (p culture, a decrease from the initial 15.58 ± 1.29 degrees. These results demonstrate that axial twist can stimulate artery remodeling. These findings complement our understanding of arterial wall remodeling under mechanical stress resulting from pressure and flow variations. PMID:25503524
Method to measure tone of axial and proximal muscle.
Gurfinkel, Victor S; Cacciatore, Timothy W; Cordo, Paul J; Horak, Fay B
2011-01-01
The control of tonic muscular activity remains poorly understood. While abnormal tone is commonly assessed clinically by measuring the passive resistance of relaxed limbs, no systems are available to study tonic muscle control in a natural, active state of antigravity support. We have developed a device (Twister) to study tonic regulation of axial and proximal muscles during active postural maintenance (i.e. postural tone). Twister rotates axial body regions relative to each other about the vertical axis during stance, so as to twist the neck, trunk or hip regions. This twisting imposes length changes on axial muscles without changing the body's relationship to gravity. Because Twister does not provide postural support, tone must be regulated to counteract gravitational torques. We quantify this tonic regulation by the restive torque to twisting, which reflects the state of all muscles undergoing length changes, as well as by electromyography of relevant muscles. Because tone is characterized by long-lasting low-level muscle activity, tonic control is studied with slow movements that produce "tonic" changes in muscle length, without evoking fast "phasic" responses. Twister can be reconfigured to study various aspects of muscle tone, such as co-contraction, tonic modulation to postural changes, tonic interactions across body segments, as well as perceptual thresholds to slow axial rotation. Twister can also be used to provide a quantitative measurement of the effects of disease on axial and proximal postural tone and assess the efficacy of intervention. PMID:22214974
An Axial-Vector Photon in a Mirror World
Sharafiddinov, Rasulkhozha S.
2016-03-01
The unity of symmetry laws emphasizes, in the case of a mirror CP-even Dirac Lagrangian, the ideas of the left- and right-handed axial-vector photons referring to long- and short-lived bosons of true neutrality, respectively. Such a difference in lifetimes expresses the unidenticality of masses, energies and momenta of axial-vector photons of the different components. They define the unified field theory equation of C-odd particles with an integral spin. Together with a new equation of a theory of truly neutral particles with the half-integral spin, the latter reflects the availability in their nature of the second type of the local axial-vector gauge transformation responsible for origination in the Lagrangian of C-oddity of an interaction Newton component giving an axial-vector mass to all the interacting particles and fields. The mirror axial-vector mass, energy and momentum operators constitute a CP-invariant equation of quantum mechanics, confirming that each of them can individually influence on matter field. Thereby, findings suggest at the level of the mass-charge structure of gauge invariance a new equation for the C-noninvariant Lagrangian.
Senthil Kumaran, R.; Kamble, Sachin; Swamy, K. M. M.; Nagpurwala, Q. H.; Bhat, Ananthesha
2015-12-01
Axial Velocity Density Ratio (AVDR) is an important parameter to check the two-dimensionality of cascade flows. It can have significant influence on the cascade performance and the secondary flow structure. In the present study, the effect of AVDR has been investigated on a highly loaded Controlled Diffusion airfoil compressor cascade. Detailed 3D Computational Fluid Dynamics (CFD) studies were carried out with the cascade at five different AVDRs. Key aerodynamic performance parameters and flow structure through the cascade were analyzed in detail. CFD results of one AVDR were validated with the experimental cascade test data and were seen to be in good agreement. Loss characteristics of the cascade varied significantly with change in AVDR. Increase in AVDR postponed the point of separation on the suction surface, produced thinner boundary layers and caused substantial drop in the pressure loss coefficient. Strong end wall vortices were noticed at AVDR of 1.177. At higher AVDRs, the flow was well guided even close to the end wall and the secondary flows diminished. The loading initially improved with increase in AVDR. Beyond a certain limit, further increase in AVDR offered no improvements to the loading but rather resulted in drop in diffusion and deviation.
Longitudinal Weld Land Buckling in Compression-Loaded Orthogrid Cylinders
Thornburgh, Robert P.; Hilburger, Mark W.
2010-01-01
Large stiffened cylinders used in launch vehicles (LV), such as the Space Shuttle External Tank, are manufactured by welding multiple curved panel sections into complete cylinders. The effects of the axial weld lands between the panel sections on the buckling load were studied, along with the interaction between the acreage stiffener arrangement and the weld land geometry. This document contains the results of the studies.
Gui, Xingmin; Zhu, Fang; Wan, Ke; Jin, Donghai
2013-10-01
Swept blades have been widely used in the transonic fan/compressor of aircraft engines with the aids of 3D CFD simulation since the design concept of controlling the shock structure was firstly proposed and successfully tested by Dr. Wennerstrom in the 1980s. However, some disadvantage phenomenon has also been induced by excessively 3D blade geometries on the structure stress insufficiency, vibration and reliability. Much confusion in the procedure of design practice leading us to recognize a new view on the flow mechanism of sweep aerodynamical induction: the new radial equilibrium established by the influence of inlet circumferential fluctuation (CF) changes the inlet flows of blading and induces the performance modification of axial fans/compressors blade. The view is verified by simplified models through numerical simulation and circumferentially averaged analysis in the present paper. The results show that the CF source items which originate from design parameters, such as the spanwise distributions of the loading and blading geometries, contribute to the changing of averaged incidence spanwise distribution, and further more affect the performance of axial fans/compressors with swept blades.
Performance Test and Flow Measurement of Contra-Rotating Axial Flow Pump
Institute of Scientific and Technical Information of China (English)
Akinori Furukawa; Toru Shigemitsu; Satoshi Watanabe
2007-01-01
An application of contra-rotating rotors has been proposed against a demand for developing higher specific speed axial flow pump. In the present paper, the advantage and disadvantage of using contra-rotating rotors are described in comparison with conventional type of rotor-stator, based on theoretical and experimental investigations. The advantages are as follows: (1) The pump is inherently designed as smaller sized and at lower rotational speed. (2) A stable head-characteristic curve for flow rate with negative slope appears. (3)As the rear rotor rotational speed is varied as independent control of front rotor, the wider range of high performance operation is obtained by rear rotor speed control in addition to front rotor speed control. The disadvantages are as follows: (1) The structure of double shaft system becomes complex. (2) The pump performance is inferior at over flow rate as the rear rotor loading is weakened. (3) The blade rows interaction from rear rotor to front rotor more strongly appears. Then the rear rotor design is a key to achieve higher pump performance. Some methods to overcome these disadvantages will be discussed in more details toward wider usage of contra-rotating axial flow pump in various industrial fields.
Inception mechanism and suppression of rotating stall in an axial-flow fan
International Nuclear Information System (INIS)
Inception patterns of rotating stall at two stagger-angle settings for the highly loaded rotor blades were experimentally investigated in a low-speed axial-flow fan. Rotor-tip flow fields were also numerically investigated to clarify the mechanism behind the rotating stall inception. The stall inception patterns depended on the rotor stagger-angle settings. The stall inception from a rotating instability was confirmed at the design stagger-angle settings. The stall inception from a short length-scale stall cell (spike) was also confirmed at the small stagger-angle setting. The spillage of tip-leakage flow and the tip-leakage vortex breakdown influence the rotating stall inception. An air-separator has been developed based on the clarified inception mechanism of rotating stall. The rotating stall was suppressed by the developed air-separator, and the operating range of fan was extended towards low flow rate. The effect of developed air-separator was also confirmed by application to a primary air fan used in a coal fired power plant. It is concluded from these results that the developed air-separator can provide a wide operating range for an axial-flow fan
Low-pressure reversible axial fan with straight profile blades and relatively high efficiency
Directory of Open Access Journals (Sweden)
Spasić Živan T.
2012-01-01
Full Text Available The paper presents the design and operating characteristics of a model of reversible axial fan with only one impeller, whose reversibility is achieved by changing the direction of rotation. The fan is designed for the purpose of providing alternating air circulation in wood dryers in order to reduce the consumption of electricity for the fan and increase energy efficiency of the entire dryer. To satisfy the reversibility of flow, the shape of the blade profile is symmetrical along the longitudinal and transversal axes of the profile. The fan is designed with equal specific work of all elementary stages, using the method of lift forces. The impeller blades have straight mean line profiles. The shape of the blade profile was adopted after the numerical simulations were carried out and high efficiency was achieved. Based on the calculation and conducted numerical simulations, a physical model of the fan was created and tested on a standard test rig, with air loading at the suction side of the fan. The operating characteristics are shown for different blade angles. The obtained maximum efficiency was around 0.65, which represents a rather high value for axial fans with straight profile blades.
Fuel loading and homogeneity analysis of HFIR design fuel plates loaded with uranium silicide fuel
International Nuclear Information System (INIS)
Twelve nuclear reactor fuel plates were analyzed for fuel loading and fuel loading homogeneity by measuring the attenuation of a collimated X-ray beam as it passed through the plates. The plates were identical to those used by the High Flux Isotope Reactor (HFIR) but were loaded with uranium silicide rather than with HFIR's uranium oxide fuel. Systematic deviations from nominal fuel loading were observed as higher loading near the center of the plates and underloading near the radial edges. These deviations were within those allowed by HFIR specifications. The report begins with a brief background on the thermal-hydraulic uncertainty analysis for the Advanced Neutron Source (ANS) Reactor that motivated a statistical description of fuel loading and homogeneity. The body of the report addresses the homogeneity measurement techniques employed, the numerical correction required to account for a difference in fuel types, and the statistical analysis of the resulting data. This statistical analysis pertains to local variation in fuel loading, as well as to ''hot segment'' analysis of narrow axial regions along the plate and ''hot streak'' analysis, the cumulative effect of hot segment loading variation. The data for all twelve plates were compiled and divided into 20 regions for analysis, with each region represented by a mean and a standard deviation to report percent deviation from nominal fuel loading. The central regions of the plates showed mean values of about +3% deviation, while the edge regions showed mean values of about -7% deviation. The data within these regions roughly approximated random samplings from normal distributions, although the chi-square (χ2) test for goodness of fit to normal distributions was not satisfied
STED microscopy based on axially symmetric polarized vortex beams
Zhehai, Zhou; Lianqing, Zhu
2016-03-01
A stimulated emission depletion (STED) microscopy scheme using axially symmetric polarized vortex beams is proposed based on unique focusing properties of such kinds of beams. The concept of axially symmetric polarized vortex beams is first introduced, and the basic principle about the scheme is described. Simulation results for several typical beams are then shown, including radially polarized vortex beams, azimuthally polarized vortex beams, and high-order axially symmetric polarized vortex beams. The results indicate that sharper doughnut spots and thus higher resolutions can be achieved, showing more flexibility than previous schemes based on flexible modulation of both phase and polarization for incident beams. Project supported by the National Natural Science Foundation of China (Grant Nos. 61108047 and 61475021), the Natural Science Foundation of Beijing, China (Grant No. 4152015), the Program for New Century Excellent Talents in Universities of China (Grant No. NCET-13-0667), and the Top Young Talents Support Program of Beijing, China (Grant No. CIT&TCD201404113).
Identification du comportement de composites en fatigue bi-axiale
Busca, Damien
2014-01-01
La connaissance du comportement de composites sous un état de contraintes multi-axial reste un enjeu majeur pour l’optimisation du dimensionnement des structures. La machine de fatigue bi-axiale présente au LGP permet de générer un état de contrainte bi-axial par l’utilisation d’éprouvettes cruciformes. La conception des éprouvettes reste un enjeu majeur pour les chercheurs pour répondre aux problèmes spécifiques liés aux matériaux composites. Un nouveau type d’éprouvette cruciforme en compos...
Liquid Axial Mixing in Packed Tower at Elevated Pressure
Institute of Scientific and Technical Information of China (English)
唐忠利; 张鹏; 等
2003-01-01
Liquid phase axial mixing was measured with the tracer technique in a packed column with inner diameter of 0.15m,in which the structured packing,Mellapak 350Y,was installed.Tap water as the liquid phase flowed down through the column and stagnant gas was at elevated pressure ranging from atmospheric to 2.0MPa.The model parameters of Bo andθwere estimated with the least square method in the time domain.As liquid flow rate was increased,the liquid axial mixing decreased.under our experimental conditions,the effect of pressure on Bo number on single liquid phase was negligible,and eddy diffusion was believed to be the primary cause of axial mixing in liquid phase.
Axial Shock in a Cylindrical Plasma with Current
International Nuclear Information System (INIS)
Hugoniot relations of a two-dimensional axial shock with current and magnetic field in a cylindrical shock tube were investigated by a numerical method. The radial profiles of the magnetic field, electric current, pressures, flow velocities and temperatures between the up- and down-stream radial force-balanced plasma of the shock were revealed by numerical analysis. It is clearly found that the axial shock can lead to two effects: one is an inverse skin effect (i.e., the current density rises towards the center of the conductor), the another is a reversed current effect which occurs near the edge and about a half radius. It is also found that the radial gradient of pressure, density and temperature all become very large near the center due to the axial shock
Ball Screw Actuator Including an Axial Soft Stop
Wingett, Paul T. (Inventor); Forrest, Steven Talbert (Inventor); Abel, Steve (Inventor); Woessner, George (Inventor); Hanlon, Casey (Inventor)
2016-01-01
An actuator includes an actuator housing, a ball screw, and an axial soft stop assembly. The ball screw extends through the actuator housing and has a first end and a second end. The ball screw is coupled to receive a drive force and is configured, upon receipt of the drive force, to selectively move in a retract direction and an extend direction. The axial soft stop assembly is disposed within the actuator housing. The axial soft stop assembly is configured to be selectively engaged by the ball screw and, upon being engaged thereby, to translate, with compliance, a predetermined distance in the extend direction, and to prevent further movement of the ball screw upon translating the predetermined distance.
Fast imaging of mean, axial and radial diffusion kurtosis
DEFF Research Database (Denmark)
Hansen, Brian; Shemesh, Noam; Jespersen, Sune Nørhøj
2016-01-01
benefit from more efficient acquisition and computational methods. To meet this demand, we recently developed a method capable of estimating mean kurtosis with only 13 diffusion weighted images. This approach was later shown to provide very accurate mean kurtosis estimates and to be more efficient in...... terms of contrast to noise per unit time. However, insofar, the computation of two other critical DKI parameters, radial and axial kurtosis, has required the estimation of all 22 variables parameterizing the full DKI signal expression. Here, we present two strategies for estimating all of DKI......'s principal parameters – mean kurtosis, radial kurtosis, and axial kurtosis – using only 19 diffusion weighted images, compared to the current state-of-the-art acquisitions typically requiring about 60 images. The first approach is based on axially symmetric diffusion and kurtosis tensors, presented here for...
Modified approach for calculating axial vector vacuum susceptibility
International Nuclear Information System (INIS)
We generalize our previous work [Phys. Rev. C 72, 035202 (2005)] on the linear response theory of the dressed quark propagator in the presence of a constant external field to the case of a variable external field in order to make it applicable to a wider class of problems. Using the axial vector vacuum susceptibility as an illustration, we apply this general formalism to extract a new expression for the axial vector vacuum susceptibility in the quantum chromodynamical (QCD) sum rule two-point external field formula. The numerical values of the axial vector vacuum susceptibility are calculated within the framework of the rainbow-ladder approximation of the Dyson-Schwinger approach. A comparison with the results of the previous approaches is given
Numerical analysis of cavitation within slanted axial-flow pump
Institute of Scientific and Technical Information of China (English)
张睿; 陈红勋
2013-01-01
In this paper, the cavitating flow within a slanted axial-flow pump is numerically researched. The hydraulic and cavitation performance of the slanted axial-flow pump under different operation conditions are estimated. Compared with the experimental hydraulic performance curves, the numerical results show that the filter-based model is better than the standard k-e model to predict the parameters of hydraulic performance. In cavitation simulation, compared with the experimental results, the proposed numerical method has good predicting ability. Under different cavitation conditions, the internal cavitating flow fields within slanted axial-flow pump are investigated. Compared with flow visualization results, the major internal flow features can be effectively grasped. In order to explore the origin of the cavitation performance breakdown, the Boundary Vorticity Flux (BVF) is introduced to diagnose the cavitating flow fields. The analysis results indicate that the cavitation performance drop is relevant to the instability of cavitating flow on the blade suction surface.
The small axial charge of the N(1535) resonance
an, C S
2008-01-01
There is a natural cancellation between the contributions of the $qqq$ and $qqqq\\bar q$ components to the axial charge of the N(1535) resonance. While the probability of the former is larger than that of the latter, its coefficient in the axial charge expression is exceptionally small. The magnitude of two of the corresponding coefficients of the $qqqq\\bar q$ components are in contrast large and have the opposite sign. This result provides a phenomenological illustration of the recent unquenched lattice calculation result that the axial charge of the N(1535) resonance is very small, if not vanishing \\cite{takah}. The result sets an upper limit on the magnitude of the probability of $qqqq\\bar q$ components as well.
Optimum axial flow taper in a countercurrent gas centrifuge
Energy Technology Data Exchange (ETDEWEB)
Von Halle, E.
1979-02-01
The effect of an axially varying countercurrent circulation rate in a gas centrifuge on the efficiency factors, e/sub I/, the ideality efficiency, and e/sub C/, the circulation efficiency, is investigated and compared with the case in which the countercurrent circulation rate is constant throughout the centrifuge. The optimum variation of the centrifuge parameter m, which is a measure of the countercurrent circulation rate, as a function of axial position in the centrifuge is determined. It is shown that when the countercurrent circulation rate has its optimum value at every axial position in the centrifuge, the product of the efficiency factors, e/sub I/ x e/sub C/, can exceed 81 per cent, the nominal upper limit of the value of the product of the efficiency factors for a constant countercurrent circulation rate, and can be quite close to unity. This is illustrated by numerical examples based on a centrifuge previously described in the literature.
Twenty axial level handling in the APOSTOL code
International Nuclear Information System (INIS)
In many high-resolution calculation it has been proved that, in assemblies beside the control rod the pin-wise linear heat rate is different from linear heat rate calculated by pin-wise diffusion codes using only ten axial level code. In the linear heat rate of these assemblies there is a positive peak beside the intermediate part of control rod, which is the connection between the absorber and the fuel. In the ten level calculation cases this peak is not observable because of the homogenisation of the levels. Therefore more detailed axial division has to be used for the calculations. In this paper it is presented the application of a twenty axial level division in the APOSTOL code. It is presented the geometry of the nodes and the calculation of the cross sections of the nodes. Furthermore, the twenty level handling in the APOSTOL code is described. The same calculation result in realistic cases are presented. (author)
The effect of non-uniform damping on flutter in axial flow and energy harvesting strategies
Singh, Kiran; de Langre, Emmanuel
2012-01-01
The problem of energy harvesting from flutter instabilities in flexible slender structures in axial flows is considered. In a recent study, we used a reduced order theoretical model of such a system to demonstrate the feasibility for harvesting energy from these structures. Following this preliminary study, we now consider a continuous fluid-structure system. Energy harvesting is modelled as strain-based damping and the slender structure under investigation lies in a moderate fluid loading range, for which {the flexible structure} may be destabilised by damping. The key goal of this work is to {analyse the effect of damping distribution and intensity on the amount of energy harvested by the system}. The numerical results {indeed} suggest that non-uniform damping distributions may significantly improve the power harvesting capacity of the system. For low damping levels, clustered dampers at the position of peak curvature are shown to be optimal. Conversely for higher damping, harvesters distributed over the wh...
Institute of Scientific and Technical Information of China (English)
LI Yang; LIU Jie; OUYANG Hua; DU Zhao-Hui
2008-01-01
This article presents the flow mechanism analysis and experimental study of a forward-skewed impeller and a radial impeller in low pressure axial fan. The forward-skewed blade was obtained by the optimization design of the radial blade and CFD technique. Measurement of the two blades was carried out in aerodynamic and aeroacoustic performance. Compared to the radial blade, the forward-skewed blade has demonstrated the improvements in efficiency, total pressure ratio, Stable Operating Range (SOR) and less aerodynamic noise. Detailed flow measurement and computation were performed for outlet flow field for investigating the responsible flow mechanisms. The results show the forward-skewed blade can cause a spanwise redistribution of flow toward the blade mid-span and reduce tip loading. This results in reduced significantly total pressure loss near hub and shroud endwall region, despite the slight increase of total pressure loss at mid-span.
Optimization Design and Experimental Study of Low-Pressure Axial Fan with Forward-Skewed Blades
Directory of Open Access Journals (Sweden)
Li Yang
2007-01-01
Full Text Available This paper presents an experimental study of the optimization of blade skew in low pressure axial fan. Using back propagation (BP neural network and genetic algorithm (GA, the optimization was performed for a radial blade. An optimized blade is obtained through blade forward skew. Measurement of the two blades was carried out in aerodynamic and aeroacoustic performance. Compared to the radial blade, the optimized blade demonstrated improvements in efficiency, total pressure ratio, stable operating range, and aerodynamic noise. Detailed flow measurement was performed in outlet flow field for investigating the responsible flow mechanisms. The optimized blade can cause a spanwise redistribution of flow toward the blade midspan and reduce tip loading. This results in reduced significantly total pressure loss near hub and shroud endwall region, despite the slight increase of total pressure loss at midspan. In addition, the measured spectrums show that the broadband noise of the impeller is dominant.
Electromagnetic and axial structures of Baryon ground and resonant states
International Nuclear Information System (INIS)
This thesis is devoted to the investigation of the electroweak structures of baryons. One performs a comprehensive study of the electromagnetic and axial form factors of baryon ground states with flavors 'up', 'down', and 'strange'; regarding baryon resonances the axial charges are investigated. The dynamics for the description of baryons is furnished by the relativistic constituent-quark model, of which three different variants are applied here. The calculations are performed in the framework of relativistic quantum mechanics, where the electromagnetic and axial current operators are constructed along a spectator model in the point-form.While the evaluations of the electroweak form factors are based on an already established formalism, one develops a generally valid formulation for the axial charges. Thereby it becomes possible to calculate these quantities for arbitrary baryon states and completely general interaction models.It turns out that relativistic constituent-quark models can describe in the framework of a Poincare-invariant formalism not only the electromagnetic but also the axial form factors, which are calculated here for the first time for all baryons. Globally, a good agreement with experiment is achieved up to momentum transfers of about 4 GeV/c. With regard to the particularly sensitive quantities, like the electric radii and magnetic moments, the constituent-quark model based on Goldstone-boson exchange yields the best results. In cases, where no experimental data exist, the predictions agree well with results from lattice quantum chromodynamics. The analogue is true for the axial charges of baryon ground and resonant states. Except for some special cases, their values are presented here for the first time comprehensively and consistently. (author)
A three-dimensional nodal method with Channel-wise Intrinsic Axial Mesh Adaptation
International Nuclear Information System (INIS)
Highlights: • CIAMA solves axial heterogeneity without iterative node re-homogenization. • CIAMA can easily resolve the control rod cusping problem. • CIAMA result shows great potential for 3-D pin-by-pin calculation. - Abstract: In a conventional coarse mesh nodal method the more accurate treatment of intra-nodal axial heterogeneity requires iterative axial node re-homogenization using axial flux profiles either reconstructed from core-wise coarse mesh solution or obtained from channel-wise axial fine mesh calculation. In this paper a new nodal method formulation, using Channel-wise Intrinsic Axial Mesh Adaptation (CIAMA), is proposed to solve this problem in a more fundamental way. For a given transverse (radial) leakage, along each axial channel a rigorous sub-node heterogeneous calculation is performed with the explicit axial heterogeneity within each coarse axial node. However, the transverse leakage between the axial channels is still calculated on the basis of coarse axial nodes, using the axially averaged radial current in each coarse axial node. Since the coupling between the axial channels is through the coarse axial nodes, it is not necessary to match the boundaries of the axial sub-nodes of neighboring axial channels in order to incorporate the axial sub-node calculation as an intrinsic part of the whole core global calculation. Therefore in the CIAMA nodal method, each axial channel is allowed to have its own sub-nodes adapting to its own axial heterogeneity variation. The CIAMA method has been implemented in the commercial code EGRET, which is used to qualify CIAMA. Excellent results of modeling fuel grid and control rod movement are presented. Application of CIAMA to three-dimensional pin-by-pin core calculation is also discussed and demonstrated to work well
Bolt Pull-Out Tests of Anchorage Body under Different Loading Rates
Directory of Open Access Journals (Sweden)
Tong-bin Zhao
2015-01-01
Full Text Available Based on the force analysis and mechanical transmission mechanism of grouting bolts, the self-developed test apparatus for interfacial mechanics is used to study the distribution rule of axial force and interfacial stress of bolts in anchorage body. At the same time, pull-out tests of anchorage body are simulated with the particle flow code software PFC2D, and stress distribution and failure patters are researched under different loading rates. The results show that the distribution of axial force and interfacial shear stress is nonuniform along the anchorage section: axial force decreases, shear force increases first and then decreases, and the maximum value of both of them is closed to the pull-out side; with the increase of loading rates, both of axial force and interfacial shear stress show a trend of increase in the upper anchorage section but changes are not obvious in the lower anchorage section, which causes serious stress concentration; failure strength of pull-out and loading rates show a linear correlation; according to loading rates’ impact on the anchoring effect, the loading rates’ scope can be divided into soft scope (v100 mm/s.
Garðar Páll Gíslason 1979
2011-01-01
A load cell is a small object which has only one goal and that is to measure load. This is an old invention from the mid-eighteenth century and remains very popular today. Load cells are only one portion of a bigger totality. That is why the shape of the load cell changes between objects. Optimization of a load cell is an effective way to get the highest signal from the cell. The main object of this thesis is optimization of a load cell which is a part of the Rheo Knee® from Össur. This kn...
A simple approach to the ABJ axial anomaly
International Nuclear Information System (INIS)
A very simple semi-quantitative derivation of the Adler-Bell-Jackiw (ABJ) axial anomaly is given, based on an investigation of the absorptive part of the VVA triangle graph and dispersion relations. Essential ingredients of our discussion are: normal Ward identities for the absorptive part of the relevant diagram, dimensional analysis, unitarity, and energy-momentum conservation. An explanation of the physical origin of axial anomaly, proposed in some earlier treatments within such a dispersive framework, is critically examined. In particular, the interpretation of the ABJ anomaly as an analogy of the Lee-Nauenberg effect occurring in the massless limit of spinor electrodynamics is shown to be fallacious
Axial-symmetrical domain structures in ferrite-garnet films
International Nuclear Information System (INIS)
Applying the improved technique of double ultrahigh-speed photography one studied occurrence and progress of domain structure upon magnetization of a small section of (BiLaTm)3(FeGa)5O12 ferrite-garnet film prior to saturation. The radial deformation affecting the specimen on the magnetized coil side was determined to break single-axis anisotropy resulting in occurrence of axial-oriented band domain structure inside the magnetized range. That structure period reduced with growth of the pulse field amplitude. Band axial-oriented domain structure is formed under the effect of the magnetostatic axisymmetric field
Vector and axial currents in Wilson chiral perturbation theory
International Nuclear Information System (INIS)
We reconsider the construction of the vector and axial-vector currents in Wilson Chiral Perturbation Theory, the low-energy effective theory for lattice QCD with Wilson fermions. We discuss in detail the finite renormalization of the currents that has to be taken into account in order to properly match the currents. We explicitly show that imposing the chiral Ward identities on the currents does, in general, affect the axial-vector current at O(a). As an application of our results we compute the pion decay constant to one loop in the two-flavor theory. Our result differs from previously published ones.
Instability of Meridional Axial System in f(R) Gravity
Sharif, M
2015-01-01
We analyze dynamical instability of non-static reflection axial stellar structure by taking into account generalized Euler's equation in metric $f(R)$ gravity. Such an equation is obtained by contracting Bianchi identities of usual anisotropic and effective stress-energy tensors, which after using radial perturbation technique gives modified collapse equation. In the realm of $R+\\epsilon R^n$ gravity model, we investigate instability constraints at Newtonian and post-Newtonian approximations. We find that instability of meridional axial self-gravitating system depends upon static profile of structure coefficients while $f(R)$ extra curvature terms induce stability to the evolving celestial body.
The gravitational axial superfield and the formalism of differential geometry
International Nuclear Information System (INIS)
The formalism of differential geometry in the physical 4+4-dimensional superspace (SS) is developed on the basis of the simplest supergravity group of general transformations of the coordinates of the left and right chiral SS. In this formalism the only independent dynamical variable is the axial gravitational superfield (SF). All the geometrical objects - supertetrades, affinities, etc. - are expressed in terms of the axial gravitational SF. Analysis of the transformation properties of the spinor-coordinate derivatives has led to a natural definition of the local Lorentz group for SF. The simplest Lagrangian for pure supergravity is discussed
Axial crack propagation and arrest in pressurized fuselage
Kosai, M.; Shimamoto, A.; Yu, C.-T.; Walker, S. I.; Kobayashi, A. S.; Tan, P.
1994-01-01
The crack arrest capability of a tear strap in a pressurized precracked fuselage was studied through instrumented axial rupture tests of small scale models of an idealized fuselage. Upon pressurization, rapid crack propagation initiated at an axial through crack along the stringer and immediately kinked due to the mixed modes 1 and 2 state caused by the one-sided opening of the crack flap. The diagonally running crack further turned at the tear straps. Dynamic finite element analysis of the rupturing cylinder showed that the crack kinked and also ran straight in the presence of a mixed mode state according to a modified two-parameter crack kinking criterion.
Experimental investigation on ducted counter-rotating axial flow fans
Nouri, Hussain; Ravelet, Florent; Bakir, Farid; Sarraf, Christophe
2011-01-01
An experimental study on counter-rotating axial-flow fans was carried out. The fans of diameter D = 375 mm were designed using an inverse method. The counter-rotating fans operate in a ducted-flow configuration and the overall performances are measured in a normalized test bench. The rotation rate of each fan is independently controlled. The axial spacing between the fans can vary from 10 to 50 mm by steps of 10 mm. The results show that the efficiency is strongly increased compared to a conv...
An effective theory for QCD with an axial chemical potential
Andrianov, Alexander A; Espriu, Domenec; Planells, Xumeu
2013-01-01
We consider the low energy realization of QCD in terms of meson fields when an axial chemical potential is present; a situation that may be relevant in heavy ion collisions. We shall demonstrate that the presence of an axial charge constitutes an explicit source of parity breaking. The eigenstates of strong interactions do not have a definite parity and interactions that would otherwise be forbidden compete with the familiar ones. In this work, we first focus on scalars and pseudoscalars that are described by a generalized linear sigma model; and next, we give some hints on how the Vector Meson Dominance model describes the vector sector.
Infrared and terahertz radiation of a crystal at axial channeling
International Nuclear Information System (INIS)
Basic properties of radiation of a crystal lattice excited by an axial channeling particle are considered. It is shown that a coherent radiation of atoms occurs if the frequency of oscillations of the channeled particle comes to a resonance with the vibrational mode of the crystal. Spectral and angular distribution of radiation and its polarization are calculated. In case of a relativistic channeled particle, the radiation of atoms is generated into a narrow cone in the direction of a crystallographic axis along which the particle is channeling. The radiation of atoms exited at axial channelling has significant degree of circular polarization
Spectral analysis in thin tubes with axial heterogeneities
Ferreira, Rita
2015-01-01
In this paper, we present the 3D-1D asymptotic analysis of the Dirichlet spectral problem associated with an elliptic operator with axial periodic heterogeneities. We extend to the 3D-1D case previous 3D-2D results (see [10]) and we analyze the special case where the scale of thickness is much smaller than the scale of the heterogeneities and the planar coefficient has a unique global minimum in the periodic cell. These results are of great relevance in the comprehension of the wave propagation in nanowires showing axial heterogeneities (see [17]).
Fracture of long bones: rate effects under singular and combined loading states.
Peterson, D L; Skraba, J S; Moran, J M; Greenwald, A S
1984-01-01
This study was undertaken to determine the effect of loading rate on bone failure under singular and combined loading states. Using the entire loading range of an Instron Materials Testing Machine, 190 pairs of canine radii were tested. One bone of each pair was subjected to either torsional or a combination of axial and torsional loads, and compared with a control specimen. Compressive loads of 4.6 and 11.5 N were utilized. Torque to failure and energy data versus loading rate were plotted. As loading rate increased, the torque and energy values were found to increase, reach a peak, and then decline at higher rates. Fractures produced under the combined state of loading are representative of those clinically found in human trauma situations. PMID:6481507
Institute of Scientific and Technical Information of China (English)
薛建阳; 崔卫光; 陈宗平; 马辉; 高亮
2013-01-01
According to static experiment of six steel reinforced recycled aggregate concrete composite columns, the axial compression load-bearing capacity was studied. Two factors, which were the recycled coarse aggregate replacement rate and slenderness ratio, were taken into consideration. Load-displacement curves of composite columns under axial loads were obtained. The fracture of composite columns and the influence of recycled coarse aggregate replacement rate and slenderness ratio on axial compression load-bearing capacity were analyzed. The formula for axial compression load of steel recycled concrete composite column was also presented.%通过6个型钢再生混凝土组合柱的静载试验,对型钢再生混凝土组合柱轴压承载力进行了研究.试验主要考虑再生粗骨料取代率和长细比两个参数对构件承载力的影响.由试验得出组合柱在轴心荷载下的荷载-位移曲线,分析型钢再生混凝土组合柱的破坏机理及再生粗骨料取代率、长细比对其轴压承载力的影响,提出型钢再生混凝土组合柱轴压承载力计算公式.
International Nuclear Information System (INIS)
Compaction characteristics of granular materials subjected to axial loading are investigated for both sphere and non-sphere granular assemblies. The computational study is based on the discrete element method (DEM). The compressive stress-strain relation obtained from three-dimensional DEM simulations is compared with that of an idealized two-dimensional plane-strain compression test and physical experiments using a bronze sphere assembly. We observed good agreement between the experimental and three-dimensional DEM simulation results, while two-dimensional simulations significantly underestimate the stiffness of particulate bed, particularly at large strains. This demonstrates that two-dimensional analysis is generally inadequate to model the compaction characteristics of granular systems. We performed a detailed analysis on the force-transmission characteristics of granular materials at microscopic level and present a connection between the directional orientation of force-networks and the invariants of the macroscopic stress tensor: the non-sphere systems were able to build up a strongly anisotropic network of heavily loaded contacts. Several complex phenomena, both geometric and kinematic, that are operative in sphere and non-sphere assemblies due to inter-particle interactions during compression are presented here. It is often assumed that the ratio of invariants of the stress tensor is uniform and constant in uni-axial compression tests. Our results show that the ratio of invariants of the stress tensor is non-uniform and non-constant even when the granular assemblies are subjected to the so-called uni-axial compressive loading, which is in agreement with other recent studies (e.g. Gu et al 2001 Int. J. Plasticity 17 147) performed using the finite element method. The non-homogeneous characteristics that are reported at the particulate scale need to be accounted in considering possible continuum models for the granular systems
ALPS: An advanced loading pattern search program
International Nuclear Information System (INIS)
In-core fuel management continues to be affected by trends toward longer cycles, increased discharge burnup, increasingly complex fuel assembly features such as axial blankets and reduced-length burnable absorbers. Obtaining efficient core loading patterns which meet several, often conflicting, design criteria is becoming difficult to perform manually. To address this need, Westingouse has developed the Advanced Loading Pattern Search program, ALPS, a self-contained fuel management tool. The computer program establishes a variety of loading pattern candidates, based on the existing fuel inventory of spent and fresh fuel assemblies, and burnable absorber configurations defined by the user. The possible loading pattern candidates are established based on a reactivity distribution target and an appropriate matching of available fuel and burnable absorber configurations. An extensive search algorithm evaluates thousands of alternatives, and selects the candidates that meet specific design criteria. This search approach offers several advantages over conventional methods, as no specific knowledge and/or constraints are fixed in the algorithm. ALPS includes an innovative approach to take into account the reactivity effects of three-dimensional features. Such an approach permits accurate and fast representation of 3D features, using a two-dimensional core physics model. The software is now operational on a workstation computer, with an advanced graphical user interface of streamline input setup and output review. (author). 2 refs, 2 figs, 1 tab
Effect of axial groove and resin luting cements on the retention of complete cast metal crowns
Directory of Open Access Journals (Sweden)
K Rajkumar
2009-01-01
Full Text Available Background : The design of the tooth preparation and the cementing medium are important consid-erations in the retention of crowns and fixed partial dentures. The purpose of this invitro study was to determine the effect of axial groove on the retention of complete cast metal crowns using two resin luting cements. Methods: Forty freshly extracted intact human molar teeth were prepared in their long axis to receive complete cast metal crowns. The specimens were randomly divided into two groups (one control and one study group. An axial groove of uniform size and shape was made on the prepared teeth under the study group. Axial surface area of prepared teeth specimens was measured. Complete cast metal crowns were fabricated for each specimen. Specimens of each group were divided into subgroups of 10 samples and were cemented with two resin luting cements, RelyX Unicem® and Calibra®, re-spectively. The cemented crowns were loaded in tension using a Universal Instron testing machine. The maximal tensile strength was recorded. Data were compared using the Mann-Whitney U test (α=0.05. Results: No significant differences in the tensile stress values were noted between the control (mean: 5.76±0.392 MPa and study (mean: 5.93±0.751 MPa groups cemented with RelyX Unicem. No sig-nificant differences in the tensile stress values were noted between the control (mean: 4.92±0.641 MPa and study (mean: 5.15 ±0.478 MPa groups cemented with Calibra. However, significant dif-ference in the tensile stress values was found between the two resin cements in the control and study groups. Conclusion: Axial groove placed in tooth preparations for resin bonded complete cast metal crowns had no statistically significant effect on retention. The use of (RelyX Unicem® yielded greater reten-tion values when compared to Calibra®.
Analysis of PWR ex-vessel steam explosion for axial and side melt release
International Nuclear Information System (INIS)
Highlights: • PWR ex-vessel steam explosion study was performed with the MC3D code. • The conditions of the OECD project SERENA reactor exercise were considered. • The influence of jet breakup modelling on the fuel coolant interaction was analysed. • The pressure loads on the cavity wall significantly depend on the release location. • For reactor simulations it is important that FCI codes have 3-D capabilities. - Abstract: A steam explosion, in the frame of nuclear reactor safety, is a process resulting from the interaction between the core melt and water. Steam explosions are an important nuclear safety issue because they can potentially jeopardize the primary system and the containment integrity of the nuclear power plant. In the year 2007 the OECD project SERENA was launched, trying to resolve the open issues in steam explosion understanding and modelling, with the focus on reactor applications. To verify the progress made in the understanding and modelling of the fuel coolant interaction key phenomena for reactor applications a reactor exercise has been performed at the end of the project. In the paper the PWR ex-vessel steam explosion study, which was carried out with the MC3D code in conditions of the SERENA reactor exercise, is presented and discussed. The axial melt release case was simulated in 2-D and the side release case in 3-D. In reactor calculations the largest uncertainties in the prediction of the steam explosion strength may be expected due to the large uncertainties related to the jet breakup. Therefore the premixing simulations were performed with both available jet breakup models, i.e. a global and a local one, to get some insight in these uncertainties. For each premixing simulation an explosion simulation was performed, triggering the explosion around the time of the melt bottom contact. It turned out that despite the different jet breakup in both considered approaches, the calculated pressure loads are in the same range due to
Analysis of PWR ex-vessel steam explosion for axial and side melt release
Energy Technology Data Exchange (ETDEWEB)
Leskovar, Matjaž, E-mail: matjaz.leskovar@ijs.si; Uršič, Mitja
2015-03-15
Highlights: • PWR ex-vessel steam explosion study was performed with the MC3D code. • The conditions of the OECD project SERENA reactor exercise were considered. • The influence of jet breakup modelling on the fuel coolant interaction was analysed. • The pressure loads on the cavity wall significantly depend on the release location. • For reactor simulations it is important that FCI codes have 3-D capabilities. - Abstract: A steam explosion, in the frame of nuclear reactor safety, is a process resulting from the interaction between the core melt and water. Steam explosions are an important nuclear safety issue because they can potentially jeopardize the primary system and the containment integrity of the nuclear power plant. In the year 2007 the OECD project SERENA was launched, trying to resolve the open issues in steam explosion understanding and modelling, with the focus on reactor applications. To verify the progress made in the understanding and modelling of the fuel coolant interaction key phenomena for reactor applications a reactor exercise has been performed at the end of the project. In the paper the PWR ex-vessel steam explosion study, which was carried out with the MC3D code in conditions of the SERENA reactor exercise, is presented and discussed. The axial melt release case was simulated in 2-D and the side release case in 3-D. In reactor calculations the largest uncertainties in the prediction of the steam explosion strength may be expected due to the large uncertainties related to the jet breakup. Therefore the premixing simulations were performed with both available jet breakup models, i.e. a global and a local one, to get some insight in these uncertainties. For each premixing simulation an explosion simulation was performed, triggering the explosion around the time of the melt bottom contact. It turned out that despite the different jet breakup in both considered approaches, the calculated pressure loads are in the same range due to
Strain Measurement System Developed for Biaxially Loaded Cruciform Specimens
Krause, David L.
2000-01-01
A new extensometer system developed at the NASA Glenn Research Center at Lewis Field measures test area strains along two orthogonal axes in flat cruciform specimens. This system incorporates standard axial contact extensometers to provide a cost-effective high-precision instrument. The device was validated for use by extensive testing of a stainless steel specimen, with specimen temperatures ranging from room temperature to 1100 F. In-plane loading conditions included several static biaxial load ratios, plus cyclic loadings of various waveform shapes, frequencies, magnitudes, and durations. The extensometer system measurements were compared with strain gauge data at room temperature and with calculated strain values for elevated-temperature measurements. All testing was performed in house in Glenn's Benchmark Test Facility in-plane biaxial load frame.
Creep Damage Characteristics of Soft Rock under Disturbance Loads
Institute of Scientific and Technical Information of China (English)
Fu Zhiliang; Guo Hua; Gao Yanfa
2008-01-01
This article focuses on the process of rock creep damage and micro-damage evolution properties of gray green mudstone under impacting disturbance load conditions for the first time using the real time computerized tomography (CT) testing technique. The results indicate that axial load comes into limit strength neighborhood, rock micro-crack links into larger crack, creep rate increases in a short time, larger plastic deformation happens; this is called disturbance accelerating creep stage. When rock is within limit strength neighborhood, there occurs creep micro-damage under smaller disturbance load. When disturbance load is larger, rock directly enters into disturbance accelerating creep stage, failure occurs instantaneously. On the basis of experimental research, the CT scanning method was used to describe the creep micro-damage of soft rock, also helpful in the prediction of roadways' service life and evaluation of geotechnicai engineering stability.
Analysis of piping loads on shells of revolution
International Nuclear Information System (INIS)
The work of Bijaard as presented by Wichman, et al., Welding Research Council Bulletin 107 (1965), is widely used in industry to evaluate the effects of concentrated loads on cylinders and spheres. But many axially symmetric structures have configuration which preclude the use of this work. In such cases, the procedure given in this paper can greatly reduce the computational effort needed to obtain accurate stresses and deflections due to loads such as occur at piping connections. The paper provides a method of calculating the truncation error due to terminating the Fourier expansion of a loading at a given point. Also for various common loading situations, it provides points where the truncation error is zero. (Auth.)
International Nuclear Information System (INIS)
The static method for the evaluation of the limit loads of a perfectly elasto-plastic structure is presented. Using the static theorem of Limit Analysis and the Finite Element Method, a lower bound for the colapso load can be obtained through a linear programming problem. This formulation if then applied to symmetrically loaded shells of revolution and some numerical results of limit loads in nozzles are also presented. (Author)
International Nuclear Information System (INIS)
We reinvestigate Adler's partially conserved axial-vector current relation in the presence of an external electromagnetic field within the framework of QCD coupled to external fields. We discuss pion electroproduction within a tree-level approximation to chiral perturbation theory and explicitly verify a chiral Ward identity referred to as the Adler-Gilman relation. We critically examine soft-momentum techniques and point out how inadmissable approximations may lead to results incompatible with chiral symmetry. As a result we confirm that threshold pion electroproduction is indeed a tool to obtain information on the axial form factor of the nucleon
Resiliently loaded lateral supports for cantilever-mounted rod guides of a pressurized water reactor
International Nuclear Information System (INIS)
This patent describes a resiliently loaded top end support for each of plural rod guides disposed in closely spaced, parallel axial relationship within the inner barrel assembly of a pressurized water reactor vessel. The inner barrel assembly occupying a central portion of the vessel and being of a vertical height extending from a first plate of lower elevation to the second plate of higher elevation within the vessel. The second plate being moveable axially into and out of assembled relationship with the inner barrel assembly. Each the rod guides having a thin sidewall portion of elongated configuration and being of an axial length corresponding substantially to the vertical height of the inner barrel assembly and being mounted at the lower end thereof to the first plate and accommodating in axial, sliding relationship therewithin plural, respectively associated rod clusters
Elevated temperature axial and torsional fatigue behavior of Haynes 188
Bonacuse, Peter J.; Kalluri, Sreeramesh
1992-06-01
The results of high-temperature axial and torsional low-cycle fatigue experiments performed on Haynes 188, a wrought cobalt-base superalloy, are reported. Fatigue tests were performed at 760 C in air on thin-walled tubular specimens at various ranges under strain control. Data are also presented for coefficient of thermal expansion, elastic modulus, and shear modulus at various temperatures from room to 1000 C, and monotonic and cyclic stress-strain curves in tension and in shear at 760 C. The data set is used to evaluate several multiaxial fatigue life models (most were originally developed for room temperature multiaxial life prediction) including von Mises equivalent strain range (ASME boiler and pressure vessel code), Manson-Halford, Modified Multiaxiality Factor (proposed here), Modified Smith-Watson-Topper, and Fatemi-Socie-Kurath. At von Mises equivalent strain ranges (the torsional strain range divided by the square root of 3, taking the Poisson's ratio to be 0.5), torsionally strained specimens lasted, on average, factors of 2 to 3 times longer than axially strained specimens. The Modified Multiaxiality Factor approach shows promise as a useful method of estimating torsional fatigue life from axial fatigue data at high temperatures. Several difficulties arose with the specimen geometry and extensometry used in these experiments. Cracking at extensometer probe indentations was a problem at smaller strain ranges. Also, as the largest axial and torsional strain range fatigue tests neared completion, a small amount of specimen buckling was observed.
Improving axial depth of cut accuracy in micromilling
DEFF Research Database (Denmark)
Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo
2004-01-01
and their rapid warming and cooling, which prevent the achievement of a steady state. Several other factors, independent on the tool-workpiece interaction, influence the machining accuracy. The cutting parameter most heavily affected is the axial depth of cut which is the most critical when using...
Elevated temperature axial and torsional fatigue behavior of Haynes 188
Bonacuse, Peter J.; Kalluri, Sreeramesh
1995-01-01
The results are reported for high-temperature axial and torsional low-cycle fatigue experiments performed at 760 C in air on thin-walled tubular specimens of Haynes 188, a wrought cobalt-based superalloy. Data are also presented for mean coefficient of thermal expansion, elastic modulus, and shear modulus at various temperatures from room to 1000 C, and monotonic and cyclic stress-strain curves in tension and in shear at 760 C. This data set is used to evaluate several multiaxial fatigue life models (most were originally developed for room temperature multiaxial life prediction) including von Mises equivalent strain range (ASME Boiler and Pressure Code), Manson-Halford, modified multiaxiality factor (proposed in this paper), modified Smith-Watson-Topper, and Fatemi-Socie-Kurath. At von Mises equivalent strain ranges (the torsional strain range divided by the square root of 3, taking the Poisson's ratio to be 0.5), torsionally strained specimens lasted, on average, factors of 2 to 3 times longer than axially strained specimens. The modified multiaxiality factor approach shows promise as a useful method of estimating torsional fatigue life from axial fatigue data at high temperatures. Several difficulties arose with the specimen geometry and extensometry used in these experiments. Cracking at extensometer probe indentations was a problem at smaller strain ranges. Also, as the largest axial and torsional strain range fatigue tests neared completion, a small amount of specimen buckling was observed.
Axial heterogeneous core concept applied for super phoenix reactor
International Nuclear Information System (INIS)
Always maintaining the current design rules, this paper presents a parametric study on the type of axial heterogeneous core concept (CHA), utilizing a core of fast reactor Super Phenix type, reaching a maximum thermal burnup rate of 150000 M W d/t and being managed in single batch. (author)
Defining active sacroiliitis on MRI for classification of axial spondyloarthritis
DEFF Research Database (Denmark)
Lambert, Robert G W; Bakker, Pauline A C; van der Heijde, Désirée;
2016-01-01
OBJECTIVES: To review and update the existing definition of a positive MRI for classification of axial spondyloarthritis (SpA). METHODS: The Assessment in SpondyloArthritis International Society (ASAS) MRI working group conducted a consensus exercise to review the definition of a positive MRI for...