Literatura académica sobre el tema "Constant deflection contour method"
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Artículos de revistas sobre el tema "Constant deflection contour method"
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Banerjee, M. M. y G. A. Rogerson. "On the application of the constant deflection-contour method in nonlinear vibrations of elastic plates". Archive of Applied Mechanics (Ingenieur Archiv) 72, n.º 4-5 (1 de julio de 2002): 279–92. http://dx.doi.org/10.1007/s00419-002-0206-0.
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Wei, Zhao Cheng, Min Jie Wang, Wu Chu Tang y Liang Wang. "Tool Deflection Error Regularization and Compensation in End Milling of Contour Surfaces". Applied Mechanics and Materials 217-219 (noviembre de 2012): 1341–45. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.1341.
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This paper presents a new approach of tool deflection error regularization and compensation in end milling of contour surfaces. The material removal rate (MRR) is adopted as the dominant factor of surface dimensional error. A mathematics model of determining the MRR in generalized contour surfaces machining is proposed. Feedrate scheduling methodology is applied to regulate a constant MRR along curved tool path. The expectation with the constant MRR is that it will potentially produce a constant surface dimensional error. Thus, the compensation can be conveniently achieved by offsetting the nominal finishing path. The desired MRR and corresponding offsetting value of finishing tool path are determined by a peripheral milling test. Machining results obtained in this study reveal that the proposed approach can significantly reduce the surface dimensional error and the smooth variation of feedrate can get a few variation of surface dimensional error. Comparing to the existing methods, the time-consuming iterative process in error compensation is omitted.
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Li, Dong, Zhi-Chao Lai, Ying Wang y Zhou-Lian Zheng. "A non-contact method for estimating the pre-tension of a rectangular membrane structure". Insight - Non-Destructive Testing and Condition Monitoring 62, n.º 8 (1 de agosto de 2020): 464–70. http://dx.doi.org/10.1784/insi.2020.62.8.464.
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The stiffness of membrane structures widely used in modern buildings is provided by pre-tension, which means that any loss of pre-tension during service life may endanger structural safety and lead to engineering accidents. Therefore, the pre-tension of membrane structures needs to be estimated effectively and a corresponding estimation method is proposed in this study. Firstly, a theoretical model of a rectangular membrane structure is established using the constant deflection contour method (CDCM) to analytically derive a relationship between the pre-tension and the frequency. Then, the pre-tension is calculated using the frequency obtained experimentally by non-contact modal testing using a three-dimensional digital image correlation (3D-DIC) technique. Furthermore, the estimation method is validated by experimental study. The results show that the proposed method can provide a satisfactory assessment of the pre-tension in rectangular membrane structures and has significant potential to be utilised by industry.
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Surianinov, Mykola, Yurii Krutii, Dariya Kirichenko y Oleksii Klimenko. "TO THE CALCULATION OF RING PLATES ON A VARIABLE ELASTIC BASE". Urban development and spatial planning, n.º 83 (14 de abril de 2023): 304–13. http://dx.doi.org/10.32347/2076-815x.2023.83.304-313.
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The article examines the bending of ring plates on a variable elastic base. There are different models of elastic base. The simplest is the Winkler model, or the spring model. For beams on a constant elastic base, this model allows obtaining an exact solution, but not for slabs. The case is even more complicated when the elastic basis is variable. There is no single approach to building a universal analytical solution. Therefore, numerical calculation methods are used in engineering practice. The analytical method of direct integration and computer modeling in PC LIRA-CAD with subsequent calculations by the method of finite elements are used. Two examples are considered: a steel plate, which is rigidly clamped along the inner contour, and its outer contour is hinged, and a concrete slab, which is rigidly clamped along the outer contour, and its inner contour is hinged. The results of the numerical implementation show that the values of deflections when calculated by the author's method and the method of finite elements in PC LIRA-CAD practically coincide, and the difference in the values of bending moments reaches 10%. Moreover, the difference in deflections is manifested only in the fourth (and sometimes in the fifth) sign after the comma. It is noted that the method of direct integration demonstrated very high accuracy when solving numerous test problems that have an exact solution. The authors explain the discrepancy in the values of the bending moments obtained here by the semi-automatic breakdown of the finite-element mesh in PC LIRA-CAD. This statement is based on the fact that when the mesh is thickened in the circumferential direction, the results obtained by the two methods for determining the radial and circumferential bending moments are substantially converged.
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Surianinov, M. H., Y. S. Krutii, А. S. Karnaukhova y О. M. Klymenko. "ANALYTICAL METHOD FOR CALCULATING ANNULAR PLATES ON A VARIABLE ELASTIC BASE". Modern construction and architecture, n.º 2 (28 de diciembre de 2022): 37–43. http://dx.doi.org/10.31650/2786-6696-2022-2-37-43.
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The paper considers the application of the method of direct integration to calculations of annular plates and slabs on a continuous variable elastic base. Ring-shaped plates with variable geometric and mechanical parameters are increasingly used. Not only the elastic base, but also the plate thickness and cylindrical stiffness can be variable parameters here. The need for an analytical method for calculating such structures raises no doubts, since it makes it possible to evaluate the accuracy of finite-element analysis. To date, there are no proposals in the literature regarding a general analytical method for the calculation of annular plates on a variable elastic base. A detailed description of the algorithm of the direct integration method is not given in the paper, and all the calculation formulas for the annular plate are taken from the authors' already published article. The results of numerical implementation of this algorithm for specific examples are considered: a concrete plate, which is rigidly pinch on the inner contour, and its outer contour is free, and a steel plate, which is rigidly pinch on the outer contour, and its inner contour is free. To estimate the results of calculation by the author's method, computer modeling of the considered structures in PC LIRA-SAPR and their calculations by the finite-element method have been executed. The foundation reaction is described by Winkler model with a variable bedding factor. In the first case a bed factor is assumed constant, and in the second case it changes under the linear law. Calculations have shown that discrepancy between deflections calculated by the finite-element method and the author's method does not exceed 1 %, and the results of radial and circumferential moments calculation differ more considerably, amounting to 10 %. The authors explain this difference by the inaccuracy of the numerical analysis associated with the semi-automatic method of constructing a finite-element mesh, which should be made finer. The densification of the mesh in the manual mode of its partitioning significantly reduces the discrepancy between the results of calculating the deflections, radial and circumferential bending moments by the finite-element method and the author's method.
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Surianinov, M., Y. Krutii, D. Kirichenko y O. Klimenko. "CALCULATION OF ANNULAR PLATES ON AN ELASTIC BASE WITH A VARIABLE BEDDING FACTOR". Mechanics And Mathematical Methods 4, n.º 2 (31 de diciembre de 2022): 43–52. http://dx.doi.org/10.31650/2618-0650-2022-4-2-43-52.
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The application of the analytical method ‒ the method of direct integration ‒ to calculations of building structures in the form of circular plates and plates on a continuous variable elastic base is considered. It is noted that there are no proposals for a general analytical method for calculation of annular plates on a variable elastic base in the literature. And the need for such a method is obvious, since it makes it possible to estimate the accuracy of finite element analysis. A detailed description of the algorithm of the direct integration method is not given in the paper, and all the calculation formulas for the circular plate are taken from the authors’ already published article. The results of numerical implementation of this algorithm for specific examples are considered. In order to verify the results of calculations by the author’s method, computer modeling of the considered circular plates in PC LIRA-SAPR and their calculations by the finite element method have been performed. The reaction of the foundation is described by the Winkler model with a variable bedding factor. The calculation of a concrete slab that is rigidly pinched on the inner contour and articulated on the outer contour is performed. And calculation of a steel plate with rigid pinching on the outer contour and articulated on the inner contour. In the first case, the bedding factor is assumed constant, and in the second case, it changes according to the linear law. The calculations showed that the discrepancy between deflections calculated by the finite-element method and the author’s method does not exceed 1%, and the results of radial and circumferential moments calculation differ more considerably, amounting to 10%. The authors explain this difference by the inaccuracy of the numerical analysis associated with a semi-automatic method of constructing a finite-element mesh, which should be made finer. The densification of the mesh in the manual mode of its partitioning significantly reduces the discrepancy between the results of calculating the deflections, radial and circumferential bending moments by the finite-element method and the author’s method.
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Petrakov, Yury y Yan Romanov. "Ensuring accuracy of contour milling on CNC machines". Mechanics and Advanced Technologies 7, n.º 1 (13 de abril de 2023): 51–60. http://dx.doi.org/10.20535/2521-1943.2023.7.1.276162.
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Contour milling is characterized by quasi-stationary, which leads to the occurrence of a machining error caused by elastic deflections of the machining system. Moreover, such an error cannot be eliminated by sub-adjusting the control program "for size", since it not is constant and changes along the contour in a wide range. To ensure the accuracy of contour milling, a new method of combined control is proposed, which uses a posteriori information of machine verification measurements of the machined surface and a priori information of modeling the material removal process. In case of single manufacturing, the allowance on the last pass is divided into two parts, and after machining the first part, verifications are performed, then modeling and machining of the second half according to the corrected control program. In mass manufacturing, verifications are performed on the first part, and all subsequent ones are machined according to the adjusted control program. To obtain the necessary a posteriori information, the technology of machine verifications on CNC-machine with a three-coordinate probe according to standard control programs is proposed, and it is enough to perform two measurements or one, in the presence of surfaces inclined to the coordinate axes of the contour. A computer program was created, the core of which is a mathematical model of the process, which reproduces the structural diagram of the machining system closed behind two elastic deflections. The primary control file is loaded in G-codes with measurement data, and as a result of the process simulation, a new control file for the CNC-machine tool is formed, which eliminates the error from elastic deflections of machining system. Preliminary tests showed the possibility of increasing the accuracy of contour machining by more than 3 times.
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RAJASEKARAN, S. y K. NALINAA. "STABILITY AND VIBRATION ANALYSIS OF NON-PRISMATIC THIN-WALLED COMPOSITE SPATIAL MEMBERS OF GENERIC SECTION". International Journal of Structural Stability and Dynamics 05, n.º 04 (diciembre de 2005): 489–520. http://dx.doi.org/10.1142/s0219455405001714.
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This paper presents a detailed treatment of the formulation of static, bucking and vibration analysis of non-prismatic thin-walled composite spatial members of generic section. The theory is limited to small strains, moderate deflections and small rotations. The torsional shear strain on the middle surface of the beam wall is zero for an open contour while it corresponds to constant shear flow for a closed contour. Rigorous expressions for strains based on membrane theory of shells are obtained through which the effect of nonlinear tapering is considered. Solutions for classical buckling and vibration analysis by the finite element method are discussed. Numerical integration by using Gaussian quadrature on the cross-sections for the computation of sectorial properties and stress resultants and over the length for the computation of flexural, geometric and mass matrices is suggested. Some examples are solved and critical bucking loads, natural frequencies and the corresponding buckled and mode shapes are obtained by the Jacobi iteration procedure.
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ASTAKHOV, Sergey A. y Vasiliy I. BIRYUKOV. "Buckling under the action of loading by aerodynamic and inertial forces during ground track tests of aviation equipment". INCAS BULLETIN 13, S (3 de agosto de 2021): 5–12. http://dx.doi.org/10.13111/2066-8201.2021.13.s.1.
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The article analyses the choice of a rational layout of the test object with a propulsion system (PS). One of the design examples of calculating the longitudinal stability and strength of the structure is given. The purpose of the article is to solve the problem of bending the elastic line of a cantilever tubular rod with a hinged termination during tests of a propulsion system for various aircrafts. On the example, the estimates of the approximate test object, accelerated on the track to a speed of 1200 m/s, are carried out. The aerodynamic loading of the structure of the mobile track installation is considered using the methods of mathematical modelling and the development of an algorithm for the numerical solution of the problem of bending the elastic line of a cantilever tubular rod. The deflection from the forces of external and internal loads of the outer shell of a movable track installation is considered, provided that the diameter of the outer contour is equal to the minimum and it is constant along the entire length.
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Starovoitov, Eduard I. y Denis V. Leonenko. "Repeated alternating loading of a elastoplastic three-layer plate in a temperature field". Izvestiya of Saratov University. New Series. Series: Mathematics. Mechanics. Informatics 21, n.º 1 (24 de febrero de 2021): 60–75. http://dx.doi.org/10.18500/1816-9791-2021-21-1-60-75.
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Axisymmetric deformation of a three-layer circular plate under repeated alternating loading from the plastic region by a local load is considered. To describe kinematics of asymmetrical on the thickness of the plate pack is adopted the hypothesis of a broken line. In a thin elastic-plastic load-bearing layers are used the hypothesis of Kirchhoff. A non-linearly elastic relatively thick filler is incompressible in thickness. It is taken to be a hypothesis of Tymoshenko regarding the straightness and the incompressibility of the deformed normals with linear approximation of the displacements through the thickness layer. The work of the filler in the tangential direction is taken into account. The physical relations of stress-strain relations correspond to the theory of small elastic-plastic deformations. The effect of heat flow is taken into account. The temperature field in the plate was calculated by the formula obtained by averaging the thermophysical parameters over the thickness of the package. The system of differential equations of equilibrium under loading of the plate from the natural state is obtained by the Lagrange variational method. Boundary conditions on the plate contour are formulated. The solution of the corresponding boundary value problem is reduced to finding the three desired functions: deflection, shear and radial displacement of the shear surface of the filler. A non-uniform system of ordinary nonlinear differential equations is written for these functions. Its analytical iterative solution is obtained in Bessel functions by the method of elastic solutions of Ilyushin. In case of repeated alternating loading of the plate, the solution of the boundary value problem is constructed using the theory of variable loading of Moskvitin. In this case, the hypothesis of similarity of plasticity functions at each loading step is used. Their analytical form is taken independent of the point of unloading. However, the material constants included in the approximation formulas will be different. The cyclic hardening of the material of the bearing layers is taken into account. The parametric analysis of the obtained solutions under different boundary conditions in the case of a local load distributed in a circle is carried out. The influence of temperature and nonlinearity of layer materials on the displacements in the plate is numerically investigated.
Tesis sobre el tema "Constant deflection contour method"
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Chakraborty, (Sengupta) Suparna. "Application of "constant deflection contour" method to problems of dynamic response of structures". Thesis, University of North Bengal, 2002. http://hdl.handle.net/123456789/2736.
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Boyle, Cameron. "A Closed-Form Dynamic Model of the Compliant Constant-Force Mechanism Using the Pseudo-Rigid-Body Model". BYU ScholarsArchive, 2003. https://scholarsarchive.byu.edu/etd/53.
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A mathematical dynamic model is derived for the compliant constant-force mechanism, based on the pseudo-rigid-body model simplification of the device. The compliant constant-force mechanism is a slider mechanism incorporating large-deflection beams, which outputs near-constant-force across the range of its designed deflection. The equation of motion is successfully validated with empirical data from five separate mechanisms, comprising two configurations of compliant constant-force mechanism. The dynamic model is cast in generalized form to represent all possible configurations of compliant constant-force mechanism. Deriving the dynamic equation from the pseudo-rigid-body model is useful because every configuration is represented by the same model, so a separate treatment is not required for each configuration. An unexpected dynamic trait of the constant-force mechanism is discovered: there exists a range of frequencies for which the output force of the mechanism accords nearer to constant-force than does the output force at static levels.
Capítulos de libros sobre el tema "Constant deflection contour method"
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M. Markad, Kanif y Nilesh Tiwari. "Study of Temperature Variation over Shape Memory Polymer Hybrid Composite under Transverse Loading". En Soft Robotics - Recent Advances and Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.107988.
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The chapter presents a nonlinear bending analysis of layered shape memory polymer composite beams under the influence of uniformly distributed transverse load. Simplified Co continuity Finite Element Method based on Higher Order Shear Deformation Theory has been adopted for bending analysis of shape memory polymer composite (SMPC) and shape memory polymer nanocomposite sandwich (SMPNCS) beam. The numerical solutions are obtained by the iterative Newton-Raphson method with Von-Karman nonlinear kinematics. Material properties of SMPC with shape memory polymer (SMP) as matrix and carbon fiber as reinforcements have been calculated by the theory of volume averaging. The effect of temperature on SMP, SMPC, SMP hybrid composite, and SMPNCS has been evaluated for various parameters such as aspect ratio, number of layers, boundary conditions, the volume fraction of carbon fiber, and laminate stacking orientation. The present study provides a detailed explanation of the influence of various parameters on the bending of SMPC and hybrid beam for large strain over a wide range of temperatures, which encompasses the glass transition region (Tg) of SMP. The deflection of the beam over this range of temperature indicates the elastic behavior of SMPC before and after its glass transition region due to constant modulus.
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Veenadevi, A., P. Srinivasa Babu y Pallavi Kurra. "Development and Optimization of Niosomes for Brain Targeting Using Response Surface Methodology". En Current Trends in Drug Discovery, Development and Delivery (CTD4-2022), 477–92. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/9781837671090-00477.
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The current research work deals with the combination of surfactants for vesicular drug delivery of potent chemotherapeutic drugs like capecitabine with advantages of controlled release as well as brain specific targeting. Niosomes formulation was optimized by employing a surface response method in which central composite designed was selected for getting a less number of formulations with better results using Design Expert software version V 11. The niosomes were formulated by using combination of span-80 and brij-78 as non-ionic surfactant by thin film hydration technique in which cholesterol and diacetyl phosphate in constant ratio as per design. Optimized formulation was evaluated for the following parameters like microscopic examination, vesicular size, zeta potential, drug entrapment efficiency, drug content, In-vitro drug release, kinetic studies, and stability studies. Results revealed that the combination of surfactant concentration on the response parameters from statistical optimization method employing various 3D plots and some contour plots for achieving significant results for exhibited a higher retention of Capecitabine inside the vesicles. In-vitro drug release rate was slower at period of 12 hours about 57.01% for optimized formulation. Kinetic evaluation of optimized F10 formulation reported first order drug release with R2 value of 0.9803. The Korsmeyer Peppas model was represented by the release exponent (n) value of 0.0564 indicates that the optimized Niosomal formulation follows a non-Fickian type of drug transport or anomalous diffusion process.
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Ram-Mohan, L. Ramdas. "The BEM and surface plasmons". En Finite Element and Boundary Element Applications in Quantum Mechanics, 435–70. Oxford University PressOxford, 2002. http://dx.doi.org/10.1093/oso/9780198525219.003.0017.
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Abstract The boundary element method (BEM) can be used to advantage for solving differential equations in a region occupied by more than one material. Here the integral equations are formulated for each subregion, and the matrices obtained on discretization of the contour integrals are put together in a manner analogous to overlaying element matrices in the finite element method (FEM). In this chapter, we begin by solving Laplace’s equation for a physical domain having two rectangular regions with dielectric constants EJ and EIJ in a constant electric field. The example makes use of the calculations of Section 16.6, where the solution at the boundary is given in terms of the linear interpolation between nodal values of the potential, and also the normal derivatives of the potential, at the extremities of a boundary element. We then discuss the issues in using Hermite interpolation polynomials in a multiregion BEM. We note here that when the physical region has a large aspect ratio and is elongated in one direction the boundary integrals will be nearly equal for destination points along the shorter side with source points at the farther end. This leads to ill-conditioning qf the final matrices. The problem can be alleviated by breaking up the region into sub regions, each with its own boundary integral. Again, a multiregion BEM can be employed.
Actas de conferencias sobre el tema "Constant deflection contour method"
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Akin, M. Bugra, Wolfgang Sanz y Paul Pieringer. "Endwall Contour Optimization of a Turning Mid Turbine Frame Using an Adjoint Method". En ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26038.
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This paper presents the application of a viscous adjoint method in the optimization of the endwall contour of a turning mid turbine frame (TMTF). The adjoint method is a gradient based optimization method that allows for the computation of the complete gradient information by solving the governing flow equations and their corresponding adjoint equations only once per function of interest (objective and constraints), so that the computation time of the optimization is nearly independent of the number of parameters. With the use of a greater number of parameters a more detailed definition of endwall contours is possible, so that an optimum can be approached more precisely. A Navier-Stokes flow solver coupled with Menter’s SST k–ω turbulence model is utilized for the CFD simulations, whereas the adjoint formulation is based on the constant eddy viscosity approximation for turbulence. The total pressure ratio is used as the objective function in the optimization. The effect of contouring on the secondary flows is evaluated and the performance of the axisymmetric TMTF is calculated and compared with the optimized design.
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Kulesza, Zbigniew y Jerzy T. Sawicki. "Controlled Deflection Approach for Rotor Crack Detection". En ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-68960.
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A transverse shaft crack is a serious malfunction that can occur due to cyclic loading, creep, stress corrosion, and other mechanisms to which rotating machines are subjected. Though studied for many years, the problems of early crack detection and warning are still in the limelight of many researchers. This is due to the fact that the crack has subtle influence on the dynamic response of the machine and still there are no widely accepted, reliable methods of its early detection. This paper presents a new approach to these problems. The method utilizes the coupling mechanism between the bending and torsional vibrations of the cracked, non-rotating shaft. By applying an external lateral force of constant amplitude, a small shaft deflection is induced. Simultaneously, a harmonic torque is applied to the shaft inducing its torsional vibrations. By changing the angular position of the lateral force application, the position of the deflection also changes opening or closing of the crack. This changes the way the bending and torsional vibrations are being coupled. By studying the coupled lateral vibration response for each angular position of the lateral force one can assess the possible presence of the crack. The approach is demonstrated with a numerical model of a rotor. The model is based on the rigid finite element method (RFE), which has previously been successfully applied for the dynamic analysis of many complicated, mechanical structures. The RFE method is extended and adopted for the modeling of the cracked shafts. An original concept of crack modeling utilizing the RFE method is presented. The crack is modeled as a set of spring-damping elements (SDEs) of variable stiffness connecting two sections of the shaft. By calculating the axial deformations of the SDEs, the opening/closing mechanism of the crack is introduced. The results of numerical analysis demonstrate the potential of the suggested approach for effective shaft crack detection.
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Rajalingham, C., R. B. Bhat y G. D. Xistris. "Natural Frequencies and Mode Shapes of Elliptic Plates With Boundary Characteristic Orthogonal Polynomials As Assumed Shape Functions". En ASME 1991 Design Technical Conferences. American Society of Mechanical Engineers, 1991. http://dx.doi.org/10.1115/detc1991-0294.
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Abstract The natural frequencies and natural modes of vibration of uniform elliptic plates with clamped, simply supported and free boundaries are investigated using Rayleigh-Ritz method. A modified polar coordinate system is used to investigate the problem. Energy expressions in Cartesian coordinate system are transformed into the modified polar coordinate system. Boundary characteristic orthogonal polynomials in the radial direction, and trigonometric functions in the angular direction are used to express the deflection of the plate. These deflection shapes are classified into four basic categories, depending on its symmetrical or antisymmetrical property about the major and minor axes of the ellipse. The first six natural modes in each of the above categories are presented in the form of contour plots.
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Kim, Doo Hwan y Tulga M. Ozsoy. "New Sampling Strategies for Form Evaluation of Free-Form Surfaces". En ASME 1999 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/detc99/cie-9103.
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Abstract New strategies to determine the location of the measurement points for form evaluation of free-form surfaces by using Coordinate Measuring Machines are investigated. The newly developed corrected length method locates the measurement points on constant curvature contour lines. The length and the rank of each contour line are used as parameters to control the distribution of the measurement points. The experimental results have shown that the proposed method is more robust than the known methods currently being used for form evaluation of free-form surfaces. The method also offers opportunities for developing more efficient probe-path generation strategies, since the measurement points are located on continuous paths formed by constant curvature contour lines.
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Bilancia, Pietro, Alessandro Geraci y Giovanni Berselli. "On the Design of a Long-Stroke Beam-Based Compliant Mechanism Providing Quasi-Constant Force". En ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/smasis2019-5519.
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Abstract In this paper the design of a linear long-stroke quasi-constant force compliant mechanism (CM) is presented and discussed. Starting from a flexure-based slider-crank mechanism, providing the required constant force within a rather limited deflection range, the paper reports about the shape optimization carried out with the specific aim of extending the available CM operative range. The proposed device is suitable in several precision manipulation systems, which require to maintain a constant-force at their contact interface with the manipulated object. Force regulation is generally achieved by means of complex control algorithms and related sensory apparatus, resulting in a flexible behavior but also in high costs. A valid alternative may be the use of a purposely designed CM, namely a purely mechanical system whose shape and dimensions are optimized so as to provide a force-deflection behavior characterized by zero stiffness. In the first design step, the Pseudo-Rigid Body (PRB) method is exploited to synthesize the sub-optimal compliant configuration, i.e. the one characterized by lumped compliance. Secondly, an improved design alternative is evaluated resorting to an integrated software framework, comprising Matlab and ANSYS APDL, and capable of performing non-linear structural optimizations. The new embodiment makes use of a variable thickness beam, whose shape and dimensions have been optimized so as to provide a constant reaction force in an extended range. Finally, a physical prototype of the beam-based configuration is produced and tested, experimentally validating the proposed design method.
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Saghafi, Fariborz y Afshin Banazadeh. "Coanda Surface Geometry Optimization for Multi-Directional Co-Flow Fluidic Thrust Vectoring". En ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59715.
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The performance of Co-flow fluidic thrust vectoring is a function of secondary flow characteristics and the fluidic nozzle geometry. In terms of nozzle geometry, wall shape and the secondary slot aspect ratio are the main parameters that control the vector angle. The present study aims to find a high quality wall shape to achieve the best thrust vectoring performance, which is characterized by the maximum thrust deflection angle with respect to the injected secondary air. A 3D computational fluid dynamics (CFD) model is employed to investigate the flow characteristics in thrust vectoring system. This model is validated using experimental data collected from the deflection of exhaust gases of a small jet-engine integrated with a multi-directional fluidic nozzle. The nozzle geometry is defined by the collar radius and its cutoff angle. In order to find the best value of these two parameters, Quasi-Newton optimization method is utilized for a constant relative jet momentum rate, a constant secondary slot height and insignificant step size. In this method, the performance index is described as a function of thrust deflection angle. Optimization parameters (wall geometric parameters) are estimated in the direction of gradient, with an appropriate step length, in every iteration process. A good guess of initial optimization parameters could lead to a rapid convergence towards an optimal geometry and hence maximum thrust deflection angle. Examination over a range of geometric parameters around the optimum point reveals that this method promises the best performance of the system and has potential to be employed for all the other affective factors.
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Howell, Larry L. y Ashok Midha. "Evaluation of Equivalent Spring Stiffness for Use in a Pseudo-Rigid-Body Model of Large-Deflection Compliant Mechanisms". En ASME 1994 Design Technical Conferences collocated with the ASME 1994 International Computers in Engineering Conference and Exhibition and the ASME 1994 8th Annual Database Symposium. American Society of Mechanical Engineers, 1994. http://dx.doi.org/10.1115/detc1994-0219.
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Abstract Compliant mechanisms gain some or all of their mobility from the flexibility of their members rather than from rigid-body joints only. More efficient and usable analysis and design techniques are needed before the advantages of compliant mechanisms can be fully utilized. In an earlier work, a pseudo-rigid-body model concept, corresponding to an end-loaded geometrically nonlinear, large-deflection beam, was developed to help fulfill this need. In this paper, the pseudo-rigid-body equivalent spring stiffness is investigated and new modeling equations are proposed. The result is a simplified method of modeling the force/deflection relationships of large-deflection members in compliant mechanisms. Flexible segments which maintain a constant end angle are discussed, and an example mechanism is analyzed. The resulting models are valuable in the visualization of the motion of large-deflection systems, as well as the quick and efficient evaluation and optimization of compliant mechanism designs.
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Wang, Jianjun, Minfu Lu, Daqing Zou y Sheng Liu. "Investigation of Interfacial Fracture Behavior of a Flip-Chip Package Under a Constant Concentrated Load". En ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0505.
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Abstract In this paper, the interfacial fracture behavior of a flip-chip package subjected to a constant concentrated line load was investigated using a unique 6-axis submicron tester coupled with a high density laser moiré interferometry. The real-scale three-point bending flip-chip specimen, capable of measuring the crack growth rate (along the interface) and the interfacial fracture toughness was developed. The results show that the crack propagation along the interface of the passivated silicon chip/underfill under a constant concentrated load can be categorized into three stages: (1) stable crack propagation stage, (2) unstable crack propagation stage, and (3) quasi-crack arrest stage. There exist two obvious transition points between the stable crack propagation stage and the unstable crack propagation stage, and between the unstable crack propagation stage and the quasi-crack arrest stage. The moiré interferometry technique was used to monitor and measure the crack length during the test. The crack growth rate along the interface of the passivated silicon chip/underfill was calculated in terms of the load line deflection vs. time curve obtained from the test. In addition, the relationship between the crack length and the load line deflection was calibrated by using finite element analysis. The near tip displacement fields of the flip-chip package was also determined by the same method. The energy release rate was computed by using these near tip displacement variables through an analytical expression derived by authors. The interfacial fracture toughness Gc was determined by the energy release rate corresponding to the crack length at the quasi-crack arrest stage measured in the test. The interfacial fracture toughness Gc and the phase angle ϕ of the flip-chip package considered at the interface where the passivated silicon chip meets the underfill are about 35 J/m2 and −65° respectively.
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Logan, Philip J. y Craig P. Lusk. "Pseudo-Rigid-Body Models for End-Loaded Heavy Cantilever Beams". En ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-46526.
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The large deflection of cantilever beams has been widely studied. A number of models and mathematical techniques have been utilized in predicting the path coordinates and load-deflection relationships of such beams. The Pseudo-Rigid-Body Model (PRBM) is one such method which replaces the elastic beam with rigid links of a parameterized pivot location and torsional spring stiffness. In this paper, the PRBM method is extended to include cases of a constant distributed load combined with a parallel endpoint force. The phase space of the governing differential equations is used to store information relevant to the characterization of the PRBM parameters. Correction factors are also given to decrease the error in the load-deflection relationship and extend the angular range of the model, thereby further aiding compliant mechanism design. Our calculations suggest a simple way of representing the effective torque caused by a distributed load in a PRBM as a function of easily calculated model parameters.
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Wang, Jianhua y Decheng Wan. "Direct Simulations of Turning Circle Maneuver in Waves Using RANS-Overset Method". En ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78376.
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In the present work, a RANS-overset method is used to numerically investigate turning circle maneuver in waves for a twin-screw ship. CFD solver naoe-FOAM-SJTU is used for the numerical computations of the fully appended ONR Tumblehome ship model. Overset grids are used to fully discretize the ship hull, twin propellers and rudders. The simulation of turning circle maneuver is carried out at constant propeller rotational speed with 35° rudder deflection. Open source toolbox waves2Foam is utilized to generate desired waves for the moving computational domain. Predicted ship trajectory and 6DoF motions, hydrodynamic forces and moments acting on the ship and the moving components are presented. The main parameters of the turning circle maneuver, such as the advance, the transfer, the tactical diameter, and the turning diameter, are presented and compared with the available experiment. Wave effects on the free running turning circle maneuver are discussed through detailed flow visualizations. The trajectory and main parameters agree well with the experiment, which show that the present RANS-overset method is a reliable approach to directly simulate turning circle maneuver in waves.
Informes sobre el tema "Constant deflection contour method"
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FATIGUE TESTS OF COMPOSITE DECKS WITH MCL CONNECTORS. The Hong Kong Institute of Steel Construction, diciembre de 2022. http://dx.doi.org/10.18057/ijasc.2022.18.4.7.
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Full-scale fatigue tests were performed on three composite decks with the MCL (modified clothoid) connectors to investigate their fatigue performance. Fatigue life and failure mode of the composite bridge decks were explored by measuring the specimens with three different stress amplitudes. The deflection, strain, carrying capacity, and stiffness degradation of the composite decks were measured and analyzed in the test. In addition, parameter analysis was performed using finite-element method in this study. Results showed that the mechanical performance of the composite decks accorded with the plane-section assumption under constant amplitude load, and the fatigue failure mode of the composite decks was the local fracture of the bottom steel plate. The stiffness degradation law and S-N curve were obtained in this study. Moreover, the concrete slab depth had a remarkable effect on the fatigue performance of the composite decks.