Browsing by Author "KAM, TY"

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A PROCEDURE FOR PROBABILISTIC ANALYSIS OF NONLINEAR STRUCTURES
(1990)
KAM, TY
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LIN, SC
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交大名義發表
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機械工程學系
;
National Chiao Tung University
BUCKLING ANALYSIS OF IMPERFECT FRAMES USING A STOCHASTIC FINITE-ELEMENT METHOD
(1992-03-17)
LIN, SC
;
KAM, TY
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
A stochastic finite element method is developed for the buckling analysis of frames with random initial imperfections, uncertain sectional and material properties. The random geometrical imperfections of the frames are described by member initial crookednesses which are modeled as given initial displacement functions with amplitudes treated as random variables. The effects of the random initial geometric imperfections are formulated as a set of equivalent random nodal coordinates in the finite element discretization of the members. The mean-centered second-order perturbation technique is used to formulate the stochastic finite element method for the buckling analysis of the imperfect frames. Use of the present method is illustrated by several examples of buckling analysis of random frames. Results derived from the Monte Carlo method are also obtained for comparison.
BUCKLING FAILURE PROBABILITY OF IMPERFECT ELASTIC FRAMES
(1992-07-17)
LIN, SC
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KAM, TY
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機械工程學系
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Department of Mechanical Engineering
Probabilistic buckling failure of random imperfect frames is studied via the stochastic finite clement method. The statistics of buckling strengths of elastic frames with random initial imperfections, uncertain sectional and material properties are inferred from the statistics of the basic system parameters through the utilization of the stochastic finite element method. The effects of variations in geometric imperfections, sectional and material properties on variation in buckling strength are investigated. The failure probability of imperfect frames consisting of random system parameters subject to random loads is computed in load space. Factors affecting the reliability of the frames are identified and discussed. It was found that sectional properties, the shape of geometric imperfection, and the magnitude of imperfection may have important effects on frame reliability.
BUCKLING OF SHEAR DEFORMABLE LAMINATED COMPOSITE PLATES
(1992)
KAM, TY
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CHANG, RR
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
A shear deformable finite element is developed for the buckling analysis of laminated composite plates. The finite element formulation is based on Mindlin's theory in which shear correction factors are derived from the exact expressions for orthotropic materials. A variety of problems on uniaxial and shear bucklings of laminated composite plates are solved. The effects of material properties, plate aspect ratio, length-to-thickness ratio, number of layers and lamination angle on the buckling loads of symmetrically and anti-symmetrically laminated composite plates are investigated. Optimal lamination arrangements of layers for maximizing the buckling loads of the plates are determined.
CRACK SIZE IDENTIFICATION USING AN EXPANDED MODE METHOD
(1994-04-01)
KAM, TY
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LEE, TY
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交大名義發表
;
機械工程學系
;
National Chiao Tung University
An expanded mode method constructed based on the modal analysis method and an energy approach is presented for size identification of a crack with given location in a damaged structure. Measured natural frequencies and mode shapes of the structure with or without a crack are used to compute the strain energies of the structures subject to free vibration via a quasi-static approach. The two types of strain energy are then combined with the work required for the crack formation to construct the energy balance equation from which the size of the crack is evaluated through an iteration procedure. The theory of fracture mechanics is used to derive the work required for crack formation. Examples of the identification of crack sizes for a number of damaged beam structures are given to illustrate the applications of the proposed expanded mode method. Factors affecting the accuracy of crack size identification are investigated using a cracked cantilever beam as an example. The results show that the present method is promising for practical applications.
DESIGN OF LAMINATED COMPOSITE PLATES FOR MAXIMUM BUCKLING LOAD AND VIBRATION FREQUENCY
(1993-07-01)
KAM, TY
;
CHANG, RR
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
The optimal lamination arrangement of thick laminated composite plates for maximum buckling load and vibration frequency is studied via a multi-start global optimization technique. A shear deformable finite element in which the exact expressions for determining shear correction factors are adopted has been developed for the buckling and free vibration analysis of the plates. Utilizing the finite element, the optimal layups for the plates with maximum buckling loads or natural frequencies are designed via the multi-start global optimization technique. The proposed optimization algorithm has been proved to be efficient and effective in designing thick laminated composite plates. A number of examples of the design of symmetrically and antisymmetrically laminated composite plates with various material properties, side-to-thickness ratios, aspect ratios and different numbers of layers are given to illustrate the practical applications of the present method.
DESIGN OF LAMINATED COMPOSITE PLATES FOR MAXIMUM SHEAR BUCKLING LOADS
(1993-12-01)
CHANG, RR
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CHU, KH
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KAM, TY
;
交大名義發表
;
機械工程學系
The optimal lamination arrangements of laminated composite plates with maximum shear buckling loads are studied via a multi-start global optimization technique. A previously proposed shear deformable finite element is used to evaluate the positive and negative shear buckling loads of laminated composite plates in the optimal design process. Optimal lay-ups of thin as well as moderately thick composite plates with global maximum positive or negative shear buckling loads are determined utilizing the multi-start global optimal design technique. A number of examples of the optimal shear buckling design of symmetrically and antisymmetrically laminated composite plates with various material properties, length-to-thickness ratios, aspect ratios and different numbers of layer groups are given to illustrate the trends of optimal layer orientations of the plates. Since the existence of in-plane axial forces is possible, the effects of axial compressive load on the optimal layer orientations for maximum shear buckling load are also investigated.
DESIGN OF LAMINATED COMPOSITE PLATES FOR OPTIMAL DYNAMIC CHARACTERISTICS USING A CONSTRAINED GLOBAL OPTIMIZATION TECHNIQUE
(1995-02-01)
KAM, TY
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LAI, FM
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交大名義發表
;
機械工程學系
;
National Chiao Tung University
The lamination arrangements of moderately thick laminated composite plates for optimal dynamic characteristics are studied via a constrained multi-start global optimization technique. In the optimization process, the dynamical analysis of laminated composite plates is accomplished by utilizing a shear deformable laminated composite finite element, in which the exact expressions for determining shear correction factors were adopted, and the modal damping model constructed based on an energy concept. The optimal layups of laminated composite plates with maximum fundamental frequency or modal damping are then designed by maximizing the frequency or modal damping capacity of the plate via the multi-start global optimization technique. The effects of length-to-thickness ratio, aspect ratio and number of layer groups upon the optimum fiber orientations or layer group thicknesses are investigated by means of a number of examples of the design of symmetrically laminated composite plates.
DESIGN OF THICK LAMINATED COMPOSITE PLATES FOR MAXIMUM DAMPING
(1994)
KAM, TY
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CHANG, RR
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
The optimal lamination arrangement of thick laminated composite plates for maximum damping is studied via a multi-start global optimization technique. In the optimization process, the damping analysis of a laminated composite plate is accomplished by utilizing a shear-deformable laminated composite finite element, in which the exact expressions for determining shear correction factors are adopted, with the damping model of Adams and associates. The optimal layup of the plate with maximum damping is then designed by maximizing the specific damping capacity of the plate via the multi-start global optimization technique. The effects of length-to-thickness ratio, aspect ratio, Young's modulus ratio, and number of ply groups upon the optimum ply group orientations and the value of damping are investigated by means of a number of examples of the design of symmetrically laminated composite plates.
DETECTION OF CRACKS IN STRUCTURES USING MODAL TEST DATA
(1992-05-01)
KAM, TY
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LEE, TY
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
A nondestructive evaluation procedure is presented for identifying a crack in a structure using modal test data. The structure is discretized into a set of elements and the crack is assumed to be located within one of the elements. Measured vibration frequencies and mode shapes are used in an identification process to identify the cracked element based on a simple reduced stiffness model. Static deflection analyses of the structure with and without a crack are performed and a strain energy equilibrium equation is constructed for determining the size of the crack. The detection of a crack on a damaged beam is used to illustrate the applications of the proposed procedure. The present procedure is general and can be easily extended to complex structures with multiple cracks.
FINITE-ELEMENT ANALYSIS OF SHEAR DEFORMABLE LAMINATED COMPOSITE PLATES
(1993-03-01)
KAM, TY
;
CHANG, RR
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
A shear deformable finite element is developed for the analysis of thick laminated composite plates. The finite element formulation is based on Mindlin's plate theory in which shear correction factors are derived from the exact expressions for orthotropic materials. The element is used to solve a variety of problems on deflection, stress distribution, natural frequency and buckling of laminated composite plates. The effects of material properties, plate aspect ratio, length-to-thickness ratio, number of layers and lamination angle on the mechanical behaviors of laminated composite plates are investigated. Optimal lamination arrangements of layers for laminated composite plates of particular applications are determined.
FIRST-PLY FAILURE ANALYSIS OF LAMINATED COMPOSITE PLATES BASED ON THE LAYERWISE LINEAR DISPLACEMENT THEORY
(1995)
KAM, TY
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JAN, TB
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交大名義發表
;
機械工程學系
;
National Chiao Tung University
A finite element formulated on the basis of the layerwise linear displacement theory is used to study the first-ply failure of moderately thick laminated composite plates. In the finite element formulation, a laminated composite element is divided into a number of mathematical layer groups and displacements are assumed to vary linearly in each layer group which contains eight nodal points. The accuracy of the finite element in predicting displacements and stresses has been verified by comparing results with experimental data and previously obtained analytical results. The finite element is used to determine the first-ply failure loads of a number of laminated composite plates on the basis of several phenomenological failure criteria. The capabilities of the failure criteria in predicting first-ply failure loads are investigated by comparing the finite element first-ply failure loads with the experimental ones. It has been found that the failure criteria can yield reasonably good results for the cases considered.
LARGE DEFLECTION ANALYSIS OF INELASTIC PLANE FRAMES
(1988-01-01)
KAM, TY
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交大名義發表
;
機械工程學系
;
National Chiao Tung University
;
Department of Mechanical Engineering
MAXIMUM STIFFNESS DESIGN OF LAMINATED COMPOSITE PLATES VIA A CONSTRAINED GLOBAL OPTIMIZATION APPROACH
(1995)
KAM, TY
;
LAI, FM
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
The optimal lamination arrangements of laminated composite plates with maximum stiffness subject to side constraints are investigated via a constrained multi-start global optimization approach. In the optimal design process, the deformation analysis of laminated composite plates is accomplished by utilizing a shear deformable laminated composite finite element and the optimal design problem, which has been converted into an unconstrained minimization problem via the general augmented Lagrangian method, is solved by utilizing the proposed unconstrained multi-start global optimization technique to determine the optimal fiber angles and layer group thicknesses of the laminated composite plates for attaining maximum stiffness and simultaneously satisfying the imposed side constraints. The feasibility of the proposed constrained multi-start global optimization algorithm is validated by means of a simple but representative example and its applications are demonstrated by means of a number of examples on the maximum stiffness design of symmetrically laminated composite plates. The effects of length-to-thickness ratio, aspect ratio, and number of layer groups upon the optimum fiber angles and layer group thicknesses of the plates are investigated.
MULTILEVEL OPTIMAL-DESIGN OF LAMINATED COMPOSITE PLATE STRUCTURES
(1989)
KAM, TY
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LAI, MD
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交大名義發表
;
機械工程學系
;
National Chiao Tung University
NONLINEAR AND FIRST-PLY FAILURE ANALYSES OF LAMINATED COMPOSITE CROSS-PLY PLATES
(1995)
KAM, TY
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SHER, HF
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交大名義發表
;
機械工程學系
;
National Chiao Tung University
A method is presented to study the nonlinear behaviors and first-ply failure strengths of centrally loaded laminated composite plates with semi-clamped edges. The method which is developed from the von Karman-Mindlin plate theory and the Ritz method is used to construct the nonlinear load-deflection curves of the composite plates with or without considering the reduction in plate stiffness induced by ply failure and predict the first-ply failure loads of the plates based on various commonly used strength-of-material type failure criteria. Experiments on laminated composite plates loaded to failure are performed to construct the experimental load-displacement curves of the plates. During testing, the first-ply failure loads of the plates are identified using the acoustic emission technique. The experimental results are used to investigate the capabilities of the present method in predicting the nonlinear behaviors and first-ply failure loads of the laminated composite plates. It has been found that when compared with the experimental load-deflection curves the present method with the consideration of stiffness reduction can yield reasonable results on load-deflection curve and even for some cases the ultimate strength. As for the determination of first-ply failure load, the inconsistent results predicted by the adopted failure criteria indicate that the strength-of-material approach may be inappropriate for the first-ply failure analysis of laminated composite plates. Hence, more research on failure mechanism and, especially, the development of appropriate failure criteria for composite laminates is needed.
NONLINEAR DYNAMIC ANALYSIS OF INELASTIC STEEL PLANE FRAMES
(1988)
KAM, TY
;
LIN, SC
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
NONLINEAR-ANALYSIS OF STEEL PLANE FRAMES WITH INITIAL IMPERFECTIONS
(1986)
KAM, TY
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LEE, FS
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交大名義發表
;
機械工程學系
;
National Chiao Tung University
NONLINEAR-ANALYSIS OF TUBULAR STEEL FRAMED STRUCTURES
(1989)
KAM, TY
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交大名義發表
;
機械工程學系
;
National Chiao Tung University
;
Department of Mechanical Engineering
OPTIMAL PARAMERERS FOR CURING GRAPHITE-EPOXY COMPOSITE LAMINATES
(1995-01-15)
KAM, TY
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LAI, FM
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SHER, HF
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交大名義發表
;
機械工程學系
The optimal curing parameters of a cure cycle for achieving maximum mechanical properties of Gr/ep composite laminates are determined via a multi-level optimization approach. Laminated composite specimens cured under various pressures, temperatures and times are tested with an Instron testing machine. Test results: are then used in the proposed multi-level optimization method to determine the optimal curing parameters. The effects of the curing parameters on the mechanical properties of the laminates are studied and discussed It was found that a cure cycle with two pressure-temperature-time steps can yield composite laminates with comparatively good material properties.