In the design optimization of robot arms, the use of simulation technologies for modeling and opt... more In the design optimization of robot arms, the use of simulation technologies for modeling and optimizing the objective functions is still challenging. The difficulty is not only associated with the large computational cost of high-fidelity structural simulations but also linked to the reasonable compromise between the multiple conflicting objectives of robot arms. In this paper we propose a surrogate-based evolutionary optimization (SBEO) method via a global optimization approach, which incorporates the response surface method (RSM) and multi-objective evolutionary algorithm by decomposition (the differential evolution (DE ) variant) (MOEA/D-DE) to tackle the shape design optimization problem of robot arms for achieving high speed performance. The computer-aided engineering (CAE) tools such as CAE solvers, computer-aided design (CAD) Inventor, and finite element method (FEM) ANSYS are first used to produce the design and assess the performance of the robot arm. The surrogate model c...
Experimental and theoretical methods are presented to study the first-ply failure strength of lam... more Experimental and theoretical methods are presented to study the first-ply failure strength of laminated composite plates under different loading conditions. An acoustic emission technique is used to measure the energy released in the plates during the failure process. The first-ply failure strength of the plates is then identified via the energy vs load diagrams which are constructed on the basis of the measured acoustic emissions. A finite element analysis, which is constructed on the basis of the layerwise linear displacement theory, and the Tsai–Wu failure criterion are used to predict the first-ply failure strength of the plates. The comparison between the experimental and theoretical results shows good agreement.
A procedure for failure probability evaluation of composite laminates subjected to inplane loads ... more A procedure for failure probability evaluation of composite laminates subjected to inplane loads is proposed. The material properties, fiber angles and layer thicknesses of the laminates are treated as random variables in the reliability analysis. The statistics of first-...
This paper presents a method for nondestructively evaluating the system parameters of elastically... more This paper presents a method for nondestructively evaluating the system parameters of elastically restrained shear deformable laminated composite plates using measured natural frequencies. The proposed method is established on the basis of a multi-start global minimization method in which an objective function measuring the differences between the predicted and measured natural frequencies is constructed and a design variables normalization technique for expediting the convergence of the search of the solution is adopted. Vibration testing of several laminated composite plates with different boundary conditions was performed. Seven natural frequencies extracted from the vibration data of each of the plates were used in the proposed method to identify the system parameters of the plate. Excellent results have been obtained for the plates.
Optimum design of laminated composite sandwich plates with both continuous (core thickness) and d... more Optimum design of laminated composite sandwich plates with both continuous (core thickness) and discrete (layer group fiber angles and thicknesses) design variables subjected to strength constraint is studied via a two-level optimization technique. The strength of a sandwich plate is determined in a failure analysis using the Tsai–Wu failure criterion and the finite element method which is formulated on the
A method for investigating the dynamic response of shear deformable laminated composite plates su... more A method for investigating the dynamic response of shear deformable laminated composite plates subject to low-speed impact is presented. The equations of motion of the impactor and the plate are derived via a virtual work approach. The contact force between the impactor and the plate is calculated by using an experimentally established contact law. The effects of existing in-plane forces, plate aspect ratio, length-to-thickness ratio, fiber angles, and number of layer groups on the contact force with or without the consideration of ply failure are studied. Optimal fiber angles and number of layer groups for angle-ply plates with maximum first-ply failure impact velocity are determined based on the maximum stress criterion.
Singapore International Conference on Intelligent Control and Instrumentation [Proceedings 1992], 1992
k method for identifying a crack in a structure using vibration test data is presented. In the id... more k method for identifying a crack in a structure using vibration test data is presented. In the identification process, the cracked structure is discretized into a number of elements. The location of the crack is identified through the determination of the sectional parameters of the elements using a statistical identification technique. The crack size is estimated based on an ener
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 1999
The static burst strength of a frangible laminated composite canister cover subjected to uniform ... more The static burst strength of a frangible laminated composite canister cover subjected to uniform pressure is studied via both theoretical and experimental approaches. The frangible canister cover, which is fabricated with four plate-like laminated composite parts, is designed to fail in a predetermined pattern. The stress distribution in the canister cover is determined using the finite element method and the failure of the cover is identified on the basis of a failure criterion. A number of laminated composite canister covers were fabricated and subjected to static burst pressure testing. The failure modes of the frangible covers are studied and the experimental results are used to verify the theoretical predictions. Close agreements between the experimental and theoretical results have been observed. The canister covers that had been tested did fail in accordance with the predetermined pattern.
An energy method for identifying the size of a crack at given location in structures using one me... more An energy method for identifying the size of a crack at given location in structures using one measured eigencouple of the cracked structures is presented. The method utilizes the maximum strain energies of the structures both with and without a crack and the additional strain energy induced by the crack to construct the energy balance equation from which the size
In the design optimization of robot arms, the use of simulation technologies for modeling and opt... more In the design optimization of robot arms, the use of simulation technologies for modeling and optimizing the objective functions is still challenging. The difficulty is not only associated with the large computational cost of high-fidelity structural simulations but also linked to the reasonable compromise between the multiple conflicting objectives of robot arms. In this paper we propose a surrogate-based evolutionary optimization (SBEO) method via a global optimization approach, which incorporates the response surface method (RSM) and multi-objective evolutionary algorithm by decomposition (the differential evolution (DE ) variant) (MOEA/D-DE) to tackle the shape design optimization problem of robot arms for achieving high speed performance. The computer-aided engineering (CAE) tools such as CAE solvers, computer-aided design (CAD) Inventor, and finite element method (FEM) ANSYS are first used to produce the design and assess the performance of the robot arm. The surrogate model c...
Experimental and theoretical methods are presented to study the first-ply failure strength of lam... more Experimental and theoretical methods are presented to study the first-ply failure strength of laminated composite plates under different loading conditions. An acoustic emission technique is used to measure the energy released in the plates during the failure process. The first-ply failure strength of the plates is then identified via the energy vs load diagrams which are constructed on the basis of the measured acoustic emissions. A finite element analysis, which is constructed on the basis of the layerwise linear displacement theory, and the Tsai–Wu failure criterion are used to predict the first-ply failure strength of the plates. The comparison between the experimental and theoretical results shows good agreement.
A procedure for failure probability evaluation of composite laminates subjected to inplane loads ... more A procedure for failure probability evaluation of composite laminates subjected to inplane loads is proposed. The material properties, fiber angles and layer thicknesses of the laminates are treated as random variables in the reliability analysis. The statistics of first-...
This paper presents a method for nondestructively evaluating the system parameters of elastically... more This paper presents a method for nondestructively evaluating the system parameters of elastically restrained shear deformable laminated composite plates using measured natural frequencies. The proposed method is established on the basis of a multi-start global minimization method in which an objective function measuring the differences between the predicted and measured natural frequencies is constructed and a design variables normalization technique for expediting the convergence of the search of the solution is adopted. Vibration testing of several laminated composite plates with different boundary conditions was performed. Seven natural frequencies extracted from the vibration data of each of the plates were used in the proposed method to identify the system parameters of the plate. Excellent results have been obtained for the plates.
Optimum design of laminated composite sandwich plates with both continuous (core thickness) and d... more Optimum design of laminated composite sandwich plates with both continuous (core thickness) and discrete (layer group fiber angles and thicknesses) design variables subjected to strength constraint is studied via a two-level optimization technique. The strength of a sandwich plate is determined in a failure analysis using the Tsai–Wu failure criterion and the finite element method which is formulated on the
A method for investigating the dynamic response of shear deformable laminated composite plates su... more A method for investigating the dynamic response of shear deformable laminated composite plates subject to low-speed impact is presented. The equations of motion of the impactor and the plate are derived via a virtual work approach. The contact force between the impactor and the plate is calculated by using an experimentally established contact law. The effects of existing in-plane forces, plate aspect ratio, length-to-thickness ratio, fiber angles, and number of layer groups on the contact force with or without the consideration of ply failure are studied. Optimal fiber angles and number of layer groups for angle-ply plates with maximum first-ply failure impact velocity are determined based on the maximum stress criterion.
Singapore International Conference on Intelligent Control and Instrumentation [Proceedings 1992], 1992
k method for identifying a crack in a structure using vibration test data is presented. In the id... more k method for identifying a crack in a structure using vibration test data is presented. In the identification process, the cracked structure is discretized into a number of elements. The location of the crack is identified through the determination of the sectional parameters of the elements using a statistical identification technique. The crack size is estimated based on an ener
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 1999
The static burst strength of a frangible laminated composite canister cover subjected to uniform ... more The static burst strength of a frangible laminated composite canister cover subjected to uniform pressure is studied via both theoretical and experimental approaches. The frangible canister cover, which is fabricated with four plate-like laminated composite parts, is designed to fail in a predetermined pattern. The stress distribution in the canister cover is determined using the finite element method and the failure of the cover is identified on the basis of a failure criterion. A number of laminated composite canister covers were fabricated and subjected to static burst pressure testing. The failure modes of the frangible covers are studied and the experimental results are used to verify the theoretical predictions. Close agreements between the experimental and theoretical results have been observed. The canister covers that had been tested did fail in accordance with the predetermined pattern.
An energy method for identifying the size of a crack at given location in structures using one me... more An energy method for identifying the size of a crack at given location in structures using one measured eigencouple of the cracked structures is presented. The method utilizes the maximum strain energies of the structures both with and without a crack and the additional strain energy induced by the crack to construct the energy balance equation from which the size
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