Optimal sensor placement for mode shapes using improved simulated annealing

K.H. Tong,Norhisham Bakhary,A.B.H. Kueh,A.Y. Mohd Yassin 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.13 No.3

Optimal sensor placement techniques play a significant role in enhancing the quality of modal data during the vibration based health monitoring of civil structures, where many degrees of freedom are available despite a limited number of sensors. The literature has shown a shift in the trends for solving such problems, from expansion or elimination approach to the employment of heuristic algorithms. Although these heuristic algorithms are capable of providing a global optimal solution, their greatest drawback is the requirement of high computational effort. Because a highly efficient optimisation method is crucial for better accuracy and wider use, this paper presents an improved simulated annealing (SA) algorithm to solve the sensor placement problem. The algorithm is developed based on the sensor locations‟ coordinate system to allow for the searching in additional dimensions and to increase SA‟s random search performance while minimising the computation efforts. The proposed method is tested on a numerical slab model that consists of two hundred sensor location candidates using three types of objective functions; the determinant of the Fisher information matrix (FIM), modal assurance criterion (MAC), and mean square error (MSE) of mode shapes. Detailed study on the effects of the sensor numbers and cooling factors on the performance of the algorithm are also investigated. The results indicate that the proposed method outperforms conventional SA and Genetic Algorithm (GA) in the search for optimal sensor placement.

Optimal sensor placement for mode shapes using improved simulated annealing

Tong, K.H.,Bakhary, Norhisham,Kueh, A.B.H.,Yassin, A.Y. Mohd Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.13 No.3

Optimal sensor placement techniques play a significant role in enhancing the quality of modal data during the vibration based health monitoring of civil structures, where many degrees of freedom are available despite a limited number of sensors. The literature has shown a shift in the trends for solving such problems, from expansion or elimination approach to the employment of heuristic algorithms. Although these heuristic algorithms are capable of providing a global optimal solution, their greatest drawback is the requirement of high computational effort. Because a highly efficient optimisation method is crucial for better accuracy and wider use, this paper presents an improved simulated annealing (SA) algorithm to solve the sensor placement problem. The algorithm is developed based on the sensor locations' coordinate system to allow for the searching in additional dimensions and to increase SA's random search performance while minimising the computation efforts. The proposed method is tested on a numerical slab model that consists of two hundred sensor location candidates using three types of objective functions; the determinant of the Fisher information matrix (FIM), modal assurance criterion (MAC), and mean square error (MSE) of mode shapes. Detailed study on the effects of the sensor numbers and cooling factors on the performance of the algorithm are also investigated. The results indicate that the proposed method outperforms conventional SA and Genetic Algorithm (GA) in the search for optimal sensor placement.

Analytical study of slant end-plate connection subjected to elevated temperatures

F. Zahmatkesh,M.H. Osman,E. Talebi,A.B.H. Kueh 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.17 No.1

Due to thermal expansion, the structural behaviour of beams in steel structures subjected to temperature increase will be affected. This may result in the failure of the structural members or connection due to extra internal force in the beam induced by the thermal increase. A method to release some of the thermally generated internal force in the members is to allow for some movements at the end supports of the member. This can be achieved by making the plane of the end-plate of the connection slanted instead of vertical as in conventional design. The present paper discusses the mechanical behaviour of beams with bolted slant end-plate connection under symmetrical gravity loads, subjected to temperature increase. Analyses have been carried out to investigate the reduction in internal force with various angles of slanting, friction factor at the surface of the connection, and allowable temperature increase in the beam. The main conclusion is that higher thermal increase is tolerable when slanting connection is used, which means the risk of failure of structures can be reduced.

Flexural behavior of sandwich beams with novel triaxially woven fabric composite skins

M.Y. Al-Fasih,A.B.H. Kueh,M.H.W. Ibrahim 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.2

This study aims to carry out the experimental and numerical investigation on the flexural behavior of sandwich honeycomb composite (SHC) beams reinforced with novel triaxially woven fabric composite skins. Different stacking sequences of the carbon fiber reinforcement polymer (CFRP) laminate; i.e., 0°-direction of TW (TW0), 0°-direction of UD (UD0), and 90°-direction of UD (UD90) were studied, from which the flexural behavior of SHC beam behaviors reinforced with TW0/UD0 or TW0/UD90 novel laminated skins were compared with those reinforced with UD0/90 conventional laminated skins under four-point loading. Generally, TW0/UD0 SHC beams displayed the same flexural stiffness as UD0/90 SHC beams in terms of load-deflection relationships. In contrast, TW0/UD90 SHC beams showed a 70% lower efficiency than those of UD0/90 SHC. Hence, the TW0/UD0 laminate arrangement is more effective with a mass reduction of 39% compared with UD0/90 for SHC beams, although their stiffness and shear strength are practically identical.

Tow waviness and anisotropy effects on Mode II fracture of triaxially woven composite

M.Y. Al-Fasih,A.B.H. Kueh,S.H. Abo Sabah,M.Y. Yahya 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.26 No.2

Mode II fracture toughness, <i>K</i>_IIC, of single-ply triaxially woven fabric (TWF) composite due to tow waviness and anisotropy effects were numerically and experimentally studied. The numerical wavy beam network model with anisotropic material description denoted as TWF anisotropic was first validated with experimental Mode II fracture toughness test employing the modified compact tensile shear specimen configuration. 2D planar Kagome and TWF isotropic models were additionally constructed for various relative densities, crack lengths, and cell size parameters for examining effects due to tow waviness and anisotropy. <i>K</i>_IIC generally increased with relative density, the inverse of cell size, and crack length. It was found that both the waviness and anisotropy of tow inflict a drop in <i>K</i>_IIC of TWF. These effects were more adverse due to the waviness of tow compared to anisotropy.

Computational impact responses of reinforced concrete slabs

S.N. Mokhatar,A.B.H. Kueh,R. Abdullah 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.12 No.1

The responses of reinforced concrete slabs subject to an impact loading near the ultimate load range are explored. The analysis is carried out on a simply supported rectangular reinforced concrete slab using a nonlinear explicit dynamic procedure and considering three material models: Drucker-Prager, modified Drucker-Prager, and concrete damaged plasticity, available in the commercial finite element software, ABAQUS/Explicit. For comparison purposes, the impact force-time response, steel reinforcement failure, and concrete perforation pattern are verified against the existing experimental results. Also, the effectiveness of mesh density and damage wave propagation are studied independently. It is shown that the presently adopted finite element procedure is able to simulate and predict fairly accurate the behavior of reinforced concrete slab under impact load. More detailed investigations are however demanded for the justification of effects coming from an imperfect projectile orientation as well as the load and structural surface conditions, including the impulsive contacted state, which are inevitable in an actual impact environment.

Quantitative impact response analysis of reinforced concrete beam using the Smoothed Particle Hydrodynamics (SPH) method

S.N. Mokhatar,Y. Sonoda,A.B.H. Kueh,Z.M. Jaini 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.56 No.6

The nonlinear numerical analysis of the impact response of reinforced concrete/mortar beam incorporated with the updated Lagrangian method, namely the Smoothed Particle Hydrodynamics (SPH) is carried out in this study. The analysis includes the simulation of the effects of high mass low velocity impact load falling on beam structures. Three material models to describe the localized failure of structural elements are: (1) linear pressure-sensitive yield criteria (Drucker-Prager type) in the pre-peak regime for the concrete/mortar meanwhile, the shear strain energy criterion (Von Mises) is applied for the steel reinforcement (2) nonlinear hardening law by means of modified linear Drucker-Prager envelope by employing the plane cap surface to simulate the irreversible plastic behavior of concrete/mortar (3) implementation of linear and nonlinear softening in tension and compression regions, respectively, to express the complex behavior of concrete material during short time loading condition. Validation upon existing experimental test results is conducted, from which the impact behavior of concrete beams are best described using the SPH model adopting an average velocity and erosion algorithm, where instability in terms of numerical fragmentation is reduced considerably.