Johor Bahru, Malaysia
Johor Bahru, Malaysia

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Speich M.,Aalen University of Applied Sciences | Merkel M.,Aalen University of Applied Sciences | Ochsner A.,Technical University of Malaysia
Materialwissenschaft und Werkstofftechnik | Year: 2010

Sandwich panels represent a basic design unit for light weight structures. Sandwich panels typically consist of at least two different materials for core and skin. Within the scope of this paper, the large deformation behaviour of different cellular core materials for sandwich panels is investigated. The large deformation behaviour for different core materials is analysed experimentally by compression tests.We investigate metallic hollow sphere structures (MHSS) and synthetic polyvinyl chloride (PVC) foams. In addition, appropriate computational models are presented to account for the deformation mechanisms and to compare computational to experimental results. With these models we will be able to already validate the future experimental test set-ups with numerical simulations before the test set-up is build. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ochsner A.,Technical University of Malaysia | Ochsner A.,University of Newcastle | Hosseini S.M.H.,Technical University of Malaysia | Merkel M.,Aalen University of Applied Sciences
Journal of Materials Science and Technology | Year: 2010

This paper investigated the uniaxial mechanical properties of a new type of hollow sphere structures. For this new type, the sphere shell was perforated by several holes in order to open the inner sphere volume and surface. The mechanical properties, i.e. elastic properties and initial yield stress of perforated hollow sphere structures (PHSS) in a primitive cubic arrangement were numerically evaluated for different hole diameters and different joining techniques of the hollow spheres. The results are compared to classical configurations without perforation. © 2010 The Chinese Society for Metals.


Winkler R.,Aalen University of Applied Sciences | Pannert W.,Aalen University of Applied Sciences | Merkel M.,Aalen University of Applied Sciences | Ochsner A.,Technical University of Malaysia
Materialwissenschaft und Werkstofftechnik | Year: 2011

Metallic hollow sphere structures (MHSS) form a relatively new group of advanced composite materials characterised by high geometry reproduction leading to stable mechanical and physical properties. The MHSS combine the well-known advantages of cellular metals in terms of their high ability for energy adsorption, good damping behaviour, excellent heat insulation and high specific stiffness without major scattering of their material parameters. A combination of these properties opens a wide field of potential applications, e. g. in automotive (crash absorber) and aerospace industry (sandwich panels). Various joining technologies such as sintering, soldering and adhering can be used to assemble single metallic hollow spheres to interdependent structures and allow different macroscopic properties. In this study the behaviour of Metallic Hollow Spheres Structures due to structure-borne sound is investigated. Longitudinal vibrations within a rod serve as an example. Experimental data are compared with analytical solutions and results computed by the finite element method. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Hosseini S.M.H.,Technical University of Malaysia | Ochsner A.,Technical University of Malaysia | Ochsner A.,University of Newcastle | Fiedler T.,University of Newcastle
Finite Elements in Analysis and Design | Year: 2011

This paper investigates the initial yield surface of a new type of hollow sphere structure (HSS). For this new type, the sphere shell is perforated by several holes in order to open the inner sphere volume and surface. Multi-axial tensile loading is applied to investigate the initial yield surface of perforated HSS with ideal plastic base material properties. The influence of the hole diameters and different geometries of linking elements on the initial yield surface are shown. The results are compared to classical configurations without perforation. It is shown that the initial yield surface can be represented as a cone in the principal stress coordinate system. Increasing of the hole diameter (decreasing of the average density) decreases the diameter of this cone. Compared to the changes for different hole diameters, the shape of the initial yield surface is less sensitive to the geometry of the link between two spheres. In addition, the elastic properties of PHSS, i.e. Young's modulus and Poisson's ratio, are investigated. To this end, three-dimensional finite element analysis is used to investigate primitive cubic unit cell models. © 2011 Elsevier B.V.


Sulaiman M.N.I.,University of Technology Malaysia | Choo Y.-H.,University of Technology Malaysia | Chong K.E.,Technical University of Malaysia
Conference on Data Mining and Optimization | Year: 2011

This work presents an approach based on the ant colony optimization technique to address the assembly line balancing problem. An improved ant colony optimization with look forward ant is proposed to solve the simple assembly line balancing problem of type 1 (SALBP-1). The proposed algorithm introduces an approach to dynamically assign the value of priority rule or heuristic information during the task selection phase by allowing the ant to look forward its direct successors during the consideration in selecting a task to be assigned into a workstation. The proposed algorithm is tested and compared with literature data sets and the result from the proposed algorithm shows competitive performance against them. © 2011 IEEE.


Abdi B.,Technical University of Malaysia | Mozafari H.,Technical University of Malaysia | Ayob A.,Technical University of Malaysia
Applied Mechanics and Materials | Year: 2012

In this paper, we used the Imperialist Competitive Algorithm (ICA) and Genetic Algorithm (GA) to find the minimum weight design of torispherical dome ends under external pressure load. According to fabrication and strength of material requirements, a group of compromised counters are selected and studied. Based on ASME Section VIII and BS5500 pressure vessel codes, a reasonable buckling pressure limit is proposed. Four-centered ellipse method is quite effective in designing and constructing the dome structure and it is used here to construct the torispherical dome ends. Two different size torispherical dome end models are selected and studied. Imperialist competitive algorithm is found to be very efficient and easy to use for the applications. © (2012) Trans Tech Publications, Switzerland.


Esmaeili M.,Technical University of Malaysia | Ochsner A.,Technical University of Malaysia | Ochsner A.,University of Newcastle
Materialwissenschaft und Werkstofftechnik | Year: 2011

A one-dimensional numerical implementation of the Lemaitre damage model is presented. The implementation is close to classical finite element schemes but can be realised by simple codes or by the application of commercial computer algebra systems. Based on the presented theory and computational algorithm, the elasto-plastic deformation of a one-dimensional bar is simulated. The damage evolution is evaluated for different isotropic hardening behaviour and stated as a function of the plastic strain. The described algorithm allows a simple investigation of the influence of different parameters on the damage evolution. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Veyhl C.,University of Newcastle | Belova I.V.,University of Newcastle | Murch G.E.,University of Newcastle | Ochsner A.,Technical University of Malaysia | Fiedler T.,University of Newcastle
Finite Elements in Analysis and Design | Year: 2010

This paper addresses the mesh-dependence of non-linear mechanical finite element analysis. To this end, finite element meshes that are assembled by various element types and their solutions are compared. Voxel, tetrahedron, hexahedron and mixed (hex-dominant) meshes are considered. Different benchmarking parameters for the elastic and plastic solutions as well as for the computational load are determined. First, bending beams with a square, a circular and a rail cross-section are calculated accounting for non-linear material behaviour (plasticity). A strong dependence on the mesh type is observed and the best results are obtained for mixed meshes and hexahedron-only meshes. In the second part of this study, finite element models that are based on the complex geometry of metallic foam are considered. Computed tomography data is used to generate geometrically complex finite element models and a convergence analysis is performed. Again, superior performance is found for mixed meshes. Crown Copyright © 2010.


Nechaev Y.S.,RAS Institute of Metallurgy | Ochsner A.,Technical University of Malaysia
Journal of Nanoscience and Nanotechnology | Year: 2012

Empirical evaluations of fundamental characteristics of the physical and chemical interaction of hydrogen with graphene layers in different kinds of graphite and novel carbonaceous nanomaterials of graphene layer structure have been carried out. This was done by using the approaches of the thermodynamics of reversible and irreversible processes for analysis of the adsorption, absorption, diffusion, the temperature-programmed desorption (TPD) and other experimental data and comparing such analytical results with first-principles calculations. Such an analysis of a number of the known experimental and theoretical data has shown a real possibility of the multilayer specific adsorption (intercalation) of hydrogen between graphene layers in novel carbonaceous nanomaterials. This is of relevance for solving the bottle-neck problem of the hydrogen on-board storage in fuel-cell-powered vehicles, and other technical applications. Copyright © 2012 American Scientific Publishers. All rights reserved.


Abdullah A.R.,Technical University of Malaysia Malacca | Sha'Ameri A.Z.,Technical University of Malaysia
Eurasip Journal on Advances in Signal Processing | Year: 2010

Bilinear time-frequency distributions (TFDs) are powerful techniques that offer good time and frequency resolution of time-frequency representation (TFR). It is very appropriate to analyze power quality signals which consist of nonstationary and multi-frequency components. However, the TFDs suffer from interference because of cross-terms. Many TFDs have been implemented, and there is no fixed window or kernel that can remove the cross-terms for all types of signals. In this paper, the bilinear TFDs are implemented to analyze power quality signals such as smooth-windowed Wigner-Ville distribution (SWWVD), Choi-Williams distribution (CWD), B-distribution (BD), and modified B-distribution (MBD). The power quality signals focused are swell, sag, interruption, harmonic, interharmonic, and transient based on IEEE Std, 1159-1995. A set of performance measures is defined and used to compare the TFRs. It shows that SWWVD presents the best performance and is selected for power quality signal analysis. Thus, an adaptive optimal kernel SWWVD is designed to determine the separable kernel automatically from the input signal. © 2010 Abdul Rahim Abdullah and Ahmad Zuri Sha'ameri.

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