. (2014) 'Structural optimisation based on the boundary element and level set methods. ', Computers and structures., Further information on publisher's website:http://dx.doi.org/10. 1016/j.compstruc.2014.01.004 Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in Computers Structures. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reected in this document. Changes may have been made to this work since it was submitted for publication. A denitive version was subsequently published in Computers Structures, 137, 2014Structures, 137, , 10.1016Structures, 137, /j.compstruc.2014.01.004. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractA new method of structural topology optimisation is proposed in which an evolutionary approach is used with boundary element and level set methods. During the optimisation iterations, the proposed method automatically introduces internal cavities and does not rely on an initial guess topology with pre-existing holes. The zero level set contours describing both the external geometry and the internal cavities are converted to non-uniform rational B-splines (NURBS) for smooth boundary element meshing at each iteration. The optimal geometries generated by the proposed method for two-dimensional cases closely resemble to those available in the literature for a range of benchmark examples in the field of topology optimisation.

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(2013) 'Correlation between hole insertion criteria in a boundary element and level set based topology optimisation method.', Engineering analysis with boundary elements., 37 (11). pp. 1457-1470.Further information on publisher's website:http://dx.doi.org/10. 1016/j.enganabound.2013.08.003 Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in Engineering analysis with boundary elements. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reected in this document. Changes may have been made to this work since it was submitted for publication. A denitive version was subsequently published in Engineering analysis with boundary elements, 37, 11, 2013, 10.1016/j.enganabound.2013.08.003 Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractThe research work presented in this paper is based on the correlation between two hole insertion criteria in a boundary element method (BEM) and level set method (LSM) based structural topology optimisation scheme for 2D elastic problems. The hole insertion criteria used in this work are based on the von Mises stress and the topological derivative approaches. During the optimisation process holes are automatically inserted in the design domain using each of the two criteria. The LSM is used to provide an implicit description of the structural geometry, and is also capable of automatically handling topological changes, i.e. holes merging with each other or with the boundary. The evolving structural geometry (i.e. the zero level set contours)is represented by NURBS, providing a smooth geometry throughout the optimisation process and completely eliminate jagged edges. In addition the optimal NURBS geometry can be used directly in other design processes.

The high demand of low cost wind energy needs to design large scale turbine blades with reduced weight which poses great challenges to their structural integrity while prone to extreme wind gusts. The loading can cause large-deflection bending and damage leading to significant drop in the load-bearing ability of long composite wind turbine (WT) blades. In this study, a comprehensive finite element (FE) modelling procedure is developed to simulate structural integrity and damage in composite blade using ANSYS software. The three-dimensional blade model is analyzed by carrying out geometrically nonlinear FE analysis to investigate the blade deformation and highly stressed regions leading to possible failure modes. The results show that the blade suction side is subjected to high compressive stress causing local skin buckling, which is further investigated using linear buckling analysis. Such local buckling drives interfacial debonding between skin and spar joined with a weak adhesive. Subsequently, the interfacial damage in the identified critical region is modelled by developing a damage submodel employing cohesive zone model (CZM) approach at the skin-spar interface. The analysis results indicate that buckling driven skin-spar debonding at adhesive interface is initial damage mode which can lead to progressive failure of the blade structure. Consequently, the ultimate load bearing capacity of WT blade is governed by a coupled buckling and debonding phenomenon even at load level below the ultimate design load. The simulation methodology adopted in this study can be employed to develop reliable and cost-effective computational tools for analyzing structural integrity and assessing damage in blade structure than expensive experimental testing.

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