This paper deals with the shape control of composite laminated beams with nonlinear piezoelectric patch actuators. The governing electromechanical coupled equations for nonlinear material behaviour are developed for a general three-dimensional structural element using Gibbs free energy formulation. In the analysis, nonlinearity is accounted for by incorporating enough nonlinear terms in the Gibbs free energy expression. Since many of the higher-order material properties are not available for most of the piezoelectric materials, the experimental data that are available for the nonlinear relationship between the electric field and the electric displacement are used. A finite element model is developed for the beam with piezoelectric actuators using a modified bilinear four-noded quadratic element. The expression for the actuation voltages required for shape control is then obtained by minimizing an error function, which is a measure of the area between the achieved and desired shape. The final system of coupled equations is solved by an iterative finite element procedure. Numerical results are obtained for several piezoelectric patch configurations on beams with various boundary conditions. The results show the significance of nonlinear effects in the shape control of beams with piezoelectric actuators, which has hitherto not been accounted.

Sustainable use of the ocean for food and energy production is an emerging area of research in different countries around the world. This goal is pursued by the Australian aquaculture, offshore engineering and renewable energy industries, research organisations and the government through the “Blue Economy Cooperative Research Centre”. To address the challenges of offshore food and energy production, leveraging the benefits of co-location, vertical integration, infrastructure and shared services, will be enabled through the development of novel Multi-Purpose Offshore-Platforms (MPOP). The structural integrity of the designed systems when being deployed in the harsh offshore environment is one of the main challenges in developing the MPOPs. Employing structural reliability analysis methods for assessing the structural safety of the novel aquaculture-MPOPs comes with different limitations. This review aims at shedding light on these limitations and discusses the current status and future directions for structural reliability analysis of a novel aquaculture-MPOP considering Australia’s unique environment. To achieve this aim, challenges which exist at different stages of reliability assessment, from data collection and uncertainty quantification to load and structural modelling and reliability analysis implementation, are discussed. Furthermore, several solutions to these challenges are proposed based on the existing knowledge in other sectors, and particularly from the offshore oil and gas industry. Based on the identified gaps in the review process, potential areas for future research are introduced to enable a safer and more reliable operation of the MPOPs.

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Mechanical properties of Carbon Nanotube (CNT) reinforced composites are obtained utilizing finite element (FE) method-based indentation simulations considering large strain elasto-plastic behavior of elements. This study includes nanoindentation simulations for chemically non-bonded CNT/matrix interface, including the length scale effect of nanocomposites. In order to investigate the mechanical properties of CNT reinforced nanocomposites, a number of FE models for nanoindentation tests have been simulated. Sample nanocomposites are examined to determine the suitable types of CNTs and their effectiveness as a reinforcement of different potential matrices. The Parametric study is conducted to obtain the influence of wall thickness, relative positioning, and volume fraction of CNT and strain hardening parameter of matrix on the mechanical properties of nanocomposites. The obtained results indicate that, properties such as modulus of elasticity and hardness of the nanocomposites are largely dependent on wall thickness of CNT and strain hardening parameter of the matrix. This study also suggests, the minimum wall thickness of CNT to avoid local buckling in nanocomposite which is required to be at least 0.2 nm for a diameter to thickness ratio of 5.0. Moreover, a matrix having a value of strain hardening parameter near 0.1 is expected to be significantly effective for nanocomposite.

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