Advances in Computational Mechanics: Selected, Peer Reviewed Papers from the 1st Australasian Conference on Computational Mechanics (ACCM 2013), October 3-4, 2013, Sydney, Australia

This volume contains the selected full-length papers from the 1st Australasian Conference of Computational Mechanics held in Sydney, Australia on 3-4 October 2013 (ACCM2013), where the authors represented 15 different countries, including Australia, New Zealand, China, Japan, South Korea, USA and European countries. The conference is organized by The University of Sydney under the Australian Association for Computational Mechanics (AACM). Scientifically, these collected articles in this special issue well reflected the latest progress made in some emerging areas of computational mechanics, including finite element, finite volume, particle and discrete element methods, structural and solid mechanics, aerospace engineering, geomechanics, advanced materials and multiscale modelling, biomechanics and biomedical engineering, structural and topology optimization, fracture and damage mechanics, computational fluid dynamics and vibration and dynamics

Advances in Structural and Multidisciplinary Optimization: Proceedings of the 11th World Congress of Structural and Multidisciplinary Optimization (WCSMO-11), June 7-12, 2015, Sydney, Australia

The book contains the full-length papers from the 11th World Congress on Structural and Multidisciplinary Optimisation (WCSO-11) held in Sydney, Australia on 7-12 June 2015. The full length papers reflect the latest progress in some traditional and emerging areas of structural and multidisciplinary optimization, ranging from mathematical foundations to algorithmic development as well as advanced applications in multiscale, uncertainty, nonlinearity, additive manufacturing, multidisciplinary and multiphysics in metamaterials, phonics, photonics, plasmonics, piezoelectricity, electromagnetics, thermofluids, renewable energy, and acoustics for aerospace, automotive, biomedical, mechanical, civil and structural engineering

Characterization of tissue scaffolds for time-dependent biotransport criteria – a novel computational procedure

This study aims to establish a new computational framework that allows modeling transient oxygen diffusion in tissue scaffolds more efficiently. It has been well known that the survival of cells strongly relies on continuous oxygen/nutrient supply and metabolite removal. With optimal design in scaffold architecture, its ability to sustain long distance oxygen supply could be improved considerably. In this study, finite element based homogenization procedure is first used to characterize the initial effective biotransport properties in silico. These initial properties are proper indicators to prediction of the on-going performance of tissue scaffolds over time. The transient model by adopting an edge-based smoothed finite element method with combination of mass-redistributed method is then established to more efficiently simulate the transient oxygen transfer process in tissue scaffolds. The proposed new method allows large time steps to model the oxygen diffusion process without losing numerical accuracy, thereby enhancing the computational efficiency significantly, in particular for the design optimization problems which typically require numerous analysis iterations. A number of different scaffold designs are examined either under net diffusion without cell seeding, or under cellular oxygen/nutrient uptake with or without considering cell viability. The association between the homogenized effective diffusivity of net scaffold microstructures and corresponding transient diffusion and time-dependent cellular activities is divulged. This study provides some insights into scaffold design

Optimization of bone tissue scaffolds fabricated by robocasting technique

While excellent biological and mechanical properties of ceramic scaffolds place them amongst the main candidates for applications of bone and cartilage repair, an optimum trade-off between critical biological and mechanical functions remains challenging during design process. These ceramic scaffolds should not only enhance tissue regeneration function, but also be of adequate mechanical strength particularly in load-bearing applications. One of the techniques used for the fabrication of ceramic scaffolds is robocating which has so far received little attention in the currently available optimization analyses related to the design of these scaffolds. In this study a vigorous optimization analysis based on finite element (FE) method is performed to maximize compressive strengths of such scaffolds while maintaining the minimum biological functions required for tissue ingrowth. The results demonstrate that an optimized functionality of ceramic scaffolds fabricated by robocasting needs a careful design of critical geometrical features

Transient modelling of thermal processing for ceramic prostheses

This study aims to present a numerical and experimental transient characterisation for mono- or bi-layered ceramic samples and dental restorations under a controlled cooling process from high temperature (typically 900°C) to room temperature (25°C). The processes may undergo different cooling rates: namely rapid cooling, normal cooling and slow cooling. The cooling rate is not a constant during convection. Cooling rate dependencies of the temperature distribution about the glass transition temperature during cooling will be taken into account. The heat transfer coefficients used in this numerical simulation are derived from experimental data. The FEA results are correlated to experimental results and a good agreement is achieved. The transient material processing models showed a significant potential for development of optimal prosthetic devices

Stability analysis of generalized mass formulation in dynamic heat transfer

In this article, the generalized mass formulation is developed in an explicit analysis of transient transport problems. It has been well known that the time step is typically smaller in explicit analysis than in implicit analysis when the same size mesh is used. Further, the over-stiffness of conventional finite-element model may result in poor accuracy with linear triangular or tetrahedral elements. In order to improve the computational efficiency and numerical accuracy, this article proposes a generalized mass formulation by matching the mass matrix to the smoothed stiffness matrix using linear triangular elements in 2-D problems. The proposed mass matrix can be obtained by simply shifting the integration points from the conventional locations. Without loss of generality, several 2-D examples, including conduction, convection, and radiation heat transfer problems, are presented to demonstrate that the generalized mass formulation allows a larger time step in explicit analysis compared with the lumped and consistent mass matrices. In addition, it is found that the maximum allowable time step is proportional to the softened effect of the discretized model in an explicit analysis

Proceedings of the 1st International Conference on Mechanical and Manufacturing Engineering Research and Practice (iCMMERP-2019): 24-28 November 2019, Sydney, Australia

The International Conference on Mechanical and Manufacturing Engineering Research (iCMMERP-2019), aims to provide an international platform for effective exchange of ideas, reaffirming the existing collegial contacts, provide opportunities of professional interaction amongst researchers, industrials and students, to present and share their latest research and practice and to showcase latest advancements, trends and future challenges in a broad range of disciplines related to Mechanical and Manufacturing Engineering

Residual stresses in fabrication of core-veneered ceramic prostheses

Fabrication of multilayered ceramics signifies an important topic in many advanced applications aerospace and prosthetic dentistry. This paper presents a numerical approach to characterising the transient thermal responses and corresponding thermal residual stresses that are developed in the bi-layered dental ceramic crowns model under a controlled cooling rate from a temperature around its glass transition temperature (typically 550°C) to room temperature (25°C). Finite element method (FEM) is adopted to model the residual stresses in normal or rapid cooling fabrication process. The demonstrative examples take into account the effect of thickness in core veneered all-ceramic restorative prosthesis (specific porcelain bonded to an alumina or zirconia core layer), cooling rates and mismatches in temperature-dependent material properties such as thermal expansion coefficients, specific heat and Young’s modulus. The model of transient ceramic fabrication processing showed significant potential to development of optimal prosthetic devices

Homogenization for composite material properties using smoothed finite element method

Numerical homogenization is an efficient way to determine effective material properties of composite materials. Conventionally, the finite element technique has been widely used in implementing the homogenization. However, the standard finite element method (FEM) leads to an overly-stiff model which gives poor accuracy especially using triangular elements in 2D or tetrahedral elements in 3D with coarse mesh. In this paper, the smoothed finite element methods (S-FEMs) are developed to analyse the effective mechanical properties of composite materials. Various examples, including modulus with multiphase composites and permeability of tissue scaffold, have demonstrated that smoothed finite element method is able to provide more accurate results using the same set of mesh compared with the standard finite element method. In addition, the computation efficiency of smoothed finite element method is also much better than the FEM counterpart

Sensitivity analysis of bi-layered ceramic dental restorations

Objectives. The reliability and longevity of ceramic prostheses have become a major concern. The existing studies have focused on some critical issues from clinical perspectives, but more researches are needed to address fundamental sciences and fabrication issues to ensure the longevity and durability of ceramic prostheses. The aim of this paper was to explore how “sensitive” the thermal and mechanical responses, in terms of changes in temperature and thermal residual stress of the bi-layered ceramic systems and crown models will be with respect to the perturbation of the design variables chosen (e.g. layer thickness and heat transfer coefficient) in a quantitative way. Methods. In this study, three bi-layered ceramic models with different geometries are considered: (i) a simple bi-layered plate, (ii) a simple bi-layer triangle, and (iii) an axisymmetric bi-layered crown. Results. The layer thickness and convective heat transfer coefficient (or cooling rate) seem to be more sensitive for the porcelain fused on zirconia substrate models. Significance. The resultant sensitivities indicate a critical importance of the heat transfer coefficient and thickness ratio of core to veneer on the temperature distributions and residual stresses in each model. The findings provide a quantitative basis for assessing the effects of fabrication uncertainties and optimizing the design of ceramic prostheses