title: Using micro-mechanical modelling to predict short-fibre composite properties in computer-aided design of sporting equipment

authors: Ewart, Paul

subjects: flexural modulus

abstract: Computer-aided design (CAD) of sporting equipment requires knowledge of the mechanical properties of proposed materials. The mechanical properties of composite materials are often not as simple to obtain as those of conventional materials, in which case micro-mechanical modelling could be used in conjunction with CAD software. A micro-mechanical model was used to predict the flexural modulus of composite materials, based on the assumption of partial interfacial adhesion between composite components. It was found that the partial adhesion model was both practical and consistently accurate. The partial adhesion model accounted for adhesion between components by considering an ‘effective shear value’ at the interface. The model was compared to experimental data for glass, wood and carbon-fibre reinforced polyethylene. It was shown that the adhesion coefficient ranged between 0.1 for carbon fibre, 0.5 for glass fibre and 0.8 for the wood fibre composites. It was shown that using micro-mechanical modelling to predict composite mechanical properties, as opposed to simulating the comprehensive composites structure, computer processing time and file size can be reduced with little compromise in simulation accuracy.

text: Using micro-mechanical modelling to predict short-fibre composite properties in computer-aided design of sporting equipment Computer-aided design (CAD) of sporting equipment requires knowledge of the mechanical properties of proposed materials. The mechanical properties of composite materials are often not as simple to obtain as those of conventional materials, in which case micro-mechanical modelling could be used in conjunction with CAD software. A micro-mechanical model was used to predict the flexural modulus of composite materials, based on the assumption of partial interfacial adhesion between composite components. It was found that the partial adhesion model was both practical and consistently accurate. The partial adhesion model accounted for adhesion between components by considering an ‘effective shear value’ at the interface. The model was compared to experimental data for glass, wood and carbon-fibre reinforced polyethylene. It was shown that the adhesion coefficient ranged between 0.1 for carbon fibre, 0.5 for glass fibre and 0.8 for the wood fibre composites. It was shown that using micro-mechanical modelling to predict composite mechanical properties, as opposed to simulating the comprehensive composites structure, computer processing time and file size can be reduced with little compromise in simulation accuracy.

year: 2010

title: Identifying appropriate sampling and modelling approaches for analysing distributional patterns of Antarctic terrestrial arthropods along the Victoria Land latitudinal gradient

authors: Caruso, Tancredi

subjects: Antarctica

abstract: Biotic communities in Antarctic terrestrial ecosystems are relatively simple and often lack higher trophic levels (e.g. predators); thus, it is often assumed that species’ distributions are mainly affected by abiotic factors such as climatic conditions, which change with increasing latitude, altitude and/or distance from the coast. However, it is becoming increasingly apparent that factors other than geographical gradients affect the distribution of organisms with low dispersal capability such as the terrestrial arthropods. In Victoria Land (East Antarctica) the distribution of springtail (Collembola) and mite (Acari) species vary at scales that range from a few square centimetres to regional and continental. Different species show different scales of variation that relate to factors such as local geological and glaciological history, and biotic interactions, but only weakly with latitudinal/altitudinal gradients. Here, we review the relevant literature and outline more appropriate sampling designs as well as suitable modelling techniques (e.g. linear mixed models and eigenvector mapping), that will more adequately address and identify the range of factors responsible for the distribution of terrestrial arthropods in Antarctica.

text: Identifying appropriate sampling and modelling approaches for analysing distributional patterns of Antarctic terrestrial arthropods along the Victoria Land latitudinal gradient Biotic communities in Antarctic terrestrial ecosystems are relatively simple and often lack higher trophic levels (e.g. predators); thus, it is often assumed that species’ distributions are mainly affected by abiotic factors such as climatic conditions, which change with increasing latitude, altitude and/or distance from the coast. However, it is becoming increasingly apparent that factors other than geographical gradients affect the distribution of organisms with low dispersal capability such as the terrestrial arthropods. In Victoria Land (East Antarctica) the distribution of springtail (Collembola) and mite (Acari) species vary at scales that range from a few square centimetres to regional and continental. Different species show different scales of variation that relate to factors such as local geological and glaciological history, and biotic interactions, but only weakly with latitudinal/altitudinal gradients. Here, we review the relevant literature and outline more appropriate sampling designs as well as suitable modelling techniques (e.g. linear mixed models and eigenvector mapping), that will more adequately address and identify the range of factors responsible for the distribution of terrestrial arthropods in Antarctica.

year: 2010

title: Māori and indigenous views on R and R: Resistance and Resilience

authors: Penehira, Mera

subjects: resilience

abstract: This article explores the development of Mäori and Indigenous frameworks of resilience, considering the impact of engaging with largely State- led notions of resilience on Mäori development. We highlight the closely linked notion of resistance, asserting the necessity of a fi rm political analysis from Indigenous researchers engaged in this discourse. One of the Indigenous criticisms of resilience theories is that by defi nition they assume an acceptance of responsibility for our position as disadvantaged individuals. That is, by examining and developing theories and models of resilience we buy into the idea that this is the way it is and we need simply to get better at bouncing back and being resilient. Resistance, however, represents an approach of collective fi ght- back, exposing the inequitable distribution of power, and actively opposing negative social, political and economic infl uences. This article represents a Mäori Indigenous political response to the resilience discourse.

text: Māori and indigenous views on R and R: Resistance and Resilience This article explores the development of Mäori and Indigenous frameworks of resilience, considering the impact of engaging with largely State- led notions of resilience on Mäori development. We highlight the closely linked notion of resistance, asserting the necessity of a fi rm political analysis from Indigenous researchers engaged in this discourse. One of the Indigenous criticisms of resilience theories is that by defi nition they assume an acceptance of responsibility for our position as disadvantaged individuals. That is, by examining and developing theories and models of resilience we buy into the idea that this is the way it is and we need simply to get better at bouncing back and being resilient. Resistance, however, represents an approach of collective fi ght- back, exposing the inequitable distribution of power, and actively opposing negative social, political and economic infl uences. This article represents a Mäori Indigenous political response to the resilience discourse.

year: 2014