Browsing by Author "Cave, Ian Douglas"

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The magnetisation of some New Zealand pleistocene varved glacial sediments
(Te Herenga Waka—Victoria University of Wellington, 1961) Cave, Ian Douglas
A palaeomagnetic survey in order to determine the possibility of obtaining the secular variation of the earth's field in the Pleistocene from New Zealand's glacial lake sequences, has been carried out. The sediments from Bryant's Gully, Rakaia Valley are found to possess consistent and stable magnetisation directions, and the scatter is such that good statistical accuracy of the mean directions of magnetisation is easily attainable. The differences in the means of beds separated in time has been attributed to a secular variation of the field of the same order as at present. It has also been shown that wide variations in intensity of magnetisation are likely to be found in sediments from differing localities. Fairly large variations between beds and smaller within-bed variations also occur.
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Mechanical Properties of Fibre-Reinforced Materials The Wood-Water System
(Te Herenga Waka—Victoria University of Wellington, 1973) Cave, Ian Douglas
The mechanical properties of wood are investigated from a "quasi-elastic point of view that makes allowance for variation in moisture content. The theoretical work is divided into three parts. The first part shows that wood may be regarded as a fibre-reinforced composite material and then builds up models of wood structure in terms of an assemblage of basic fibre-composite elements. The second part derives the constitutive relations for a fibre-reinforced composite consisting of, an inert fibrous phase embedded in a water reactive matrix; and the third part is concerned with the properties of the matrix of wood substance. The theoretical work is then tested against mechanical data from a set of specimens for which individual models have been devised. From this work, functions describing the behaviour of the matrix with moisture contest are obtained and the structural modelling procedures and the constitutive relation are shown to be not inconsistent with the observations. It was found that in. addition to the mean cellulose microfibril angle, the matrix sorption properties are of great importance in correctly predicting Longitudinal shrinkage behaviour.