No description available.

No description available.

The New Zealand Structural Loading Standard, until its latest revision, was using the structural displacement ductility factor as a measure of the deformation demand of all potential plastic hinges in a structure. In the revised version of New Zealand Structural Loading Standard for Earthquake Actions (NZS 1170.5:2004) the detailing of potential plastic regions is determined according to the local inelastic deformation demand in these regions. The change has been prompted by evidence that the structural ductility factor gives a poor indication of the demand on individual plastic regions. This is a major paradigm shift in international design codes. This new approach has been adopted by the New Zealand Concrete Structures Standard (NZS 3101:2006) which classifies potential plastic regions into three categories (namely ductile, limited ductile and nominally ductile) based upon their inelastic deformation demand which has been specified in terms of material strain limits in the form of curvatures or shear deformations. The values of material strain limits currently used in New Zealand Concrete Standard (NZS 3101:2006) to categorise the plastic regions are based on limited evidence and need a closer revision. This research attempts to obtain more justifiable values of material strain limits through experimental data existing in literature. Moreover, experimental testing is also conducted to compensate for a lack of data in the nominally ductile range of detailing. The experimental work explores the effects of transverse reinforcement arrangement, reinforcing steel grade and plastic hinge type. Together the literature review and experimental work provide a sound basis for re-defining the material strain limits for different plastic regions.

This creative project has investigated the engineering principles relative to the design and construction of a blown tubular film take-off system. The study has also made a careful analysis of the equipment necessary to construct a blown tubular film extrusion line.In addition, the creative project has discussed alternate methods of producing polyolefin filets, it has suggested possible solutions for troubleshooting which can provide valuable assistance in the successful production of quality blown tubular film.

Introduction: The Canadian Standards Association (CSA) Z94.3-07 ballistic impact test for industrial lenses, tests the ability of a lens material to withstand the impact of a 6.4 mm diameter steel ball travelling at a speed of 46.5 ± 0.5 m/s. The specific testing is waived if the lens made of various materials meets a minimum centre thickness requirement. New lens materials, like Hi-Vex, are not included in this list. The first study compared the breakage speed of Hi-Vex lenses to CR39 lenses at different conditioned temperatures. In the process of carrying out the literature review, it became apparent that the definition of lens failure varied. This led to the question as to how naïve individuals may interpret a National Standard definition of lens failure after being impacted by a missile. Naïve subjects were asked to classify impacted lenses as either pass or fail based on the written CSA Z94.3-07 failure criterion. Purpose:   Study 1: To investigate the impact resistance of a mid-index plastic lens material Hi-Vex (n=1.56) at different temperatures. Study 2: To investigate if people actually understood what the CSA classifies as a failed lens. Methods:  Study 1: Two groups of plano hard coated lenses were tested: CR39 and Hi-Vex. Lenses were ordered with 3mm centre thickness, cut to 50mm diameter and edged to achieve the Hide-a-Bevel® which was in agreement with the CSA requirement for prescription industrial safety lenses and frames. A pneumatic gun was used to propel a 6.35mm steel ball at the centre of each lens. Impact speed was varied using the Zippy Estimation by Sequential Testing (ZEST) protocol to determine the threshold breakage speed. Combined uncertainties as defined in the International organization for standardization (ISO) Guide to the expression of uncertainty in measurement were used to determine the statistical significance of all comparisons of the data sets. Study 2: Ten graduate students from the School of Optometry and ten patients from the general public were given 25 spectacle lenses that had been subjected to the ballistic impact test. They were asked to classify the lenses as either a pass or fail after reading the definition of a failure under the ballistic impact test in CSA Z94.3-07 clause 6.1.3.1. Lenses were presented to the participants in the same order. The responses of both groups of participants were compared to the classification of two experienced researchers who agreed on 100% of the lens outcomes. Results:  Study 1: The threshold breakage speeds of the industrial thickness Hi-Vex and CR39 lenses at 24°C were 50.88m/s and 50.64 m/s and at -29°C, 52.57m/s and 52.56 m/s respectively. Both comparisons were not statistically significant. The corresponding threshold breakage speeds for Hi-Vex and CR39 lenses at -49°C were 66.38m/s and 49.66m/s and at 50°C were 57.01m/s and 53.54m/s respectively. Both comparisons were statistically significant. Study 2: There were only two lenses in which all participants agreed with the outcome. These lenses were failed lenses. The naïve subjects were more likely to classify a lens that passed as a failure than a failed lens as a pass. This trend was more obvious in the general public results although the results across the various lenses for the graduate students and general public were not statistically different. Conclusions:  Study 1: We found that the mean breakage speeds of the Hi-Vex and CR39 lenses were greater than the level required of eye protector lenses by the Standards American National Standards institute (ANSI) Z87.1-2010 and CSA Z94.3-07. Hi-Vex was also superior to CR39 at more extreme temperatures with a threshold breakage speed of 57.01±3.51m/s at 50°C and 66.38±4.00m/s at -49°C. Although its impact resistance was less than that of both Trivex and Polycarbonate lenses, Hi-Vex may provide an acceptable level of impact protection in industrial settings. This is the first study to concomitantly assess impact resistance of a new lens material as well as compare the impact resistance at various temperatures. Study 2: Simply reading the definition of a lens failure is insufficient. Some type of training with actual lenses may be necessary. Whether revising the text of the Standard or repeating the instructions several times would reduce this problem is uncertain. Both the graduate students and general public tended to be more conservative in their classification of failure. If there were any visible damage to the lens as a result of the impact, at least one person would classify the lens as a failure regardless of whether the damage met the CSA definition. This result suggests that the vision care community and CSA may need to educate the public on the meaning of impact resistance of eye protectors.

No description available.

No description available.

No description available.

Severe plastic deformation (SPD) has been used over the past few decades for producing submicron grain (SMG) structures in range of metals and alloys. Equal channel angular pressing (ECAP) is a useful process for producing these types of structures whereby the material is deformed to very high plastic strains by passing a billet several times through the ECAP die. This process has an added advantage maintaining the initial dimensions of the billet. SMG materials produced by ECAP and related routes are useful as they usually exhibit excellent properties including high strength and hardness, and excellent superplastic formability: these and other properties make SMG materials useful for industrial and aerospace applications. In this thesis, a binary aluminium alloy containing a very low concentration of scandium (0.1 wt. %) Sc alloy was investigated and compared with higher Sc-containing alloys. The material was deformed by ECAP in the solution treated condition to an equivalent von Mises strain of 9.2 then pre-aged at 250 0C to generate a submicron grained material containing a relatively uniform dispersion of nanosized Al3Sc dispersiods. The thermal stability of this pre-aged microstructure was investigated by annealing at temperatures up to 450 0C resulted in continuous grain coarsening by the process of continuous recrystallization whereby the initial microstructure evolves gradually with no marked change in the grain size distribution, texture and grain boundary character. However, extended annealing (> 1h) at 4500 C resulted in discontinuous grain coarsening (often termed recrystallization) whereby a few grains grow rapidly to eventually produce a coarse-grained final microstructure. Throughout annealing, there was a good correlation between the dispersion parameter, (f/d) where f and d is the volume fraction and the mean diameter of Al3Sc particles in the alloy, respectively, and both the mean grain size (D ) and D /D max where max D is the maximum grain diameter observed in the microstructure. The grain structure was found to undergo moderate coarsening at the high f/d-values but converted to a coarsegrained structure for f/d ~<0.5/μm, and this change occurred when the mean grain diameter was ~ 3-4μm. Hence, the critical value of the dispersion parameter for the transition from continuous to discontinuous coarsening falls between the theoretical value for submicron grain size alloys (f/d ~ 1.5/μm) and the value found for conventionally-deformed alloys (f/d ~ 0.1/μm). This behaviour is the result of the alloy no longer being ultra-fine grained at the onset of discontinuous coarsening.

Linear Low Density Polyethylene (LLDPE) is a relatively new plastic that is becoming widely used in many applications. In fact the production rate of LLDPE is vital in determining the process characteristics and subsequent properties of the end products. In this work we have examined, specifically, the influence of surfaces and structure on the rheology and processing properties of LLDPE. A review of the effect of surfaces on the rheology and processing of polymers is given, with particular emphasis on the interaction between metals and polymers. The influence of oxidative degradation and radiation on the structural modification of polymers is also reviewed. Standard rheological characterisation tests determined there was no effect of various metal and teflon surfaces on the rheology of LLDPE. There was also no evidence of wall slip on metal or teflon surfaces. The generalised Maxwell model (with Wagner's damping function) predicted dynamic and steady shear properties at standard characterisation rates well. The effects of degradation of LLDPE were quantified, and an increase in elasticity due to increased crosslinking of long polymer chains was noted during degradation tests. This effect increased with time (after a degradation time) and temperature. There was no effect of metals on the degradation properties of LLDPE, however, there was evidence of increased carbon-oxygen species (or increased oxidation) at the metal/LLDPE interface for metals containing copper at the interface (copper and brass). The migration of copper was facilitated by the low heat of formation of the oxides on the copper-containing metals. Increasing gamma and ion beam radiation dose decreased melting temperatures, heats of melting and crystallinity due to increased crosslinking at the crystallite surfaces and the reduction in crystal sizes. Gel fraction and tightness of gel increased with radiation dose due to increased crosslinking. Increased radiation dose also increased the elasticity and flow resistance of the samples as shown by rheological tests. The extension of a power law representation of the relaxation modulus of irradiated samples was extended to predict stress build-up and relaxation properties in steady shear tests. There was little effect of type of radiation (gamma or ion beam) on physical and rheological properties. However, there was a marked increase in the effects of irradiation in the melt (150degC) on the physical and rheological properties of LLDPE, which was due to the increased effective amorphous nature of the sample in the melt. The equivalence of the effects of degradation and irradiation are discussed. Viscosity was well predicted by the generalised Maxwell model (with Wagner's damping function) at processing rates. The normal stress differences calculated by Boger and Denn's model correlated well with this generalised Maxwell model, which was due to the inclusion of a flow rearrangement term. There was a marked increase in exit pressures, exit losses, flow rearrangement length, flow singularity, and exit stresses for flow over brass inserts at the die exit. These effects coincided with the production of a porous, copper-rich brass surface and it was postulated that this was the results of surface dezincification which caused increased adhesion between the LLDPE and the brass via physical interlocking at the porous surface. Extension of these results to melt fracture are discussed.