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The bending strength of a commercial 0.82-inch-thick three-layered particleboard was investigated in terms of its bending moment resistance capacity. Experimental results indicated that the bending moment resistance capacity of the particleboard was governed by the tensile and compressive strengths of each of four-layered materials composing of the particleboard. A proposed mechanical model for prediction of the bending moment resistance capacity of the particleboard based on the tensile and compressive strengths of each of three-layered materials was validated experimentally. The developed mechanical model can be used to explain four different variations in terms of different combinations of layer strength properties commonly occurred in real manufacturing environment due to process variations. The optimal combination in terms of each layer tensile and compressive strength property can be obtained.

Chip and scrub seal treatments are common pavement preservation practices that use asphalt emulsions. Their performance has been studied for several years, yet many questions remain. The primary thesis objective was to study near surface behaviors of flexible pavements that are candidates for seal treatments. This study investigated the ability of the bending beam rheometer (BBR) to detect pavement surface changes due to the application of asphalt emulsion. Estimated stiffness and m-value data was recorded for three asphalt concrete mixtures using mixture beams approximately 120 mm long by 12 mm wide by 7.7 mm thick sawn from the surface of asphalt specimens. One mixture was plant mixed and laboratory compacted, while the other two were field-aged mixtures. This study gauges effect of treating specimens with emulsions commonly used in Mississippi in conditioned and unconditioned states.

This graduation thesis is concerned with implementing the SPC (Statistical process control) to the process plan. The aim of this thesis is an analysis of present status of manufacture laths bending and a selection of useful methods, which is possible to apply in a company processes. The main reason for SPC implementation is continual improvement of quality in manufacturing concern. The theoretical part of thesis consist of bending description, control of process quality, quality control instruments and errors in measurement. In practical part is described an actual status of manufacture and a solution of query.

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Composites have high strength-to-weight ratios, which is particularly desired for applications with weight restrictions. Common composite materials such as carbon fiber reinforced plastic (CF) and fiber glass reinforced plastic (FG) were used in this research. While composite materials possess high stiffness and strength properties, the stiffness of composite laminates may be maximized by changing the geometry. By adding corrugations, the flexural stiffness is increased in one direction compared to the stiffness of a flat part with the same amount of material. Thus, stiffness increases without a change in weight. The primary goal of this research was to investigate the stiffness characteristics of corrugated composite laminates under tensile and flexural load. The chosen corrugation geometry for investigation was a trapezoid. To observe the effects of corrugations, both flat and corrugated coupons were tested experimentally with the same procedures. Stiffness was calculated experimentally, analytically, and numerically in both directions. In this study, the longitudinal direction was defined as perpendicular to the corrugations and transverse direction was defined as the direction along the corrugations. The effects on stiffnesses of corrugated and flat composites were measured by comparing changes to the stiffness ratios in tension and bending. The stiffness ratio is the ratio of longitudinal stiffness to transverse stiffness. The secondary aim of this research was to compare the corrugation effects on FG weave and cross-ply CF. This was interesting to observe the difference in corrugation effects on different composite materials. The FG laminates were manufactured from four plies of pre-impregnated Cytec MXB 7701/7781. The CF laminate consisted of five plies of pre-impregnated unidirectional Tencate TC250/M46J. The layup orientation of the CF laminate had alternating 0◦ and 90◦ plies, where the 0 ◦ plies were in the transverse direction. Plies were directly laid on a flat plate and aluminum mold for flat and corrugated specimens, respectively. All flat and corrugated composites were cured in an autoclave under respective recommended cure cycles for each material. The tension and three-point bend tests were conducted on an Instron 8800 where the load was applied at a rate of 0.05 inches per minute. The tensile ultimate load was the same between corrugated and flat specimens in the longitudinal direction. Meanwhile, the tensile ultimate load was greatly reduced for corrugated specimens in the transverse direction when compared to the flat specimens. Thus, corrugations had a larger impact in the transverse direction under tensile load for both materials. By corrugating the composite layups, the ratio of stiffness in the longitudinal to extensional direction increases. For FG test coupons, the extensional stiffness ratio was increased from 1.0 to 49.3 due to corrugations. The flexural stiffness ratio was increased from 0.3 to 187.1 in corrugated FG coupons. For CF test coupons, the extensional stiffness ratio increased from 0.7 to 61.3. The flexural stiffness ratio of CF test coupons increased from 0.3 to 81.4. Corrugations had a greater effect on the cross-ply CF for both extensional and flexural stiffnesses.

Clay, quartz and feldspar are widely available in Uganda. The location and properties of various clay deposits are reported in the literature, but little is reported on feldspar and quartz deposits. In this work an extended literature on ceramics and porcelains in particular, is documented. Samples from two deposits of feldspar and two deposits of quartz are characterised and found to possess requisite properties for making porcelain insulators. Sample porcelain bodies are made from materials collected from selected deposits using different mixing proportions of clay, feldspar and quartz. Their properties in relation to workability, firing temperature, dielectric and bending strengths are studied. It is found that a mixture consisting of 30% Mutaka kaolin, 15% Mukono ball clay, 30% Mutaka feldspar and 25% Lido beach flint yields a body with highest mechanical strength (72MPa) and dielectric strength (19kV/mm) when fired at 1250°C. The strength (both mechanical and dielectric) is found to decrease with increasing firing temperature. At high firing temperatures, the undissolved quartz in the body decreased, the glass content increases and pores are formed. Mullite content on the other hand does not change at temperatures above 1200°C but there are significant differences in the morphologies of the mullite crystals in the samples. Optimum mechanical and electrical properties are found at maximum virtification and a microstructure showing small closely packed mullite needles. / QC 20101122

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<p> Manufacturing processes such as cold-bending flat sheet to a small radius produces a rather complex residual stress state through the thickness of light gauge structural steel sections. When the load-application device is released the sheet exhibits a phenomenon called "spring-back".</p> <p> The purpose of this research was to develop an exact method of computing the residual stresses in a wide sheet of ideal plastic metal after spring back and subsequently to study their effect on the behaviour of cold-formed sections. An approximate analysis based on the assumption of elastic spring back is presented for comparison purposes. It is demonstrated that plastic flow occurs within a thin core of sheet below the neutral axis and that the spring back is not completely elastic beyond a certain curvature. Such behaviour is particularly significant in cases where the radius of bend is of the same order as the thickness. An exact analysis based on a more realistic approach is then performed considering the adjustments in the stress components due to the plastic core. Computer programs have been developed to calculate the residual stresses associated with any given radius of bend. It is found that the choice of one yield criterion rather than the other does not have any effect on the present analysis and the stress components for Von Mises' material are (2/√3) times the components for Tresca's material. Furthermore, the effect of lateral stretching on the behaviour of cold-formed sections is briefly viewed.</p> <p> The purpose of the experimental work in this thesis was to verify the validity of some of the assumptions made in the analysis.</p> <p> Conclusions are drawn and suggestions made for further research.</p> / Thesis / Master of Engineering (MEngr)