The present study explores some of the materials native to the Texas Gulf Coast between Corpus Christi and Beaumont relative to their adaptability to weaving. The problem is three-fold: first, to collect and identify the indigenous materials which might prove suitable for weaving; second, to determine the range of uses which each might serve in a weaving program; and third, to test further each selected specimen by making a sample into a finished woven product.

The shear strength of unidirectional glass-epoxy composites was determined experimentally by three standard shear tests. The tests consisted of short beam interlaminar shear tests, saw-cut shear tests, and torsion tests on circumferentially wound cylinders. Test results show that the short beam interlaminar shear tests and the torsion tests of circumferentially wound cylinders give approximately the same maximum shear stress. Test results also showed that the saw-cut shear test is not a good interlaminar shear test because of stress concentrations at the base of the saw cuts and high tearing stresses normal to the plane of shear. The shear strength determined by the beam and torsion tests is approximately 10 ksi, whereas the average shear strength for the saw-cut specimens is approximately 2.5 ksi. / Master of Science

The effect of process conditions, temperature, time and rate of temperature rise, on the exhaustion of disperse dye on polyester yarn under High-Temperature dyeing conditions was investigated. Two ply spun type Dacron 54 polyester yarn was dyed with Disperse Red 60 in 0.5 g/l dye bath concentration using an Ahiba Texomat Dyeing Apparatus under High-Temperature Dyeing conditions. The dyeing process design used, consists of three levels of dyeing temperature (105°C, 120°C, 135°C), four levels of holding time (0 min, 15 min, 30 min, 60 min) and two levels of rate of temperature rise (1ºC/min, 3°C/min). After the dyeing process, the dye concentration in the yarn was obtained through extraction and measured spectrophotometrically. A factorial analysis of variance (ANOVA) test was used to determine whether or not significant differences existed among dyeing process conditions in regard to the dye uptake of the yarn. If significant differences existed, which parameter of process conditions (temperature, time, rate of temperature rise or their interactions) was responsible. The results of this study indicated that a three-way interaction of temperature, time, and rate of temperature rise was responsible for the differences in dye uptake of the yarn. The dye uptake of the yarn increased by increasing dyeing temperature from 105°C to 120°C for all levels of holding time and rate of temperature rise. However, increasing dyeing temperature from 120°C to 135°C, did not increase dye uptake of the yarn. The dye uptake of the yarn increased by increasing holding time from zero to 15 minutes for dyeing temperature of 120°C. However, increasing holding time from 15 to 60 minutes, did not increase dye uptake of the yarn. At the dyeing temperature of 120°C, a slower rate of temperature rise resulted in greater dye uptake of the yarn. It can be concluded that high temperature dyeing of polyester yarn at 120°C for 15 minutes with a rate of temperature rise of 1°C/min was the optimum dyeing process in achieving full exhaustion. / Master of Science

An experimental investigation was made to determine the role of gravitational and surface tension forces in the migration of liquid water through fiberglass insulation materials. Straightforward experimental procedures were devised to effectively isolate and quantify flow parameters considered important in describing the flow mechanisms involved. The study was conducted to supplement an earlier investigation into the thermal performance of wetted insulation materials. Darcy's Law was found to apply for the regime of flow encountered in which liquid water flows under the force of its own weight in horizontal rooftop insulation. Experimental determination of the constant of proportionality in Darcy's Law, the hydraulic conductivity, is all that is needed to describe the migration of liquid water in saturated fiberglass insulation. Capillary forces, originally thought to play a significant role in the movement of liquid water through fiberglass insulation, were found to be negligible. Capillary rise up a column of insulation measured no higher than 13 mm. / M.S.

A practical fiber optic strain sensor has been developed to measure strains in the range of 0.0 to 2.0 percent strain with a resolution ranging between 10 and 100 microstrain depending on sensor design choices. This intensity based sensor measures strain by monitoring strain induced longitudinal misalignment in a novel fiber interconnection. This interconnection is created by aligning fibers within a segment of hollow core fiber. Related splice loss mechanisms are investigated for their effect on resolution. The effect of gauge length and launch conditions are also investigated. / Master of Science

A novel method of fabricating low reflectance mirrors has been developed based on the photosensitivity of hydrogen-loaded, germanium-doped optical fibers. Using a side-writing technique, point-wise refractive index changes have been induced in the core of Ge-doped optical fibers via ultraviolet light from a high power excimer laser. These refractive index changes cause Fresnel reflections at the boundary of the higher photoinduced index change and the lower index in the unexposed core. The boundary of the two refractive indices may be considered a low reflectance mirror. Several techniques have been explored to characterize the Fresnel reflectors including optical time domain reflectometry (OTDR) and spectral analysis. In-line, optical fiber Fresnel reflectors have applications as internal mirrors in intrinsic Fabry-Perot interferometric (IFPI) sensors and OTDR distributed strain sensors. Photoinduced IFPI sensors have performed well as temperature sensors, strain sensors, and vibration sensors. Improved manufacturing techniques are also discussed for future developments. The photoinduced IFPI sensor is inexpensive to manufacture and involves little skill, in contrast to the labor-intensive fabrication techniques of conventional IFPI sensors. The IFPI sensor has commercial applications in embedded structures, high temperature environments, and situations with large EMI conditions. / Master of Science

Noise and distortion limit the channel capacity and degrade the system performance in AM-VSB SCM CATV Distribution Networks. The use of star couplers and fiber amplifiers is an approach to overcome these problems and meet the increasing demand for large capacity and high quality. The capacity and performance analyses of three different network configurations are compared based on the results of computer modeling. In practice, the best configuration depends on the optical amplifiers and the pump lasers used in the system as well as the requirement on the number of channels and the number of subscribers. It is found that in a two-stage star network the largest improvement in the capacity and performance may be achieved when the optical amplifiers between the stages are individually pumped. For example, a capacity of 200 channels and 572 output nodes may be obtained. There is an optimal length of the erbium-doped fiber amplifier (EDFA) and there is also an optimal position where the EDFA is located between the two star couplers. The modeling is based on an extensive analysis of noise and distortion in the system. A discrepancy in the power behavior of laser relative intensity noise (RIN) is pointed out. A previous analysis on reflection-induced noise is extended to include the effect of quadruply-reflected light and optical amplifiers. Since chirp-dispersion distortion and gain tilt distortion are found to be negligible, clipping distortion is the main limitation on the system capacity. Optical amplifier noise provides an additional limitation to the system. Because the gain and amplified spontaneous noise depend on the input signal power and pump power, the gain and spontaneous emission factor are modeled for the comparison of the different systems. / Master of Science

Energy absorption during complete penetration of thin graphite composites is experimentally shown to be significantly improved by low volume fractions of embedded superelastic shape memory alloy (SMA) fibers. Graphite/Bismaleimide laminates were embedded with 3% and 6% volume fractions of superelastic nitinol fibers. Quasi-static tests were performed on wide clamped-clamped beams to identify progressive damage mechanisms. Low velocity (13.9 ft/s) impact tests, at an impact energy of 31.5 ft-lbs, resulting in complete penetration were also performed on wide clamped-clamped beams. These tests show that only after peak load is there a contribution made by the SMA to the load deflection behavior of the composite. Owing to the SMA's high strength and high strain to failure it remains undamaged after failure of the base composite. The interaction between the base composite and the SMA creates an increase in absorbed energy over the base composite of as much as 41 % in a Graphite/Bismaleimide laminate embedded with a 6% volume fraction of nitinol fibers. C-scans of the hybrids embedded with bi-directional nitinol fibers show a 22% larger delamination areas compared to plain graphite epoxy. The larger delaminations are a result of the nitinol fibers distributing the impact energy to a larger area of the base composite. This interaction between the nitinol and the graphite is one of the reasons for the increases in absorbed energy. Fiber pull-out and strain energy of the nitinol fibers also adds to the increase in absorbed energy. Although damage initiation and peak loads do not seem to be affected by the embedded nitinol fibers, the energy absorption after peak loads is greatly improved. This improvement is a result of increased energy distribution through the SMA to the graphite. The large improvements in energy absorbing capabilities offered by SMA fibers give SMA hybrid material systems promise in applications where penetration resistance is imperative. / Master of Science

Fiber optics technology is being used in many applications, both in the military world and in the industrial world. A broad overview of this technology is provided, including a discussion of the fundamentals of fiber operation and component characteristics. Applications of fiber optics in both military and industrial communities is addressed, identifying specific examples in both cases. In addition, market projections and technology trends are discussed for both the military and industrial communities. / Master of Science

Abrasive blasting is a common process for cleaning or roughening the surface of a material prior to the application of a coating. Although the process has been in practice for over 100 years, the lack of a comprehensive understanding of the complex interactions that exist with the process can still yield an inferior surface quality. Subsequently, parts can be rejected at one of many stages of the manufacturing process and/or fail unexpectedly upon deployment. The objective of this work is to evaluate the effect of selected input parameters on the characteristics of the blasted surface characteristics so that a more useful control strategy can be implemented. To characterize surface roughness, mechanical profilometry was used to collect average roughness parameter, Ra. Decreasing blast distance from 6” to 4” gave ΔRa = +0.22 µm and from 8” to 6” gave ΔRa = +0.22 µm. Increasing blast pressure from 42 psi to 60 psi decreased the Ra by 0.33 µm. Media pulsation reduced Ra by 0.56 µm and the use of new media reduced Ra by 0.47 µm. Although blasting under the same conditions and operator on different days led to ΔRa due to shorter blast times, there was no statistically significant variance in Ra attributed to blasting on different days. Conversely, a ΔRa = +0.46 µm was observed upon blasting samples with different cabinets. No significant ΔRa was found when switching between straight and Venturi nozzles or when using different operators. Furthermore, the feasibility of fiber optic sensing technologies was investigated as potential tools to provide real time feedback to the blast machine operator in terms of substrate temperature. Decreasing the blast distance from 6” to 4” led to ΔT = +9.2 °C, while decreasing the blast angle to 45° gave ΔT= -11.6 °C for 304 stainless steel substrates. Furthermore, increasing the blast pressure from 40 psi to 50 psi gave ΔT= +15.3 °C and changing from 50 psi to 60 psi gave ΔT= +9.9 °C. The blast distance change from 8” to 6” resulted in ΔT = +9.8 °C in thin stainless steel substrate temperature. The effects of substrate thickness or shape were evaluated, giving ΔT= +7.4 °C at 8” distance, ΔT= +20.2 °C at 60 psi pressure, and ΔT= -15.2 °C at 45° blasting when comparing thin stainless steel against 304 stainless steel (thick) temperatures. No significant ΔT in means was found when going from 6” to 8” distance on 304 stainless steel, 40 psi and 60 psi blasting of thin SS, as well as angled and perpendicular blasting of thin SS. Comparing thick 304 and thin stainless steel substrates at a 6” blast distance gave no significant ΔT. / Master of Science