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.

Polymer fiber sensors have been extensively explored over the past few decades for biomedical, structural health monitoring, and environmental monitoring applications. Their low melting point and well-established processing methods make them easily integrable with other materials, such as metals, semiconductor devices, and composites, to create multimaterial sensors with versatile sensing capabilities. However, the high viscoelasticity of polymer materials and the limitations of existing sensing mechanisms constrain the precision and stability of these sensors. This research focuses on enhancing the sensitivity of multimaterial polymer sensors by improving both the sensing mechanisms (chapter 2 and 3) and sensor structures (chapter 4 and 5). Chapters 2 and 3 discuss the integration of silica optical fiber sensors into magnetostrictive composite materials for distributed magnetic field sensing. A series of Fiber Bragg Gratings (FBGs) were inscribed in the core of a silica fiber, which was then thermally embedded at the center of a magnetostrictive composite made of Terfenol-D and thermoplastic elastomers. The magnetostrictive properties of the composite, using various polymer matrices, were thoroughly investigated. A detailed study of the sensor's response under different boundary conditions and applied tensions demonstrated its tunable frequency response and bandwidth capabilities. Furthermore, the sensor's magnetic field sensing performance was characterized under applied AC magnetic fields, showing a responsivity of up to 4.5 ppm/mT and a resolution of 0.1 mT. Theoretical modeling of the magnetostrictive fiber's behavior was also conducted, with the strain transfer coefficient being calculated and compared to the bulk material's response. This thermally drawn magnetostrictive fiber exhibits significant potential for fully distributed sensing applications. In Chapters 4 and 5, the development of a stretchable fiber strain sensor is presented, with improvements in sensitivity achieved through structural optimizations. Polymer fibers, known for their high stretchability, flexibility, and softness, are promising candidates for sensing applications. However, their high viscoelasticity often leads to significant hysteresis. To address this, a double-coil strain sensor was introduced in this research. A theoretical model of the double-coil capacitance was developed to inform future sensor designs. Based on this model, a stretchable miniature fiber sensor was constructed, featuring a stretchable core tightly coiled with parallel conductive wires. This sensor demonstrated low hysteresis, a theoretical resolution of 0.015%, a response time of less than 30 milliseconds, and outstanding stability after more than 16,000 cycles of testing. Its potential as a wearable device was showcased by embedding it into belts, gloves, and knee protectors, with applications ranging from bladder monitoring to life safety rope systems. The dissertation concludes with a discussion of the research findings and suggestions for future directions in the development of multimaterial fiber sensors. / Doctor of Philosophy / This research focuses on enhancing the sensitivity of polymer fiber sensors, which are widely used in healthcare monitoring, infrastructure safety, and environmental observation. These sensors offer the advantage of integrating with other materials to create versatile, multi-functional devices. However, their soft nature and limited sensing mechanisms pose challenges to measurement accuracy and stability. This dissertation proposes improvements in the sensitivity of multimaterial polymer fiber sensors by enhancing both their sensing mechanisms and structural designs. In the first part, new techniques were developed to improve magnetic field sensing by embedding optical fibers into magnetically responsive materials. A scalable method called thermal drawing was used to fabricate magnetostrictive fibers, enabling the sensors to measure magnetic fields at various locations with a minimum detectable change of 0.1 mT. This approach enhances the accuracy of magnetic field detection, which is valuable for monitoring magnetic field distributions in industrial applications. The second part introduces a stretchable sensor designed for strain detection in wearable, biomedical, and structural health monitoring applications. Featuring a double-coil design, this sensor demonstrated stability, durability, and accuracy in real-time monitoring by detecting changes in relative capacitance. Overall, this research offers significant insights into improving the reliability and effectiveness of polymer fiber sensors, paving the way for future innovations in smart sensing technologies. The dissertation concludes with a discussion of potential improvements and future research directions.

This dissertation addresses several theoretical issues in low-finesse fiber optic Fabry-Perot Interferometric (FPI) sensors. The work is divided into two levels: modeling of the sensors, and signal processing based on White-Light-Interferometry (WLI). In the first chapter, the technical background of the low-finesse FPI sensor is briefly reviewed and the problems to be solved are highlighted. A model for low finesse Extrinsic FPI (EFPI) is developed in Chapter 2. The theory is experimentally proven using both single-mode and multimode fiber based EFPIs. The fringe visibility and the additional phase in the spectrum are found to be strongly influenced by the optical path difference (OPD), the output spatial power distribution and the working wavelength; however they are not directly related to the light coherence. In Chapter 3, the Single-Multi-Single-mode Intrinsic FPI (SMS-IFPI) is theoretically and experimentally studied. Reflectivity, cavity refocusing, and the additional phase in the sensor spectrum are modeled. The multiplexing capacity of the sensor is dramatically increased by promoting light refocusing. Similar to EFPIs, wave-front distortion generates an additional phase in the interference spectrogram. The resultant non-constant phase plays an important role in causing abrupt jumps in the demodulated OPD. WLI-based signal processing of the low-finesse FP sensor is studied in Chapter 4. The lower bounds of the OPD estimation are calculated, the bounds are applied to evaluate OPD demodulation algorithms. Two types of algorithms (TYPE I & II) are studied and compared. The TYPE I estimations suffice if the requirement for resolution is relatively low. TYPE II estimation has dramatically reduced error, however, at the expense of potential demodulation jumps. If the additional phase is reliably dependent on OPD, it can be calibrated to minimize the occurrence of such jumps. In Chapter 5, the work is summarized and suggestions for future studies are given. / Ph. D.

Within this research, factors affecting the orientation of injection molded long fiber composites in an end-gated plaque were investigated. Matrix viscosity was found to have a small effect on fiber orientation. The impact matrix viscosity had on orientation was dependent on fiber loading. At lower fiber loadings, the higher viscosity material had a more asymmetric orientation profile throughout the samples and less of a shell-core-shell orientation. At higher fiber loadings, there were few differences in orientation due to matrix viscosity. Fiber concentration was found to have a larger influence on fiber orientation than matrix viscosity. Increased fiber concentration led to a lower degree of flow alignment and a broader core region at all locations examined, following the trend previously reported for short fiber composites. The orientations of three different fiber length distributions of glass fiber (GF) were compared. The longer fibers in the fiber length distribution were shown to have a disproportionate effect on orientation, with weight average aspect ratio being better than number average aspect ratio at indicating if the GF and CF samples orientated comparably. To improve properties transverse to the main flow direction, the super critical carbon dioxide aided deagglomeration of multi-walled carbon nanotubes (CNTs) was used to create injection molded multiscale composites with CNT, CF, and polypropylene. The addition of CNTs greatly improved the tensile and electrical properties of the composites compared to those without CNTs. The degree of improvement from adding CNTs was found to be dependent on CF concentration, indicating that the CNTs were most likely interacting with the CF and not the polymer. A CNT concentration of 1 wt% with a tenfold degree of expansion at 40 wt% CF proved to be optimum. A large improvement in the tensile properties transverse to the flow direction was found implying that the CNTs were not highly flow aligned. Tensile and electrical properties began to fall off at higher CNT loadings and degrees of expansion indicating the importance of obtaining a good dispersion of CNTs in the part. / Ph. D.

This work is concerned with determining empirical parameters in stress and fiber orientation models required to accurately simulate the fiber orientation in injection molded composites. An independent approach aims to obtain the material parameters using a sliding plate rheometer to measure the rheology of fiber suspensions at increased fiber lengths subjected to transient shear flow. Fiber orientation was measured in conjunction with shear stress to determine the relationship between stress and fiber orientation. Using a compression molding sample preparation procedure, the transient shear stress response was measured for glass and carbon fiber suspensions up to a number average fiber aspect ratio (length/diameter) of 100. Increases in concentration or fiber aspect ratio caused the magnitude of the stress response to increase by as much as an order of magnitude when compared to the suspending matrix. The degree of shear thinning at low shear rates also increased with increases in aspect ratio and concentration. The compression molding sample preparation procedure provided poor control of the initial fiber orientation which led to the investigation of samples subjected to flow reversal and samples generated through injection molding. The samples prepared through injection molding provided improved repeatability in the measured shear stress response and fiber orientation evolution during the startup of flow compared to compression molded samples and samples subjected to flow reversal. From repeatable stress and orientation evolution data, models for stress and fiber orientation were assessed independently. Current theories for stress were unable to reflect the overshoot in the measured stress response and could at best capture the steady state. The transient behavior of the fiber orientation models were found to be highly dependent on the initial fiber orientation. The repeatable orientation data obtained from the injection molding sample preparation procedure provided material parameters in the strain reduction factor and reduced strain closure models. The injection molded samples provided evolution data from different initial fiber orientations to provide further scrutiny or validation of the material parameters. Orientation model parameters that provided reasonable agreement to multiple sets of fiber evolution data in simple shear flow should allow for a better assessment of the orientation models in complex flow simulations. / Ph. D.

The appeal of hybrid composites is the ability to create materials with properties which normally do not coexist such as high specific strength, stiffness, and toughness. One possible application for hybrid composites is as backplate materials in layered armor. Fiber reinforced composites have been used as backplate materials due to their potential to absorb more energy than monolithic materials at similar to lower weights through microfragmentation of the fiber, matrix, and fiber-matrix interface. Composite backplates are traditionally constructed from graphite or glass fiber reinforced epoxy composites. However, continuous alumina fiber-reinforced aluminum metal matrix composites (MMCs) have superior specific transverse and specific shear properties than epoxy composites. Unlike the epoxy composites, MMCs have the ability to absorb additional energy through plastic deformation of the metal matrix. Although, these enhanced properties may make continuous alumina reinforced MMCs advantageous for use as backplate materials, they still exhibit a low failure strain and therefore have low toughness. One possible solution to improve their energy absorption capabilities while maintaining the high specific stiffness and strength properties of continuous reinforced MMCs is through hybridization. To increase the strain to failure and energy absorption capability of a continuous alumina reinforced Nextel" MMC, it is laminated with a high failure strain Saffil® discontinuous alumina fiber layer. Uniaxial tensile testing of hybrid composites with varying Nextel" to Saffil® reinforcement ratios resulted in composites with non-catastrophic tensile failures and an increased strain to failure than the single reinforcement Nextel" MMC. The tensile behavior of six hybrid continuous and discontinuous alumina fiber reinforced MMCs are reported, as well as a description of the mechanics behind their unique behavior. Additionally, a study on the effects of fiber damage induced during processing is performed to obtain accurate as-processed fiber properties and improve single reinforced laminate strength predictions. A stochastic damage evolution model is used to predict failure of the continuous Nextel" fabric composite which is then applied to a finite element model to predict the progressive failure of two of the hybrid laminates. / Ph. D.

The design of fiber-reinforced thermoplastic (FRT) parts is hindered by the determination of the various empirical parameters associated with the fiber orientation models. A method for obtaining these parameters independent of processing doesn't exist. The work presented here continues efforts to develop a rheological test that can obtain robust orientation model parameters, either by fitting directly to orientation data or by fitting to stress-growth data. First, orientation evolution in a 10 wt% long-glass-fiber-reinforced polypropylene during two homogeneous flows (startup of shear and planar extension) was compared. This comparison had not been performed in the literature previously, and revealed that fiber orientation is significantly faster during planar extension. This contradicts a long-held assumption in the field that orientation dynamics were independent of the type of flow. In other words, shear and extension were assumed to have equal influence on the orientation dynamics. A non-lubricated squeeze flow test was subsequently implemented on 30 wt% short-glass-fiber-reinforced polypropylene. An analytical solution was developed for the Newtonian case along the lateral centerline of the sample to demonstrate that the flow is indeed a superposition of shear and extension. Furthermore, an existing fiber orientation model was fit to the gap-wise orientation profile, demonstrating that NLSF can, in principle, be used to obtain fiber orientation model parameters. Finally, model parameters obtained for the same FRT by fitting to orientation data from startup of steady shear are shown to be inadequate in predicting the gap-wise orientation profile from NLSF. This work is rounded out with a comparison of the fiber orientation dynamics during startup of shear and non-lubricated squeeze flow using a long-fiber-reinforced polypropylene. Three fiber concentrations (30, 40, and 50 wt%) were used to gauge the influence of fiber concentration on the orientation dynamics. The results suggest that the initial fiber orientation state (initially perpendicular to the flow direction and in the plane parallel to the sample thickness) and the fiber concentration interact to slow down the fiber orientation dynamics during startup of shear when compared to the dynamics starting from a planar random initial state, particularly for the 40 and 50 wt% samples. However, the orientation dynamics during non-lubricated squeeze flow for the same material and initial orientation state were not influenced by fiber concentration. Existing orientation models do not account for the initial-state-dependence and concentration-dependence in a rigorous way. Instead, different fitting parameters must be used for different initial states and concentrations, which suggests that the orientation models do not accurately capture the underlying physics of fiber orientation in FRTs. / Ph. D. / In order to keep pace with government fuel economy legislation, the automotive and aerospace industries have adopted a strategy they call “lightweighting”. This refers to decreasing the overall weight of a car, truck, or plane by replacing dense materials with less-dense substitutes. For example, a steel engine bracket in a car could be replaced with a high-temperature plastic reinforced with carbon fiber. This composite material will be lighter in weight than the comparable steel component, but maintains its structural integrity. Thermoplastics reinforced with some kind of fiber, typically carbon or glass, have proven to be extremely useful in meeting the demands of lightweighting. Thermoplastics are materials that can be melted from a feedstock (typically pellets), reshaped in the melted state through use of a mold, and then cooled to a solid state, and some common commodity-grade thermoplastics include polypropylene (used for Ziploc bags) and polyamides (commonly called Nylon and used in clothing). Although these commodity applications are not known for their strength, the fiber reinforcement in the automotive applications significantly improves the structural integrity of the thermoplastics. The ability to melt and reshape thermoplastics make them incredibly useful for highthroughput processes such as injection molding. Injection molding takes the pellets and conveys them through a heated barrel using a rotating screw. The melted thermoplastic gathers at the tip of the barrel, and when a set volume is gathered, the screw is rammed forward to inject the thermoplastic into a closed mold of the desired shape. This process typically takes between 30-60 seconds per injection. This rate of production is crucial for the automotive industry, as manufacturers need to put out thousands of parts in a short period of time. The improvement to mechanical properties of the thermoplastics is strongly influenced by the orientation of the reinforcing fibers. Although design equations connecting the part’s mechanical properties to the orientation of the fibers do exist, they require knowledge of the orientation of the fibers throughout the part. Fibers in injection-molded parts have an extremely complicated orientation v state. Measuring the orientation state at each point would be too laborious, so empirical models tying the flow of the thermoplastic through the mold to the evolving orientation state of the fibers have been developed to predict the orientation state in the final part. These predictions can be used in lieu of direct measurements in the part design equations. However, the orientation models rely on empirical fitting parameters which must be obtained before injection molding simulations are performed. There is currently no standard test for obtaining these parameters, nor is there a standardized look-up table. The work presented in this dissertation continues efforts to establish such a test using simple flows in a laboratory setting, independent of injection molding. Previous work focused exclusively on using shearing flow (e.g. pressure-driven flow found in injection molding) to obtain these parameters. However, when these parameters were used in simulations of injection molding, the agreement between measured and predicted fiber orientation was mediocre. The work here demonstrates that another type of flow, namely extensional flow, must also be considered, as it has a non-negligible influence on fiber orientation. this is crucial to injection molding, as injection molding flows have elements of both shearing and extensional flow. The first major contribution from this dissertation demonstrates that extensional flow (e.g. stretching a film) has a much stronger influence than shearing flow, even at the same overall rate of deformation. The second major contribution used a combination shear/extensional flow to demonstrate that the empirical model parameters, thought to be characteristic of the composite, are actually strongly influenced by the type of flow experienced by the sample, and that no single set of model parameters can fit the full orientation state. The final major contribution extends the previous case to long-fiber reinforcement at multiple fiber concentrations which are of industrial interest. This finds the same results, that the model parameters are dependent on the type of flow experienced by the sample. The flow-dependence of the parameters is a crucial point to address in future work, as the flows found in injection molding contain both shearing and extensional flow. By further developing this flow-type dependence, future injection molding simulations should become more accurate, and this will make computer-aided injection-molded part design much more efficient.

Gas Sensing Has Become a Very Important and Attractive Technique Because of Its Various Applications, Such as in the Increasingly Concerning Case of Environmental Issues, Automobile Emission Detection, Natural Gas Leakage Detection, Etc. It Also Has Significant Applications in Industries, Such as Safety and Health Monitoring in Underground Mines. Among Those Sensing Areas, Fiber-optic Sensors Have Drawn Considerable Attention Because of Its Small Size, Light Weight, High Sensitivity, and Remote Sensing Capability. However, Current Fiber-optic Gas Sensing Techniques Have Several Limitations on Their Potential for Multiplexed or Distributed Sensing Due to Difficulties Such as High Complexity or Large Loss. To Accomplish the Goal for Multiplexed Gas Sensing, an Off-centered Core Fiber Design Is Investigated. The Eccentric Core Can Reduce Attenuation, Keep Mechanical Strength, and Lower Fabrication Cost. To Verify the Feasibility of the Design, Fiber Field Distribution Is First Studied in Simulation, Which Will Be Discussed in Detail in Chapter 2. Then Two Fiber Samples with a Length of 10 Cm and 40 Cm Are Prepared and Placed in a Custom Methane Sensing System for Gas Absorption Testing, Which Is Detailed in Chapter 3. From Etching Analysis, Localized Surface Defects Are Found as the Main Reason for Power Loss. Performance Such as Detection Resolution and Sensitivity Are Investigated. In Chapter 4, Theoretical Evaluations Have Been Conducted for Multiplexed Sensors Performances Using the Off-centered Core Fiber to Study the Impact Fiber Parameters on Sensing System Design. The Conclusion and Summary Are Presented in Chapter 5. / Master of Science / Gas Sensing Has Become a Very Important and Attractive Technique Because of Its Various Applications, Such as in the Increasingly Concerning Case of Environmental Issues, Automobile Emission Detection, Natural Gas Leakage Detection, Etc. It Also Has Significant Applications in Industries, Such as Safety and Health Monitoring in Underground Mines. Among Those Sensing Areas, Fiber-optic Sensors Have Drawn Considerable Attention Because of Its Small Size, Light Weight, High Sensitivity, and Remote Sensing Capability. However, Current Fiber-optic Gas Sensing Techniques Have Several Limitations on Their Potential for Long Distance Distributed Sensing Due to Difficulties Such as High Fabrication Complexity. In This Work, a Fiber-optic Gas Sensor with Special Structure Was Designed. The Sensor Can Reduce Attenuation, Keep Mechanical Strength, and Lower Fabrication Cost. To Verify the Feasibility of the Design, Theory Analysis and Simulation Were Conducted, Which Will Be Discussed in Detail in Chapter 2. Then Two Samples with a Length of 10 Cm and 40 Cm Were Prepared and Placed in a Custom Methane Sensing System for Testing. And Their Performance Such as Sensitivity Is Investigated. In Chapter 4, Theoretical Evaluations Have Been Conducted for Multiplexed Sensors Performances Evaluation to Study the Impact Fiber Parameters on Sensing System Design. The Conclusion and Summary Are Presented in Chapter 5.

Medium density fiberboard (MDF) production uses thermomechanically refined fiber processed under shear with high pressure steam. The industry evaluates fiber quality with visual and tactile inspection, emphasizing fiber dimensions, morphology, and bulk density. Considering wood reactivity, the hypothesis is that a variety of chemical and physical changes must occur that are not apparent in visual/tactile inspection. An industry/university cooperation, this work studies effects of refining energy (adjusted by refiner-plate gap) on fiber: size, porosity, surface area, surface and bulk chemistry, fiber crystallinity and rheology, and fiber interaction with amino resins. The intention is to reveal novel aspects of fiber quality that might impact MDF properties or process control efficiency, specific to a single industrial facility. In cooperation with a North American MDF Douglas fir plant, two refining energies were used to produce resin and additive-free fibers. Refining reduced fiber dimensions and increased bulk density, more so at the highest energy. Thermoporosimetry showed increases in sub-micron scale porosity, greatest at the highest energy. Mercury intrusion porosimetry (MIP) revealed porosity changes on a higher dimensional scale. Brunauer-Emmett-Teller gas adsorption and MIP showed that refining increased specific surface area, more so at the highest energy. Inverse gas chromatography showed that the lowest refining energy produced surfaces dominated by lignin and/or extractives. The highest energy produced more fiber damage, revealing higher energy active sites. A novel rheological method was devised to study fiber compaction and densification; it did not distinguish fiber types, but valuable aspects of mechano-sorption and densification were observed. Refining caused substantial polysaccharide degradation, and other degradative effects that sometimes correlated with higher refining energy. Lignin acidolysis was detected using nitrobenzene oxidation, conductometric titration of free phenols, and formaldehyde determination. Formaldehyde was generated via the C2 lignin acidolysis pathway, but C3 cleavage was the dominant lignin reaction. Observations suggested that in-line formaldehyde monitoring might be useful for process control during biomass processing. According to rheological and thermogravimetric analysis, lignin acidolysis was not accompanied by repolymerization and crosslinking. Lignin repolymerization must have been prevented by the reaction of benzyl cations with non-lignin nucleophiles. This raises consideration of additives that compete for lignin benzyl cations, perhaps to promote lignin crosslinking and/or augment the lignin network with structures that impart useful properties. Fiber/amino resin interactions were studied with differential scanning calorimetry (DSC) and X-ray diffraction (XRD). All fiber types, refined and unrefined, caused only a slight increase in melamine-urea-formaldehyde (MUF) resin reactivity. Generally, all fiber types decreased the enthalpy of MUF cure, suggesting fiber absorption of small reactive species. But DSC did not reveal any dependency on fiber refining energy. According to XRD, all fiber types reduced crystallinity in cured MUF, more so with refined fiber, but independent of refining energy. The crystallinity in cured urea-formaldehyde resin was studied with one fiber type (highest refining energy); it caused a crystallinity decrease that was cure temperature dependent. This suggests that resin crystallinity could vary through the thickness of an MDF panel. / PHD / Medium density fiberboard (MDF) is a wood-based composite which is widely used for making kitchen cabinets and furniture. In the process of making MDF, wood particles are softened under steam pressure and under high temperature and pressure, inside a refiner, mechanically cut into wood fibers. Wood fibers are then mixed with adhesive and additives then hot-pressed and form the final board. In the MDF industry, wood fiber quality has significant effect on final board properties and is evaluated based on visual and tactile inspections. The research hypothesis is that, during the refining, a variety of chemical and physical changes must occur that are not apparent in visual/tactile inspection. An industry/university cooperation, this work studies effects of refining energy (adjusted by refiner-plate gap) on fiber: size, porosity, surface area, surface and bulk chemistry, fiber crystallinity and rheology, and fiber interaction with adhesive. The intention is to reveal novel aspects of fiber quality that might impact MDF properties or process control efficiency, specific to a single industrial facility. It was found that refining had significant effect on wood fiber properties: increased surface area, porosity, and changed the surface energy; and also on wood fiber chemistry: significant degradation in wood fiber main chemical components: poly saccharides and lignin. These changes also had effect on fiber/adhesive interaction. Therefore the hypothesis was confirmed that MDF fiber quality must involve more than a simple visual/tactile evaluation and the effect of refining can be detected on other fiber quality aspects. However more research needs to be conducted to test and find feasible new methods for fiber quality evaluation.

Invention of silica based optical fiber not only led to revolution in communication but also provided fundamental basis for many research areas. One example area is distributed optical fiber sensing, which has been attracting research interests for decades. Optical fiber sensors are immune to electromagnetic interference, and resistant to corrosion and can endure harsh environment so they have found applications such as structural health monitoring, intrusion detection and oil downhole measurement. Significant research efforts have been paid to fiber sensing area, many techniques have been developed and some of them have been successfully demonstrated, however achieving both high-speed and long-range is still under intensive research. This dissertation proposes and demonstrates a technique with the capability of simultaneous long-range and high-speed sensing by employing serial ultra-weak fiber Bragg gratings (UW-FBGs) and dispersive components. Various factors which have influence on the system performance, including wavelength resolution, spatial resolution and sensing rate, are analyzed. Different types of light sources and dispersive units were designed and a sensing system was built. With this system, both static and dynamic response were measured, and a sensing link consisting of more than 2000 UW-FBGs was successfully measured at the speed of 20kHz. The noise sources of the system were also theoretically analyzed and experimentally measured. This demonstrated sensing technique can be applied to long range temperature and strain sensing. / Ph. D. / Optical fiber is a thin glass rod with normally two layers of slightly different silica. Because of its low loss, optical fiber can guide light for a long distance without causing significant signal fading. Modifications can be made to a small section of an optical fiber to form a fiber Bragg grating, whose optical characteristics are dependent on its temperature or the strain applied to it. This dissertation proposes a technique with the ability of measuring the temperature or strain of a long length of optical fiber which has large quantity of fiber Bragg gratings fabricated in it. Along with the capability of long range sensing, this technique also has high sensing speed. It has been demonstrated that the sensing system could perform measurement in every 50µs when the optical fiber has about 2000 fiber Bragg gratings in it. The resolution, if converted to temperature, is about 1.5°C and the accuracy is 2°C. With the ability of monitoring temperature or strain of a large span at high speed, this technique could be used in areas such as civil structure and air craft health monitoring, instruction detection and high speed temperature monitoring.