<p>HUANG, WENSHENG. Online Characterization of Fabric Compressional Behavior. (Under the direction of Tushar K. Ghosh and Winser E. Alexander)Response of a fabric to applied forces normal to its plane is known as fabric compressional behavior. It is one of the important properties that determine fabric performance in many applications. The principle of a system used to measure fabric compressional characteristics, online, is proposed in this paper. A controllable nip formed by a pair of rollers is employed to apply compressional deformation to a moving fabric while the compression force and displacement are continuously recorded. The influence of various system parameters on the sensitivity of the system has been analyzed. By assuming a stepwise anisotropic behavior in the thickness direction, Incremental Differential Algorithm (IDA) is developed to calculate the pressure-displacement relationship from the measured force-displacement data obtained from the online system. A prototype online measurement system has been developed based on this principle. A number of woven and nonwoven fabrics have been evaluated using the online system as well as a number of other commercially available fabric compression testers. The compressional characteristics obtained from the online measurement system compare well with the same parameters measured using the other commercially available compressional testers.<P>

<p>IKIZ, YUKSEL. Fiber Length Measurement by Image Processing. (Under the direction of Dr. Jon P. Rust.) This research studied the accuracy and feasibility of cotton fiber length measurement by image processing as an alternative to existing systems. Current systems have some weaknesses especially in Short Fiber Content (SFC) determination, which is becoming an important length parameter in industry. Seventy-two treatments of five factors were analyzed for length and time measurements by our own computer program. The factors are: Sample preparation (without fiber crossover and with fiber crossover), lighting (backlighting and frontlighting), resolution (37-micron, 57-micron, 106-micron, and 185-micron), preprocessing (4-neighborhood and 8-neighborhood), and processing (outlining, thinning, and adding broken skeletons). The best results in terms of accuracy, precision and analysis time for images without fiber crossovers were: 106-micron resolution with frontlighting using an 8-neighborhood thresholding algorithm and using an outline algorithm for length determination. With fiber crossovers, 57-micron resolution with backlighting using an 8-neighborhood thresholding algorithm and using a thinning algorithm combined with an adding algorithm for combining broken skeletons. Using the above conditions, 1775 area can be analyzed using our current equipment in 15 seconds. In the case of images with crossovers, only 117 can be analyzed in 15 seconds. This research demonstrates that successful sample preparation without fiber crossovers would create the best fiber length measurement technique, however with fiber crossovers the system efficiency has been proven as well.<P>

<p>Bauer-Kurz, Ina. Fiber Crimp and Crimp Stability in Nonwoven Fabric Processes. (Under the direction of Dr. William Oxenham and Dr. Donald A. Shiffler.)In nonwovens, crimp characteristics of synthetic fibers are, along with finish, major contributors to processing efficiency, web cohesion, fabric bulk and bulk stability. However, the meaning of measurable crimp parameters and their influence on processing and fabric characteristics has not been quantified. The purpose of this study is to quantify the mechanical fiber behavior during crimp removal, and relate it to fundamental fiber properties, nonwoven fabric properties, and processibility in nonwoven equipment.Single fiber tensile tests in the crimp removal region have been performed on various fibers with the Textechno FAVIMAT and have also been monitored optically. Based on empirical evidence, a basic understanding of the physical crimp removal mechanism is obtained. A methodology is developed, to identify the true crimp removal region of the whole single fiber load-extension curve during a tensile test. A mechanical model accounting for the nonlinear load-deflection behavior during crimp removal is developed. According to this model, a logarithmic function can be used to describe the material behavior in the crimp node during crimp removal. This function is fit to experimental data and delivers two fitting parameters that characterize the shape of the experimental load-extension curve in the crimp region.The extracted characteristic crimp parameters are being evaluated in terms of fiber material characteristics, such as fiber type, crimp processing settings and carding performance during nonwoven production. A dependence of the shape of the crimp removal curve on crimping settings during crimp production is established. The characteristic crimp parameters are also correlated to the sequence of processing stages during nonwoven production and cylinder speed during carding.<P>