Evaluating Single Fiber and Fiber Bundle Tensile Curves

Abstract

Most research on estimations of fiber bundle tensile curves from single fiber tensile properties is based on knowledge of the frequency density distribution of fiber breaking extension and the linear elastic spring constant. Such research focuses on cotton fibers and fiber bundles. On the other hand, there are few methods to predict the tenacity of single wool fibers from fiber bundle tensile curves. Using characteristics of specific stress-strain curves from both single fiber and fiber bundle tensile testing, new theoretical calculations to estimate the tenacity and breaking extension distribution of single fibers from bundle tensile curves are described in detail for wool fibers. The experimental results show that these algorithms are effective and reliable for such evaluations, the experimental and estimated results obtained from the TENSOR fiber bundle tests and the SIFAN single fiber measurements agree with each other, and single fiber tenacity or even its urve can be evaluated using the tail of the bundle tensile curve.

Study on static and fatigue behaviors of carbon fiber bundle and the statistical distribution by experiments

“…Based on the data of residual strength tests, the parameters involved in equation (12) can be obtained. The results for residual strength tests at high and low stress amplitudes are shown in Table 7 and the related curves are plotted in Figure 8.…”

“…The results for residual strength tests at high and low stress amplitudes are shown in Table 7 and the related curves are plotted in Figure 8. Additionally, the corresponding residual strength under 87% and 80% stress levels for 1/3N f and 2/3N f cycles calculated by the equation (12) are listed in Table 8. According to the results, the maximum error was only 8.14%, which took place under 80% stress levels for 2/3N f , therefore, it is reasonable to accept the theoretical formula (12) to predict the residual strength of fiber bundle.…”

“…Phani 11 put forward a new modified Weibull distribution function used to analyze the strength of single fiber. Yu et al 12 studied the relationships between the tensile curves of fiber bundles and single fibers and then proposed an approach to predict the stress-strain curve of single fibers based on fiber bundles. Joffe et al 13 showed that two-parameter Weibull distribution could be used to describe the tensile strength of fibers at a fixed length and some experimental research for cellulose fibers were performed.…”

“…A segmented function was proposed to describe the S-N curve of carbon fiber bundles and the related parameters were then obtained based on the fatigue Residual strength curve obtained by Eq (12) of 87% stress level Average value of 87% stress level Experimental data of 87% stress level Residual strength R(strength curve obtained by Eq(12) of 80% stress level Average value of 80% stress level Experimental data of 80% stress level Residual strength curves of carbon fiber bundle at high stress level (a) and low stress level (b).…”

“…Comparison between the predicted values of residual strength based on equation(12) and test data. N f * and N f ** means the fatigue life of 87% and 80% stress levels, respectively.…”