Mechanical behavior of irregular fibers part I : modeling the tensile behavior of linear elastic fibers

Fiber irregularities are inherent to textile fibers, natural fibers in particular. This series of papers examines the impact of fiber irregularity on the mechanical behavior of textile fibers. In the first part, the effect of fiber dimensional irregularities on the tensile behavior of linear elastic fibers is examined, using the finite element method (FEM). Fiber dimensional irregularities are simulated with sine waves of different magnitude and frequency. The results indicate that increasing the level or magnitude of irregularity will decrease the breaking load, breaking elongation and method Young’s modulus of the fiber, while increasing the frequency of irregularity will decrease the breaking load and method Young’s modulus, but the breaking elongation will increase. Fiber dimensional irregularity and the gauge length effect are also simulated in this study.

The combined tensile and torsional behavior of irregular fibers

Most fibers are irregular, and they are often subjected to combined loading conditions during processing and end-use. In this paper, polyester and wool fibers under the combined tensile and torsional loads have been studied for the first time, using the finite element method (FEM). The dimensional irregularities of these fibers are simulated with sine waves of different magnitude and frequency. The breaking load and breaking extension of the fibers at different twist or torsion levels are then calculated from the finite element model. The results indicate that twist and level of fiber irregularity have a major impact on the mechanical properties of the fiber and the effect of the frequency of irregularity is relatively small.

Modeling the tensile behavior of fibers with geometrical and structural irregularities

Virtually all fibers exhibit some dimensional and structural irregularities. These include the conventional textile fibers, the high-performance brittle fibers and even the newly developed nano-fibers. In recent years, we have systematically examined the effect of fiber dimensional irregularities on the mechanical behavior of the irregular fibers. This paper extends our research to include the combined effect of dimensional and structural irregularities, using the finite element method (FEM). The dimensional irregularities are represented by sine waves with a 30 % magnitude of diameter variation while the structural irregularities are represented by longitudinal and horizontal cavities distributed within the fiber structure. The results indicate that fiber geometrical or dimensional variations have a marked influence on the tensile properties of the fiber. It affects not only the values of the breaking load and extension, but also the shape of the load-extension curves. The fiber structural irregularities simulated in this study appear to have little effect on the shape of the load-extension curves.

Numerical modeling of the dynamic tensile behavior of irregular fibers

Most fibers are irregular, and they are often subjected to rapid straining during mechanical processing and end-use applications. In this paper, the effect of fiber dimensional irregularities on the dynamic tensile behavior of irregular fibers is examined, using the finite element method (FEM). Fiber dimensional irregularities are simulated with sine waves of different magnitude (10%, 30% and 50% level of diameter variation). The tensile behavior of irregular fibers is examined at different strain rates (333%/sec, 3,333%/sec and 30,000%/sec). The breaking load and breaking extension of irregular fibers at different strain rates are then calculated from the finite element model. The results indicate that strain rate has a significant effect on the dynamic tensile behavior of an irregular fiber, and that the position of the thinnest segment along the fiber affects the simulation results markedly. Under dynamic conditions, an irregular fiber does not necessarily break at the thinnest segment, which is different from the quasi-static results.

Propagation characteristics of lamb waves in stringer-stiffened panels

Stringer-stiffened plate-like structure is a typical engineering structure and its structural integrity is critical. A guided Lamb wave-based damage identification scheme and an online structural health monitoring (SHM) system with an integrated PZT-sensor network were developed. In the previous studies, the specimens were relatively simple. In this paper, the above mentioned method was extended to the stiffened plate-like structure—a flat plate reinforced by stringer. FE dynamic simulation was applied to investigate the Lamb wave propagation characteristics due to the existence of stringer with the consideration of its material and geometric configurations.

Breaking the boundaries : improving the assessibility, extent and responsiveness of support services for distance education students

Massey University, in common with other tertiary distance education providers, faces the challenge of improving the accessibility, extent and responsiveness of the support services it provides to extramural students. In particular, the university is challenged by the need to develop and deliver support services responsive to the changing needs of an increasingly diverse student population. This paper outlines the key findings of a comprehensive review of Massey’s support policy and services for extramural students. It describes how the review findings, and material from the body of literature on the provision of support for distance students, were used to inform the development of a new support policy for extramural students. How this policy is being made operational in practice, through the design, development and implementation of an extensive range of new student support services, including a range of services provided online, is outlined. A summary of progress made so far is provided. The paper concludes with some guidelines that may be useful in informing the practice of colleagues working to break the boundaries to student participation in support services.

Breaking the cultural mould : the key to women`s career success

This white paper explores the role of organisational culture in either supporting or constraining the success of women in the workplace and investigates the benefits of gender diversity and what organisations can do to prevent ongoing gender bias.

Earth bound: the rise and fall of a ground-breaking venture

Earth Sanctuaries Ltd (ESL) intends to offer its entire asset base for sale. ESL's primary objective is to conserve Australia's biodiversity, by breeding and preserving fauna profitably by running sanctuaries, environmental consultancies and related tourist facilities. This "ailing company" is also undergoing a management restructuring and attempting cost reduction. ESL was was one of the first firms to adopt AASB 1037. The implications for the accounting profession are discussed.

Cinema's new waves : an interview with Albie Thoms

Albie Thomas is a seminal figure in the history of Avant-Garde film in Australia. In the mid-1960s he helped found UBU Films, the precursor of the Sydney Film-Makers' Co-operative, and he has made a number of short and feature-length experimental films. Thoms has written on film and film cultures for an array of journals and maintains an active involvement with aspects of the surf film industry in Australia. In this interview, Thoms discusses his early UBU films, and the connections between those films and Palm Beach (1979). Styles of surf film and the influences on Thoms' filmmaking are also discussed.