Bundle Strength Research Articles

The design of self-collapsed super-strong nanotube bundles

The study reported in this paper suggests that the influence of the surrounding nanotubes in a bundle is nearly identical to that of a liquid having surface tension equal to the surface energy of the nanotubes. This surprising behaviour is supported by the calculation of the polygonization and especially of the self-collapse diameters, and related dog-bone configurations, of nanotubes in a bundle, in agreement with atomistic simulations and nanoscale experiments. Accordingly, we have evaluated the strength of the nanotube bundle, with or without collapsed nanotubes, assuming a sliding failure: the self-collapse can increase the strength up to a value of about ∼30%, suggesting the design of self-collapsed super-strong nanotube bundles. Other systems, such as peapods and fullerites, can be similarly treated, including the effect of the presence of a liquid, as reported in the appendices.

Short communication. Deterioration of cotton fibre characteristics caused by cotton leaf curl disease

The effect of cotton leaf curl disease found at Burewala (Pakistan) on the ginning out turn (GOT) and the physical and chemical characteristics of cotton fibre was evaluated by comparing healthy and cotton leaf curl disease (CLCuD)- infected plants of four cotton varieties. A highly susceptible response to CLCuD was found in all varieties tested. The disease incidence ranged from 42.6 to 81.4%. Significant differences were observed between the fibre of healthy and diseased cotton plants, of all varieties, for GOT, fibre length, fibre uniformity index, short fibre index, fibre fineness, fibre bundle strength, reflectance degree (Rd-value), yellowness (+b value) and maturity ratio. The cv. CIM-473 exhibited the highest reduction in all the quality parameters studied with the exception of Rd-value which was the lowest in cv. NIAB-999. The disease also significantly affected cellulose, protein, wax and pectin content. CLCuD adversely deteriorated the cotton fibre characteristics, however the varietal difference exists. The varieties with less deteriorated fibre by CLCuD should be an essential criterion for the selection of resistant germplasm against CLCuD.

Size effects on the strength of nanotube bundles

We numerically investigate the scaling of mechanical properties of carbon nanotube bundles, with the objective of evaluating the potential characteristics of large-scale structures. The simulations are carried out using a fibre bundle model adapted at various size scales according to a self-similar scheme. Scaling of both strength and Young's modulus is analysed, comparing results for defective and non-defective bundles, i.e. in the absence or in the presence of voids. Various types of defects are considered, with different size, shape, density and distribution. Analytical laws are also proposed and compared to numerical results.

국내 재배 엽맥섬유의 특성에 관한 연구

Leaf fibers have many good properties; they are strong, long, cheap, abundant and bio-degradable. Since they, however, contain a great quantity of non-cellulose components, they have been used for the materials of mats, ropes, bags and nets rather than those of clothing. In this study, we investigated the characteristics of leaf fibers in order to promote the use of leaf fibers for the materials of clothing as well as develop the high value-added textile fibers. Leaf fiber plants including New Zealand Flax, Henequen and Banana plant, which have various nature and shape, were used. New Zealand Flax and Henequen leaves were cut from lower part of plants. Banana leaves and pseudo-stems were peeled and cut from the stem of Banana plants. First, the thin outer skins like film of leaves, veins and stems were removed before retting. The chemical retting had been processed for 1hour, at 100 in 0.4% <TEX>$H_2SO_4$</TEX> aqueous solution(liquid ratio 50:1). Then, the retted leaf fibers had been soaked for 1hour, at room temperature in 0.5% NaClO solution(v/v) to remove the miscellaneous materials. We investigated the physical characteristics of three leaf fibers including the transversal and longitudinal morphology, the contents(%) of pectin, lignin and hemicellulose, the length and diameter of fibers, the tensile strength of the fiber bundles, and the fiber crystallinity and the moisture regain(%). The lengths of fiber from three leaf fibers were similar to their leaf lengths. The fiber bundles were composed of the cellulose paralleled to the fiber axis and the non-cellulose intersecting at right angle with the fiber axis. The diameters of New Zealand Flax, Henequen and Banana fibers were <TEX>$25.13{\mu}m$</TEX>, <TEX>$18.16{\mu}m$</TEX> and <TEX>$14.01{\mu}m$</TEX>, respectively and their tensile strengths were 19.40 Mpa, 32.16 Mpa and 8.45 Mpa, respective. The non-cellulose contents of three leaf fibers were relatively as high as 40%. If the non-cellulose contents of leaf fibers might be controlled, leaf fibers could be used for the materials of textile fiber, non-wovens and Korean traditional paper, Hanjee.

Increased strength of boron-doped carbon nanotube bundles produced by applying an electric field along their length

Application of electric field along a boron-doped carbon nanotube bundle triggers straightening and lengthening activities and underlying mechanism arises from the field induced nanotube alignment into closed packed rod. Calculation reveals that the cohesive energy and elastic modulus of the field treated bundle are two orders of magnitude greater than the reported data on raw nanotube aggregates.

Study on tensile properties and Interfacial Shear Strength of bamboo fibre bundles

The tensile properties and Interfacial Shear Strength (IFSS) of bamboo fibre bundles were studied. Bamboo fibres were extracted by three different methods: steam explosion, mercerisation and chemical treatment. The diameter, tensile strength and modulus of the extracted-bamboo fibre bundles were decreased by all the processes compared to untreated bamboo fibres. But the tensile properties of mercerised bamboo fibre bundles were better than those of other treatments with the exception of untreated bamboo fibres. The interfacial shear stress distribution of chemically treated fibres was higher than that of steam explosion and mercerised bamboo fibres.

J0407-1-2 レジンレス竹繊維強化グリーンコンポジットの成形性(バイオマス由来材料の成形加工と特性評価(1))

Formabilities and mechanical properties of resinless bamboo fiber green composites were experimentally investigated by changing molding conditions; temperature and pressure. The green composites composed of only bamboo fibers which obtained from a steam explosion method were fabricated by a hot-press method. The molding temperature has a much greater effect on the mechanical properties such as tensile property and bending property. Molding pressure has an insignificant effect on tensile and bending strength of green composites. Fracture elongation of the composites tends to decrease with rise of temperature above 140℃ due to the decreasing of the strength of single fiber bundle during hot-pressing.

Strength degradation of glass fibers at high temperatures

This article presents an experimental investigation into the effects of temperature and heating time on the tensile strength and failure mechanisms of glass fibers. The loss in strength of two glass fiber types (E-glass and Advantex®, a boron-free version of E-glass) was investigated at temperatures up to 650 °C and heating times up to 2 h. The tensile properties were measured by fiber bundle testing, and the maximum strength was found to be temperature and time dependent. The higher softening point of the Advantex® fibers is reflected in superior high-temperature performance. A phenomenological model is presented for calculating the residual strength of glass fiber bundles as functions of temperature and time. The strength reduction mechanism was determined by single-fiber testing. Fracture mirror sizes on the E-glass fibers were related to the fiber strength after high-temperature treatment. Based on fracture mirror measurements, it was established that (1) the mirror constant of the glass, which reflects the network structure, does not change during heat treatment and (2) the strength degradation is a result of larger surface flaws present after heat treatment.

Registration of Five Exotic Germplasm Lines of Cotton Derived from Multiple Crosses among Gossypium Tetraploid Species

Species polycross (SP) cotton germplasm was developed from multiple crosses among Gossypium tetraploid species. SP156 (Reg. No. GP‐903, PI 654087), SP177 (Reg. No. GP‐904, PI 654088), SP179 (Reg. No. GP‐905, PI 654089), SP205 (Reg. No. GP‐906, PI 654090), and SP225 (Reg. No. GP‐907, PI 654091) were released by the USDA‐ARS for their highly desirable combinations of yield, yield components, and fiber properties. The SP lines were tested for yield and fiber quality in 2005, 2006, and 2007 at six year‐locations. SP179 and SP225 averaged 1221 and 1348 kg ha−1, respectively, for yield in three years' trials compared with 1359 kg ha−1 for ‘Deltapine 555BR’. Fiber bundle strength of these two lines is 233 and 228 kN m kg−1, respectively, compared with 227 kN m kg−1 for ‘FiberMax 960B2R’ (FM960B2R). Yields of SP156, SP177, and SP205 are at least 7% higher than the average, 965 kg ha−1, of FM960B2R and ‘Phytogen 72’ (PHY72). Strength of SP156, SP177, and SP205 is 241, 238, and 236 kN m kg−1, respectively, compared with 241 kN m kg−1, the average of FM960B2R and PHY72. Span length and short fiber content in these lines are also comparable to FM960B2R and PHY72.

Registration of Eight Extra‐Long Staple Upland Cotton Germplasm Lines

Eight extra‐long staple (ELS) upland cotton (Gossypium hirsutum L.) germplasm lines, TAM A106‐15 ELS (Reg. No. GP‐894, PI 654359), TAM A106‐16 ELS (Reg. No. GP‐895, PI 654360), TAM B147‐21 ELS (Reg. No. GP‐896, PI 654361), TAM B182‐33 ELS (Reg. No. GP‐897, PI 654362), TAM C66‐16 ELS (Reg. No. GP‐898, PI 654363), TAM C66‐26 ELS (Reg. No. GP‐899, PI 654364), TAM C147‐42 ELS (Reg. No. GP‐900, PI 654365), and TAM C155‐22 ELS (Reg. No. GP‐901, PI 654366), were developed by the Cotton Improvement Laboratory, Department of Soil and Crop Sciences, Texas AgriLife Research (Texas A&amp;M University, College Station), and released in 2008 as part of an ongoing effort to create germplasm with combinations of improved fiber quality parameters, especially upper half mean (UHM) length and fiber bundle strength. All ELS lines exhibited high volume instrument (HVI) UHM fiber length greater than 32.0 mm, which is the minimum UHM to be classified as ELS upland according to Cotton Incorporated. Seven of the eight lines equaled or exceeded the minimum UHM length of 34.8 mm for pima (G. barbadense L.) in the USDA 2007 pima loan schedule in at least one performance trial. Fiber bundle strengths of the eight lines were equal to or higher than ‘Fibermax 832’.

Impact of occupational noise on pure-tone threshold and distortion product otoacoustic emissions after one workday

The aim of this study was to investigate whether distortion product otoacoustic emissions (DPOAEs) are a suitable means for detecting small changes in cochlear amplifier functionality due to occupational noise exposure of one workday and whether efferent reflex strength of the medial olivocochlear bundle is able to predict the ear’s susceptibility to noise. High-resolution (Δ f 2 = 47 Hz) DPOAEs were recorded between 3.5 and 4.5 kHz at close-to-threshold primary tone levels. For comparison, pure-tone audiometry was conducted. Efferent reflex strength was measured by means of DPOAEs at a specific frequency with and without contralateral acoustic stimulation. A statistically significant change was found for pure-tone thresholds (Δ L ht = +1.6 ± 3.0 dB, n = 155) and DPOAE levels (Δ L dp = −1.0 ± 2.4 dB, n = 646; L 2 = 20 dB SPL) in factory workers but not in office workers (Δ L ht = −1.3 ± 3.3 dB, n = 80; Δ L dp = 0.0 ± 1.6 dB, n = 336) (control group). However, the influence of systematic biases due to, e.g. ear probe calibration or measurement sequence effects, has to be considered. Moreover, there was no significant correlation between efferent reflex strength and shifts in pure-tone thresholds or shifts in DPOAE levels. Thus, the applied measures of efferent reflex strength do not seem to be suitable for predicting temporary changes in hearing capability.

Development of Extra‐Long Staple Upland Cotton

An objective of U.S. cotton breeding programs is to provide raw material that processes efficiently and produces better textile products without compromising yield. Annual domestic consumption dropped from 10.4 million bales in 1998 to 5.5 million bales in 2007. Exports increased from 4.3 to 16.2 million bales. Increased reliance on export markets will require the United States to compete more effectively in price and quality. The desired minimum upper half mean (UHM) fiber length in international markets is 28 mm, while the traditional U.S. minimum is 27 mm. To compete at this higher UHM length expectation, breeding programs should target minimums well above the international base. Extra‐long staple (ELS) upland cotton (Gossypium hirsutum L.) germplasm lines were developed by the Cotton Improvement Lab, Dep. of Soil and Crop Sciences, Texas A&amp;M AgriLife Research, as part of an effort to create germplasm with combinations of improved fiber quality, especially UHM length and fiber bundle strength. These ELS upland lines exhibit high volume instrument UHM length &gt;32.0 mm, and several strains exceed 34.8 mm, which is the minimum UHM length for pima (G. barbadense L.). These ELS strains range in agronomic performance from less than to equal to that of ‘Fiber Max 832’ (PI 603955). TAM 94L‐25 (PI 631440), or its full sib 94L‐2 (unreleased), is the common parent in these ELS strains and is proposed as the major contributor of favorable allelic combinations for this exceptional UHM length.

Experimental and simulation investigations of tensile response of (Al 2O 3f/Al) w/2024Al composite

Tensile response of a 2024Al alloy reinforced with Al 2O 3f/Al composite wires [(Al 2O 3f/Al) w/2024Al composite] has been investigated by both performing tensile tests and using the finite element method (FEM). Microstructure and tensile fracture surfaces of (Al 2O 3f/Al) w/2024Al composites were examined using optical microscope (OM) and scanning electron microscope (SEM), respectively. It is found that the longitudinal tensile response of (Al 2O 3f/Al) w/2024Al composite is nearly elastic up to failure. The longitudinal tensile strength of (Al 2O 3f/Al) w/2024Al composite reaches its fiber bundle strength and the longitudinal elastic modulus is consistent with that predicted using the rule of mixture. The contribution of matrix is negligible to the longitudinal tensile strength but not to the modulus of elasticity. Coating composite wires (CWs) with Ni can improve the interfacial bonding between the CWs and 2024Al alloy. Diffusion annealing can further improve the interfacial bonding. The transverse tensile strength is dependent strongly on the interfacial bonding between the CWs and 2024Al alloy. The stronger the interfacial bonding, the higher the transverse tensile strength. Following the diffusion annealing, ageing treatment can improve the transverse tensile strength of (Al 2O 3f/Al) w/2024Al composite to a higher level due to the increased strength of matrix 2024Al alloy. To reveal the fracture mode of (Al 2O 3f/Al) w/2024Al composite under transverse loading, the transverse tensile response of a model material, (Al 2O 3f/matrix1) w/matrix2 composite, whose microstructure is similar to that of the (Al 2O 3f/Al) w/2024Al composite, was analyzed using FEM. FEM results indicate that, under transverse loading, the stress distribution in the (Al 2O 3f/matrix1) w/matrix2 composite depends on the strength of matrix2. When matrix1 and matrix2 are both pure Al, failure initiates in matrix1. When matrix1 is pure Al and matrix2 is aged 2024Al alloy, however, failure initiates in matrix2 (2024Al). Therefore, for (Al 2O 3f/Al) w/2024Al composites with weak interfacial bonding between CWs and 2024Al matrix, cracks initiate at interfaces between the CWs and 2024Al matrix and propagate along the interfaces and then through 2024Al matrix, resulting in the global fracture. For (Al 2O 3f/Al) w/2024Al composite with strong interfacial bonding between CWs and 2024Al matrix, cracks initiate in either pure Al or 2024Al alloy and then propagate in both Al and 2024Al, resulting in the global fracture.

Registration of TAM 01E‐22 Upland Cotton Germplasm Line with Improved Fiber Bundle Strength

TAM 01E‐22 upland cotton (Gossypium hirsutum L.) germplasm line (Reg. No. GP‐889, PI 652865) was developed by the Cotton Improvement Laboratory, Department of Soil and Crop Sciences and released in 2007 by Texas AgriLife Research. TAM 01E‐22 exhibits high volume instrument (HVI) Upper Half Mean fiber length and HVI fiber bundle strength exceeding the best medium staple uplands commonly grown by Texas producers for these traits. All other HVI fiber properties are within acceptable ranges and lint yield potential is lower than current cultivars.

Short communication. Cotton cultivars with moderate resistance to African cotton mosaic virus

A 3 year screening of 25 long staple cotton cultivars for resistance to African cotton mosaic virus (ACMoV) conducted in northern Nigeria during the 1999-2001 wet seasons indicated that no cultivar was immune or resistant. Two cultivars, Pima S1 and Pima S4 were moderately resistant (16% infection), four cultivars Pima S2, Pima S3, Giza 45 and Giza 69 were moderately susceptible (31% infection), while the remaining 19 cultivars were highly susceptible. The moderately resistant cultivars are high yielding, have high quality lint characteristics such as crin percentage, bundle strength, and micronaire fineness. They can be used to reduce the menace caused by ACMoV on cotton in Nigeria.

Effect of Molding Conditions on Mechanical Properties of Binderless Bamboo Fiber Green Composite

Hot pressing of bamboo (Phyllostachys pubescens) fibers that were obtained by using steam explosion was carried out under various molding conditions such as temperature and pressure. In this paper, the effects of the molding conditions on the bulk density, tensile strength, and bending strength are discussed. Further, the effect of the heating temperature on the strength of a single fiber bundle is also examined. The experimental results reveal that the bulk density increased with the molding temperature up to 130°C and was saturated at a constant value above 130°C due to a decrease in the void content. This is because of the parenchyma cells of the fibers melt as the molding temperature rises. The tensile and bending strengths of the composite depend on the molding temperature. These strengths increased with the molding temperature up to 130°C as well as with the bulk density. This increase in the strengths was achieved by improving the adhesive property. However, the strengths of the composite decreased above 130°C due to the decomposition of the single fiber by heating. Thus, it was clarified that the optimum molding temperature was approximately 130°C. In addition, it was also clarified that the molding pressure has no effect on the bulk density, the tensile strength, and the bending strength of the pressed products.

Determination of tensile strength distribution of nanotubes from testing of nanotube bundles

Single-walled carbon nanotube (SWNT) bundles are subject to tensile testing using a self-developed nano-mechanical testing device. The tensile strength of SWNT bundles, as well as reported data of multi-walled carbon nanotubes (MWNTs) and SWNT ropes, are studied by statistical approach. It is shown that the tensile strength distributions of carbon nanotubes (CNTs) or SWNT ropes can be adequately described by a two-parameter Weibull model. Considering the nonlinear elastic behavior of CNTs, a relation between individual CNT and CNT bundle strengths is studied, and a method for determining the tensile strength distribution of individual CNTs or CNT sub-bundles from experimental measurements on CNT bundles is proposed. Therefore the process for determining the strength distributions of individual CNTs can be greatly simplified by testing CNT bundles instead.

Statistical strength of twisted fiber bundles with load sharing controlled by frictional length scales

We develop Monte Carlo simulation and theory to study the statistical strength characteristics of twisted fiber bundles. These consist of fibers that follow a Weibull distribution for strength with shape parameter , and are arranged in an ideal helical structure with surface helix angle s. Fiber interactions are considered in terms of frictional forces that control stress recovery along broken fibers away from the breaks. A twist-modified global load sharing (TM-GLS) rule is developed for stress redistribution from fibers that are slipping and thus only partially loaded near the breaks. Expressions for the radial pressure distribution in the yarn and corresponding lengths of frictional zones in broken fibers in the various layers are derived considering the discrete nature of the fibers in the bundle. Three different characteristic length scales of strength development for a twisted bundle are proposed, which depend on friction coefficient, f , and surface twist angle, s. These are min c , avg c , or max c , arising from the consideration of the minimum, average, or maximum stress recovery length among the fibers in the bundle along its axis. We show that the normalized strengths of a twisted bundle with length equal to any one of these characteristic lengths approximately follow a Gaussian distribution. Compared to a TM-ELS (twist-modified equal load sharing) bundle, the TM-GLS bundle has improved strength because through friction a broken fiber can recover its stress within the bundle length. We also show that the relationship between the normalized bundle strength and s depends on the characteristic length scale used: for min the normalized strength drops quickly with s; for avg it decreases as well, but at a slower rate; and for max the normalized strength first attains a maximum at an optimal value of s before ultimately decreasing with s. Finally, we compare the simulation results for optimal twist angle with experimental data in the literature and get excellent agreement.

Load capacity and rupture displacement in viscoelastic fiber bundles

We study the creep rupture of viscoelastic fiber bundles under uniaxial constant tensile loading, assuming global load sharing (GLS) for the redistribution of load following fiber failure. We consider loading paths such that the stress raises to a value sigma0 under a time-independent loading (negligible creep strain) and remains fixed thereafter. Motivated by experimental observations, we introduce an "effective" strain controlled failure criterion to incorporate damage into the system, thus damage is distributed over time. In addition, when a "limit" value for the effective stress is reached, failure of the remaining alive fibers is instantaneous. This enables us to show both analytically and numerically that creep rupture occurs for external loads above a critical value that is less than the static fracture bundle's strength in accordance with experimental observations. An analytical expression for this critical load is given. For stress levels below the critical value, the system suffers only partial failure since the deformation tends to a stationary solution for which the effective stress is below the limit value giving rise to an infinite lifetime. On the other hand, if the time-independent loading process ends in the softening regime, the deformation of the system monotonically increases in time resulting in global failure at finite time irrespectively of the applied load. Moreover, the applied model is found to be consistent with the experimentally observed increase of the creep rupture displacement with decreasing steady external load (above the critical value).

A Nonlinear Mechanical Model for Tension of Bundles of Single-Walled Carbon Nanotubes

Tensile strength distributions of multi-walled carbon nanotubes (MWNTs), single-walled carbon nanotube (SWNT) ropes and sub-bundles are studied by statistical approach based on the experimental data sets. It shows that the distributions can be adequately described by a two-parameter Weibull model. Considering further their nonlinear stress-strain behavior, the force-strain relation and tensile strength of SWNT bundles are studied. The Weibull modulus of the sub-bundles in a SWNT bundle can be estimated in terms of the maximum sustained force and the failure strain of the bundle. A SWNT bundle was subjected to tensile testing using a nano-mechanical testing device. The result suggests that the nonlinear behavior of SWNTs does affect the force-strain relation of SWNT bundles, mainly at large strain.