Fracture Strength Of Fibers Research Articles

Study on the Distribution of Frictional Forces on Z-yarn Continuous Implanted Preforms and Their Applications

To improve the quality and efficiency of Z-directional 3D preform forming, the Z-yarn frictional force distribution model of the preform and its wear mechanism were investigated. In this study, a tensile force measuring device was designed to measure the force required to replace the guide sleeve, which is equivalent to the Z-yarn frictional forces. The frictional force is proportional to the number of preform layers and is applied to the preform decreased from the corner, edge, sub-edge, and middle in order. A back propagation neural network model was established to predict the friction at different positions of the preform with different layers, and the error was within 1.9%. The wear of Z-yarn was studied at different frictional positions and after different times of successive implantation into the preform. The results showed that with an increase in the number of Z-yarn implantations and frictional forces, the amount of carbon fiber bundle hairiness gradually increased, and the tensile fracture strength damage of the fiber was increasingly affected by the frictional forces. In the corner position of the preform, when the number of implantations was 25, the fiber fracture strength decreased non-linearly and substantially; in order to avoid fiber fracturing in the implantation process, the Z-yarn needs to be replaced in time after 20–25 cycles of continuous implantation. This study solves the problem of difficulty in measuring the force required for individual replacements owing to the excessive number of guide sleeves, puts forward the relationship between fiber wear, preform position, and implantation times, solves the phenomenon of fracture in the preform during Z-direction fiber implantation, and realizes the continuous implantation of fibers.

Preparation and Characterization of Flame Retardant PET Fiber via Melt Blending

Poly(ethylene terephthalate) (PET) fiber with excellent flame retardant property was prepared with introducing a containing phosphorus flame retardant 10-(2’,5’-dihydroxyphenyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (ODOPB) into PET by melt blending method. The intrinsic viscosity of the modified PET was decreased after melt blending, indicated that ODOPB could promote the degradation of PET. The addition of ODOPB can increase the amount of carbon residue of PET, which can effectively reduce the heat transfer. The movement and regularity of PET molecular chain are affected by ODOPB, resulting in the reducing of the crystallization of PET. The Raman curves indicate that the addition of ODOPB can improve the regularity of carbon layer, which is conducive to achieve the effect of flame retardant. When the mass fraction of P is 0.7 %, the limiting oxygen index of sample reaches 32.4% and UL-94 vertical reaches V-2, the fiber fracture strength is 2.6 cN/dtex, which has excellent flame retardant and mechanical properties.

Effects of fiber cracking on elastoplastic-damage behavior of fiber-reinforced metal matrix composites

A micromechanical multi-level elastoplastic evolutionary damage framework is proposed to predict the overall transverse mechanical behavior and damage evolutions of cylindrical fiber-reinforced ductile composites. Progressively cracked fibers are modeled using the double-inclusion theory. The effective elastic moduli of three-phase composites, consisting of a matrix, randomly located yet monotonically aligned cylindrical uncracked fibers and cracked fibers, are derived by using a micromechanical formulation. In order to characterize the homogenized elastoplastic behavior, a micromechanical effective yield criterion is derived based on the ensemble-area averaging process and the first-order effects of eigenstrains. The resulting effective yield criterion, together with the overall associative plastic flow rule and the hardening law, constitutes the analytical framework for the estimation of effective transverse elastoplastic-damage responses of ductile composites containing both uncracked and cracked fibers. An evolutionary fiber cracking process, governed by the internal stresses and the fracture strength of fibers, is incorporated into the proposed work. The Weibull’s probabilistic distribution is employed to describe the varying probability of fiber cracking. Further, systematic numerical simulations are presented to illustrate the potential of the proposed methodology.

Fracture Strength Distribution in E-Glass Fiber Using Acoustic Emission

The strength of unidirectional composites is essentially dependent on the mechanical behavior of their reinforcement. The variability in mechanical properties of glass fibers has been studied using bundles of about 1400 filaments. This article proposes an experimental study on the fiber fracture strength distributions during tensile test by using acoustic emission (AE) in order to verify individual filament failures. AE monitoring of a bundle of E-glass fibers provides a convenient and relatively quick method to obtain the Weibull parameters of strength distribution. Results show that AE can be used as an effective tool to recognize the failure strength distribution as well as flaw population of fibers.

The effect of reinforcing methods on fracture strength of composite inlay bridge

The purpose of this study is to evaluate the effects of surface treatment and composition of reinforcement material on fracture strength of fiber reinforced composite inlay bridges. The materials used for this study were I-beam, U-beam TESCERA ATL system and ONE STEP(Bisco, IL, USA). Two kinds of surface treatments were used; the silane and the sandblast. The specimens were divided into 11 groups through the composition of reinforcing materials and the surface treatments. On the dentiform, supposing the missing of Maxillary second pre-molar and indirect composite inlay bridge cavities on adjacent first pre-molar disto-occlusal cavity, first molar mesio-occlusal cavity was prepared with conventional high-speed inlay bur. The reinforcing materials were placed on the proximal box space and build up the composite inlay bridge consequently. After the curing, specimen was set on the testing die with ZPC. Flexural force was applied with universal testing machine (EZ-tester; Shimadzu, Japan). at a cross-head speed of 1 mm/min until initial crack occurred. The data was analyzed using one-way ANOVA/Scheffes post-hoc test at 95% significance level. Groups using I-beam showed the highest fracture strengths (p0.05) Most of the specimens in groups that used reinforcing material showed delamination. 1. The use of I-beam represented highest fracture strengths (p0.05). 3. The reinforcing materials affect the fracture strength and pattern of composites inlay bridge. 4 The holes at the U-beam did not increase the fracture strength of composites inlay bridge.

310 繊維配向したTiN薄膜の破壊強度に及ぼす膜厚の影響(材料力学-機能材料)

310 繊維配向したTiN薄膜の破壊強度に及ぼす膜厚の影響(材料力学-機能材料)

Intermediate‐Temperature Stress Rupture of a Woven Hi‐Nicalon, BN‐Interphase, SiC‐Matrix Composite in Air

Woven Hi‐Nicalon™‐reinforced melt‐infiltrated SiC‐matrix composites were tested under tensile stress‐rupture conditions in air at intermediate temperatures. A comprehensive examination of the damage state and the fiber properties at failure was performed. Modal acoustic emission analysis was used to monitor damage during the experiment. Extensive microscopy of the composite fracture surfaces and the individual fiber fracture surfaces was used to determine the mechanisms leading to ultimate failure. The rupture properties of these composites were significantly worse than expected compared with the fiber properties under similar conditions. This was due to the oxidation of the BN interphase. Oxidation occurred through the matrix cracks that intersected the surface or edge of a tensile bar. These oxidation reactions resulted in strong bonding of the fibers to one another at regions of near fiber‐to‐fiber contact. It was found that two regimes for rupture exist for this material: a high‐stress regime where rupture occurs at a fast rate and a low‐stress regime where rupture occurs at a slower rate. For the high‐stress regime, the matrix damage state consisted of through‐thickness cracks. The average fracture strength of fibers that were pulled out (the final fibers to break before ultimate failure) was controlled by the slow‐crack‐growth rupture criterion in the literature for individual Hi‐Nicalon fibers. For the low‐stress regime, the matrix damage state consisted of microcracks which grew during the rupture test. The average fracture strength of fibers that were pulled out in this regime was the same as the average fracture strength of individual fibers pulled out in as‐produced composites tested at room temperature.

Crack‐Wake Debonding and Toughness in Fiber‐ or Whisker‐Reinforced Brittle‐Matrix Composites

Solutions are obtained for the mechanics of debonding in the crack wake in fiber‐ or whisker‐reinforced composites for the case where a finite shear traction exists at the fiber/matrix interface in the debonded zone. These solutions are then applied to derive expressions for the steady‐state toughness increases obtained in bonded composites wherein the toughness contribution is provided by crack‐wake fiber/matrix debonding and crack bridging. The solutions for an unbonded composite containing a frictional fiber/matrix interface can be obtained from the derived equations in the limit of the fiber/matrix interface toughness equal to zero. In this limit, the debond crack length reduces to the slip length and the expressions for the crack opening and the predicted toughness increase reduce to previously derived expressions for unbonded composites. The steady‐state toughness is found to depend sensitively on the interface toughness, the fiber fracture strength, and the shear tractions in the debonded zone including other material parameters, such as fiber radius and volume fraction and the moduli of the constituent phases. It is shown that in order to obtain finite toughness increases, the fiber/matrix interface toughness must be less than a critical value dependent on the fiber fracture strength, fiber radius and volume fraction, and fiber and matrix moduli. The predictions of the model are applied to published experimental results from a detailed and complete study of toughness increases in a bonded whisker‐reinforced composite.