Effect Of Gauge Length Research Articles

Weibull analysis of the tensile behavior of fibers with geometrical irregularities

This paper further develops the conventional Weibull/weakest-link model by incorporating the within-fiber diameter variation. This is necessary for fibers with considerable geometrical irregularities, such as the wool and other animal fibers. The strength of wool fibers has been verified to follow this modified Weibull/weakest-link distribution. In addition, the modified Weibull model can predict the gauge length effect more accurately than the conventional model.

Mechanical Behavior of Irregular Fibers. Part II: Nonlinear Tensile Behavior

To further our study of the linear tensile behavior of irregular fibers, in this paper we examine the nonlinear tensile behavior of irregular fibers. As before, we simulate the fiber dimensional irregularities with sine waves of different magnitude and frequency, and report results on the tensile behavior and gauge length effect of the simulated fibers.

Mechanical Behavior of Irregular Fibers. Part I: Modeling the Tensile Behavior of Linear Elastic Fibers

Fiber irregularities are inherent to textile fibers, particularly natural fibers. This series of papers examines the impact of fiber irregularity on the mechanical behavior of textile fibers. Part I examines the effect of fiber dimensional irregularities on the tensile behavior of linear elastic fibers using the finite element method. 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.

Mechanical properties of jute fibers and interface strength with an epoxy resin

Four different forms of jute fibers, namely untreated jute filament (UJF), sliver jute filament (SJF), bleached jute filament (BJF), and mercerized jute filament (MJF), have been subjected to tensile strength analysis following Weibull's theory. The MJF and BJF were obtained by the chemical modification of the UJF. A minimum of 50 fibers of each type, at three different gauge lengths, i.e., 15, 30, and 50 mm, were used to study the strength distribution and the effect of gauge length. The mean fiber strength was found to be the maximum for UJF followed, in the order, by BJF, MJF, and SJF (∼ 700, ∼ 660, ∼ 580, and ∼ 540 MPa, respectively, at 50-mm gauge length). The strength was also found to decrease with an increase in gauge length. In all cases, good agreement was found with Weibull's statistical model. Single fiber composite tests, with an epoxy resin as the matrix, were carried out determine the critical fragment lengths and interfacial strength, following the Kelly–Tyson approach. The BJF was found to have the maximum interfacial adhesion (τ ≈ 140 MPa) followed by UJF, SJF, and MJF having τ values of ∼ 83, ∼ 57, and ∼ 47 MPa, respectively. Scanning electron microscope pictures showed the fiber surface was physically modified by the various treatments. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1585–1596, 2000

Effects of gauge length and strain rate on fracture toughness of polyethylene terephthalate glycol (PETG) film using the essential work of fracture analysis

AbstractEssential Work of Fracture (EWF) analysis was used to study the fracture toughness of a PETG film. In the study of the gauge length (Z) effect on the specific essential work (we) using Z = 50, 100, 150, 200 and 250 mm, it is observed that we is Independent of gauge length, except that a slightly lower we value was measured for Z = 50 mm. Interestingly, for specimens with long gauge lengths (Z ≥ 150 mm in this study), brittle fracture occurred. The minimum ligament length at which ductile/brittle transition took place was observed to decrease with increasing gauge length. There is a small strain rate effect on we with loading rates less than 1 mm/min. But with higher loading rates, we showeld no strain rate sensitivity.

Quantitative Evaluation of Size Effect based on Statistical Behaviors of Fatigue Limit. (Rotating Bending Fatigue Limit of S35C, SFA55-Steel and AC8A-Al Cast Alloy).

To investigate the of rotating bending fatigue test are carried out on solid bar specimens with various gage lengths, that is, the length of the parallel part, and the same cross section of S35C steel, SFA55 steel and AC8A aluminum alloy. Statistical test of significance about the effect of gage length on fatigue limit was carried out by using the mean and the standard deviation of fatigue limits obtained by an up-and-down method. The result of the statistical tests show that a significant difference exists among fatigue limits of each gage length. Experimental values of the size effect are coincide with the calculated value by means of the assumption that strength of micro defect in material belongs to Weibull distribution. In the experimental results, shape factor : m of Weibull distribution is 30∼80 and depends heavily on the material and metallurgical structure.

Oxidation Induced Stress-Rupture of Fiber Bundles

The effect of oxidation on the stress-rupture behavior of fiber bundles was modeled. It is shown that oxidation-induced fiber strength degradation results in the delayed failure of the associated fiber bundle and that the fiber bundle strength decreases with time as t-1/4. It is also shown that the temperature dependence of the bundle loss of strength reflects the thermal dependence of the mechanism controlling the oxidation of the fibers. The effect of gauge length on the fiber bundle strength was also analyzed. Numerical examples are presented for the special case of Nicalon™ fibers.

Statistical tensile strength of Nextel TM 610 and Nextel TM 720 fibres

The properties of fibre-reinforced composites are dependent not only on the strength of the reinforcement fibre but also the distribution of fibre strength. In this study, the single filament strength of several lots of NextelTM 610 and NextelTM 720 ceramic fibres was measured. Fracture statistics were correlated with the effects of gauge length and diameter variation, and the Weibull modulus was calculated using several different techniques. It was found that the measured Weibull modulus at a single gauge length did not accurately predict either the gauge length or diameter dependence of tensile strength.

The size effects on the mechanical behaviour of fibres

The size of a fibre affects its mechanical properties and thus is of theoretical and practical importance for studies of the rupturing process during loading of a fibrous structure. This paper investigates the overall effects of length on the mechanical behaviour of single fibres. Four types of fibres, ranging from brittle to highly extensible, were tested for their tensile properties at several different gauge lengths. Different from most previous studies where the focus has been on the gauge length effects on a single property such as fibre strength or breaking strain, this paper look comprehensively into the effects of length on all three of the most commonly studied mechanical properties, namely strength, breaking strain and initial modulus. Particular emphasis is placed on initial modulus and on the interactions between all three parameters. Influences of strain rate and fibre type on the size effects are also investigated. The effect of potential fibre slippage on experimental error is examined. An image analysis method is used to measure the real fibre elongation in comparison to the same fibre elongation obtained directly from an Instron tester. Finally, a statistical analysis is carried out using the experimental data to test the fitness of the Weibull theory to polymeric fibres. This was done as the Weibull model has been extensively utilized in examining fibre strength and breaking strain, although it is supposed to be valid only for the so-called classic fibres to which more extensible polymeric fibres do not belong.

Weibull Analysis of the Strength of Carbon Fibers Using Linear and Power Law Models for the Length Effect

The single-filament test measurements for strength of carbon fibers obtained by Bader and Priest [5] are analyzed using a broader class of Weibull models with the scale parameter assumed to be a function of fiber gauge length. Two specific models are proposed for the fiber gauge length effect on tensile strength: The power law model and a linear model. The methods of maximum likelihood estimation and Weibull plots provide tools for the parameter estimation and assessment of the fitted models. In particular, the models provide excellent prediction of the fiber strength distributions at longer gauge lengths not tested, but illustrate that extrapolation to very short gauge lengths yield larger predicted fiber strengths than those actually observed experimentally, and extrapolation to very long gauge lengths yield smaller predicted fiber strength than observed experimentally. Analysis of the Bader-Priest data using the proposed models supports the observed "end effects" (or "clamp effects) for short gauge lengths studied initially by Phoenix and Sexsmith [3] and reported also by Stoner, Edie and Durham [4].

Tensile Strength of SiC Fibers

An experimental investigation has been conducted on the effects of gauge length on the tensile strength of SiC fibers. The results show that the overall strength distribution cannot be described solely in terms of the two‐parameter Weibull function. The overall distribution is found to be consistent with two concurrent flaw populations, one of them being characteristic of the pristine fibers, and the other characteristic of the additional flaws introduced into the fiber during processing of the composite.

Effect of inhomogeneity on strength and deformation characteristics of concrete : G. Balazs, J. Borjan, A. Horvath & F. Schwerteczky, Periodica Polytechnica: Civil Engineering, 37(4), 1993, pp 313–320

The article discusses the experimentaI results of the inhomogeneity of concrete influences the next factors: - preparation of road concrete - moulding the concrete prism in a lying position and testing in standing position - the effect of gauge length - the effect of the type, shape and size of the aggregate used.

On the tensile properties of a fiber reinforced titanium matrix composite—I. Unnotched behavior

An investigation of the ultimate tensile strength and fracture strain of a fiber-reinforced Ti-matrix composite has been conducted. Comparisons have been made between experimental measurements and predictions of two micromechanical models: one assumes that the fibers behave independently of the matrix, i.e. as in a dry fiber bundle, and the other assumes frictional coupling between the fibers and the matrix, characterized by a constant interfacial sliding stress. To conduct such comparisons, a number of constituent properties have been measured, including the fiber strength distribution, the thermal residual stress and the interfacial sliding stress. In addition, the effects of gauge length on the tensile properties of the composite have been studied. The comparisons indicate that the model prediction based on frictional coupling provide a good representation of the experimental results. In constrast, predictions based on the dry fiber bundle approach strongly underestimate both the ultimate strength and the fracture strain and predict a gaunge length dependence that is inconsistent with the experiments.

Weibull analysis of strength-length relationships in single Nicalon SiC fibres

Nicalon SiC fibre is naturally brittle and offers high-temperature application in fibrous composites. Due to the randomly distributed flaws along the fibre, the statistical variability in single-fibre strength is obvious. In this paper, the effect of heat-cleaning procedures on Nicalon fibres has been investigated, and the statistical strength and variability of single Nicalon fibres have been characterized in tension and compared. Experimental results show that the strengths of single Nicalon fibres among the three types of heat-cleaning procedures are less than that of as-received unsized fibres by 22–30%. In addition, both the failure load and the failure stress of the fibres, for a given gauge length (50 mm) and yarn cross-section, can be well fitted to a two-parameter Weibull distribution. The effect of gauge length over the range from 10–175 mm, holding the strain rate constant, was also studied. The logarithmic strength-length plots show that the strength of single Nicalon fibres follows the weakest-link rule.

Length effect on the performance of lumber in tension

A study was conducted to evaluate the effect of gauge length on the short-term performance of visually graded Select Structural and No. 2 kiln-dried nominal 38 × 89 mm spruce-pine-fir lumber in tension parallel-to-grain. The short-term tensile strength properties of three groups of lumber, matched for modulus of elasticity and having gauge lengths of 2642, 3683, 4877 mm, were obtained from test results where the effect of gauge length was isolated from the effect of grade. The performance of the lumber was evaluated by first-order second-moment reliability analyses. In the analyses, the lumber was treated as single tension members under uniform tensile stress along the member length, undergoing snow load conditions at various locations in Canada. The results indicate that the performance factor for Select Structural spruce-pine-fir lumber in tension parallel-to-grain should be multiplied by a factor of 0.92 to adjust for doubling the length from 2500 to 5000 mm to achieve a common reliability index of 3.0. The effect of doubling the length from 2500 to 5000 mm on the performance of No. 2 spruce-pine-fir lumber appears to be negligible. Key words: length effect, tensile strength, lumber, performance factor, reliability index.

Effect of Gauge Length on Compression Properties of Unidirectional Fiber Composites

Compression modulus and strength have been measured for unidirectional carbon fiber/thermoplastic matrix composites Values obtained from the use of a Northrop loading fixture are compared to those from an IITRI fixture Low Northrop modulus values are explained using buckling theory and the effect of fiber curvature within the lam inate. Also, data are compared tor composites with different fiber forms with emphasis on fiber curvature.

Plastic Strain Ratio (r) for Sheet Metal: Effect of Gage Length and Width Measurement Locations Using Reduced Section Specimens

Abstract Recent advances in computer-controlled testing technology have resulted in the capability of determining r-values during routine tension testing. During axial straining, there are differences in width reduction over the length of the reduced parallel section due to shoulder constraint. Because of these changes in width reduction, the magnitude of the calculated r-value is dependent upon the gage length and width measurement location. The use of a 50 mm (2 in.) or less longitudinal strain sensor with a single transverse center width sensor does not presently comply with ASTM Test for Plastic Strain Ratio r for Sheet Metal (E 517). Yet the data from this work demonstrate that excellent r-value results can be obtained using a 50 mm (2 in.) longitudinal sensor with a single center transverse sensor while still maintaining a 57 mm (2¼ in.) reduced parallel section which complies with ASTM Tests and Definitions for Mechanical Testing of Steel Products (A 370) and Tension Testing of Metallic Materials (E 8).

Gauge Length Effect on the Strength of Silicon Carbide and Sapphire Filaments

A modification of the Weibull type of flaw distribution function has been suggested for analysing the strength distribution of sapphire and SiC on carbon filaments. The function provides an upper and lower strength limit and is characterised by two shape parameters. The strength distributions of sapphire and SiC filaments, reported by previous workers, were analysed in terms of the proposed distribution function. Strength distribu tion data obtained at greater lengths (254 mm) were used to predict strength distribution at shorter length of 75 mm. The predicted values were in close agreement with the ex perimental ones. The average strength values calculated down to a length of 12.5 mm also agreed with the experimental values quite well.

Statistical Analysis of Tensile Strength of ARALL® Laminates

Variability in the strength of ARALL® laminates is studied. Standard statis tical procedures are used to determine the distribution function that best fits ARALL® laminates strength data. The normal, log-normal, and two-parameter Weibull distributions are compared using the Kolmogorov-Smirnov goodness-of-fit test. At the 5 % significance level none of these distributions is rejected. However, the data indicate that the strength of laminates, for a given gauge length and cross section, can be best fitted to a two-parameter Weibull distribution. In addition, some small panel-to-panel variations in strength are also found. The effect of gauge length on the strength of ARALL® laminates is examined. The strength of ARALL® laminates seems to exhibit no gauge length effects over the range from 2 to 20 inches, holding the strain rate constant. This effect, if true in general, would be a substantial advantage for ARALL® laminates, because scaling effects would be mini mized.

Effects of Strain Rate and Gauge Length on the Failure of Ultra-High Strength Polyethylene Fibers

Ultra-high strength polyethylene filaments taken from a single spool of yarn were examined for strain rate and gauge length effects. As noted in previous research, high strength polyethylene exhibits pronounced strain rate effects that may be seen in strength changes, stress-strain behavior, and and topography of the fracture zones. Unlike most polymeric fibers, ultra-high strength polyethylene seems to exhibit no gauge length effects over the range from 10 to 200 mm, holding the strain rate constant. This latter effect, if true in general, would be a substantial advantage for polyethylene fibers, because scaling effects would be minimized.