Effect Of Gauge Length Research Articles

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.

Estimation of Fatigue Life at Elevated Temperature of Electron Beam Weldments of Alloy 718

Abstract Axial displacement-controlled fatigue tests were conducted at 600°C on smooth solid cylindrical specimens of Alloy 718 with electron beam weldments. By monitoring the diametral strain response of the heat-softened region, relationships between strain amplitude and fatigue life, and between cyclic stress and strain, were obtained. Using the cyclic stress-strain curve of the soft region, the load-controlled fatigue test results corresponded to the axial displacement-controlled test results. Subsequently, a simple model of strain sharing in the weldment was established for cyclic loading in order to estimate the fatigue life. Using the model, the fatigue life of a welded specimen under axial loading was estimated as a function of gage length, considering the effect of gage length on strain concentration in the soft region.

Statistical aspects of tensile strength of aramid fibers and unidirectional composites

AbstractThe effect of gage length and temperature on tensile strength of aramid monofilaments, yarns, and strands has been studied in view of statistical models of the theory of strength. The tensile strength of monofilaments and yarns is found to decrease as the gage length is increased. The strength of strands remains constant. The temperature resistance of strands is determined by the glass transition temperature of a polymeric matrix.

A Study of Statistical Variability in the Strength of Single Aramid Filaments

Variability in the failure load, tenacity, and linear density of single aramid filaments is studied experimentally. Data indicate that both the failure load and the tenacity of filaments, for a given gauge length and yarn cross section, can be fitted to a two parameter Weibull distribution; however the fit is better for tenacity than for failure load, and the Weibull shape parameter for the former is typically smaller. Within a yam cross section filaments vary significantly in linear density (and diameter), and this variability contributes a component to the variability in failure load, but not to the tenacity. Also, the mean tenacity and the variability in linear density and in failure load may differ greatly from spool to spool. The implications of the variability are discussed in light of the work of Bunsell. The effect of gauge length on the strength distribution of filaments is examined. Weibull statistics are used to separate out this effect. As previously shown for other brittle filaments, the Weibull shape parameter for aramid filaments depends on the gauge length; however values for the shape parameter calculated at a fixed gauge length are substantially lower than those obtained by a procedure based on varying the gauge length. This suggests short range correlations in flaw strengths along a filament.

The effect of gauge length on the tensile strength of R.A.E. carbon fibres

Tensile tests using 0·5, 5·0 and 10·0 cm lengths of R.A.E. carbon fibre after heat-treatments to 1000, 1500, 2500 and 3000°C have shown that the length tested has a significant effect on the strengths obtained. With fibres heat-treated to 2500°C, the average strength of 0·5 cm lengths was 400 × 10 3 lb in −2, this being about 30% higher than the corresponding result obtained with 5 cm lengths. The highest strengths were found after the heat-treatment to 1500°C, the average for the 0·5 cm lengths being 450 × 10 3 lb in −2, again about 30% higher than the value for 5 cm lengths. Similar gauge length effects were found after each heat-treatment temperature, and the ratios of the standard deviations of the strengths to the average strengths in general remained constants at about 25%. It appears therefore that the type of defects limiting the strengths and their distribution have not been influenced by the different heat treatments. The strengths of the 0·5 cm lengths have been used to predict values for the longer lengths by means of weak link theory and these values have been compared with the experimental results.

The Effect of Gage Length on Fiber Strength Measurements

The Effect of Gage Length on Fiber Strength Measurements

Tensile Properties Affecting the Formability of Aluminum-Alloy Sheet at Elevated Temperatures

Tensile Properties Affecting the Formability of Aluminum-Alloy Sheet at Elevated Temperatures