Effect Of Specimen Width Research Articles

Three-dimensional modelling of tensile behaviour for standard aluminium specimens

The effect of specimen width and incorporation of a circular hole on the tensile behaviour of commercially available aluminium alloy AA 1100 was studied using finite element analysis (FEA) for convergence with the already published experimental work of other researchers. Static structural analysis was conducted to simulate tensile loading of Japanese industrial standard (JIS) specimen JIS Z 2201 No. 13B and No. 5 until the point of the ultimate tensile strength (UTS) was reached. A strain rate of 0.25 mm/s was used for both the neat specimen and the one bearing a circular hole of 8 mm in diameter at the centre of the specimen. The numerical results exhibited a good agreement with the experimental work by comparison of the percentage elongation for numerical and experimental data. The normal stresses calculated using analytical and numerical approaches also reflected a good convergence. For neat specimens of JIS Z 2201 No. 13B and No. 5, a 100 % increase in specimen width enhanced the load required to reach UTS by 100 %, while elongation was increased by 30 %. On the other hand, for specimens of JIS Z 2201 No. 13B and No. 5, bearing an 8 mm circular hole reduced the load required to reach UTS by 300 %, while elongation was only increased by 25 %. The 200 % decrease in load required to reach UTS and 57 % reduction in elongation was observed by incorporating an 8 mm circular hole in the neat specimens.

Investigation of the tearing properties of a new airship envelope fabric based on experimental and theoretical methods

In the present work, a new phenomenal model is proposed for modeling and simulating tearing mechanical properties on an airship envelope fabric. The greatest advantage of the phenomenal model is that such model is capable of calculating the tearing strength of a plain weave fabric by simply uniaxial tearing tests rather than the expensive and complex pressurized cylinder tests. The geometric progression technique is employed to calculate the stress distribution on the crack tip. The stress transfer coefficient Q is derived to be 0.9656. Three types of SEN (single-edge-notched) specimens were researched by the uniaxial tearing tensile tests. The effects of specimen width and the crack length ratio on the tearing strength of the airship envelope fabric are studied thoroughly. A good agreement between such model and experimental data is obtained, and the deviation is lower than 5%. Meanwhile, compared with the new phenomenal model and the Thiele’s formula, this new phenomenal model is verified to be more accurate while calculating the tearing strength of a plain weaving airship envelope fabric in the uniaxial tearing tensile load.

Effect of specimen width on the failure behavior in resistance spot weld tensile shear testing

Specimen dimensions have significant effect on the tensile shear strength (TSS) of resistance spot welds (RSW) in the commonly employed tensile shear testing. Minimum required dimensions specified in different industrial test standards vary somewhat however. In this paper, the most influential dimension, the tensile shear test specimen width, is investigated for a low-strength steel (galvanized steel Q235), a high-strength steel (TRIP980), and aluminum alloy 5052. The relationships between the specimen width and weld properties, such as TSS, energy absorption, and failure modes, were investigated experimentally. The results show that there is a critical width of the specimen beyond which the TSS of the RSW maintains a constant value and the failure is at the spot weld. This constant TSS is a saturated value. The perceived TSS from the tensile shear testing is lower than the saturated TSS when the width is smaller than the critical value. The displacement at the TSS and the energy up to failure from the tensile shear testing, however, shows opposite trend due to the large plastic deformation from the base sheet metal in narrower specimens. From the results, a minimum width of tensile shear test specimen for determining saturated TSS is recommended.

Anisotropic size effect law for notched strength of unidirectional carbon/epoxy laminates – Part 1: Formulation

A multiaxial quasi-brittle failure criterion for notched orthotropic composites is developed with an emphasis on establishment of an analytical formula to predict their anisotropic notched strength for any notch size under any multiaxial proportional loading. It is formulated by replacing the principal unnotched strengths with the principal notched strengths in the framework of the Tsai–Hill static failure criterion for orthotropic composites. The effects of notch size and specimen width on the principal notched strengths are described by means of the Suo-Ho-Gong model that can consider notch ductile-to-brittle transition. From the proposed multiaxial quasi-brittle failure criterion, an analytical formula is derived to predict the notched strength of finite orthotropic composite plates under multiaxial proportional loading at any angle with the principal directions of material anisotropy. The notched strength prediction formula involves a generalized notch sensitivity parameter that can be defined for any multiaxial state of stress. The multiaxial notch sensitivity parameter allows uniquely defining an intrinsic equivalent mode-I fracture toughness that is independent of notch size as well as of specimen width for any multiaxial proportional loading. Furthermore, an anisotropic size effect law for apparent equivalent mode-I fracture toughness that considers not only the effect of notch size but also the effect of specimen width is derived from the failure criterion. Finally, a quasi-brittle failure criterion for notched interface is briefly discussed as a particular case of the proposed quasi-brittle failure criterion for notched orthotropic composites.

Effect of Specimen Width on the Contact State between the Three-Point Bending Specimen and Supports in Hopkinson Bar

The effect of specimen width on the contact state between the three-point bending (TPB) specimen and supports has been investigated with the apparatus of Hopkinson pressure bar using the analysis method of the propagation of stress wave. The results indicate that, the time for loss of contact decreases linearly with the increase of specimen width when the specimen width is less than a critical value, and the relationship between the time for loss of contact and the specimen width shows a parallel line to the abscissa when the specimen width is greater than the critical value.

Effects of Specimen Width and Specimen Length on Stress Intensity Factor Solutions for Spot Welds in U-Shape Specimens

Effects of Specimen Width and Specimen Length on Stress Intensity Factor Solutions for Spot Welds in U-Shape Specimens

The effect of specimen width on the bending strength of ceramic matrix textile composites

Effects of specimen width on the bending strength of textile composites were investigated. 4 points bending tests were conducted on the 8-harness satin Nicalon/SiC (NICAROCERAM) composites. The width of the specimen was varied. Experimental results indicated that the bending strength increases with increasing width and drops at the multiples of the unit cell size. Analytical approach based on Curtin's model was conducted to characterize the experimental results. The analytical prediction was compared with the experimental results.

Effect of specimen size on strength reliability of SiC/Al composite

A tensile test was carried out for SiC/Al composite specimens which have different width. A Monte Carlo simulation using finite element method was performed with changing the width of SiC/Al composite model. The size effect of composite strength and its reliability was examined and discussed. The results showed that composite strength does not appear to have large change but its reliability is improved with increasing the composite specimen width. Effect of specimen width on composite strength and its reliability is dependent on the both factors, that is, (a) the accumulating of fracture process and (b) fibre strength and its scatter of the weaker fibres in the composite. The accumulation of the fracture process is related to the fibre stress distribution in the composite.

Failure Analysis of ±45° Off-Axis Woven Fabric Composite Specimens

The purpose of this research is to evaluate the mechanical response of eight harness satin woven graphite/polyimide composite specimens using the ±45° test. A series of tensile tests have been conducted at room temperature to evaluate the effect of specimen width as well as monotonic, progressive, and multiple loadings on the response of the composite specimens. Acoustic emission techniques have been employed to monitor damage initiation and progression in the specimens at different stages of loading. In addition, nonlinear finite element computations have been conducted to determine stress distributions in the ±45° fabric specimens. It has been shown that the specimen width effect is strong and should not be ignored in a failure analysis of the fabric composite using the ±45° test. The shear strength of the composite determined from the maximum loads increases substantially with the width of the specimen. It has also been shown in this research that the initiation of intralaminar damage in the graphite/polyimide composite can be monitored using acoustic emission. The initiation of interlaminar damage can be determined either from the characteristic knees on the load/displacement diagrams or from the acoustic emission data.

Width effects on the tensile strength and fatigue behavior of angle-ply laminates

The effects of the specimen width on the tensile strength and fatigue behavior of fiberglass/epoxy coupons was investigated experimentally. Monotonic and fatigue tensile tests of [±Θ 2] s laminates with six fiber angle orientations (ranging from ±25° to ±75°) and five different widths were conducted. The ultimate tensile strength and fatigue behavior depend on both the fiber angle orientation and specimen width. The effects of specimen width are more apparent at smaller angles, Θ≤45°. In general, the tensile strength and fatigue life increases and approachs a steady value as the specimen width increases. For larger fiber angles, Θ>45°, the width effects are less pronounced for both monotonic and fatigue loading.

Determination of the fracture toughness of polymeric films by the essential work method

Complete ligament yielding before crack advance is one of the criteria in the essential work method. It is found that this criterion also holds when the essential work method is used to obtain the fracture toughness of polymeric films. This is done by using two specimen geometries to test each of two nylons. The criterion is then used to find the fracture toughness of three polyethylenes, a cast, amorphous poly(ethylene terephthalate) and two kaptons. In addition, the effects of specimen width and strain rate on the specific essential work of fracture w e are studied.

Effect of Specimen Width on Stress Corrosion Cracking of Type 304 Stainless Steel

Abstract Corrosion current density was related to crack tips (js, time to failure (tf), and crack propagating length (Lss during the secondary region in the corrosion elongation curve under constant-load conditions. This yielded the relation: Lss/jstf. Under constant environmental conditions, tf was inversely proportional to Lss, with js presumed constant. The effect of width at gauge length on stress corrosion cracking (SCC) of a solution-annealed type 304 austenitic stainless steel (UNS S304000) was investigated in 0.82 M sulfuric acid solution using a constant-load method, under the assumption that Lss was proportional to width. Results showed tf increased with increasing width, but the steady state elongation rate (iss was constant independent of width. This implied that the predicted relationship was correct. A process for SCC was discussed on the basis of that relationship.

A study of the J-COD relationship

The effects of specimen width W, ratio ( a jW ) , slow stable crack growth ( Δa) and toughness value on the interrelation of crack opening displacement and the J-integral were experimentally investigated. A series of tests were performed on a structural steel where the specimen size and the crack depth/specimen width ratio ( a W ) were varied. Results show that the specimen width W does not appear to significantly affect the m value; a lower a W ratio yields a higher m, and m icreases with increasing toughness value; however, m does not show any clear tendency of dependency with the slow stable crack growth Δa.

Effects of clamp force in Limiting Dome Height (LDH) Test

The effects of specimen width and blankholder (clamp) force on LDH were investigated in tests with bare DDQ SK steel strip. Specimen width ranged from 109 to 143 mm (4.29 to 5.63 in.). The die set comprised a ball-bearing ball punch of 101.6 mm (4 in.) diameter and blankholders with a triangular clamping bead. Clamp forces ranged from 100 to 500 kN (11.25 to 56 tons). Draw-in, critical blank width, and LDH diminished with increasing clamp force, and draw-in and LDH reached their minimum at forces of 250 kN (28 tons) and above. The results showed that if an insufficient clamp force or a blank of excessive width is used, the LDH value will be above its true (minimum) value.

Within-Panel Variability and Scaling Effects in Composite Materials

In the process of fabricating specimens for a fatigue investigation, we found that the panels had a systematic thickness and density variation. Because this could bias test results, we conducted an experimental study to assess the consequences of the observed variability within the panels. Moreover, we obtained data on the effect of specimen width on the static strength.

多点スポット溶接継手の応力分布と疲労強度 Ｉ 応力分布について

As a part of investigation on the fatigue strength of multi-spot welded joints arranged in perpendicular to load direction, plane stress distributions of single- and multi-spot welded joints were studied. The purposes are to make clear effects of specimen width and/or lap length on stress distribution of single-spot welded joint and of spot space and/or lap length on that of multi-spot welded joint. Moreover, it was intended to find out a relationship between plane stress distributions of single- and multi-spot welded joints.First, qualitative studies of stress distribution on line (the X-axis in Fig. 1) including nugget front where fatigue crack may generate were carried out. Second, based on the above qualitative studies, quantitative studies of stress distribution by means of finite element method were carried out. Main conclusions obtained in this investigation are as follows:(1) Effects of specimen width and/or lap length on stress distribution of single-spot welded joint were made clear.(2) Effects of spot space and/or lap length on stress distribution of multi-spot welded joint were made clear.(3) Effects of specimen width on stress distribution of single-spot welded joint and of spot space of the same length on that of multi-spot welded joint are equivalent, as long as ratio of specimen width of single-spot welded joint or of spot space of multi-spot welded joint to nugget diameter is not extremely small.(4) If the stress distribution (σy on the X-axis) of single-spot welded joint with sufficiently large specimen width is known, it is possible to estimate. approximately stress distributions of single- and multi-spot welded joints with different specimen widths or spot spaces but with the same lap length.(5) Moreover, if an applied load that either maximum stress of single-spot welded joint with some specimen width and lap length or of multi-spot welded joint with some spot space and lap length becomes a specific stress value is known, it is possible to estimate, by using the graph shown in Fig.12 (This figure shows the relationships between specimen width or spot space and load ratios, using lap length as parameter), a similar load for single-spot welded joint with any specimen width and lap length or for multi-spot welded joint with any spot space and lap length.

Testing of Geotechnical Fabric for Use as Reinforcement

Abstract Twenty-seven commercially available petrochemical-based geotechnical fabrics, both woven and nonwoven, and one fiberglass fabric were evaluated for suitability as reinforcement in an embankment test section to be constructed on soft foundation at Pinto Pass in Mobile Harbor, Ala. by the U.S. Army Corps of Engineers Mobile District. All fabrics were subjected to initial testing in uniaxial tension and fabrics meeting or exceeding established strength criteria were subjected to additional testing to determine creep behavior, soil-fabric frictional resistance, and the effects of immersion and water absorption on developed tensile strength. The effects of specimen width and testing strain rate on uniaxial tension test results were also investigated. Four woven geotechnical fabrics plus the woven fiberglass fabric were found to meet or exceed required tensile strength criteria: Nicolon 66475, Nicolon 66186, Polyfilter-X, Advance Type I, and Bay Mills 196-380-000 (fiberglass). Both Nicolon materials were found to have minimal creep tendency and strength loss after soaking. Polyfilter-X was found to have moderate creep tendencies and high strength loss upon soaking, while Advance Type I was found to have high creep tendencies and moderate strength loss upon soaking. Bay Mills 196-380-000 had zero creep tendency and was not tested for soaking strength loss. Minimum soil-fabric frictional resistance for all five fabrics approximated soil-alone behavior for a loose relative density condition.

The K-COD relationship for compact tension specimen

In this paper a K-COD (δ) relationship proposed in the case of single edge notched tension (SENT) speciments is applied to the compact tension ( CT) specimen. According to this relationship, K- δ is a linear relationship dependent on specimen dimensions and a/ W ratio. The effect of specimen width and a/ W ratio can be taken into account by plotting K vs δ√ a/ W instead of K- δ. K vs δ√ a/ W is an unique relationship independent of the specimen width and a/ W ratio. However δ is defined here as the resultant displacement at the crack tip obtained by joining the notch mouth opening displacement to strain reversal point. In the linear elastic and small yielding situations, the strain reversal point position is different from the apparent rotation axis position as obtained by the crack profile extrapolation. This analysis is further validated by comparing the results of this analysis with the published experimental results on CT specimens.

Low Cycle Fatigue Strength of Welded Joint with Angular Distortion in 80 kg/mm2 Class High Tensile Steel

The authors investigate low cycle fatigue strength of welded joint with angular distortion of 80 kg/mm2 class high tensile steel plate. Experiment is carried out at room temperature and low temperature of about -70°C, and the effects of specimen width, amount of welding distortion and testing temperature on low cycle fatigue strength are examined.

シャルピー衝撃試験における試験片巾の影響

シャルピー衝撃試験における試験片巾の影響