Tensile test specimens

Fig. 11. Flatwise tensile test specimen. Reproduced by permission of the Boeing Company.

When testing finished wire-rope tensile test specimens to their breaking strength, suitable sockets shall be attached by the correct method. The length of test specimen shall not be less than 3 ft (0.91 m) between sockets for wire ropes up to 1-in. (25.4 mm) diameter and not less than 5 ft (1.52 m) between sockets for wire ropes 1 -J-in. (28.6 mm) to 3-in. (77 mm) diameter. On wire ropes larger than 3 in. (77 mm), the clear length of the test specimen shall be at least 20 times the rope diameter. The test shall be valid if failure occurs 2 in. (50.8 mm) from the sockets or holding mechanism. 

A fairly direct way of observing galvanic effects, which also permits changes in mechanical properties to be measured, involves the preparation of a composite specimen formed by attaching a strip, or strips, of one metal to a panel of another one. Tensile test specimens that include the areas of galvanic action can be cut from these panels after exposure, as shown in Fig. 19.30. 

Several additional, non-microstructural, inputs are required for the fracture model (i) Particle critical stress intensity factor, KIc. Here, the value determined in a previous study (Klc = 0.285 MPa in )[3] was adopted for all four graphites studied. This value is significantly less than the bulk Klc of graphites (typically -0.8-1.2 MPa rn). However, as discussed in the previous section, when considering fracture occurring in volumes commensurate in size with the process zone a reduced value of Klc is appropriate (ii) the specimen volume, taken to be the stressed volume of the ASTM tensile test specimens specimen used to determine the tensile strength distributions and (iii) the specimen breadth, b, of a square section specimen. For cylindrical specimens, such as those used here, an equivalent breadth is calculated such that the specimen cross sectional area is identical, i.e.,... 

Mechanical Property Testing. Mechanical tests were performed on both unirradiated and irradiated materials at -157°C, 24°C, and 121°C. Specimens were kept dry prior to testing in an environmental chamber mounted in a tensile testing machine. Tensile test specimens of [0]4, [10]4, [45]4, and [90]4 laminates were cut from 4-ply composite panels. All specimens were straight-sided coupons. For tension and shear tests the length/width aspect ratio was 8. For the compression tests the aspect ratio was 0.25 and the unsupported length was 0.64 cm. The [0]4 laminates were used to measure the ultimate tension and compression strength, Xit the axial... 

Fig. 3.26. Schematic drawing of transverse tensile test specimen.

We shall try to explain this on the basis of the thermoplastic PVC which is completely amorphous. The polymers chain form a tangle and each chain has the well-known zigzag shape of the carbon chain (figure 10.7). In figure 10.8 you can see the a- curve of the PVC tensile test. Plastic tensile test specimens are flat and those of metals are often cylindrical. 

Tensile test specimen, polymer tangle and individual chain before the test... 

Fig. 10.7 The shape of a plastic tensile test specimen and the polymer chain before and at the beginning of the elongation of the carbon chain.

Suppose a tensile force F is applied in the direction of the fibres to a tensile test specimen made of a fibre-reinforced composite and the following formula applies F = c x A. 

As can be seen, some larger fragments are seen in the sample held at elevated temperature, and sodium has segregated to the surface. Such segregation is very common in high temperature cured specimens, where sodium is often found at the failure surface in an adhesive failure mode. ISS/SIMS data from the adhesive side of a titanium-epoxy failure interface from a tensile test specimen are shown, in Figure 8. 

An investigation was made where the same tensile test specimens as were used to study the luminescence after yield were treated with S02 to destroy the hydroperoxides and thus prevent luminescence from hydroperoxide decomposition. Luminescence was, however, still found at fracture but only in an oxidative atmosphere. In pure nitrogen no luminescence could be detected. From this, the conclusion was drawn that some chains are ruptured at fracture and that radicals are formed [77]. 

The ASTM D 897 tensile button test is widely used to measure the tensile strength of a butt joint made with cylindrical specimens (Fig. 20.3). The tensile strength of this bond is defined as the maximum tensile load per unit area required to break the bond (measured in pounds per squre inch). The cross-sectional bond area is usually specified to be equal to 1 in.2. The specimen is loaded by means of two grips that are designed to keep the loads axially in line. The tensile test specimen requires considerable machining to ensure parallel surfaces. 

FIGURE 20.3 Standard button tensile test specimen and tensile test grips. 

Tensile test specimens have been fabricated based on ASTM D 3039 for off-axis angles. The materials chosen for fiber and matrix were E-Glass UD-weaves and ML-506 Epoxy resin, respectively. UD-weave fiber lay-up and test specimen geometry are shown in Figure 1 and Figure 2 ... 

Electron Microscopy. We replicated the surfaces developed from the double cantilever cleavage test and the surface developed from the tensile test specimen. Replicas are first taken with a gelatin solution from the fracture surface (9). A typical electron micrograph of a CTBN-epoxy system is shown in Figure 1. This micrograph is from a surface of a fractured cantilever cleavage specimen. It shows a uniformly dispersed rubber phase in a brittle epoxy matrix. 

Figure 6-7. A load-extension surve is plotted as a tensile test specimen is slowly pulled.

Figure 12.2. (a) Tensile test specimen Narrow-waisted... 

FIG. 6—Effect of adhesive thickness on load at failure and location from which cracks grow for button tensile test. Specimens made of PMMA with a diameter of 1,5 in. The model adhesive was Thiokol Chemical Corp. Solithane polyurethane. Crack growth was observed and recorded with a video camcorder. 

The mechanical properties of the polylmide film were measured in tension tests. To do this polylmide films were cast and cured on glass substrates. The films were removed and tensile test specimens were stamped from the films using a die. The specimens were then pulled to fracture at a cross-head speed of 10 mm/min. The mechanical properties obtained from the load-elongation curves are given in Table I. 

Fig. 25.10 A bonded interface of a tensile test specimen after failure. The bond, diameter 10 mm, contained an adhesive defect (diameter 3.5 mm) obtained by waxing. The adhesive was Terokal-5070MB-25 lk-EP from Henkel Teroson.

Figure 10.21 (a) A fractured semi-ductile steel tensile test specimen, showing necking and cup and cone fracture, (b)... 

Detail of cup and cone fracture surface from a copper tensile test specimen. The diameter of the neck is approximately... 

The notched tensile test specimens used in this investigation are shown in Fig. 1. For most tests, the notched specimens were used with a notch concentration factor of Kt — 6.3, as determined after Neuber [ ]. In one series of tests a of 15.0 was used. Each notched specimen was checked with a Jones Lamson optical comparator at 50 x. Only those specimens with notched dimensions within the specified tolerances were tested. 

Current density-potential curves for stressed and unstressed tensile test specimens in crack inducing media show that the unstressed specimen exhibits no rise in current until approximately... 

Special laboratory investigation of the resistance to stress corrosion cracking may include the use of machinery. In snch cases, tensile test specimens are tested under defined mechanical conditions, such as constant stress or constant strain rate. 

The most important goal for each NASA-developed CMC system was to be able to operate under potential component stress levels for long time at its selected upper use temperature (UUT). To evaluate this capability, tensile test specimens from the various CMC panels were subject to creep-rupture testing in ambient air at their goal UUT and at stresses of -60% of their room-temperature cracking stress. The primary performance objective was to demonstrate greater than 500-hour life without specimen rupture. Since high-temperature mpture of an initially uncracked CMC is typically controlled by CMC... 

Fig. 1 Equipment used in the present work. Detail of the clamping between jaws of the tensile test specimen and detail of the local heating of the fracture zone.

The tested material is AISI 304 austenitic stainless steel whose chemical composition is shown in Table 1. The tensile test specimens are obtained, from sheets whose thickness is 1.5 mm, according to UNE-EN-ISO 6892-1 and have a gage length of 50 mm and a width of 12.5 mm. 

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