Notch tests

TRANSITION TEMPERATURE. 1. An arbitrarily defined temperature within die temperature range in which metal fracture characteristics determined usually by notched tests are changing rapidly such as from primarily fibrous (shear) to primarily crystalline (cleavage) fracture. 

In order to start the multiscale modeling, internal state variables were adopted to reflect void/crack nucleation, void growth, and void coalescence from the casting microstructural features (porosity and particles) under different temperatures, strain rates, and deformation paths [115, 116, 221, 283]. Furthermore, internal state variables were used to reflect the dislocation density evolution that affects the work hardening rate and, thus, stress state under different temperatures and strain rates [25, 283-285]. In order to determine the pertinent effects of the microstructural features to be admitted into the internal state variable theory, several different length scale analyses were performed. Once the pertinent microstructural features were determined and included in the macroscale internal state variable model, notch tests [216, 286] and control arm tests were performed to validate the model s precision. After the validation process, optimization studies were performed to reduce the weight of the control arm [287-289]. 

API Appendix SR 8 covers Charpy V-notch testing on pipe with diameters of 16 in. (405 mm) or greater. The minimum energy acceptance level is specified by the purchaser and... 

The Charpy V-notch energy needed to arrest ductile fracture as a function of stress level for API X6G and X70 material in a 30, 36, and 42 in. (760, 915, and 1,065 mm) diameter pipe calculated from this equation is shown graphically in Figure 5.21 (A = 0.1237). The limitation of the Charpy V-notch test is that it is not a full thickness test, whereas the DWTT is. This means in thicknesses more than in., compensation in the form of increased energy absorption requirements is often specified for thick pipe. 

In this work it was possible to demonstrate the efficiency of the core-shell nodules to toughen PET, especially when reactive shell is used and in particular for tri-axial loading conditions (notched tests). Semi-crystalline PET appears to be more demanding as ftn as the modifier-matrix interface is concerned. In that case, only a reactive modifier is able to provide a step change improvement in the energy absorbed during impact. 

The design temperature should be at least 10°F (6°C) higher than the testing temperatures shown in the table, since it will be necessary to meet Charpy V notch test requirements in the heat affected zones of welds. Also the minimum temperatures listed are for longitudinal tests. For transverse tests, the minimum testing temperature may be higher. It should also be noted that plates must be normalized or quenched and tempered to meet these requirements. 

TABLE 4.14 Izod impact resistance (notched test) of filled LDPE. For materials— see Table 4.12... 

Wood flour was more beneficial compared to fly ash in terms of notched test of impact resistance of HDPE-fllled materials and showed mixed data in terms of unnotched tests (Table 4.23). 

The test can be performed using either unnotched or notched test pieces. Three types of notches arc standardized (Fig. 13). the preferred one having a radius at the noteh base of 0.25 mm (the type A notch). A blunt 1.0 mm (type B notch) and a very sharp 0.1 mm (type C) notch are also covered. Notches of different base radius are useful for more extensive characterization of plastics than a simple quality lest or data sheet entry, in that they enable an estimate of the notch sensitivity of the plastic to be investigated. The flatwise test can also be performed notched or unnotehed. except that here the notched test has two notches machined across the 4 mm direction and directly opposite... 

Unlike the Charpy test, the notched Izod is capable of being tested either with the notch on the same side as the point of impact, which is the normal way, or on the opposite side, when it is called the reverse notched lest. Thus in the normal test the side containing the notch is placed under tension and the notch fulfils its purpose as a stress concentrator. In the case of the reverse notch, it is the unnotched face that is under tension, and no stress concentration occurs in fact the notch is placed under a compressive deformation. This arrangement is possible in the Izod test because the pendulum strikes the test piece at a point remote from the notch, and the advantage of having the reverse notch is that the test piece is otherwise identical. Eor the Charpy test, the cros.s section of the unnotched test piece must be greater than the notched test piece. 

Table 9.32 Damage propagation of aramid and E-glass fiber RPs using tensile-notched test specimen...

The notch-yield ratio was hardly affected by temperature and decreased with an increase in specimen width. The fracture strength of a very wide plate, with a notch such as a notched structure, can be evaluated using a deep-notch test specimen 400 mm wide the notch-yield ratio was found to be about 1.3. The mean line in Fig. 2 may thus be approximated by the following hyperbolic equation ... 

Also, the effect of the length of the edge notch, c, on the fracture strength was investigated using the deep-notch test specimens 400 mm wide in which c varied from 10 to 120 mm the effect could hardly be noticed [%... 

The fracture strength of the butt joint welded by the high-current GMA welding process was studied at room and low temperatures using a deep-notch test specimen, 400 mm wide. The edge notches of the specimens were located in the weld metal or along the bond. The test results are shown in Fig. 5. For comparison, the relationship between the fracture strength and the temperature of the base metal is shown with a dashed line. 

Consequently, the standard level of the fracture strength for the base metal and its welded joint has been proposed equation (3) should be met at temperatures below 110 K using the small size deep-notch test specimen 100 mm wide with two edge through-thickness notches, each 20 mm long. 

The Charpy U-notch test refers to the ASTM E23 [12], Standard Test Methods for Notched Bar Impact Testing of Metallic Material. The test was used to determine fracture energy. A Tinius Olsen Change-O-Matic impact testing machine was used in this test. 

Impact strength (notch impact resistance is the impact energy absorbed by the un-notched (notched) test object in relation to the smallest cross-section of the test object prior to the test. 

One of the disadvantages of PLA for many applications is its brittleness (20 kJ/m and 2 kJ/m for unnotched and notched Charpy, respectively). Instead of using common impact modifiers which reduce strength and stiffness, rayon fibers generate improved impact properties both in the unnotched and notched testing modes, as demonstrated in Fig. 18.19. Again, with wood or natural fibers, such a behavior caiuiot be generated [30]. 

ISO 13479 1997 Polyolefin pipes for the conveyance of fluids - Determination of resistance to crack propagation - Test method for slow crack growth on notched pipes (notch test). 

Table 4.5 gives an example of the content of capsules of 900 MWe reactors. Charpy V-notch tests are used to monitor all the materials. Additional tensile and fracture toughness tests are carried out for base and weld metals. Most reactors have four surveillance capsules to cover their design lifetime (40 years), except the first series of six 900MWe reactors known as CPO which have eight capsules. Generally, capsules are planned to be removed so that irradiation at quarter, half, three-quarters and completion of the component design end-of-life fluence can be achieved (Brillaud and Hedin, 1992 Chas et al, 2004). Table 4.6 shows the lead factors, defined by... 

Charpy impact test n. A destructive test (ASTM D 256B) of impact resistance using a centrally notched test specimen 126 mm long and typically 12.7 mm... 

In accordance with 10 CFR 50 Appendix G, Paragraph IV A, the reactor vessel beltline materials have minimum upper-shelf energy, as determined from Charpy V-notch tests on unirradiated specimens in accordance with Paragraphs NB-2322.2(a) of the ASME Code, of 75 ft-lbs. Charpy impact tests will be performed on... 

Charpy impact testing, also known as Charpy V notch testing, is performed on materials to determine toughness properties, usuaUy at low temperature. CIT enables one to determine the transition temperature between brittle and ductile faUure for any material or material specimen. CIT is also a good indication of a materials abiUty to absorb shock loads at low temperatures. CIT is used predominantly for carbon and low aUoy steels. It is not used for stainless steels because stainless steels do not fail in a brittle manner until extremely low temperatmes. 

Fig. 2.11 Load-deflection of notched test a Si3N4 -I- 30 % SiC -I- 3 % MgO b SiC - - 50 % ZrB2 -H 10 % B4C. Specimens 1 and 3 tested at room temperature and specimens 2 and 4 tested at 1400 °C [17]. With kind permission of Elsevier...

Specimens were 3x4y30mm in thickness, height and span. The SERB specimens were tested at a stroke rate of 0.5mm/min. Chevron-notch specimens were tested at 0.005mm/min. The low stroke rate used for chevron-notch testing was required to insure stable crack extension. 

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