Fatigue notched specimen

The influence of test frequency on fatigue crack propagation of notched specimens has been studied by several investigators, but mostly by Hertzberg, Manson and coworkers For PS, they observed a decrease in FCP rate as test frequency was increased from 1 Hz to 10 Hz to 100 No results were presented for HIPS... 

Many investigations of the mechanical properties of ABS and of the nature of rubber toughening in this material have been made and these findings are reviewed and discussed by Bucknall and by Mann and Williamson There have been fewer studies of fatigue performance, and most of these are concerned only with crack propagation in notched specimens Here we are concerned with the... 

With the alternative indexing parameter RTt, surveillance capsule Charpy specimens can be used by fatigue pre-cracking the V-notch specimen... 

Fatigue notch factor The ratio of the fatigue strength of a specimen with no site of stress concentration (notch) to that of a duplicate specimen having a notch. 

This section is of particular interest as a consequence of the fact that almost all ceramics have flaws, many in form of microcracks or even cracks on a larger scale. These are outcomes of the fabrication techniques however, reducing such pores or cracks to a viable, minimal level is very costly. Many such cracks end at surfaces, where they act as stress raisers. Notches may also be considered as cracks, though the difference between notches and cracks is only a matter of size, not kind. Thus, the study of notched specimens has practical significance, because, in engineering components, fatigue starts mostly at the surface, at those places where stress-... 

In Fig. 7.62, the adjusted notch-fatigue life fits within the scatter band of the S-N curve. In this case, the fatigue-stress level in the notched specimens was adjusted by using the damaged area, which extends about 0.4 mm into the specimen, and using the undamaged area beyond it. (The stress level is the load divided by the area and, to this end, an adjustment had to be made). 

Many investigations have been made on the low-temperature properties of aluminum alloys [1-4] however, in addition to the determination of tensile and elastic properties as a function of temperature, notched tensile properties and notched/unnotched tensile ratios were determined. The notched/unnotched ratios were determined as a function of temperature in order to evaluate the toughness, which is often referred to in terms of resistance to brittle fracture, or notch sensitivity [5-7]. A notched specimen with a stress concentration factor K oi 6.3 was selected for use in this investigation because previous axial fatigue tests of complex welded joints, and fatigue and burst tests of pressure vessels made of 301 extra full hard stainless steel exhibited excellent correlation with notched/unnotched tensile ratios obtained with this value of over a range of temperatures... 

Nisitani H, Noguchi H and Kim Y H (1992) Evaluation of fatigue strength of plain and notched specimens of short carbon-fiber reinforced polyetheretherketone in comparison with polyetherether-ketone, Eng Pract Mech 43 685-705. 

Dynamic fracture (by fatigue) of the composite materials with thermoplastic matrix and reinforced with short fibres In this field, the investigations were devoted to elucidate the polymer and composite materials behaviour under exploitation conditions (non-notched specimens) as well as regarding the crack propagation (notched specimens). In the first place, the attention was focused on the composite materials with thermoreactive matrix, widely used in the automobiles industry. The test results, performed... 

The fracture toughness of PEEK has been studied via fatigue tests of notched and unnotched samples and three-point bend tests using single-notched specimens. Typical fatigue behaviors of... 

In plain carbon steels and titanium alloys with body-centred cubic lattice, there is a true fatigue limit with a horizontal S-N curve at a number of cycles beyond 2 X 10 to 10 [130] (type I, figure 10.19(a)). This, however, is not true for notched specimens (and thus also for components) or if corrosion or oxidation occur during the experiment. 

If we assume that the maximum stress amplitude in the component must not exceed the fatigue limit of a smooth specimen, cte, we should expect that the maximum nominal stress amplitude for a notched specimen is... 

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