Tip of a wedge

Fig. C-2(a) shows an attached shock wave on the tip of a wedge. This is a weak shock wave formed when the associated pressure difference is small. On the other hand, as shown in Fig. C-2(b), a detached shock wave is formed when the pressure difference becomes large. An attached shock wave becomes a detached shock wave when the wedge angle becomes large.

The slow rate of hydration for buried surfaces is good from a service point of view, but makes the study and evaluation of the durability of surface treatments difficult unless wedge tests (ASTM D3762) or similar tests are used to accelerate the degradation. The stress at the crack tip of a wedge test specimen, together with the presence of moisture at the tip, serves to make this test specimen more severe than soaked lap-shear specimens or similar types for... 

Note also that the aft tip of the wedge was filled with a fiberglass/epoxy wedge. This strengthened the tip and makes it more resistant to delamination. 

The existence of a wedge-shaped cavitated or fibrillar deformation zone or craze, ahead of the crack-tip in mode I crack opening, has led to widespread use of models based on a planar cohesive zone in the crack plane [39, 40, 41, 42]. The applicability of such models to time-dependent failure in PE is the focus of considerable attention at present [43, 44, 45, 46, 47]. However, given the parallels with glassy polymers, a recent static model for craze breakdown developed for these latter, but which may to some extent be generalised to polyolefins [19, 48, 49], will first be introduced. This helps establish important links between microscopic quantities and macroscopic fracture, to be referred to later. 

The observation, inside an electron microscope, of the mechanical twinning of B shows that this twinning occurs when crystals are strained so as to relax the stress. For instance, a mechanical twin can appear at the tip of a fracture inside a crystal (fig. 15). Except for this situation it always appears at the boundary of a crystal when, for example, a mechanical twin has just occurred at the neighbouring crystal. In this case a wedge microtwin starts from the grain boundary and passes through the crystal, giving rise to a twin layer (fig. 16a,b), and this for a type I as well as for a type II twin. 

A very high stress occurs near the tip of the wedge microtwin due to the existence of the shear displacement only in that part of the crystal where there is... 

From Fig. 2 we conclude that for reasonable values of the chemical parameters, A = [BrO ] and B = [BrMA], DE(4) admits only one steady state solution in the positive quadrant. Strictly speaking, we have derived this result only in the limit - 0,i.e. C= total cerium concentration - However, numerical calculations (Witten, private communication) of the roots of Eq. (6) show that Fig. 1 is accurate for C 1. For > 1 the tip of the wedge moves up and to the left. For > 5, Eq. (6) has three real positive roots for realistic values of A and B. However, > 5 corresponds to C < 10, which is so much... 

Initial stage of oxidation and creep deformation of the wedge-tip region of a wedge-shaped specimen after preoxidation for t = 12 h at T = 1100°C. High-temperature exposure was continued for 10 min after cooling down. 

Horizontal Rotating Pan Filters. These filters (Fig. 10) represent a further development of the tipping pan filter for continuous operation. They consist of a circular pan rotating around the central filter valve. The pan is divided into wedge-shaped sections covered with the filter medium. Vacuum is appHed from below. Each section is provided with a drainage pipe which connects to a rotary filter valve of the same type as in dmm filters. 

Fig. 7. Schematic representation of hydration causing crack propagation in a wedge test specimen. The increase in volume upon hydration induces stresses at the crack tip that promote crack growth 19,391.

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