Failures ductile

The exceptions in Fig. 8.6 to only ductile failure occurring at potentials high enough to form Fe203 involve nitrates and high temperature water. In both of those systems cracks grow from pits, and within the pit-crack... 

Fig. 8.94 Nominal stress-extension curves for mild steel in oil giving ductile failure, and in 4n NaN03 producing stress-corrosion failure, at the same test temperature (104°C)...

What is the difference between brittle and ductile failure upon impact Why is ductile failure preferable for most applications ... 

The area of the tear region (03 00) shows evidence of ductile failure, as shown in Figure 46(f). To perform the analysis it was necessary to sever this connection between the partially fractured tube pieces. Therefore, the two pieces of tubing were pulled apart. The expected result is the ductile failure that was in fact... 

The polyethylene layer shows a series of fault lines that run perpendicular to the direction of applied stress. The fracture surface of the polyethylene is sharp and jagged, and shows no signs of elongation or ductility. Beneath the polyethylene layer "2" was a thin layer ("3") that was identified as ethylene/vinyl acetate copolymer (EVA). The EVA layer did show evidence of ductile failure in the SEM images. 

Special precautions must be taken regarding end bearing for these members to avoid crushing of the web at peak response. If end bearing controls, the allowable response is limited to reduce the chance for non-ductile failure. Connections for these members also present difficulty because of the thin web material. To develop the ultimate strength of a member, multiple fasteners may be required so that the shear strength of the materia is not exceeded. 

Creep leads ultimately to rupture, referred to as creep-rupture, stress-rupture or static fatigue. Creep-rupture of thermoplastics can take three different forms brittle failure at low temperatures and high strain rates ductile failure at intermediate loads and temperatures and slow, low energy brittle failure at long lifetimes. It is this transition back to brittle failure that is critical in the prediction of lifetime, and it is always prudent to assume that such a transition will occur [1], A notch or stress concentration will help to initiate failure. 

In industry, hydrostatic pressure testing of pipes is still widely used to assess their resistance to this type of failure. Typical results are shown in Fig. 6 [57, 58], where failure times of HDPE pipes are given as a function of the circumferential (or hoop) stress. At relatively high stresses, ductile failure is observed (stage I) although deformation is initially homogeneous, small local variations (arising from variations in the specimen thickness, for exam-... 

Fig. 6 Durability diagram for HDPE pipes under internal pressure, showing hoop stress vs. the time to fail at different temperatures, along with the regimes of ductile failure (I) and brittle failure (II) [57, 58]...

This situation indeed occurs frequently, for instance with PVC pipes, where high internal pressures give rise to explosive brittle fractures, while with lower pressures, after a shorter or a longer time, balloon-like fractures occur. At even lower pressures brittle hair cracks are formed, also with PE, causing the pipes to leak. This happens after very long times of use (e.g. some years), but considerably earlier than predicted from extrapolation of the curve for ductile failure. 

Ductile Failure of Brittle Polymers under Compressive Shear Stresses... 

---