Deformation ductile

Folds are features related to compressional, ductile deformation (Fig. 5.10). They form some of the largest reservoir structures known. A fold pair consists of anticline and syncline. 

Brittleness and homogeneity of a sample are indicated by a high acoustic emission pattern, while the ductile deformation mechanism due to microvoid coalescence of soft steels is characterized by low-emission signals. 

Some difficulties also arise for the interpretation of scratch tests carried out at progressively increasing normal load or indentation depth. Figure 3 indicates, for example, that a transition from ductile deformation to brittle cracking can occur when increasing the normal load whilst the contact strain is nominally fixed by the conical indenter angle. This is indeed observed in many polymer systems and the notion of a critical load at the ductile-brittle transition is largely used to characterize the scratch response. This depth... 

If a solid is stressed beyond its elastic limit, it will acquire a permanent deformation. The deformation can be either brittle or ductile depending on (i) the material, (ii) the hydrostatic pressure, (iii) the temperature, and (iv) the strain rate. In general, a solid is more likely to deform in a brittle manner at low hydrostatic pressures, low temperatures, and at high strain-rates. Convesely, high hydrostatic pressures and temperatures and low strain-rates favor ductile deformation. 

Quick J. E. and Denlinger R. P. (1993) Ductile deformation and the origin of layered gabbro in ophiolites. J. Geophys. Res. 

In Mesozoic sandstones on Tampen Spur and Haltenbanken, normal faults are usually characterized by grain reorientation and enrichment of clay minerals which suggest that ductile deformation dominates. Abundant quartz cement is only observed along these faults associated with stylolites. Open fractures were not present in the sandstones from Tampen Spur and Haltenbanken. Fractures in these sediments therefore normally represent permeability barriers for fluid flow. 

With decreasing temperature towards the surface, the top part of the mantle is sufficiently cool that it behaves asastrong, rigid solid. The cold, relatively thin, layer of solid rock above the mantle is the crust, which is c.5-7km thick under the oceans but c.30-70km thick on the continents. The topmost mantle and crust are often considered together as lithosphere. Under excessive strain, such as during earthquakes, the lithosphere undergoes brittle failure, in contrast to the ductile deformation that occurs within the asthenosphere. 

Sverdrup Bjorlykke (1997) conclude that brittle deformation may occasionally generate faults which may remain open to fluid flow along the fault planes for some time, whilst ductile deformation and abundant clay smear as found in the fault-zone of clay-rich sandstones generally will have the opposite effect. Most of the observed carbonate cements in faults in the North Sea were found to have an in-situ rather than autochthonous origin by fault parallel fluid flow. 

The modelling of regional and local deformation zones in three dimensions at Aspo was conducted on the basis of their ductile history. A ductile precursor has been documented for all modelled zones but one (and may be valid for that one as well). The assumption is that ductile high strain zones of the scale considered (half a metre or more) are normally persistent over distances of more than a few tens of metres and are commonly the location of later reactivations. Ductile deformation was therefore normally a pre-requisite for interpolating structures with a distinct strike and dip over distances larger than a few tens of metres and also to extrapolate structures beyond the point of observation. Four deformation zones penetrate the central tunnel spiral at Aspb in the new model. 

Geological modelling essentially concerns developing a description of a rock volume in terms of rock types, brittle/ductile deformations and structures. Even if a key input to such descriptions are observations on site and from boreholes, geological modelling would be impossible without a basic conceptual model (see Section 4.3). The conceptual model in turn builds on hypotheses on the (long term) geological evolutionary processes. 

Material II This has moderate strength, moderate ductility, deforms plastically prior to failure, and is the toughest of the three. This behavior is characteristic of many metals. 

V. Mises R (1913) Mechanik der festen Korper im plastisch-deformablen Zustand [Mechanics of Ductile Deformable Rigid Bodies]. Nachrichten von der Gesellschaft der Wissenschaften zu Gottingen [News of the Academic Society of Gottingen], Mathematische-Physikalische Klasse, Vol. 1913 582-592 (in German)... 

The obtainable increase in the tensile strength depends on both the plastic and the reinforcing fiber. Craze formation is caused by shear stress peaks at the fiber-plastic interface. Consequently, plastics with ductile deformation behavior lead to better mechanical properties than brittle plastics glass-fiber-reinforced polyamides exhibit the larger increase in tensile strength when compared with glass-fiber-reinforced epoxides. 

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