Shear bands plane strain compression

Figure 19.1 Thin sections cut from specimens deformed just beyond the yield point in plane-strain compression viewed through crossed polarizers in the optical microscope, (a) Microshear bands formed in polystyrene, (b) Diffuse shear bands formed in poIy(methyl methacrylate). (Reproduced with permission from ref. 2.)...

Fig. 5.38 Shear bands in polystyrene deformed in plane strain compression (courtesy Dr. R.J. Oxborough).

It is also interesting that in compression tests on oriented polypropylene at low temperatures it is not in general appropriate to describe the deformation in terms of c-slip. Deformation bands in these specimens form in general at approximately 45° to the compression axis, i.e. near to planes of maximum shear stress, independent of specimen orientation. Bands in specimens for 6 < 45° and 0 > 60° are highly localised, indicating considerable strain-softening after yield. By contrast at 0 = 45°, which... 

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