Subject uniaxial deformation state

The brittle-ductile transition temperature depends on the characteristics of the sample such as thickness, surface defects, and the presence of flaws or notches. Increasing the thickness of the sample favors brittle fracture a typical example is polycarbonate at room temperature. The presence of surface defects (scratches) or the introduction of flaws and notches in the sample increases Tg. A polymer that displays ductile behavior at a particular temperature can break in the brittle mode if a notch is made in it examples are PVC and nylon. This type of behavior is explained by analyzing the distribution of stresses in the zone of the notch. When a sample is subjected to a uniaxial tension, a complex state of stresses is created at the tip of the notch and the yield stress brittle behavior known as notch brittleness. Brittle behavior is favored by sharp notches and thick samples where plane strain deformation prevails over plane stress deformation. 

Equation (3.32) is general and is not restricted to any particular state of stress. Let us derive a stress-strain equation for a rubber specimen subjected to a constant uniaxial stress. The deformation along the stress is denoted X. It may also be assumed that the transverse deformations are equal Aj = A3. The assumption that the volume remains constant during deformation can be formulated as follows ... 

The modeling of SCC members in this chapter (i) serves primarily the computation of the response of such members when they are subjected to seismic actions and (ii) acts as a vehicle for carrying out the state determination of the section (or integration point) to a frame element and ultimately to the whole frame assembly. The outcome of the former application is typically the moment-curvature response under a constant axial load. The latter application typically returns section forces that correspond to given section deformations (in uniaxial bending axial strain, and curvature). 

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