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Technically WikiPedia is correct but we usually use apparent stress during stress strain curve (Mostly) and not actual stress . Apparent stress(or engineering stress) is the one you mentioned and the one mentioned by Wikipedia is actual strees(or true stress) As you can see in this picture A is engineering stress strain curve whereas b is true stress ...


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I read that for fixed stress (i.e. fixed elongation), I should observe decreasing strain over time. This is a misprint. Fixed elongation is a fixed strain i.e. in this experiment you apply an initial strain and measure the decreasing stress as a function of time. The phrase visco-elastic is a rather general term that covers a multitude of sins. However in ...


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I think that a good point to start are decent introductory books about continuum mechanics in general to get an idea about how the framework works in general and how systems are described, how different quantities are transported. For this I myself really liked as a starting point: Liu, Continuum Mechanics, Berlin, Heidelberg: Springer, 2002 It is by far ...


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The usual picture you see in wkipedia and other sources is indeed over-simplified. Viscosity resists more general velocity gradients, not just pure shear flows $\nabla_x v_y\neq 0$. For example, if you have a compressible fluid undergoing non-isotropic scaling expansion $$ \vec{v} = (\alpha x,\beta y,\gamma z) $$ then shear viscosity will try to equalize ...


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Strength and Toughness Image source: Materials Group - University of Cambridge We need the separate words "strength" and "toughness" because sometimes materials with high toughness and high strength are very different, like rubber and ceramic. Let's say you are designing a chair so that can support a person of a certain weight. Why not build it out ...



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