# Tag Info

### Relation between strain and velocity

your question: "Is it right to identify $\frac{\partial u_i}{\partial t}$ with the velocity vi of the particles of the material,.." The correct formula implies material derivatives (as ...

### What is the physical meaning of the third invariant of the strain deviatoric?

For a general $3\times 3$ matrix $\mathbf{A, you have: $$I_3 = \frac{1}{3!}[\mbox{tr}(\mathbf{A})^3 - 3\mbox{tr}(\mathbf{A}^2)\mbox{tr}(\mathbf{A}) + 2\mbox{tr}(\mathbf{A}^3)]$$ If you have$\text{tr}(...

### Decomposition of deformation into bend, stretch and twist?

Yes, there is a way to decompose strain (ie: deformation) into six components. The components are the three amounts of stretching along (x,y,z) and the 3 amounts of parallelepipeding in the planes ...

### Decomposition of deformation into bend, stretch and twist?

There is no such general decomposition, simply because bending and twist can only be defined for rods (where there is a longitudinal direction of reference). So it makes no sense to talk about "...