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ν ij is the Poisson ratio that corresponds to a contraction in direction j when an extension is applied in direction i. The Poisson ratio of an orthotropic material is different in each direction (x, y and z). However, the symmetry of the stress and strain tensors implies that not all the six Poisson's ratios in the equation are independent.
Conversion formulae Homogeneous isotropic linear elastic materials have their elastic properties uniquely determined by any two moduli among these; thus, given any two, any other of the elastic moduli can be calculated according to these formulas, provided both for 3D materials (first part of the table) and for 2D materials (second part).
2 Poisson's ratio. 3 Bulk modulus. 4 Shear modulus. 5 References. 6 See also. Toggle the table of contents. Elastic properties of the elements (data page) 1 language.
E 1 and E 2 are the Young's moduli in the 1- and 2-direction and G 12 is the in-plane shear modulus. v 12 is the major Poisson's ratio and v 21 is the minor Poisson's ratio. The flexibility matrix [S] is symmetric. The minor Poisson's ratio can hence be found if E 1, E 2 and v 12 are known.
The resistivity of these materials changes with strain, accounting for the / term of the defining equation above. In constantan strain gauges (the most commercially popular), the effect accounts for 20% of the gauge factor, but in silicon gauges, the contribution of the piezoresistive term is much larger than the geometric terms.
The theory described above assumes that each peridynamic bond responds independently of all the others. This is an oversimplification for most materials and leads to restrictions on the types of materials that can be modeled. In particular, this assumption implies that any isotropic linear elastic solid is restricted to a Poisson ratio of 1/4. [3]
The coefficients u i are still found by solving a system of linear equations, but the matrix representing the system is markedly different from that for the ordinary Poisson problem. In general, to each scalar elliptic operator L of order 2k, there is associated a bilinear form B on the Sobolev space H k, so that the weak formulation of the ...
It is defined as the ratio of the infinitesimal pressure increase to the resulting relative decrease of the volume. [ 1 ] Other moduli describe the material's response ( strain ) to other kinds of stress : the shear modulus describes the response to shear stress , and Young's modulus describes the response to normal (lengthwise stretching) stress.