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Invariants of tensors. In mathematics, in the fields of multilinear algebra and representation theory, the principal invariants of the second rank tensor are the coefficients of the characteristic polynomial [1] , where is the identity operator and are the roots of the polynomial and the eigenvalues of . More broadly,any scalar-valued function ...
Cauchy stress tensor. In continuum mechanics, the Cauchy stress tensor (symbol , named after Augustin-Louis Cauchy), also called true stress tensor[1] or simply stress tensor, completely defines the state of stress at a point inside a material in the deformed state, placement, or configuration. The second order tensor consists of nine ...
Continuum mechanics. In continuum mechanics, a Mooney–Rivlin solid[1][2] is a hyperelastic material model where the strain energy density function is a linear combination of two invariants of the left Cauchy–Green deformation tensor . The model was proposed by Melvin Mooney in 1940 and expressed in terms of invariants by Ronald Rivlin in 1948.
t. e. In continuum mechanics, the maximum distortion energy criterion (also von Mises yield criterion[1]) states that yielding of a ductile material begins when the second invariant of deviatoric stress reaches a critical value. [2] It is a part of plasticity theory that mostly applies to ductile materials, such as some metals.
Tensor derivative (continuum mechanics) The derivatives of scalars, vectors, and second-order tensors with respect to second-order tensors are of considerable use in continuum mechanics. These derivatives are used in the theories of nonlinear elasticity and plasticity, particularly in the design of algorithms for numerical simulations.
Lode coordinates. Surfaces on which the invariants , , are constant. Plotted in principal stress space. The red plane represents a meridional plane and the yellow plane an octahedral plane. Lode coordinates or Haigh–Westergaard coordinates . [1] are a set of tensor invariants that span the space of real, symmetric, second-order, 3-dimensional ...
Objective stress rate. In continuum mechanics, objective stress rates are time derivatives of stress that do not depend on the frame of reference. [1] Many constitutive equations are designed in the form of a relation between a stress-rate and a strain-rate (or the rate of deformation tensor). The mechanical response of a material should not ...
The group SU (3) is a subgroup of group U (3), the group of all 3×3 unitary matrices. The unitarity condition imposes nine constraint relations on the total 18 degrees of freedom of a 3×3 complex matrix. Thus, the dimension of the U (3) group is 9. Furthermore, multiplying a U by a phase, eiφ leaves the norm invariant.