^^Deformazione meccanica, fisica, ingegneristica.

librosito links

1. Deformazione ottica geometrica

2. Pesce pugno immerso in acqua nel cilindro trasparente.
3. Figura dilatata. Dilatazione geometrica.

1. Forza di deformazione, plastica e elastica; forza di richiamo elastica.
2. Corpi e deformazioni: corpo rigido, deformabile, elastico, plastico, viscoelastico, incomprimibile, inestensibile, flessibile.
3. Corpo deformabile.
4. Deformazioni e forze che le producono: allungare tirando, accorciare comprimendo, curvare flettendo, spiralizzare torcendo.
5. Energia meccanica; Trasformazioni dissipative.
6. ε = ΔL/L, allungamento relativo.
7. Invarianza del volume al variare di figura. Corpo comprimibile, incomprimibile.
8. Attrito interno del ferro.
9. L'allungamento assottiglia l'elastico. Effetto Poisson.
11. Trasformazione reversibile, irreversibile. Stato del sistema.
12. Forza elastica in corrispondenza alla deformazione, lz.
13. Le tante meccaniche. Disambiguare.

wp/Theory_of_elasticity

wp/Deformation_(physics)≡Deformation_(mechanics) | Deformation_(engineering) | Finite_strain_theory | Infinitesimal_strain_theory

Depending on the amount of strain, or local deformation,

the analysis of deformation is subdivided into 3 deformation theories:

Finite strain theory  ≡  large strain theory  ≡  large deformation theory

• deformations in which both rotations and strains are arbitrarily large
• the undeformed and deformed configurations of the continuum are significantly different and a clear distinction has to be made between them
• commonly the case with elastomers, plastically-deforming materials and other fluids and biological soft tissue.

Infinitesimal strain theory  ≡  small strain theory  ≡  small deformation theory  ≡  small displacement theory  ≡  small displacement-gradient theory

• strains and rotations are both small
• the undeformed and deformed configurations of the body can be assumed identical
• used in the analysis of deformations of materials exhibiting elastic behavior, such as materials found in mechanical and civil engineering applications, e.g. concrete and steel.

Large-displacement or large-rotation theory

assumes small strains but large rotations and displacements.

In each of these theories the strain is then defined differently.

engineering strain

1. applicable for engineering strains less than 1%
2. used in mechanical and structural engineering, where materials are subjected to very small deformations, is the most common definition of strain
3. not applicable for strains greater than 1%, with materials as elastomers and polymers, subjected to large deformations, thus other more complex definitions of strain are required, such as stretch, logarithmic strain, Green strain, and Almansi strain.
4. Engineering strain is modeled by infinitesimal strain theory

nonlinear elasticity

Elastomers and shape memory metals such as Nitinol exhibit large elastic deformation ranges as does rubber, but nonlinear elasticity.

Not all elastic materials undergo linear elastic deformation; some, such as concrete, gray cast iron, and many polymers, respond in a nonlinear fashion. For these materials Hooke's law is inapplicable.