Search results for "Solid body"
showing 7 items of 7 documents
Interphase Model and Phase-Field Approach for Strain Localization
2020
Quasi-brittle materials subjected to a high level of mechanical solicitations see the development in relatively narrow zone of micro-cracks that coalesce into stress free cracks. In this work, the problem of strain localization in elastoplastic materials exhibiting softening has been approached by applying the interphase model together with the phase-field theory. In particular, the narrow zone where strains concentrate, usually named process zone or localization band, is kinematically modeled using the interphase model, while the phase-field variable is introduced to regularize the contact strains at the interface between the plastic strain band and the surrounding material. This correspon…
Boundary/Field Variational Principles for the Elastic Plastic Rate Problem
1991
An elastic-plastic continuous solid body under quasi-statically variable external actions is herein addressed in the hypoteses of rate-independent material model with dual internal variables and of infinitesimal displacements and strains. The related analysis problem for assigned rate actions is first formulated through a boundary/field integral equation approach, then is shown to be characterized by two variational principles, one of which is a stationarity theorem, the other a min-max one.
On shakedown of elastic plastic solids
1988
Making reference to elastic perfectly plastic solids subjected to cyclic loads, the problem of the shakedown load factor is considered and the relevant Euler-Lagrange equations are discussed. It is proved that the solution to these equations describes the gradient, with respect to the load multiplier, of the steady-state response of the solid body to the cyclic loads at the shakedown limit, and that it thus enables one to predict the nature of the impending collapse. These results are then extended to the more general case of loads varying within a given load domain.
Drying of shrinking cylinder-shaped bodies
1998
Abstract A mathematical model has been developed for the prediction of sample temperature, average moisture and moisture distribution in a cylinder-shaped solid during the drying process. The effect of shrinkage was taken into account. The macroscopic heat balance and the microscopic mass balance combined with Fick's law were simultaneously solved using the Runge-Kutta-Merson method and a numerical finite difference method. The effective diffusion coefficient was expressed as a function of sample temperature and local moisture content. Using an experimental drying curve determined at 90 °C, the diffusional equation was identified for broccoli stems, and was used to predict the average and l…
Optimal Bounds on Plastic Deformations for Bodies Constituted of Temperature-Dependent Elastic Hardening Material
1997
Bounds are investigated on the plastic deformations in a continuous solid body produced during the transient phase by cyclic loading not exceeding the shakedown limit. The constitutive model employs internal variables to describe temperature-dependent elastic-plastic material response with hardening. A deformation bounding theorem is proved. Bounds turn out to depend on some fictitious self-stresses and mechanical internal variables evaluated in the whole structure. An optimization problem, aimed to make the bound most stringent, is formulated. The Euler-Lagrange equations related to this last problem are deduced and they show that the relevant optimal bound has a local character, i.e., it …
A Study on Plastic Shakedown of Structures: Part I—Basic Properties
1993
For a continuous elastic-perfectly plastic solid body subjected to a combination of cyclic (mechanical and/or kinematical) load and of a steady (mechanical) load such as to produce plastic shakedown (i.e., alternating plasticity), a number of characterizing properties are established and discussed. The conditions for the body’s transition from plastic shakedown to ratchetting are also addressed.
A Study on Plastic Shakedown of Structures: Part II—Theorems
1993
For a continuous elastic-perfectly plastic solid body subjected to a combination of cyclic (mechanical and/or kinematical) load and of a steady (mechanical) load, two theorems of plastic shakedown are presented, one stating a necessary condition, another stating a sufficient condition. The problem of the direct determination of the plastic shakedown boundary is also briefly addressed.