No abstract available

[en] In an attempt to correct the unrealistic material stiffness predicted by elastoplastic models which adopt an associative flow rule, this paper introduces an innovative technique for the computation of the inelastic contributions generated in a non-proportional loading path. The formulation of these inelastic contributions takes into account the plastic response along the direction normal to the plastic potential, neglecting the irreversible stretch caused by the tangential component of the stress rate. Here, the introduction of tangential plasticity, in combination with the return mapping technique, eliminates this drawback, allowing fast and accurate computation. The present paper focuses on the evaluation of the load-carrying capacity of a steel bridge pier, indicating the necessity of considering the additional tangential plasticity term for a correct description of the structural response.

[en] We propose an elasto-plastic model coupled with damage for the behavior of geomaterials in compression. The model is based on the properties, shown in S. Andrieux, et al., 'Un modele de materiau microfissure pour les betons et les roches', J. Mecanique Theorique Appliquee 5 (1986) 471-513, of microcracked materials when the microcracks are closed with a friction between their lips. That leads to a macroscopic model coupling damage and plasticity where the plasticity yield criterion is of the Drucker-Prager type with kinematical hardening. Adopting an associative flow rule for the plasticity and a standard energetic criterion for damage, the properties of such a model are illustrated in a triaxial test with a fixed confining pressure. (authors)

No abstract available

[en] Two types of Large Area Plastic Scintillator Detector with different size and model were described. The basic construction and working process was introduced. A Characteristics contrasting was made between the two types of Large Area Plastic Scintillator Detectors. The technology designing of the whole detector components was also described here. (authors)

[en] Thin isotropic rotation shells of constant thickness taking into account the appearance of plastic deformations under the local loads are considered. The method of running with discrete orthogonalization is used for the numerical realisation of the present problem. Thin spherical shells with the angle 90 degrees and the relation of the radius to the thickness 100 under local load are considered. (paper)

[en] Short communication

[en] A new invariant of stress tensor is introduced - the mean shearing stress, resulted from the integration with respect to Mohr's circle. The invariant is used to lay down the terms of plasticity. Determining equations are written on the basis of associated flow law. Rigid variants of the model and elastoplastic ones are obtained. Characteristic surfaces with normals, coinciding with main stresses direction are demonstrated for the rigid-plastic variant. (paper)

[en] Silk biopolymers, such as spider silk and Bombyx mori silk, behave always elastic-plastically. An elastic-plastic model is adopted and a variational principle for the small strain, rate plasticity problem is established by semi-inverse method. A trial Lagrangian is constructed where an unknown function is included which can be identified step by step. (author)

[en] Poly(vinyl chloride) (PVC) is one of the most important medical plastics. Recently, however, the safety of flexible PVC containing the common plasticizer, di(2-ethylhexyl) phthalate, has been called into question. Widely used heat stabilizers for PVC that incorporate toxic heavy metals also have fallen into disfavor. In order to address these problems, we have synthesized and tested, as potential replacements, several organic thiols that contain one or more carboxylate ester functions and thus are highly compatible with the polymer. When introduced into PVC at high loading levels (e.g., 30-35 parts by weight), the ester thiols are extremely effective as heat stabilizers and also useful as primary plasticizers. When used at a low loading level (e.g., 3 parts by weight), they still are excellent heat stabilizers for both plasticized and rigid PVC. Importantly, their high potency is achieved in the absence of any costabilizers that incorporate heavy metals. Their syntheses are simple and straightforward, and their odors are not offensive, because their volatilities are low. Described here are some typical results obtained with this new additive technology, which was licensed for commercialization in 2005