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[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] 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] 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
[en] Highlights: • The initiation of fracture at adjacent flaws can be affected by flaw interaction. • Under elastic-plastic conditions, increases in flaw interaction occur. • Inelastic behaviour should be considered when formulating interaction criteria. - Abstract: Closely-spaced cracks in structures can interact with each other; the presence of one crack can change the strain energy release rate at another crack nearby. Since this interaction is enhanced by the onset of plasticity, elastic analysis alone should not be used for judging whether interaction between cracks will have a significant effect on the integrity of a structure.
[en] The apparatus described is claimed to be an improvement of that described in BP 1403265. It comprises a housing having a plastic scintillator sheet located at its base, together with a sealing ring at the base so as to afford a hermetic light-weight seal between a supporting surface and the base of the housing. Photomultiplier means are optically coupled to the scintillator sheet to amplify the scintillations, and a pump is provided to reduce air pressure in the region of the sheet to substantially below atmospheric pressure. The pump has a variable volume chamber, manually operable to reduce the volume, with a releasable latch to secure the pump in the reduced volume condition and a spring to increase the volume of the chamber and thus reduce the air pressure in the region of the scintillator sheet when the latch is released. The pump may be formed by the housing part of which is telescopically slidable within the other part. Alternatively a lever-operated rolling diaphragm pump may be used. With this arrangement there is no need to provide a pressure relief non-return valve to vent air from the apparatus. (U.K.)