The viscoplasticity theory applied to the inelastic analysis at elevated temperatures

Monotonic and cyclic loading tests on strain rate changes are conducted on — 1Mo steel at 600°C. The examination of the tensile stress-strain response suggests that the viscosity function which characterizes the rate-dependency in the viscosity theory used previously at room temperature should not only depend on the overstress but also on the strain. A new extended viscosity control function is introduced to represent such strain dependency.The material constants of this modified viscoplasticity model are determined at temperatures of 25°C to 600°C and the model is applied to deformation tests on — 1Mo steel carried out under time-varying temperature conditions and other conditions.The extended viscoplasticity theory is shown to reproduce such various experimentally observed stress-strain behavior at elevated temperatures.     

Ion irradiation effects in EuBa2Cu3Oy thin film

The effect of He ion irradiation on the pinning potential in EuBa₂Cu₃O _y , thin film was investigated by measuring the temperature dependence of resistivity in magnetic fields. The pinning potential decreased as the ion fluence increased. A slower decrease of pinning potential was observed in higher magnetic field in the fluence region <3.5×10¹⁵ cm^–2.     

Large aperture superconducting magnet (benkei)

Benkei, which was a large window frame conventional magnet at KEK has been converted to a superconducting magnet. In the conversion, the pole gap has been doubled from 0.5 m to 1.0 m retaining an analysing power at 2 T m. Several new techniques were applied to coil windings and cryostat fabrication. The superconducting Benkei has shown satisfactory performances for long term operation.     

Advanced evaluation of thermal ratchetting of FBR components

A new prediction method for the thermal ratchetting of a cylinder subjected to an axially moving temperature distribution is proposed in this paper. This ratchetting is quite different from the conventional Bree-type ratchetting, and an advanced evaluation method has been required in the structural design of FBR components. The proposed method considers the work hardening of actual materials for FBR components. Firstly the basic scheme of the prediction method is shown, and secondly the application procedure to the actual design is shown. Predicted results by using this method coincide well with experimental results, when compared with the case by using the previous method.     

Inelastic behaviour of steel under plasticity-creep interaction condition: An interim report of the Bench Mark project by the subcommittee on inelastic analysis and life prediction of high temperature materials, JSMS

Some of the interim results of the Bench Mark Project by the Subcommittee on the Inelastic Analysis and Life Prediction of High Temperature Materials, JSMS, is presented. The purpose of the present bench mark study is to review and evaluate the inelastic constitutive models relevant to material response under the plasticity-creep interaction.By specifying normalized and tempered steel at 600°C, sixteen bench mark problems of four categories are first established: (I) tensile stress-strain relations and creep curves, (II) material response under mixed modes of plastic and creep loading, (III) ratcheting and deformation under program loads, and (IV) cyclic deformation behaviour under the combination of different strain rates. Then, the outline of seventeen inelastic constitutive models of nine types discussed in this project is presented. Finally, the interim results of these bench mark tests are compared with the corresponding predictions of the constitutive models to evaluate their accuracy in simulating the actual behaviour of the material.     

Direct observation of anion-mediated translocation of fluorescent oligoarginine carriers into and across bulk liquid and anionic bilayer membranes

The recent hypothesis that counteranion-mediated dynamic inversion of charge and solubility might contribute to diverse functions of oligoarginines in biomembranes was tested with two fluorescently labelled oligomers, FL-R(8), one of the most active cell-penetrating peptides, and its longer version, FL-R(16). We report evidence for counteranion-mediated phase transfer from water into bulk chloroform and anionic lipid-bilayer membranes as well as reverse-phase transfer from bulk chloroform and across intact lipid-bilayer membranes into water. The differences found between FL-R(8) and FL-R(16) with regard to location in the bilayer and reverse-phase transfer from bulk and lipid-bilayer membranes into water implied that the reported results may be relevant for biological function.     

Responsiveness of isolated dog veins to bradykinin and other bioactive peptides: distribution of sensitivity to bradykinin and possible correlation with genesis of the venous system

Contractile responses of isolated dog veins to bradykinin were studied. Responses to norepinephrine were taken as standards. According to their sensitivity to bradykinin, the veins obtained from 14 sites of the venous system were divided into two groups, while all the veins were almost uniform in their sensitivity to norepinephrine. One group has high sensitivity to bradykinin and the other has low sensitivity. The former includes the pulmonary, hepatic, splenic, and portal veins, the anterior vena cava, and the upper and the middle divisions of the posterior vena cava. The latter includes the external jugular, cephalic, azygos, femoral, and saphenous veins, and the lower division of the posterior vena cava. The responses of the renal vein were intermediate. A striking correlation was noted between the distribution of bradykinin sensitivity and the genesis of the venous system. Five bioactive peptides other than bradykinin were also studied. Only angiotensin induced contraction in some preparation, but, as a whole, caerulein, eledoisin-related peptide, oxytocin and vasopressin rarely showed contractile activity.     

An electrical conductivity and X-ray study of a high-temperature transition in U4O9

The high temperature transition in U₄O₉ has been studied by electrical conductivity measurements and X-ray diffraction. From the electrical conductivity measurements, a similar variation of log σ$\text{T}$ with reciprocal temperature to that in the transition range near room temperature is observed in the temperature range from about 300 to 800°C. Like the low temperature transition, a small lattice contraction is also observed in that temperature range by means of X-ray diffractometry, and the transition temperature increases from 530 to 620°C with increasing O/U ratio. After the transition the intensity of $\text{4a}{}_0$ superlattice reflections increases, but that of $\text{8a}{}_0$ superlattice reflections disappears. The mechanism of this high temperature transition is considered to be a second-order transition of the order—disorder type based on the configurational change of U⁴⁺ and U⁵⁺ with the shift of some portions of the lattice oxygen atoms from the lattice sites to the interstitial positions. The phase diagram of U₄O₉ is presented on the basis of the electrical conductivity and X-ray data.     

Homogenized elastic-viscoplastic behavior of plate-fin structures at high temperatures: Numerical analysis and macroscopic constitutive modeling

In this study, homogenized elastic-viscoplastic behavior of an ultra-fine plate-fin structure fabricated for compact heat exchangers is investigated. First, the homogenized behavior is numerically analyzed using a fully implicit mathematical homogenization scheme of periodic elastic-inelastic solids. A power-law creep relation is assumed to represent the viscoplasticity of base metals at high temperatures. The plate-fin structure is thus shown to exhibit significant anisotropy as well as noticeable compressibility in both the elastic and viscoplastic ranges of the homogenized behavior. Second, a non-linear rate-dependent macroscopic constitutive model is developed using the quadratic yield function proposed for anisotropic compressible plasticity. The resulting constitutive model is shown to be successful for simulating the anisotropy, compressibility, and rate dependency in the homogenized behavior in multi-axial stress states.