复合材料粘结层中具有双裂纹时的热应力

采用拉普拉斯-傅利叶变换和施密特(Schmidt)方法,研究了复合材料因热流在裂纹周围引起的热应力,并对用环氧树脂粘结的陶瓷-钢板进行了数值计算.     

The clinical efficacy of imipenem/cilastatin sodium in orthopedic infections and drug levels in the bone tissue]

We evaluated the clinical efficacy of imipenem/cilastatin sodium (IPM/CS--a carbapenem antibiotic) against orthopedic infections, and the drug levels of the bone tissues were determined. The clinical efficacies for 6 patients in the infection group were good in 3 cases, and fair in the other 3; giving an efficacy rate of 50%. Bacteriologically, 8 strains were isolated from patients with the infection and an eradication rate of 87.5% was obtained upon the treatment. In 39 patients that were given the drug prophylactically, no postoperative infections occurred. Mean IPM levels in the bone and the bone marrow at 1 hour after administration in 5 patients of the prophylactic group were 17.3 micrograms/ml and 5.9 micrograms/g, respectively. The ratio of concentrations the bone to those in the bone marrow was 34.6%. The results of this study suggest that IMP/CS reaches to the bone tissue providing sufficient concentrations and that the drug is efficacious for the prophylaxis and the treatment of orthopedic infections.     

Dynamic stress intensity factors around two parallel cracks in an infinite elastic plate

Summary Dynamic stresses around two parallel cracks in an infinite elastic plate are obtained. An incoming shock stress wave impinges on the cracks at right angles to their faces. The Fourier-Laplace transform technique is utilized to reduce the problem to dual integral equations. To solve these equations, the differences in the crack surface displacements are expanded in a series of functions which are zero outside the cracks. The unknown coefficients occurring in those series are solved using the Schmidt method. The stress intensity factors defined in the Laplace transform domain are inverted numerically, in the physical space.     

Microwave Assisted Synthesis of Organic-Inorganic Polymer Hybrids

Summary Organic-inorganic polymer hybrids from various organic polymers such as poly(ethylene oxide) and poly(N-vinylpyrrolidone) were prepared with the assistance of microwave heating. With the 500 W, 2.45 GHz of microwave irradiation, the formation of polymer hybrids was accelerated. The obtained polymer hybrids were optically transparent and no phase separation was observed. From the SEM images and IR spectra of the obtained polymer hybrids, the composition and the properties of the polymer hybrids synthesized with microwave heating were found to be mostly the same as that synthesized with conventional heating.     

Critical Parameters and Critical-Region ($$p,\rho,T)$$ Data of trans-1,1,1,3-Tetrafluorobut-2-ene [HFO-1354mzy(E)]

This study presents the experimental measurement of the \(p\rho T\) properties and critical parameters of a low GWP type refrigerant, trans-1,1,1,3-Tetrafluorobut-2-ene (HFO-1354mzy(E)). The sample purity of the substance was 99 area %. \(p \rho T\) property measurements and visual observations of the meniscus of HFO-1354mzy(E) were carried out using a metal-bellows volumometer with an optical cell. The critical temperature was determined by observation of the critical opalescence. The critical pressure and critical density were determined as the inflection point of the isothermal \(p \rho T\) property data at the critical temperature. For more precise clarification of the thermodynamic surface in the vicinity of the critical point, additional \(p \rho T\) property measurements were carried out on three isotherms in the supercritical region. The expanded uncertainties (\(k = 2\)) in the temperature, pressure, and density measurements were estimated to be less than 3 mK, 1.2 kPa, and 0.32 \(\hbox {kg} \cdot \hbox {m}^{-3}\), respectively. The expanded uncertainties of the critical parameters were estimated to be less than 13 mK, 1.4 kPa, and 2.3 \(\hbox {kg} \cdot \hbox {m}^{-3}\), respectively. These values are the first reported for HFO-1354mzy(E) and are necessary for the development of its equation of state in the near future.     

Structural optimization under uncertain loads and nodal locations

This paper presents algorithms for solving structural topology optimization problems with uncertainty in the magnitude and location of the applied loads and with small uncertainty in the location of the structural nodes. The second type of uncertainty would typically arise from fabrication errors where the tolerances for the node locations are small in relation to the length scale of the structural elements. We first review the discrete form of the uncertain loads problem, which has been previously solved using a weighted average of multiple load patterns. With minor modifications, we extend this solution to include loads described by continuous joint probability density functions. We then proceed to the main contribution of this paper: structural optimization under uncertainty in the nodal locations. This optimization problem is computationally difficult because it involves variations of the inverse of the structural stiffness matrix. It is shown, however, that for small uncertainties the problem can be recast into a simpler but equivalent structural optimization problem with equivalent uncertain loads. By expressing these equivalent loads in terms of continuous random variables, we are able to make use of the extended form of the uncertain loads problem presented in the first part of this paper. The optimization algorithms are developed in the context of minimum compliance (maximum stiffness) design. Simple examples are presented. The results demonstrate that load and nodal uncertainties can have dramatic impact on optimal design. For structures containing thin substructures under axial loads, it is shown that these uncertainties (a) are of first-order significance, influencing the linear elastic response quantities, and (b) can affect designs by avoiding unrealistically optimistic and potentially unstable structures. The additional computational cost associated with the uncertainties scales linearly with the number of uncertainties and is insignificant compared to the cost associated with solving the deterministic structural optimization problem.     

Numerical study on compression processes of cohesive bimodal particles and their packing structure

In this study, the compression characteristics of bimodal cohesive particles were investigated using a discrete element method (DEM) simulation. The compression and packing processes were simulated under different conditions of size ratios of 1–4 and fine particle mixing ratios of 0–0.5. The cohesive force was expressed using the surface energy proposed by the Johnson-Kendall-Roberts (JKR) cohesion model having a surface energy of 0–0.2 J/m². The calculated results demonstrated that even in the case of cohesive particles, an increase in the particle size ratio reduced the void fraction of the powder bed during the packing and compression processes. In addition, it was found that the cohesive force decreased the contact number, especially the coarse-coarse contacts, although it had little impact on the void fraction. Our DEM simulations suggested that it is necessary to evaluate the contact numbers even under similar void fractions, which will be essential in the case of different material mixtures, such as all-solid-state batteries.     

Synthesis of organic–inorganic polymer hybrids from poly(vinyl chloride) and polyhedral oligomeric silsesquioxane via CH/π interaction

The synthesis of poly(vinyl chloride) (PVC)/polyhedral oligomeric silsesquioxane (POSS) polymer hybrids was performed utilizing CH/π interaction. Poly(vinyl chloride) as an organic component was dissolved in THF with octaphenethylsilsesquioxane (Phenethyl-POSS) or octacyclohexylsilsesquioxane (Cyclohexyl-POSS) as an inorganic component. The resulting mixture was placed at 40 °C for 2 weeks. The obtained polymer hybrid was dried in vacuo at 60 °C for 2 days. The transparent polymer hybrids were obtained when Phenethyl-POSS was employed as an inorganic component. In contrast, polymer hybrid became turbid when Cyclohexyl-POSS was used. These results suggest that the CH/π interaction was found to act as an important role for the dispersion of Phenethyl-POSS in the PVC matrix.