Ratcheting limit of flat end cylindrical shell connections under internal pressure

Progressive plastic deformation, or ratcheting, is a failure mechanism in ductile structures usually associated with non-proportional actions. In the case of cylindrical shell flat end connections, with or without opening, ratcheting may occur under the action of cyclically varying pressure from zero to a maximum value, i.e. for single action and, therefore, proportional loading. In this paper the ratcheting limits for this connection under this loading and for two different models are given, for an ideal-elastic ideal-plastic constitutive law, Mises' yield condition and associated flow law. The results are compared with each other and with the limits for global plastic deformation given in the literature.     

Modeling time criticality of information

In this paper, we continue the research on formal treatment of attributes of information, based on the computational approach. In this scenario, the usefulness of advisory information is measured by the decrease in complexity of a problem we need to solve. We propose to model the time criticality via usefulness of a piece of information which is received during the computation. As a modeling tool, we use deterministic finite automata.     

Strukturaufklärung cyclischer Fettsäuremethylester V: Massenspektrometrie isomerer Phenylundecansäure-methylester

Elucidation of Structure of the Methyl Esters of Cyclic Fatty Acids V: Mass-Spectrometry of Isomeric Methyl Esters of Phenyl Undecanoic Acid Isomeric phenyl undecanoic acids obtained by the Friedel-Crafts reaction of benzene with 10-undecenoic acid were investigated as methyl esters using capillary gas-chromatography – mass spectrometry (GC-MS). The isomers could be identified as methyl esters of (5-), 6-, 7-, 8-, 9- and 10 phenyl undecanoic acids. The fragmentation due to electron bombardment is discussed.     

Die massenspektrometrische Fragmentierung von Neopentylpolyolestern III Neopentylglycoldifettsäureester

Mass Spectrometric Fragmentation of Neopentylpolyolesters, Part III: Fatty Acid Diesters of Neopentylglycole The fragmentation of the homologous fatty acid diesters of neopentylglycole (C₂ to C₁₈) upon electron impact was investigated. Main fragments arise by M-RCOO and M-RCOOH. Cyclic acetal structures for these ions are postulated. Subsequent fragmentation was elucidated by DADI-measurements and high resolution measurements. The influence of the length of the fatty acid chain upon the fragmentation is discussed. Esters of branched fatty acids can be distinguished from esters of n-fatty acids by characteristic ions.     

Massenspektrometrische Untersuchung von dimeren Fettsäuren aus einem thermisch und oxydativ belasteten Bratfett

Mass Spectrometric Investigation of Dimeric Fatty Acids from Frying Fats Subjected to Thermal and Oxidative Action Methyl esters of dimers from peanut oil subjected to thermal and oxidative action in an industrial frying plant were isolated by column chromatography and investigated by mass spectrometry. Di-unsaturated bicyclic and tetra-unsaturated acyclic structures were found to be the main components of the dimers. Dimers of very similar composition were synthesized. The mechanism of dimer formation is discussed.     

Analysis of Alkylbenzenes by Capillary Gas Chromatography

Suitable operating conditions are shown for GC separation of linear alkylbenzene (AB) samples on capillary columns. Retention data on SE-30 of n-phenylalkanes C₉-C₁₆ were measured and separation factors for n-phenylalkanes isomers were calculated. For quantitative evaluation from peaks areas of n-phenylalkanes, correction coefficients were calculated. By statistical evaluation of errors, standard deviations and further statistical parameters were calculated, showing GC method as sufficiently accurate and reliable. From results of collaborative testing of the GC procedure for quantitative AB analysis, some recommendations followed, esp. for application of capillary columns with apolar thermostable stationary phase only, with advantage under temperature programming, applying reduced sample volume at limited FID attenuation. It must be pointed out, this method is strictly limited for linear AB.     

Grinding induced effects in plasma sprayed zirconia coatings

The effect of grinding on the surface layer properties of ceria and yttria partially stabilized zirconia plasma-sprayed coatings (CePSZ, YPSZ, respectively) has been studied by X-ray diffraction methods. For this purpose, the modified model of line broadening analysis has been derived. The model considers elastic anisotropic properties along with more random paracrystal imperfections, both affecting X-ray line broadening. Grinding-induced microstructural changes were also studied using an estimation from the quantitative Orientation Distribution Function (ODF) texture. It was concluded, based on this work, that CePSZ ceramic is less mechanically stable compared to YPSZ. Consequently, more beneficial mechanical properties of a ground surface layer can be expected for CePSZ plasma-sprayed coatings.     

The rotator cuff-deficient arthritic shoulder: diagnosis and surgical management

The symptomatic rotator cuff-deficient, arthritic glenohumeral joint poses a complex problem for the orthopaedic surgeon. Surgical management can be facilitated by classifying the disorder in one of three diagnostic categories: (1) rotator cuff-tear arthropathy, (2) rheumatoid arthritic shoulder with cuff deficiency, or (3) degenerative arthritic (osteoarthritic) shoulder with cuff deficiency. If it is not possible to repair the cuff defect, surgical management may include prosthetic arthroplasty, with the recognition that only limited goals are attainable, particularly with respect to strength and active motion. Glenohumeral arthrodesis is a salvage procedure when other surgical measures have failed. Arthrodesis is also indicated in patients with deltoid muscle deficiency. Humeral hemiarthroplasty avoids the complications of glenoid loosening and is an attractive alternative to arthrodesis, resection arthroplasty, and total shoulder arthroplasty. The functionally intact coracoacromial arch should be preserved to reduce the risk of anterosuperior subluxation. Care should be taken not to "overstuff" the gleno-humeral joint with a prosthetic component. In cases of significant internal rotation contracture, subscapularis lengthening is necessary to restore anterior and posterior rotator cuff balance. If the less stringent criteria of Neer's "limited goals" rehabilitation are followed, approximately 80% to 90% of patients treated with humeral hemiarthroplasty can have satisfactory results.     

Effect of dissolved tungsten on the deformation of 70Ni-30Fe alloys

A series of Ni-Fe alloys containing various levels of tungsten in solid solution have been prepared as a means to assess the influence of solid solution strengthening on the mechanical behavior of monolithic 70Ni-30Fe. In particular, 70Ni-30Fe alloys plus equilibrium concentrations of tungsten in solid solution nominally correspond to the compositions associated with the matrix-only portion of certain tungsten heavy alloys, that is, alloys comprised of a high volume fraction of nominally pure tungsten particles embedded within a minority Ni-Fe-W based matrix. The study shows that the working solubility of tungsten within the 70Ni-30Fe base composition increases slightly with temperature, from approximately 21 wt pct at room temperature to approximately 23 wt pct at 1400 °C. Increasing the level of tungsten in solid solution leads to increases in room-temperature yield strength, tensile strength, and ductility. In contrast, the deformation characteristics of the alloys, as quantified by the power-law work-hardening exponent, n, and the strain-rate-sensitivity exponent, m, show little variation with tungsten solute concentration.     

A comparative study of direct and indirect evaluation of piezoelectric properties of electrophoreticaly deposited (Ba,Ca) (Zr,Ti)O3 lead-free piezoceramics

The development and optimisation of piezoceramics are targeted usually to enhance their piezoelectric properties evaluated by both the direct or indirect measurement methods. The presented work aims to elaborate on the correlation of one direct (Berlincourt) and two indirect (convert and field-dependent) piezoelectric measurement methods on various material states. The role of the ceramic powder treatment by ball milling and electrophoretic deposition (EPD) technique on the determined electric properties as well as basic physical and mechanical properties of (Ba_0.85Ca_0.15) (Zr_0.1Ti_0.9)O₃ ceramics (BCZT) was investigated. It was found that the EPD technologically supported by milling allows obtaining thick and dense deposits (>2 mm). After sintering, the BCZT ceramics with a relative density of >95%, hardness in the range of 2.3–2.9 GPa and piezoelectric coefficients of d₃₃* = 940 pm/V, d_33(E=0) = 427 pm/V and d₃₃ = 364 pC/N can be achieved. Reported results also suggest that indirect (field-dependent) and direct (Berlincourt) measurements of the piezoelectric coefficients can be comparable at optimal poling conditions.