Advanced Materials Research Vols. 1120-1121

Abstract: In this paper, an interaction integral is applied to evaluate the crack-tip field intensity factors for piezoelectric cracks by using BEM. Based on this, the fracture parameters for different crack configurations and loading conditions are analyzed in details for both the center crack and edge crack problem. According to the present results, the path-independent behavior of the interaction integral is verified. The comparison of the I-integral results with those by the J-integral and the displacement interpolating methods shows a good agreement.

Abstract: The determination method for analyzing trace copper in vanadium alloy by flame atomic absorption spectrometry was investigated in the paper. The sample digestion method, digestion acidity, determination conditions, matrix interferences, method precision, recovery of standard addition were investigated in detail. The method precision in RSD% was 8.6%, and the average recoveries of standard addition were from 93.9% to 95.6%. The experimental results indicated that the proposed method for determination of trace copper in vanadium alloy was simple, fast, accurate, and easy to operate, which was suitable for quality control of vanadium alloy.

Abstract: In order to exactly master effect of plutonium material’s heat power on safety and reliability of nuclear weapon, weapon-grade plutonium(WgPu) was regarded as research object in this paper. According to its component, decay heat power of WgPu per kilogram was calculated through dynamic decay cascade and decay law of plutonium. The maximum decay heat power of WgPu is 2.6158 watt per kilogram at seventy years.

Abstract: Pharmacopoeial monographs define usually requirements for the use of the particular chromatographic packing materials in a very general way. Even if a selection of particular chromatographic column packed with the defined material is suggested, it appears often that column is currently not present in the laboratory, or is no longer commercially available. With respect to those facts, there are needs to replace the given column material for another one, however with the similar physicochemical characteristics. This can be achieved by using one of the classification systems of columns’ material (e.g., the procedure developed by the researchers at the Katholieke Universiteit Leuven – and therefore called tentatively by us as KUL procedure).In the first stage of the work, it has been proven that the results obtained by KUL procedure can be related to results obtained during chemometrics verification of the suitability of selected stationary phases’ material used in the individual columns for purity test of alfuzosin as pharmaceutical substance and their impurities and related compounds. The next step was to adapt KUL procedure to allow the classification of modern and new UHPLC and Core-Shell (CS) columns’ material characterized by the novel physicochemical properties. Together, properties of 61 columns packed with variable materials have been characterized. The last step comprised the data collection to examine the possibilities to use UHPLC and CS columns materials as equivalent ones to the classical HPLC columns’ materials in view of the method transfer for the previously mentioned assay for alfuzosin.

Abstract: The collapse mechanism of plant oil storage tank was discussed in the paper. Observation made on the site indicated that No. 804 tank collapsed with disintegration. The incomplete penetration area was found by weld macro analysis. Stress intensity factor of crack in the tank which is calculated using the classical theory showed that the main reason for the accident was not the incomplete penetration weld. The hexane vapor explosion is presumably the dominant factor leading to the accident by calculation and analysis. The count measures are also proposed to prevent the similar accidents.

Abstract: The study is focused on the experimental verification of a proposed polynomial stochastic fatigue crack growth model. The model was assumed that the fatigue crack growth rate equals to a deterministic polynomial function multiplied by a stationary lognormal random factor. Compact-tension specimens cut from a 2024-T351 aluminum-alloy plate were used for fatigue crack growth experiments under constant-amplitude loads performed on thirty specimens. The comparison of median crack growth curves was made between analytical and experimental outcomes. For extreme case of lognormal random variable, the comparisons of the fatigue crack growth curve, percentile fatigue crack growth curve, probability of crack exceedance, and distribution function of random time between analytical and experimental results were also investigated.

Abstract: A novel computational model is presented for the representation of polycrystalline grain structures and crystal plasticity finite element model are used to investigate size effect due to grain orientation and number of grains through the thickness, in term of activity of slip system, roll force and the scatter involved. It is predicted that increasing the number of grains through the thickness has detrimental effects on mechanical performance. It is clear from the current study that foil thickness significantly influences the deformation heterogeneity which leads to non-uniform distributions of strain and the inhomogeneous slip systems active in the cold rolled samples. It is found that the decrease of roll force and slip systems activities in surface grains are caused by the increasing of free surface grain effect when the thickness is decreased.

Abstract: To estimate the precise mechanical properties of the three-dimensional (3D) braided composite, a geometric study is needed. Owing to the complexity of the yarn paths inside the preform, the geometric modeling for 3D braided composite is always time consuming. In this paper, an efficient method, namely preform boundary reflection (PBR) method, is proposed for motion model construction in geometric study. Furthermore, the CAD simulation system was developed for integral geometric descriptions of 3D braided preform with different parameters. Compared with the traditional method, the novel method significantly simplifies the simulation process without affecting the precision of geometric structure. As a result, the structure design for composite preform is effectively accelerated. The new method establishes the foundation of microstructure and mechanical properties analysis for the preforms with complex geometric structures.

Abstract: In the general practice of ED-XRF measurements, the values of elemental concentrations are derived from complicated calculation methods. Hereby a simple mathematical formula is suggested, which provides an easy way to prepare standard samples. On the other hand, the simulation of spectral lines may also be a helpful tool for the calibration process. In this study, measured and simulated data were used for the quantitative analysis of ternary Au-Ag-Cu alloys. To determine the calibration points, the peak intensity ratio method was applied and the calibration curves were fitted. This work presents the results of a twofold investigation aimed at: a) finding a suitable computational tool to optimise the parameters of the underlying equations and b) testing the reliability of the simulated data to determine the concentrations of multi-element standard samples. Based on comparisons of calculated concentrations it can be stated that a simple calculation method with simulated data provides an easy tool to define calibration standards. It is also demonstrated that the parameters of the linear plots can be optimised to yield improved results.

Abstract: This article introduces a semi-analytical numerical method ——method of lines(MOLs) to solve steady temperature field of Laser Engineered Net shaping (LENS). The main idea of MOLs is to semi-discretized the governing equation of thermal transfer problem into a system of ordinary differential equations (ODEs) defined on discrete lines by means of the finite difference method. The steady linear temperature fields of functionally graded materials were obtained using MOLs and the regularities of different temperature functions were also found. The effects of thermal conductivity coefficient under different formal functions on thermal temperature fields were analys. Numerical results showed that different material thermal conductivity function had obvious different effect on the temperature field.