Increasing single-lap joint strength by adherend curvature-induced residual stresses

Single-lap joint (SLJ) geometry is the most widely used type of adhesive joint geometry. In this joint, peel stresses occur at the overlap ends due to load eccentricity and the presence of shear-free adhesive termination surfaces. These peel stresses, along with the transverse tensile stresses which occur along the overlap longitudinal axes, and adhesive shear stresses, ultimately cause joint failure. Obviously, reductions in these stresses should result in higher joint strength and increased load capacity. To this end, we exploited elastic spring-back capability of (steel) metal adherends by initially forming curved segments of varying arc lengths and radii at overlap ends. These adherends with curved-end sections were then bonded in single-lap configuration, simply by applying sufficient bonding pressure to elastically flatten the curved segments to result in typically flat overlap sections subsequent to adhesive cure and the removal of bonding pressure. Since the elastic adherend overlap ends tend to revert back to their initial curved form, they exert compressive residual stresses on the adhesive layer in the overlap end regions. We determined that the compressive residual stresses induced in this fashion considerably increased the load capacity of SLJs subjected to tension.     

A comparative study on water-based coatings prepared in the presence of oligomeric and conventional protective colloids

Poly(vinyl acetate-co-butyl acrylate) latexes were prepared by using semi-continuous emulsion polymerization method in presence of two different protective colloids which were oligomeric N-methylol acrylamide and conventional poly(vinyl alcohol). The effects of these protective colloids on colloidal, surface and film properties of latexes were examined. Poly(vinyl acetate-co-butyl acrylate) synthesized with oligomeric N-methylol acrylamide, which was characterized by FT-IR, NMR and MALDI-TOF MS, was found to have lower viscosity, finer particle size, better latex stability, lower polydispersity, higher T_g and better film forming behavior compared to those synthesized from the poly(vinyl alcohol).     

Effects of use of higher strength interlayer and external cooling on properties of friction stir welded AA6061-T6 joints

Although sound AA6061-T6 joints can be produced by friction stir welding, a loss in strength takes place in the weld region. In this study, it was demonstrated that the strength of the nugget could be increased by the use of a higher strength interlayer during friction stir welding. This strength recovery cannot, however, be attainable in the heat affected zone. Although an external cooling was applied during welding in order to increase strength in the heat affected zone, it was not sufficient for achieving the required cooling condition for improved strength.     

New Evaluated Semi-Empirical Formula Using Optical Model for 14–15 MeV (<Emphasis Type="Italic">n</Emphasis>, <Emphasis Type="Italic">t</Emphasis>) Reaction Cross Sections

In the next century the world will face the need for new energy sources. Nuclear fusion can be one of the most attractive sources of energy from the viewpoint of safety and minimal environmental impact. Fusion will not produce CO₂ or SO₂ and thus will not contribute to global warming or acid rain. Achieving acceptable performance for a fusion power system in the areas of economics, safety and environmental acceptability, is critically dependent on performance of the blanket and diverter systems which are the primary heat recovery, plasma purification, and tritium breeding systems. Tritium self-sufficiency must be maintained for a commercial power plant. The hybrid reactor is a combination of the fusion and fission processes. For self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. So working out the systematics of (n, t) reaction cross-sections are of great importance for the definition of the excitation function character for the given reaction taking place on various nuclei at energies up to 20 MeV. In this study, we have calculated non-elastic cross-sections by using optical model for (n, t) reactions at 14–15 MeV energy. We have investigated the excitation function character and reaction Q-values depending on the asymmetry term effect for the (n, t) reaction cross-sections. We have obtained new coefficients for the (n, t) reaction cross-sections. We have suggested semi-empirical formulas including optical model nonelastic effects by fitting two parameters for the (n, t) reaction cross-sections at 14–15 MeV. We have discussed the odd–even effect and the pairing effect considering binding energy systematic of the nuclear shell model for the new experimental data and new cross-sections formulas (n, t) reactions developed by Tel et al. We have determined a different parameter groups by the classification of nuclei into even–even, even–odd and odd–even for (n, t) reactions cross-sections. The obtained cross-section formulas with new coefficients have been discussed and compared with the available experimental data.     

Calculations of neutron-induced production cross-sections of W up to 20 MeV

Neutron-induced cross-sections for the stable isotopes ^{180,182,183,184,186}W in the energy region up to 20 MeV have been calculated. Calculations were made with the codes CEM03.01 and ALICE/ASH, using the following models: the Dubna version of the intranuclear cascade model for the cascade stage of interaction; the hybrid, the geometry dependent hybrid and the exciton model for the pre-equilibrium component; the Hauser–Feshbach and the Weisskopf–Ewing statistical models for the equilibrium component. Effects of some important model parameters such as level density parameter and pairing correction were investigated. Calculated cross-sections were compared with available experimental data in the literature and with ENDF/B-VI T = 300 K and JENDL-3.3 T = 300 K evaluated data libraries.     

An integrated approach to machine selection and operation allocation problem

Machine selection and operation allocation is a multi-criteria decision-making problem which involves the consideration of both qualitative and quantitative factors. Thus, a hybrid model integrating the knowledge-based expert system and the genetic algorithm may be effectively applied to the decision problem. This paper proposes a two-step approach where suitable machines for every operation in a work center is selected and optimized as a whole to obtain the optimum machine park. The first step of the model determines the suitability of each machine type for every operation using the knowledge-based expert system. The second stage searches through the solution space to find the optimal machine park with the use of a genetic algorithm. A real-life case study at an outdoor advertisement manufacturing company demonstrates the applicability of the model.     

The effect of replacing fat with oat bran on fatty acid composition and physicochemical properties of meatballs

Oat bran was used as a fat substitute in the production of meatballs. The effect of oat bran addition on the fatty acid composition, trans fatty acids, total fat, some physicochemical and sensory properties of the samples was studied. Meatballs were produced with four different formulations; the addition of 5, 10, 15 and 20% oat bran. Control samples were formulated with 25% fat addition as in commercial production. The major fatty acids were cis-oleic, palmitic and stearic acid in all the meatball samples, those with oat bran added as well as the control. Meatballs containing oat bran had lower concentrations of total fat and total trans fatty acids than the control samples. Meatballs made with 20% oat bran had the highest protein, salt and ash contents, L value (lightness), b value (yellowness), and the lowest moisture content and a value (redness). There was no significant difference among the meatball samples with respect to sensory properties, and all samples had high acceptability.     

Determination of industrial pollution effects on citrus honeys with chemometric approach

The aim of this study was to determine the levels of essential, trace and toxic elements, such as K, Ca, Fe, Cu, Al, Ni, Sn, Pb and Cd in citrus honeys from different regions (industrialized and nonindustrialized) of Hatay, Turkey. K, Ca, Na and Mg were the most abundant elements, with mean contents of 363.5, 256.6, 88.1 and 37.7 mg/kg, respectively. The trace element mean contents ranged between 0.032 and 15.58 mg/kg. Significant differences in Fe, Cu, Al, Ni, Sn, Pb, Cd, Co and Sr levels were observed between two different regions. The findings that Fe, Cu, Al, Ni, Sn, Pb, Cd, Co and Sr contents in citrus honeys from industrialized regions were higher than citrus honeys from non-industrialized regions indicate that the honeys were affected by industrial pollution. Chemometric methods were applied to classify honey according to mineral content. Cluster analysis showed three clusters corresponding to the three different regions.     

Using dairy ingredients to alter texture of foods: Implications based on oral processing considerations

Food quality is directly linked to the food's appearance, texture and flavor. All three components must be in harmony for the food to be considered delicious. Understanding how various textures can be designed requires a comprehensive approach of evaluating food structure, oral processing and sensory evaluation. Oral processing considers the physiological processes in first bite, mastication and swallowing. Sensory stimuli during oral processing are used to determine the acceptance of texture. Recent research has focused on how milk proteins can be used to create desirable textures. Whey protein–polysaccharide mixtures were used to show how microstructure can be manipulated to produce a range of textures and control water release. The importance of microstructure in determining a variety of texture terms was demonstrated in whey protein emulsion gels. Finally, fat content in Cheddar cheese was shown to be critical to producing a desirable breakdown pattern. These and other applications will be discussed.