Electrochemical aspects of the immersion treatment of aluminium

The processes occurring during zinc immersion plating of aluminium have been studied in alkaline medium. The mechanism of immersion zinc deposition on aluminium has been elucidated by studying the kinetics of the partial electrode reactions involved in this complex process. The diffusion of zincate ions has been shown to play a decisive role on the cathodic reaction kinetics as well as on the global (cathodic and anodic) reaction rate.     

Directional analysis of planar fibre networks: Application to cardboard microstructure

This paper discusses the problem of determining suitable roses of intersections for systems of planar thick fibres which cross and overlap. A planar Boolean model with long rectangular (or similar) grains is suggested as an appropriate mathematical model. It leads to a statistical estimator for the rose of intersections of the system of fibre spines. The method is used to analyse the microstructure of the outer layer of two samples of cardboard.     

ADHESION CHARACTERISTICS OF ISOLATED WAX SUBSTANCES FROM FRUIT CUTICLES RELATED TO OSMOTIC DEHYDRATION OF WHOLE FRUITS I. EFFECT OF TEMPERATURE AND PRELIMINARY TREATMENT

Adhesion behavior of cuticular wax isolated from cherries, plums and grapes, in a 70% sucrose solution, is the subject of discussion in the present work. Criterion is suggested for estimation of the effectiveness of preliminary treatment and temperature conditions in osmotic treatment of whole fruits. An apparatus is described for the determination of the contact angle θ_slv according to the method of the lying drop. Calculations are made of the energy characteristics, the energy of wetting Wslv and the adhesion work A_slv, of the three phase contact, isolated cuticular wax/70% sucrose solution/air, at temperatures from 20°C to 80°C.     

Statistical characterization of TEM images of silica-filled rubber

Transmission electron microscopy is used to study the micro-dispersion of silica fillers within the polymer matrix of rubber. The resulting grey-value images are interpreted as realizations of random fields and are characterized by means of variograms. The so-called Cauchy class is a suitable model for this purpose. Statistical analysis shows that different filler dispersion properties are reflected in different variogram parameters. As a case study, the random field approach is demonstrated for four exemplary rubber compounds.     

Second-order stereology of spatial fibre systems

This paper describes methods for second‐order stereology of spatial fibre systems. For stationary and isotropic fibre processes it gives practicable estimators of the K‐function and the pair correlation function, which are based on planar sections. The second‐order methods are applied in transmission electron microscopy analysis of blood capillaries in the rat thyroid. They lead to the result that the capillaries show an inhibitory pattern of their spatial arrangement, with a hard‐core distance of about 2.6 µm. There is a close relationship to three‐dimensional size characteristics estimated recently for these elliptical capillaries.     

Methods for crack opening load and crack tip shielding determination: a review

In this paper a review of the literature on crack closure/opening load and crack tip shielding effects determination methods is presented. Commonly used ‘subjective’ (visual) and ‘non‐subjective’ approaches have been included. Procedures associated with the determination of an effective crack driving force for both Elber type and that of partial (or incremental) crack closure models have been covered. Comparison among different methods of analyses based on compliance and fatigue crack growth rate measurements is discussed together with their implications and difficulties in fatigue crack growth correlations.     

Reconstruction of random heterogeneous media

Stochastic reconstruction is a technique to generate samples of random structures with prescribed distributional properties in the sense that certain of their statistical summary characteristics match target values or forms. This technique can be used to produce structures of any wanted size for further statistical analysis starting from small samples, which may be even only lower dimensional, for instance, when three‐dimensional imaging techniques are not available. In this review we explain the main ideas of stochastic reconstruction, concentrating on the most important case of digitized binary media and with a particular emphasis on stereological reconstruction.     

Effects of spectrum modification on fatigue crack growth

The purpose of this study was to investigate experimentally the effects associated with modification of a loading spectrum recorded from P‐3 a maritime aircraft on fatigue crack growth behaviour. The material is 2324‐T39 Al alloy widely used in the aircraft industry. Experiments were conducted using the full spectrum and modified versions of it such as only ‘positive’ (no negative loads) or with reduced (clipped) high peaks. The results show that the compressive loads decrease fatigue life of the specimen by ∼300%. Furthermore, by running tests with clipped peaks it was found that the fatigue life was shorten significantly due to reduction of crack growth retardation caused by highest tensile peaks. Multiple tests were conducted in order to establish a scatter in the experimental data under spectrum loads.