Simulation and optimization of calculation of glued joints

A cylindrical structure weakened by a cut under internal pressure is used as an example for developing a technique of numerical calculation of glued joints taking into account nonlinear properties of the glue material. Calculations for two types of glues, i.e., hard and elastic, are performed. A technique for optimizing the cover-plate structure is obtained. Dependences of maximal stress in the glued layer on cover plate and pipe diameters and pressure are studied. A method for achieving more accurate calculation results using multipoint constraint in the region of junction of plane and volume finite elements is demonstrated.     

Effect of surface preparation of ABM-1 alloy on properties of glued joints

The possibility of using the bonding method to assemble beryllium ABM-1 alloy has been analyzed. Recommendations are given in relation to the types of film adhesives for bonding parts. It has been established that the soundest results in regards to strength properties and anticorrosion protection can be achieved through the anodic oxidation of alloy’s surface and an additional application of an EP-0214 coat.     

Modification of the peel test for testing of rubber-to-rubber joints

A method is described here for testing of rubber to rubber joints. This involves the modification of the 180° peel test by using a perforated plastic sheet at the interface. Filled and unfilled natural rubber to natural rubber, polybutadiene to polybutadiene, and natural rubber to polybutadiene joints have been tested using the method. It has been observed that the method is very useful for testing of all rubber to rubber joints, especially for filled rubber to filled rubber and unfilled natural rubber to natural rubber joints which could not be otherwise tested. The test results are reproducible and the variations in the peak forces are reduced. The joints with or without a perforated sheet inside give similar values of work of adhesion when a correction is introduced for width in the case of the former. The energy criteria for rupture do not change with the introduction of the perforated sheet. The sharp plastic sheet prevents tear deviation from the interface.     

Structural studies of fracture patterns in adhesive joints after pullout testing

The adhesive strength of compounds based on epoxy resin ED-20 with the TEAT and PEPA hardeners is determined by pullout testing before and after administering shungite (20 wt %) as filler in their composition. The results of structural studies of the samples after the tests, which allowed determining the fracture type (adhesive or cohesive) and the number of samples that corresponds to each fracture type, are shown.     

Attestation of glued articles by acoustic impedance method

The scope of application and exploitation potencies of two variants of acoustic impedance method are considered. The specialty of the impedance method due to the control of multilayer glued constructions and articles of stratified plastics and effects that restrict the sensitivity of approach are reported. The general recommendations on the control of articles of various types are formulated, as well as the scope and limitations of acoustic impedance method used in the mode with no use of standard samples for equipment setting.     

Control of multilayer glued constructions of polymeric composite materials

The fields of application and operational capabilities of two variants of the acoustic velocimetric method are considered. The peculiarities of temporal and phase techniques of the velocimetric method with control of multilayer adhesive constructions and articles from layered plastics are shown. Factors restricting the control sensitivity are described.     

Insight into the permeation barrier of glued Langmuir-Blodgett bilayers

Permeation measurements have been made for He, CO2, and N2 across single Langmuir-Blodgett (LB) bilayers derived from 1,2,4,5-tetrakis[(N-(undecanoamidoethyl)-N,N-dimethyl ammonium) methyl]benzene tetrabromide (2) and 1,2,4,5-tetrakis[(N-(perfluoroundecanoamidoethyl)-N,N-dimethyl ammonium)methyl]benzene tetrabromide (3) in the absence and in the presence of entrapped poly(acrylic acid) (PAA). In the absence of PAA, single LB bilayers of 3 show a higher permeance for He and N2 but a lower permeation rate of CO2, as compared with analogous LB bilayers made from 2. The relatively low permeation rate of CO2 for the former has been attributed to reduced associative interactions with the fluorocarbon-rich bilayer. The same behavior has also been observed for LB bilayers containing PAA, formed under conditions that yield glued bilayers of 2 and 3 having similar diffusional pathways, as judged by He/N2 selectivities. These results, together with the fact that glued bilayers of 2 (having a thinner PAA layer as compared with those made from 3) exhibit lower He and N2 permeances, provide compelling evidence that the main barrier for gas transport is the combination of surfactant plus PAA and not simply a thin PAA layer that is encased within the surfactant bilayer.     

牛奶的非破坏性分析

牛奶的非破坏性分析任玉林，张滨，逯家辉，邴贵德王克会（吉林大学化学系长春１３００２３）（长春市乳品公司乳品一厂长春）关键词近红外透射反射光谱，牛奶，非破坏性分析在分析牛奶时，所遇到的最大问题是在１１００～２５００ｎｍ区间水的强烈吸收，把脂肪、蛋白和乳...     

Control of glued structures made of dissimilar materials by ultrasound reverberation

This paper considers the physical bases of the ultrasound reverberation method that can detect defects in gluing of double-layer structures made of dissimilar materials, such as metal–plastic and plastic–metal. The advantages and disadvantages of this method are specified. It is shown that the capabilities of the reverberation method significantly expand when using a spectral version of reverberation based on registration of changes in the shape of the envelope of the amplitude spectrum of echo pulses depending on the quality of bonding.     

Evaluation of the humidity state of glued wooden constructions during monitoring

The work presents the research method for determining the humidity of wood in glued structures during their exploitation. The conductometric method serves a basis for the above-mentioned technique, but instead of regular sensors of humidity meter, we suggest the use of special sensors with electrodes of different lengths. It has been shown that the developed method has a number of advantages compared to the gravimetric method for determining wood humidity and can be used to monitor wooden structures during their exploitation with minimal time and labor inputs.     

Exceptional gas permeation selectivity of a glued Langmuir-Blodgett bilayer by pH control

The monolayer properties of 5,11,17,23,29,35-hexakis[(N,N,N-trimethylamonium)-N-methyl-37,38,39,40,41,42-hexakis-n-hexadecyloxy-calix[6]arene hexachloride (1) have been characterized over aqueous solutions of poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) as a function of pH. At high pH values (e.g., pH 10), such monolayers show relatively low surface viscosities. At low pH (e.g., pH 4.4), these monolayers exhibit relatively high surface viscosities. The barrier properties of single Langmuir-Blodgett bilayers of 1, which have been ionically cross-linked (i.e., "glued together") with PAA were found to correlate with changes in surface viscosity. Thus, bilayers that were fabricated under low pH conditions exhibited high permeation barriers and high permeation selectivity with respect to He and N(2). Given the extreme thinness of these glued bilayers (ca. 6 nm), the optimized He/N(2) selectivity of ca. 1000 is extraordinary. These results, taken together, demonstrate the feasibility of fine tuning the surface viscosity of monolayers of 1, and also the barrier properties of corresponding glued bilayers, by adjusting the pH of an aqueous subphase that contains a weak polyacid.     

Nondestructive characterization of nanoscale layered samples

Multilayered samples consisting of Al, Co and Ni nanolayers were produced by MBE and characterized nondestructively by means of SRXRF, μ-XRF, WDXRF, RBS, XRR, and destructively with SIMS. The main aims were to identify the elements, to determine their purity and their sequence, and also to examine the roughness, density, homogeneity and thickness of each layer. Most of these important properties could be determined by XRF methods, e.g., on commercial devices. For the thickness, it was found that all of the results obtained via XRR, RBS, SIMS and various XRF methods (SRXRF, μ-XRF, WDXRF) agreed with each other within the limits of uncertainty, and a constant deviation from the presets used in the MBE production method was observed. Some serious preliminary discrepancies in the results from the XRF methods were examined, but all deviations could be explained by introducing various corrections into the evaluation methods and/or redetermining some fundamental parameters.     

Control of glued structures by the electromagnetic acoustic variant of the impedance method

The functionality of the electromagnetic acoustic variant of the impedance method of controlling multilayer glued structures with metallic casings is studied. It is shown that the main advantage of this variant is the possibility of carrying out control without any direct contact of the working part of the converter with the surface of the examined article.     

Nondestructive analysis of the gold quarter liras

In this study, we have prepared seven Au-Cu standards in the concentration range of 18–24 (as carat) for nondestructive control of gold quarter liras. Some calibration curves for quantitative analysis of Au in the gold quarter liras that commercially present in Turkey have been plotted using these standard samples. The characteristic X-rays of Au and Cu emitted from these standard samples and the test sample with known composition are recorded by using a Ge(Li) detector. These calibration curves provide a nondestructive analysis of gold quarter liras with the uncertainties about 1.18%.     

The effect of heat-moisture aging on elastic-deformation properties and the type of failure of adhesive joints in testing for cracking resistance

Results of testing of two groups of film adhesives that differ in their chemical natures, service temperatures, and elastic-deformation characteristics, such as VK-3, VK-50, and VK-26M phenolic rubber adhesives and high-strength VK-51A epoxy adhesive, are reported. The locus of failure of adhesive joints after wedge tests in the initial state and after heat-moisture aging is studied using a scanning electron microscope. It is revealed that, as result of heat-moisture aging, the locus of failure of adhesive joints changes for VK-51A (with and without EP-0234 primer) and VK-3 adhesives, whereas it remains unchanged for VK-50 (with EP-0234 primer) and VK-26M adhesives.