310,222 research outputs found

    One-adhesive polymatroids

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    Adhesive polymatroids were defined by F. Mat\'u\v{s} motivated by entropy functions. Two polymatroids are adhesive if they can be glued together along their joint part in a modular way; and are one-adhesive, if one of them has a single point outside their intersection. It is shown that two polymatroids are one-adhesive if and only if two closely related polymatroids have any extension. Using this result, adhesive polymatroid pairs on a five-element set are characterized

    Factors Affecting the Processing of Epoxy Film Adhesives

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    The increasing awareness that adhesive performance is controlled not only by the condition of the adherend surface but also the condition or state of the adhesive and the process parameters used during fabrication is expected to result in improved reliability, as well as bond performance. The critical process variables which have been found to control adhesive bond formation and ultimate bond strength in 250F and 350F curing epoxy adhesives are described in terms of fabrication parameters and adhesive characteristics. These include the heat-up rate and cure temperature during processing and the adhesive moisture content and age condition (degree of advancement). The diagnostic methods used to delineate the effects of these process variables on adhesive performance are illustrated. These are dielectric, thermomechanical (TMA) and dynamic mechanical (DMA) analyses. Correlation of test results with measured mechanical tensile lap shear strengths of bonded joints is presented and the results briefly discussed in terms of the additives and hardeners used in the adhesive systems

    Plastic covering on airfoil structure provides smooth uninterrupted surface

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    Primed surface is covered with adhesive. Sheet of plastic film is stretched over adhesive and mechanical holder is used to apply tension to ends of sheet to make it conform to surface of airfoil. After adhesive cures, plastic can be trimmed with sharp cutting tool

    Studies on fatigue behaviour of weld-bonds of Al-Mn-Mg alloy

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    In the present paper, fatigue and metallurgical behaviour of weld-bonds and adhesive bonds developed using 2 mm thick aluminium alloys namely 5052 alloy have been reported. Weld-bonds were prepared using structural adhesive (Epoxy resin) and spot welding (20 kA welding current for 6 cycles welding time at welding pressure of 0.5 MPa). Curing after applying Epoxy resin for developing adhesive bonds and weld bonds was performed at a temperature of 100 oC for 90 min. Fatigue tests were conducted under tension–shear loading pattern with stress ratio of 0.5 and loading frequency of 5 Hz. The maximum tensile shear load for fatigue test was kept at different level i.e. 90%, 80%, 70% and 50% of the ultimate shear tensile strength of weld bond and adhesive bonds. The fatigue lives of both adhesive bond and weld-bond joints decreased with increase in maximum tensile shear load. Fatigue performance of weld bond was higher than adhesive bond especially at high load

    Nonwoven glass fiber mat reinforces polyurethane adhesive

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    Nonwoven glass fiber mat reinforces the adhesive properties of a polyurethane adhesive that fastens hardware to exterior surfaces of aluminum tanks. The mat is embedded in the uncured adhesive. It ensures good control of the bond line and increases the peel strength

    Surface finishing

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    A surface of an article adapted for relative motion with a fluid environment is finished by coating the surface with a fluid adhesive. The adhesive is covered with a sheet of flexible film material under tension, and the adhesive is set while maintaining tension on the film material

    Development of the weldbond process for joining titanium

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    High quality resistance spot welds were produced by welding through epoxy adhesive on titanium alloys. Weldbond joints were consistently stronger than those of either mechanical fasteners, structural adhesive bonds, or mechanical fasteners with adhesive at the joint interface. Weldbond joints and/or spot weld joints showed superior strength at all temperature ranges as compared to other joints tested

    An embedding theorem for adhesive categories

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    Adhesive categories are categories which have pushouts with one leg a monomorphism, all pullbacks, and certain exactness conditions relating these pushouts and pullbacks. We give a new proof of the fact that every topos is adhesive. We also prove a converse: every small adhesive category has a fully faithful functor in a topos, with the functor preserving the all the structure. Combining these two results, we see that the exactness conditions in the definition of adhesive category are exactly the relationship between pushouts along monomorphisms and pullbacks which hold in any topos.Comment: 8 page
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