Triple correlation for detection of damage-related nonlinearities in composite structures

Nonlinear effects in vibration responses are investigated for the undamaged composite plate and the composite plate with a delamination. The analysis is focused on higher harmonic generation in vibration responses for various excitation amplitude levels. This effect is investigated using the triple correlation technique. The dynamics of composite plate was modelled using two-dimensional finite elements and the classical lamination theory. The doubled-node approach was used to model delamination area. Mode shapes and natural frequencies were estimated based on numerical models. Next, the delamination divergence analysis was used to obtain relative displacements for delaminated plies. Experimental modal analysis test was carried out to verify the numerical models. The two strongest vibration modes as well as two vibration modes with the smallest and largest motion level of delaminated plies were selected for nonlinear vibration test. The Fisher criterion was employed to verify the effectiveness and confidence level of the proposed technique. The results show that the method can be used not only to reveal nonlinearities, but also to reliably detect impact damage in composites. These results are confirmed using the statistical analysis

Study of ultrathin Pt/Co/Pt trilayers modified by nanosecond XUV pulses from laser-driven plasma source

We have studied the structural mechanisms responsible for the magnetic reorientation between in-plane and out-of-plane magnetization in the (25 nm Pt)/(3 and 10 nm Co)/(3 nm Pt) trilayer systems irradiated with nanosecond XUV pulses generated with laser-driven gas-puff target plasma source of a narrow continuous spectrum peaked at wavelength of 11 nm. The thickness of individual layers, their density, chemical composition and irradiation-induced lateral strain were deduced from symmetric and asymmetric X-ray diffraction (XRD) patterns, grazing-incidence X-ray reflectometry (GIXR), grazing incidence X-ray fluorescence (GIXRF), extended X-ray absorption fine structure (EXAFS) and transmission electron microscopy (TEM) measurements. In the as grown samples we found, that the Pt buffer layers are relaxed and that the layer interfaces are sharp. As a result of a quasi-uniform irradiation of the samples, the XRD, EXAFS, GIXR and GIXRF data reveal the formation of two distinct layers composed of Pt1-xCox alloys with different Co concentrations, dependent on the thickness of the as grown magnetic Co film but with similar ∼1% lateral tensile residual strain. For smaller exposure dose (lower number of accumulated pulses) only partial interdiffusion at the interfaces takes place with the formation of a tri-layer composed of Co-Pt alloy sandwiched between thinned Pt layers, as revealed by TEM. The structural modifications are accompanied by magnetization changes, evidenced by means of magneto-optical microscopy. The difference in magnetic properties of the irradiated samples can be related to their modification in Pt1-xCox alloy composition, as the other parameters (lateral strain and alloy thickness) remain almost unchanged. The out-of-plane magnetization observed for the sample with initially 3 nm Co layer can be due to a significant reduction of demagnetization factor resulting from a lower Co concentration

Role of heat accumulation in the multi-shot damage of silicon irradiated with femtosecond XUV pulses at a 1 MHz repetition rate

The role played by heat accumulation in multi-shot damage of silicon was studied. Bulk silicon samples were exposed to intense XUV monochromatic radiation of a 13.5 nm wavelength in a series of 400 femtosecond pulses, repeated with a 1 MHz rate (pulse trains) at the FLASH facility in Hamburg. The observed surface morphological and structural modifications are formed as a result of sample surface melting. Modifications are threshold dependent on the mean fluence of the incident pulse train, with all threshold values in the range of approximately 36-40 mJ/cm². Experimental data is supported by a theoretical model described by the heat diffusion equation. The threshold for reaching the melting temperature (45 mJ/cm²) and liquid state (54 mJ/cm²), estimated from this model, is in accordance with experimental values within measurement error. The model indicates a significant role of heat accumulation in surface modification processes

Use of polymer plastic recyclings in the automotive industry

W artykule omówiono temat zagospodarowania odpadów tworzyw polimerowych, otrzymanych w drodze procesów technologicznych oraz zużycia wyrobu. Przedstawiono metody recyklingu materiałowego, surowcowego i energetycznego oraz dokonano przeglądu prawnych ustaleń dotyczących gospodarki odpadami. Ponadto podano przykłady zastosowania w/w odpadów w ponownym procesie wytwarzania komponentów stosowanych w motoryzacji oraz środowisku ruchu drogowego oraz przeprowadzono badania wpływu wykorzystania regranulatu do produkcji tych części.The article discusses the problem of waste management of polymeric plastics, obtained by technological processes and product wear. The methods of polymer waste management, including the recycling of materials, raw materials and energy, have been presented and the legal framework for waste management has been reviewed. Further examples of application of the aforementioned waste in the reprocessing of the components used in the accreditation and the traffic environment were also given, and the impact of the use of the regranulate on the production of those parts was investigated

Analysis of complex constructions of optotelecommunication micro-ducts

W artykule zaprezentowano przykład analizy konstrukcji optotelekomunikacyjnych mikro-kanałów o kształtach złożonych. Przedstawiono ideę stosowania tego typu wytworów oraz wskazano nowe ich cechy funkcjonalne, które mogą znaleźć zastosowanie w różnych dziedzinach techniki. Na przykładzie wytłoczyn w postaci zespołu z trzema mikro-kanałami przedyskutowano możliwości zmian konstrukcyjnych w wytworze złożonym. Podstawowym kryterium do porównań była ilość materiału potrzebna do uzyskania wymaganej konstrukcji.In the paper the example of construction of opto-telecommunication ducts with diverse cross-sections was analyzed. The idea of applying this type of products was presented. Their new functional features that could be used in different technology fields were pointed out. Basing on a compound product with three micro-channels, the possibilities of some improvements in the construction of such complex products were discussed. The main criterion in the comparison of different analyzed models was the amount of material which is necessary to obtaining a specific construction

Characteristic of injection molding method in medical applications

W artykule przedstawiono charakterystykę i możliwości wykorzystania metody przetwórstwa tworzyw polimerowych do zastosowań medycznych. Dokonano porównań różnych sposobów uplastyczniania na przykładzie wtryskiwania, ilustrując wady i zalety każdego z nich. Przedstawiono wpływ rodzaju materiału formy wtryskowej na jakość wypraski oraz przykłady maszyn przetwórczych do wytwarzania wyprasek stosowanych w protetyce.The article presents the characteristics and possibilities of using polymer processing methods for medical applications. There have been comparisons of different ways of plasticization on the example of the injection, illustrating the advantages and disadvantages of each. Shows the effect of the type of mold material on the molded part quality, and examples of processing machinery for the manufacture of molded parts used in dental systems

Analysis and research of polymer-gypsum mortar with increased flexibility

Intensywne poszukiwania kompozytów i mieszanin polimerowych wynikają z potrzeby otrzymania nowych materiałów o polepszonych właściwościach lub specjalnych cechach użytkowych. Do gipsu lub cementu mogą być wprowadzane różne napełniacze. Z uwagi na to, że gips i cement są materiałami wiążącymi, powszechnie stosowanymi w budownictwie, w modelarstwie, stomatologii, chirurgii i sztukatorstwie, mogą one wpływać na poprawę wybranej cechy lub określonych właściwości wyrobu. Zaprawy gipsowe mają określoną wytrzymałość mechaniczną, którą można oznaczyć podczas badań zginania i ściskania lub wyznaczając czas wiązania (twardnienia). W celu rozszerzenia przydatności spoiw gipsowych do zastosowań w budownictwie, podjęto próbę zmiany ich wytrzymałości na zginanie oraz przyspieszenie czasu wiązania, poprzez zastosowanie domieszek polimerowych. Domieszki polimerowe w postaci regranulatu polietylenowego oraz regranulatu gumy wprowadzono w różnych proporcjach do mieszaniny z gipsem.Intensive research for composites and polymer blends arising from the need to obtain new materials with improved properties and special functional properties. Accessories made of recycled materials or rubber can be incorporated into a variety of materials, including gypsum or cement. Due to the fact that these binding materials are commonly used in construction, scale-modeling, stomatology, surgery and stucco work they can affect the improvement of selected features or specific properties of parts. Gypsum mortars have a certain mechanical strength which can be adjusted during bending and compression tests or by determining the setting time (hardening). In order to expand the usefulness of gypsum binders for their application in the construction industry, an attempt has been made to increase the value of selected indicators of strength and to shorten setting time due to the use of polymer additives. Polymer admixtures in the form of rubber granulate and polyethylene granulate have been added in different proportions into mixtures with gypsum

Zastosowanie transformaty falkowej do identyfikacji parametrów modalnych układów niestacjonarnych

In the paper an application of a time-frequency signal analysis technique for modal parameters identification is presented. Procedures of wavelet filtering, which allow estimating mechanical parameters for systems with non-constant parameters have been shown. The wavelets are used to detect natural frequency of the system and transform system time response into the time-scale domain. Presented method has been verified on simulation data for a two degrees of freedom discrete system. Two cases have been considered, with a constant and with a varying damping. The procedure has been applied to a real data recorded during a flight of ISKRA airplane.W artykule przedstawiono możliwość zastosowania transformaty falkowej do identyfikacji parametrów modalnych układów mechanicznych. Pokazano procedury filtracji falkowej pozwalającej na wyznaczanie parametrów dynamicznych układów wykazujących niestacjonarność. Metodę zweryfikowano na danych symulacyjnych dla układu o dwóch stopniach swobody ze zmiennym tłumieniem. Opracowaną metodę zastosowano do badania zmian tłumienia w czasie lotu samolotu ISKRA