Disappearance of stretch-induced wrinkles of thin sheets: a study of orthotropic films

A recent paper (Healey et al., J. Nonlin. Sci., 2013, 23:777-805.) predicted the disappearance of the stretch-induced wrinkled pattern of thin, clamped, elastic sheets by numerical simulation of the F\"oppl-von K\'arm\'an equations extended to the finite in-plane strain regime. It has also been revealed that for some aspect ratios of the rectangular domain wrinkles do not occur at all regardless of the applied extension. To verify these predictions we carried out experiments on thin 20 micrometer thick adhesive covered), previously prestressed elastomer sheets with different aspect ratios under displacement controlled pull tests. On one hand the the adjustment of the material properties during prestressing is highly advantageous as in targeted strain regime the film becomes substantially linearly elastic (which is far not the case without prestress). On the other hand a significant, non-ignorable orthotropy develops during this first extension. To enable quantitative comparisons we abandoned the assumption about material isotropy inherent in the original model and derived the governing equations for an orthotropic medium. In this way we found good agreement between numerical simulations and experimental data. Analysis of the negativity of the second Piola-Kirchhoff stress tensor revealed that the critical stretch for a bifurcation point at which the wrinkles disappear must be finite for any aspect ratio. On the contrary there is no such a bound for the aspect ratio as a bifurcation parameter. Physically this manifests as complicated wrinkled patterns with more than one highly wrinkled zones on the surface in case of elongated rectangles. These arrangements have been found both numerically and experimentally. These findings also support the new, finite strain model, since the F\"oppl-von K\'arm\'an equations based on infinitesimal strains do not exhibit such a behavior.Comment: 16 pages, 5 figure

Parallels And Contrasts Between Indonesian And Hungarian Contemporary Art (Considering The History Of Art)

Comparing different cultures can give us a new perspective on how we look at the world we see and the art within it. My research is about the differences and similarities between Hungary and Indonesia, both in the personal fields and in the national aspect. After experiencing the reception and creation of art in both countries, I can draw a conclusion and use my experience in my further works. In the following pages I contrast two not only distant cultures but very different contemporary art through the works of well-known artists. However, another important part of the research is to find the similarities and the phenomenon that connects these two particular civilizations. The question arose in me as to whether it was possible to find aspects that could be found in both places. Art is global, the aim is the same. What is the purpose of art? Each country and each individual finds the answer to this central question on its own. What provided the foundations for contemporary art in Europe? Is sacredness present in art nowadays?Membandingkan budaya yang berbeda dapat memberi perspektif baru tentang bagaimana dunia dipandang beserta seni yang ada didalamnya. Penelitian ini mengenai perbedaan dan persamaan antara Hungaria dan Indonesia, baik dalam aspek pribadi maupun dalam bidang nasional. Setelah mengalami resepsi dan penciptaan seni di kedua negara, dapat ditarik kesimpulan dan menggunakan pengalaman peneliti dalam karya-karya selanjutnya. Pada bagian berikutnya, dilakukan perbandingan mengontraskan tidak hanya dua budaya yang jauh, tetapi juga seni kontemporer yang sangat berbeda melalui karya-karya seniman terkenal. Namun, bagian penting lain dari penelitian ini adalah menemukan persamaan dan fenomena yang menghubungkan dua peradaban tertentu ini

The Mullins effect in the wrinkling behavior of highly stretched thin films

Recent work demonstrates that finite-deformation nonlinear elasticity is essential in the accurate modeling of wrinkling in highly stretched thin films. Geometrically exact models predict an isola-center bifurcation, indicating that for a bounded interval of aspect ratios only, stable wrinkles appear and then disappear as the macroscopic strain is increased. This phenomenon has been verified in experiments. In addition, recent experiments revealed the following striking phenomenon: For certain aspect ratios for which no wrinkling occurred upon the first loading, wrinkles appeared during the first unloading and again during all subsequent cyclic loading. Our goal here is to present a simple pseudo-elastic model, capturing the stress softening and residual strain observed in the experiments, that accurately predicts wrinkling behavior on the first loading that differs from that under subsequent cyclic loading. In particular for specific aspect ratios, the model correctly predicts the scenario of no wrinkling during first loading with wrinkling occurring during unloading and for all subsequent cyclic loading.Comment: 15 pages, 9 figure

Disappearance of stretch-induced wrinkles of thin sheets: a study of orthotropic films

A recent paper [Healey et al., J. Nonlin. Sci., 2013, 23, 777-805.] predicted the disappearance of the stretch-induced wrinkled pattern of thin, clamped, elastic sheets by numerical simulation of the Föppl-von Kármán equations extended to the finite in-plane strain regime. It has also been revealed that for some aspect ratios of the rectangular domain wrinkles do not occur at all regardless of the applied extension. To verify these predictions we carried out experiments on thin (20 µm thick adhesive covered) elastomer sheets with different aspect ratios under displacement controlled pull tests. We found that the wrinkled shapes are strongly influenced by the emerging orthotropy during the extension. To carry out quantitative comparisons we abandoned the assumption about material isotropy and derived the governing equations for an orthotropic medium. In this way we found good agreement between numerical simulations and experimental data. Analysis of the negativity of the second Piola-Kirchhoff stress tensor showed that the critical stretch for a bifurcation point at which the wrinkles disappear must be finite for any aspect ratio. On the other hand, there is no such a bound for the aspect ratio as a bifurcation parameter. Physically this manifests as complicated wrinkled patterns with more than one highly wrinkled zones on the surface in case of elongated rectangles. These arrangements have been found both numerically and experimentally. These findings also support the new, finite strain model, since the Föppl-von Kármán equations based on infinitesimal strains do not exhibit such a behavior

Wrinkling patterns of thin films under finite membrane strain

There is a wide interest in understanding phenomena related to thin and ultrathin surfaces, such as wrinkling, cresting or folding. The classical Föppl-von Kármán plate theory is extensively used to model such phenomena. Significant in-plane strains demand the extension of the classical FvK model. The extended theory predicts the disappearance of wrinkling in the case of rectangular, clamped, stretched sheets, which was verified on thin, polyurethane sheets. In this talk we further develop the model for curved surfaces and present problems, where the extension to the finite tangential strains is essential to investigate the arising wrinkling pattern. By numerical simulation of the governing nonlinear system of PDEs, we investigate the effect of the curvature of the reference configuration on the emerging wrinkling pattern and demonstrate that disappearance of wrinkles takes place on curved surfaces, as well

Obi-ugor morfológiai elemzők és korpuszok = Ob-Ugric morphological analyzers and corpora

A projekt obi-ugor szövegek rögzítéséből, a megelemzésükhöz szükséges morfológiai elemzők építéséből és azok részleges (mutatvány céljait szolgáló) morfológiai egyértelműsítését tűzte ki maga elé céljául. A projekt céljait lényegében elérte. - A ChrVog szövegeinek egyértelműsítése elkészült, az egyértelműsítés során felbukkant hibák javítva lettek. - A WT szövegeit rögzítettük, elemzője elkészült, az egyértelműsítés folyamatban van. - A VNGY szövegeit rögzítettük, elemzője elkészült, minor hibák javítása további fejlesztést igényel, a minta egyértelműsítése folyik. - A kazimi szövegeket rögzítettük, elemző elkészült, az egyértelműsítés elkészült, az egyértelműsítés során felbukkant hibák ki lettek javítva, az újraegyértelműsítés folyamatban van. - A szinjai elemző elkészült, az egyértelműsítés elkészült, az egyértelműsítés során felbukkant hibák ki lettek javítva, az újraegyértelműsítés elkészült. Egyes homályos alakok tisztázása terepen jelenleg folyik. | The main aim of the project was to digitize Ob-Ugric texts, to develop morphological analyzers able to analyze all the word forms occuring in them, to disambiguate sample texts for demonstration. In general, all these aims were achieved. - The texts of ChrVog were disambiguated, the errors found during diasambiguation were corrected. - The text of the WT were digitized, the morphological analyzer is ready, the disambiguation is in progress. - The text of the VNGY were digitized, the morphological analyzer is ready, some minor errors have to be corrected, the disambiguation is in progress. - The Kazym Khanty texts were digitized, the morphological analyzer is ready, the disambiguation has been done, mistakes found during disambiguation are corrected, a new disambiguation process is in progress. - The Synya Khanty morphological analyzer is ready, the disambiguation has been done, mistakes found during disambiguation are corrected, a new disambiguation was made. Some issues arose during the research are examined currently on the field

Bracketing the age of freshwater carbonate formation by OSL dating near Lake Kolon, Hungary

Freshwater carbonates are unique depositions in the centre of the Carpathian Basin, with debated origin and age. Their formation on the sand covered area of the Danube-Tisza Interfluve is mainly related to lakes appearing in low lying interdune areas from time-totime. Carbonate deposition is governed by various processes, but in general it can be traced back to climatic and concomitant surface and subsurface hydrological variations. Therefore marl, limestone and dolomite layers can be a marker of environmental change. To identify the type of environmental change they may indicate absolute or numerical ages are needed. In previous studies this issue has been addressed by the means of radiocarbon dating. In the present study we attempted to bracket the age of freshwater carbonate formation with the help of optically stimulated luminescence dating and compared our results to radiocarbon data from the literature. In general, the luminescence properties of the investigated samples proved to be suitable for determining the age of the bedding and covering sediments. OSL dates confirmed previous interpretations that freshwater carbonate formation in the area could have a peak around 10,5 ka. However, the termination of the deposition could not be unambiguously determined at the present stage of the analysis. The compound geomorphology and sedimentology of the study area call for further investigations