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Deceleration behavior of multi‑layer cork composites intercalated with a non‑Newtonian material

Sheikhi Mohammad Rauf, Gürgen Selim

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 1

art. no. e2, 2023

EN

Impact or sudden accelerations are strictly avoided by sensitive systems such as electronic devices, robotic structures and unmanned aerial vehicles (UAVs). In order to protect these systems, various composites have been developed in recent years. Due to its excellent energy absorbing capabilities as well as eco-friendly and sustainable properties, cork is one of promising materials dedicated to protective applications. In this study, we beneft from cork agglomerates in multi-layer design considering its advantages such as high fexural stifnesstoweight ratio and good buckling resistance over monolithic structures. In addition, a non-Newtonian material, namely shear thickening fuid (STF) was incorporated in this design. STF shows rapid increase in its viscosity under loading and thereby enabling a stifer texture that contributes to protective performance. At rest state, STF exhibit fuidic behavior and provides fexibility for composite. In the experimental stage, deceleration behavior of these composites was investigated. According to the analyses, STF exhibits promising results to lower peak decelerations while extending time period of deceleration under impact loading. STF contribution is pronounced by using this material in a closed medium such as in wrapped foam to avoid spilling out of composite during impact. The designed eco-friendly smart composites are suggested to cover internal parts in sensitive systems. Micro-mobility helmet is another prospective application area for cork/STF structures since they provide light-weight, excellent fexibility and good deceleration behavior.

2

Fracture toughness, wear, and microstructure properties of aluminum/titanium/steel multi-laminated composites produced by cross-accumulative roll-bonding process

Wang Yaping, Tayyebi Moslem, Assari Amirhossein

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e49, 2022

EN

For more than a decade many researchers have been developing new ways to produce laminated composites. In this paper, aluminum/titanium/steel multi-laminated composites were fabricated by the cross accumulative roll bonding (CARB) process, and effects of different rolling passes on microstructure, and mechanical properties were investigated. As the number of rolling passes increased, in spite of having no voids and cracks, more instabilities were observed on titanium and steel layers. With regard to mechanical properties, by increasing the rolling passes, the values of ultimate and yield strength, as well as elongation fell, because of the non-uniform distribution of hard layers within the aluminum matrix. Based on scanning electron microscopy (SEM) images, both ductile and cleavage modes of fracture were observed on fracture surfaces. Furthermore, with an increase in the number of rolling passes, the values of fracture toughness pertaining to the crack initiation declined on account of the increased probability of delamination. Plus, the trend of the R-curves was mainly downward due to the growing number of interfaces within the matrix by increasing the number of passes; nonetheless, the upward trend of these curves may be attributed to the ductile Al matrix in which the path of cracks can be bridged. Also, based on the results of wear tests, different wear mechanisms such as adhesion, abrasion, and delamination were observed, and with an increase in the number of rolling passes, the amount of weight loss showed a decline which was due to the rise of hardness concerning the strain-hardened layers.

3

Infrared Thermography Using Thermal Eddy Current Excitation for Non-Destructive Testing of Multi-Layer Epoxy-Carbon Composites

Świderski W., Hłosta P.

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2017

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Vol. 8, Nr 2 (28)

43--54

EN

The eddy current thermography method is a new technique for the non-destructive detection of cracks in materials based on the conduction of an electric current. It is a combination of eddy current testing and thermography. Eddy currents are used to heat the tested sample, while the defect detection is based on changes in the temperature field profile on its surface, as recorded by a thermographic camera. The article discusses numerical modelling methods supporting the thermographic non-destructive testing of composites and presents example results of the tests.

PL

Metoda termografii z użyciem prądów wirowych jest nową techniką badań nieniszczących do wykrywania pęknięć w materiałach przewodzących prąd elektryczny. Jest ona połączeniem badań prądami wirowymi i termografii. Prądy wirowe wykorzystane są do ogrzania badanej próbki, a wykrycie defektu oparte jest na zarejestrowanych przez kamerę termowizyjną zmianach rozkładu pola temperatury na jej powierzchni. W artykule omówiono numeryczne metody modelowania wspomagające termograficzne badania nieniszczące kompozytów oraz przedstawiono przykładowe wyniki badań eksperymentalnych.

4

Rozkład temperatury w wieloskładnikowym wielowarstwowym kompozycie z poprzeczną gradacją właściwości efektywnych

Szlachetka O., Wągrowska M.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

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2016

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z. 63, nr 1/I

61--68

PL

Przedmiotem rozważań jest jednowymiarowe, stacjonarne zagadnienie przewodnictwa ciepła w kierunku prostopadłym do uwarstwienia w wieloskładnikowym, wielowarstwowym kompozycie o poprzecznej gradacji właściwości efektywnych. W celu wyznaczenia rozkładu temperatury wykorzystano wariant asymptotyczny modelowania tolerancyjnego. Obliczono wartości efektywnego współczynnika przewodzenia ciepła oraz wyznaczono rozkłady temperatury dla pewnych szczególnych przypadków.

EN

The object of analysis was one-dimensional, stationary problem of heat conduction problem in direction perpendicular to layers within the frames of asymptotic variant of tolerance modelling in multicomponent, multilayered composites with transversal gradation of effective material properties. The influence of the composite microstructure on the temperature distribution was investigated. It has been shown that inhomogeneous structure of the considered construction influences for the gradient of micro-temperature in the zone close to the surfaces.

5

Analiza możliwości zastosowania ultradźwiękowej termografii w podczerwieni w badaniach nieniszczących wielowarstwowych kompozytów aramidowych

Świderski W., Pracht M., Vavilov V.

Problemy Techniki Uzbrojenia

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2015

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R. 44, z. 134

7--21

PL

W artykule przedstawiono opis matematyczny algorytmu wymuszenia cieplnego generowanego źródłem ultradźwiękowym, zastosowanego w nieniszczących badaniach metodą aktywnej termografii w podczerwieni. Algorytm został użyty w numerycznym modelowaniu przepływu ciepła w opracowanym programie ThermoSon przeznaczonym do rozwiązywania zagadnień badań termicznych. Przeprowadzono symulacje numeryczne wykrywania defektów w wielowarstwowym kompozycie aramidowym, stosując ultradźwiękowe źródło wymuszenia cieplnego oraz wstępnie oceniono możliwości tej metody.

EN

The paper includes a mathematical algorithm describing a heat extortion process generated by an ultrasonic source used in non-destructive testing method of active infrared thermography. This algorithm has been used at numerical modelling of heat propagation in developed ThermoSon program designed to solve problems of thermal testing. There are carried out numerical simulations for detection of defects in multi-layer aramide composite that was heated by an ultrasonic source and a preliminary evaluation of this method usability.