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Crystal Lattice Rotations Induced by Shear Banding in fcc Metals Deformed at High Strain Rates

Mania Izabela, Paul Henryk, Chulist Robert, Petrzak Paweł, Miszczyk Magdalena, Prażmowski Mariusz

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 1

319--329

EN

In this paper, the microstructural and texture changes in polycrystalline CuZn30 alloy, copper, and AA1050 aluminium alloy have been studied to describe the crystal lattice rotation during shear bands formation. The hat-shaped specimens were deformed using a drop-hammer at the strain rate of 560 s-1. Microstructure evolution was investigated using optical microscopy, whereas texture changes were examined with the use of a scanning electron microscope equipped with the EBSD facility. The microstructural observations were correlated with nanohardness measurements to evaluate the mechanical properties of the sheared regions. The analyses demonstrate the gradual nature of the shear banding process, which can be described as a mechanism of the bands nucleation and then successive growth rather than as an abrupt instability. It was found that regardless of the initial orientation of the grains inside the sheared region, a well-defined tendency of the crystal lattice rotation is observed. This rotation mechanism leads to the formation of specific texture components of the sheared region, different from the one observed in a weakly or non-deformed matrix. During the process of rotation, one of the {111} planes in each grain of the sheared region ‘tends’ to overlap with the plane of maximum shear stresses and one of the <110> or <112> directions align with the shear direction. This allows slip propagation through the boundaries between adjacent grains without apparent change in the shear direction. Finally, in order to trace the rotation path, transforming the matrix texture components into shear band, rotation axis and angles were identified.

2

Experimental Investigation on the Compression Behaviours of 3D Angle‑interlock Woven Composites with Carbons Nanotube under High Strain Rates

Ma P, Jiang G, Zhang F, Chen Q, Miao X, Cong H

Fibres & Textiles in Eastern Europe

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2015

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Vol. 23, no. 2 (110)

44--50

EN

The compressive properties of 3D angle-interlock woven/epoxy resin composites with various carbon nanotube (CNTs) contents were investigated under quasi-static and high strain rate loading to evaluate the compressive failure modes, which were influenced by various CNT contents and different strain rates. The results indicated that the stress strain curves were strain rate sensitive, and the compressive failure stress of composites with various CNT contents were increased with a change the strain rates and CNT contents. The compressive failure modes of 3D angle-interlock woven composites without CNT tended to be in shear deformation, delamination fibre breakage and matrix crack together, and the failure modes of 3D angle-interlock woven composites with high CNT contents presented delamination and shear deformation.

PL

Badano właściwości ściskające kompozytów 3D wzmacnianych tkaninami o skośnym splocie interlokowym modyfikowanych nanorurkami węglowymi. W celu wyznaczenia uszkodzeń powstałych na skutek ściskania, na które wpływa zawartość nanorurek i szybkości odkształcania, badania przeprowadzono pod obciążeniem quasi-statycznym i przy dużych szybkościach ściskania. Wyniki wykazały, że krzywe ściskania zależały od szybkości odkształcania i zawartości nanorurek. Uszkodzenia mają charakter rozwarstwienia i deformacji pod wpływem naprężeń ścinających.

3

Badania właściwości mechanicznych staliwa LH556 i stali VP159 pod kątem zastosowania w osłonach balistycznych

Moćko W., Kowalewski Z. L., Wojciechowski A., Rudnik D.

Biuletyn Wojskowej Akademii Technicznej

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2012

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Vol. 61, nr 2

449-462

PL

Praca przedstawia charakterystyki naprężenie-odkształcenie stali austenitycznej VP159 oraz staliwa austenitycznego LH556, o dużej zawartości azotu, przy różnych prędkościach odkształcania. Do badań w zakresie obciążeń statycznych zastosowano serwohydrauliczną maszynę wytrzymałościową, natomiast w zakresie obciążeń dynamicznych metodę pręta Hopkinsona. Otrzymane rezultaty przedstawiono w formie wykresów naprężenia rzeczywistego w funkcji odkształcenia rzeczywistego. Na podstawie statycznej próby rozciągania wyznaczono również podstawowe parametry badanych materiałów, takie jak: E, R0,05, R0,2, Rm. Na podstawie badań stwierdzono, że stal VP159 ma znacznie lepszą ciągliwość niż staliwo LH556, natomiast pozostałe parametry i charakterystyki były zbliżone. Otrzymane wyniki można wykorzystać do wyznaczenia parametrów równań konstytutywnych opisujących termomechaniczne właściwości materiałów na potrzeby symulacji komputerowych.

EN

This work presents the stress-strain curves of the VP159 steel and LH556 cast alloy of high nitrogen content, at wide range of strain rates. At quasi-static deformation regime, the servohydraulic testing machine was applied, whereas for dynamic tests the Hopkinson bar was used. The results were presented as a true stress - true strain diagrams. The basic mechanical properties of materials, i.e., E, R0.05, R0.2, Rm were determined. The tests show that the VP159 steel exhibits a much better ductility than the LH556 cast alloy, whilst the other parameters were similar for both materials. The results create a base for determination of parameters appearing at different constitutive equations describing thermo-mechanical behavior of materials within finite element method codes.

4

Evaluation of a tensile test for the determination of the material behaviour of filament yarns under high strain rates

Cherif C, Seidel A., Younes A., Hausding J.

Autex Research Journal

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2010

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Vol. 10, no. 4

88--94

EN

In many technical applications, fibre-reinforced composites with textile high-performance fibres made of carbon or glass are being used. The fibres qualify for their high strength and stiffness due to their physical and chemical characteristics. It is necessary to guarantee a high safety level under all possible loading constellations. Besides the usual service loads, the topic of extreme loads that work along with high forces and high impact velocity is of increasing importance. For these so-called impact loads, the processes within the structural components have to be analysed and material models suitable for prognoses should be derived from them. The existence of suitable test machines and test methods is a prerequisite for that, yet for filament yarns they are not state of the art. Hence, tensile tests with high strain rates on filament yarns are performed on standard high-speed tensile testing machines. This leads to problems when analysing and interpreting the results and therefore, it is necessary to develop special testing machines for filament yarns.

5

Experimental and theoretical investigations of glass-fibre reinforced composite subjected to uniaxial compression for a wide spectrum of strain rates

Pieczyska E. A., Pęcherski R. B., Gadaj S. P., Nowacki W. K., Nowak Z., Matyjewski M. M.

Archives of Mechanics

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2006

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Vol. 58, nr 3

273-291

EN

Results of static and dynamic compression} tests for two types of glass fibre-reinforced polypropylene composites are presented. Stress-strain curves showing the influence of the strain rate on the composite mechanical properties have been obtained. A three-dimensional description of the material behavior during the deformation has been developed. The material constitutive parameters have been calculated. Specification of the parameters and description of the methods used for their identification have been worked out. The results are discussed in terms of the deformation processes and the material non-homogeneity.