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1

Experimental study on biaxial dynamical compressive test and PFC2D numerical simulation of artificial rock sample with single joint

Liangxiao Xiong, Chen Haijun, Gao Xinghong, Xu Zhongyuan, Hu Deye

Archives of Civil Engineering

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2023

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Vol. 69, nr 1

213--229

EN

Dynamic biaxial compression tests and Particle Flow Code numerical simulations of the cement mortar specimens with a single joint were carried out to study the mechanical properties and crack evolution of artiﬁcial rock samples with a single joint. The effects of lateral stress σ2, loading rate V, the dip angle β (between the vertical loading direction and the joint) on the biaxial compressive strength σb, and the evolution law of crack were investigated. Test results showed that; (1) when both the dip angle β and the loading rate V remained unchanged, the biaxial compressive strength σb increased with the increase in the lateral stress σ2, while σ2 had no obvious effect on the crack evolution law; (2) when both the dip angle β and the lateral stress σ2 were kept unchanged, the loading rate V had an insignificant effect on the biaxial compressive strength σb and the crack evolution law; (3) when both the lateral stress σ2 and the loading rate V were constant, the biaxial compressive strength σb decreased first and then increased with the increase in the dip angle β; however, the dip angle β did not significantly affect the crack evolution law. The conclusions obtained in this paper are presented for the first time.

2

The formation of new (Al, Zn)3Zr precipitates in an Al-Zn-Mg-Cu aluminum alloy after aging treatment and their response to dynamic compression

Khan Muhammad Abubaker, Wang Yangwei, Afifi Mohamed A., Tabish Mohammad, Hamza Muhammad, Yasin Ghulam, Ahmad Tahir, Liao Wei‑Bing

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 1

art. no. e33, 2023

EN

This study mainly focuses on the newly developed (Al, Zn)3Zr precipitates through double aging treatment in an Al-Zn-Mg-Cu alloy (Al alloy) and their response to dynamic compression. The results show that the strength of the Al alloy after aging treatment (393 K for 8 h + 433 K for 10 h) is increased with an increasing strain rate from 1.0 x 10−3 to 3.0 x 103s−1 assisted by the strain hardening rate effect. The microstructures of Al alloy after the double aging treatment and dynamic compression at ~ 3.0 x 103s−1 contain novel (Al, Zn)3Zr precipitate with LI2 ordered and tetragonal structures. The small inter-particle spacing of precipitates after double aging, solute diffusion during the aging treatment, and dynamic compression lead to the overlapping of the different precipitates. For instance, the overlapping of (Al, Zn)3Zr and θ′ precipitates is observed. The overlapped (Al, Zn)3Zr contains Cu solutes, while the θ′ precipitate contains Zr solutes assisted by solute diffusion through dislocations and the increase in temperature during the compression. Besides, the number and size of the platelet precipitates are also increased after the dynamic compression compared to the double aging treatment Al alloy. In this research, the newly observed (Al, Zn)3Zr precipitate after double aging treatment, and post-high strain rate compression is suitable for successfully tailoring the precipitation of Al-Zn-Mg-Cu alloy and achieving optimum properties in the near future.

3

Analysis of all-pass filters application to eliminate negative effects of loudness war trend

Surtel Wojciech, Maciejewski Marcin, Nowak Krzysztof Mateusz

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2020

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T. 10, nr 2

8--11

EN

In this paper the influence of all-pass filters on musical material with applied hypercompression dynamics (loudness war trend) was analyzed. These filters are characterized by shifting phase in selected frequency band of signal, not by change of their amplitude levels. Because a lot of music information is present in music tracks, the dynamic range was tested together with influence of other sound parameters like selectivity or instruments’ arrangement on scene, by running subjective tests on a group of respondents.

PL

W artykule przeanalizowana wpływ filtrów wszechprzepustowych na materiał muzyczny z zastosowaną hiperkompresją sygnału (tendencją loudness war). Filtry tego typu, charakteryzują się przesunięciem w fazie składowych częstotliwościowych, sygnału, a nie zmianą poziomu ich amplitudy. Ze względu na dużą ilość informacji w utworach muzycznych, prócz sprawdzenia zakresu dynamiki poprzez testy obiektywne, zbadano również wpływ na inne parametry dźwięku takie jak selektywność czy rozłożenie instrumentów na scenie, poprzez testy subiektywne na grupie respondentów.

4

Protocol to define material behaviour and failure strain level at low and high strain rates based on a compression test

Jankowiak T., Rusinek A., Bendarma A.

Journal of Theoretical and Applied Mechanics

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2018

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Vol. 56 nr 2

471--481

EN

Compression test is frequently used to define material behaviour. However, this test may be depending on different effects, for example friction, specimen inertia or local stress triaxiality. For this reason, a new design is proposed to analyse the previous effects and to try to minimize it on quantities measured as macroscopic stress and strain. To have a complete understanding, numerical simulations have been performed using finite element method (Abaqus/Standard and Abaqus/Explicit). It allows one to define the macroscopic behaviour and to have an access to the local values not accessible during experiments for a better understanding of the experimental measurements.

5

Properties and Structure of X30MnAlSi26-4-3 High Strength Steel Subjected to Dynamic Compression Processes

Śmiglewicz A., Jabłońska M., Moćko W., Kowalczyk K., Hadasik E.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 4

2255--2260

EN

The paper presents the results of investigation on X30MnAlSi26-4-3 austenitic steel subjected to dynamic compression using the split Hopkinson pressure bar. The strain rate was 3700 s-1. The compression test was also carried out without the use of breaking rings and then true strain was about 0.3. The split Hopkinson pressure bar test take only few milliseconds to complete during which time it is impossible to transfer the excess heat out of the specimen, therefore the test must be carried out in adiabatic conditions and so the increase of the temperature caused by the work of plastic deformation had to be calculated. The stepping load method was used in order to evaluate the effect of adiabatic heating on the properties of steel which allowed to maintain the isothermal deformation conditions. The paper presents the comparison of results obtained during deformation under adiabatic and isothermal conditions in correlation to structure changes occurring in course of dynamic compression.

6

On the Identification of Dynamic Friction Material Properties under Brake Squeal Relevant Loading Conditions

Hornig S. A., Wagner U. v.

Machine Dynamics Research

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2012

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Vol. 36, No. 3

29-44

EN

Brake squeal is a disruptive high frequency noise generated by friction-induced self excited vibrations of the brake system. Great effort is spent on the improvement of brake squeal prediction reliability, using mathematical-mechanical simulation models. In this context friction material properties are one of the decisive factors for the successful brake squeal simulation. Because of the nonlinear and load dependent friction material behavior, it is mandatory to identify friction material properties under squeal typical loading conditions. For this reason a measurement method reproducing squeal typical operating conditions is under development by the authors’ research group. The present paper shows the actual development stage of this measuremet method, presenting the dynamic compression test rig, estimated friction material characteristics, and emphasizing important influence factors on the dynamic compression measurement results. In this context a particular focus is set on the derivation of correction factors when converting the measured stiffness of specimens with restriced dimensions and boundary conditions into material stiffness.

7

Microstructure and properties of dynamically compressed copper Cu99.99

Leszczyńska-Madej B., Richert M.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 39, nr 1

35-42

EN

Purpose: The main object of this study is to establish the influence of dynamic compression on the possibility of microstructure refinement in polycrystalline copper Cu99.99. Design/methodology/approach: Polycrystalline copper Cu99.99 was dynamically compressed on a falling - weight - type impact machine with strain rate ranging from 1.75×102 to 2.7×102 s-1. After deformation, the samples were tested for microhardness and their microstructure was examined by means both optical and electron microscopy. Additionally, the width of microbands observed in the microstructure was statistically evaluate by using mean chord method. The misorientation of selected microstructural elements was determined using proprietary KILIN software. Findings: It was found that to produce materials with nanometric features is not only possible by exertion of severe plastic deformation methods (SPD) but also by deformation with moderate strains and high strain rates. The demonstrated data show, that in some range the amount of deformation and strain rate can be interchangeable parameters causing similar structural effects.n. Practical implications: The results may be utilized for determination of a relation between microstructure and properties of the copper in the process of dynamic compression. Originality/value: The results contribute to evaluation properties of the polycrystalline copper in the light of achievement of fine – grained microstructure. The obtained results indicated that dynamic compression with high strain rate can be an effective method for microstructure refinement, comparable with SPD methods

8

Assessment of Rheological Properties of Distance Weft-Knitted Fabrics, Based on Dynamic Compression and Relaxation of Forces

Bednarski G., Kowalski K.

Fibres & Textiles in Eastern Europe

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2002

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Vol. 8, no. 2 (37)

42--45

EN

In this work, rheological parameters of distance-knitted fabrics were identified on the basis of dynamic compression and relaxation, using Zener's three-element standard model. The tests concerned weft-knitted fabrics, made at 'elastic' and 'interlock' gating, differing in the diameter of monofilament threads in the intermediate layer. The impact of diameter of monofilament threads in the intermediate layer on the rheological parameters of knitted fabrics was proved.

PL

Reologiczne parametry dystansowych dzianin rządkowych określane są na podstawie dynamicznego ściskania i relaksacji, w oparciu o trzyczłonowy standardowy model Zenera. Testy przeprowadzono z dzianinami rządkowymi wykonanymi w układzie interlokowym i splocie powstałym z połączenia oczka dwuigłowego z oczkiem jednoigłowym, różniącymi się średnicą monofilamentów w warstwie pośredniej. Badano wpływ średnicy tych monofilamentów na parametry reologiczne dzianin.