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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

2023

Vol. 69, nr 1

213--229

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.

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

2023

Vol. 23, no. 1

art. no. e33, 2023

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.

Microstructure and properties of dynamically compressed copper Cu99.99

Leszczyńska-Madej B., Richert M.

Journal of Achievements in Materials and Manufacturing Engineering

2010

Vol. 39, nr 1

35-42

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