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13 pages, 7108 KB

Open AccessArticle

Accurate Finite Element Simulations of Dynamic Behaviour: Constitutive Models and Analysis with Deep Learning

by Yiwei Zhang, Chengcheng Guo, Yahui Huang, Ruizhi Zhang, Jian Zhang, Guoqiang Luo and Qiang Shen

Materials 2024, 17(3), 643; https://doi.org/10.3390/ma17030643 - 28 Jan 2024

Cited by 5 | Viewed by 2891

Abstract

Owing to the challenge of capturing the dynamic behaviour of metal experimentally, high-precision numerical simulations have become essential for analysing dynamic characteristics. In this study, calculation accuracy was improved by analysing the impact of constitutive models using the finite element (FE) model, and the deep learning (DL) model was employed for result analysis. The results showed that FE simulations with these models effectively capture the elastic-plastic response, and the ZA model exhibits the highest accuracy, with a 26.0% accuracy improvement compared with other models at 502 m/s for Hugoniot elastic limit (HEL) stress. The different constitutive models offer diverse descriptions of stress during the elastic-plastic response because of temperature effects. Concurrently, the parameters related to the yield strength at quasi-static influence the propagation speed of elastic waves. Calculation show that the yield strength at quasi-static of 6061 Al adheres to y = ax + b for HEL stress. The R-squared (R²) and mean absolute error (MAE) values of the DL model for HEL stress predictions are 0.998 and 0.0062, respectively. This research provides a reference for selecting constitutive models for simulation under the same conditions. Full article

(This article belongs to the Special Issue Impact Behaviour of Materials and Structures)

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10 pages, 3209 KB

Open AccessArticle

Experimental Study on the Dynamic Behavior of a Cr-Ni-Mo-V Steel under Different Shock Stresses

by Xinyi Zhao and Hongjun Li

Metals 2023, 13(4), 663; https://doi.org/10.3390/met13040663 - 27 Mar 2023

Cited by 6 | Viewed by 2913

Abstract

The present study aimed to provide new insights into the behavior of high-strength low-alloy steel under dynamic compression and to promote its use in high-stress applications. The dynamic compression response of a Cr-Ni-Mo-V steel under shock stresses ranging from 3.54 GPa to 19.76 GPa was investigated using loading technology. The free surface velocity of the specimen was measured using a displacement interferometer system with the range of 166–945 m/s. The Hugoniot elastic limit (HEL), spalling fracture, and microstructure evolution of specimens under different shock stresses were determined. The results showed that an α→ε phase transition occurred in the material at an impact stress of 15.63 GPa, leading to a change in particle velocity. The relationship between the shock wave velocity and particle velocity was found to be linear. The HEL of the steel was found to be consistent at 2.28 GPa, while the spall strength showed a more complex relationship with the increasing shock stress. Initially, the spall strength increased and then decreased with increasing shock stress before increasing again after the phase transformation. The fracture mode of the steel shifted from brittle fracture to ductile fracture with the increasing impact stresses, which is related to the previous plastic deformation under different impact loads. Full article

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12 pages, 3423 KB

Open AccessCommunication

Shock and Spallation Behavior of a Compositionally Complex High-Strength Low-Alloy Steel under Different Impact Stresses

by Ye Lu and Junbao Li

Appl. Sci. 2023, 13(6), 3375; https://doi.org/10.3390/app13063375 - 7 Mar 2023

Cited by 4 | Viewed by 2884

Abstract

The shock and spalling behavior of a compositionally complex high strength low-alloy steel (HSLA) was studied using plate impact testing. The free surface velocity of the specimen in the range of 194~938 m/s was measured by a displacement interferometer system for any reflector (DISAR). The Hugoniot elastic limit (HEL), spallation fracture and microstructural evolution of the HSLA under an impact stress of 3.04~18.66 GPa were analyzed. Shock Hugoniots were obtained from the measured particle velocities and calculated shock velocities. The velocity curves show clear signs of HEL and velocity fallback, indicating a transition from elastic to plastic and spalling behavior. When the impact velocity exceeds 757 m/s, the particle velocity rises to the peak and then increases again, indicating that an α→ε phase transition occurred, with a threshold of 13.51 GPa. It was found that the impact velocity is linearly related to the particle velocity of the HSLA. As the impact stress increased, the HEL remained within the range of 1.32~1.50 GPa, while the spalling strength presented an upward trend with the increasing impact stresses. Metallographic analysis shows that the impact failure is dominated by brittle fracture at lower velocities, while more ductile fracture occurs at higher velocities. Full article

(This article belongs to the Section Materials Science and Engineering)

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10 pages, 2665 KB

Open AccessArticle

Laser Peening Analysis of Aluminum 5083: A Finite Element Study

by Ali Tajyar, Noah Holtham, Nicholas Brooks, Lloyd Hackel, Vincent Sherman, Ali Beheshti and Keivan Davami

Quantum Beam Sci. 2021, 5(4), 34; https://doi.org/10.3390/qubs5040034 - 7 Dec 2021

Cited by 8 | Viewed by 5349

Abstract

In this research, a finite element (FE) technique was used to predict the residual stresses in laser-peened aluminum 5083 at different power densities. A dynamic pressure profile was used to create the pressure wave in an explicit model, and the stress results were extracted once the solution was stabilized. It is shown that as power density increases from 0.5 to 4 GW/cm², the induced residual stresses develop monotonically deeper from 0.42 to 1.40 mm. However, with an increase in the power density, the maximum magnitude of the sub-surface stresses increases only up to a certain threshold (1 GW/cm² for aluminum 5083). Above this threshold, a complex interaction of the elastic and plastic waves occurring at peak pressures above ≈2.5 Hugoniot Elastic Limit (HEL) results in decreased surface stresses. The FE results are corroborated with physical experiments and observations. Full article

(This article belongs to the Special Issue Laser Assisted Manufacturing)

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12 pages, 4119 KB

Open AccessArticle

High-Strain Deformation and Spallation Strength of 09CrNi2MoCu Steel Obtained by Direct Laser Deposition

by Olga Klimova-Korsmik, Gleb Turichin, Ruslan Mendagaliyev, Sergey Razorenov, Gennady Garkushin, Andrey Savinykh and Rudolf Korsmik

Metals 2021, 11(8), 1305; https://doi.org/10.3390/met11081305 - 18 Aug 2021

Cited by 11 | Viewed by 3033

Abstract

In this work, the critical fracture stresses during spalling of high-strength steel 09CrNi2MoCu samples obtained by direct laser deposition (DLD) were measured under shock compression of up to ~5.5 GPa. The microstructure and mechanical properties of DLD steel samples in the initial state and after heat treatment were studied and compared to traditional hot rolled one. The microstructural features of steel before and after heat treatment were revealed. The heat treatment modes of the deposit specimens on their strength properties under both static and dynamic loads have been investigated. The spall strength of the deposited specimens is somewhat lower than the strength of steel specimens after hot rolling regardless of their heat treatment. The minimum elastic limit of elasticity is exhibited by the deposit specimens. After heat treatment of the deposit samples, the elastic limit increases and approximately doubles. Subsequent heat treatment in the form of hardening and tempering allows obtaining strength properties under Hugoniot loads in traditional hot-rolled products. Full article

(This article belongs to the Special Issue Laser Processing of Metals and Alloys)

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9 pages, 4949 KB

Open AccessCommunication

Amorphization Mitigation in Boron-Rich Boron Carbides Quantified by Raman Spectroscopy

by Mark C. Schaefer and Richard A. Haber

Ceramics 2020, 3(3), 297-305; https://doi.org/10.3390/ceramics3030027 - 23 Jul 2020

Cited by 26 | Viewed by 6108

Abstract

Boron carbide is an extremely hard and lightweight material used in armor systems. Upon impact above the Hugoniot elastic limit (HEL), boron carbide loses strength and suddenly fails. Atomistic models suggest that boron-rich boron carbides could mitigate amorphization. Such samples were processed, and indentation-induced amorphous zones were created throughout the boron-rich samples of varying degrees and were mapped with Raman spectroscopy to assess changes in the amorphization intensity. Boron-rich samples with a B/C ratio of 6.3 showed a large reduction in amorphization intensity compared to commonly used stoichiometric B₄ C, in agreement with recent TEM results. Additionally, hardness trends were also noted as boron content is varied. This offers another pathway in which doping boron carbide can reduce amorphization. Full article

(This article belongs to the Special Issue High-Temperature Ceramics)

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23 pages, 6771 KB

Open AccessArticle

Johnson–Holmquist-II(JH-2) Constitutive Model for Rock Materials: Parameter Determination and Application in Tunnel Smooth Blasting

by Jianxiu Wang, Yao Yin and Chuanwen Luo

Appl. Sci. 2018, 8(9), 1675; https://doi.org/10.3390/app8091675 - 16 Sep 2018

Cited by 91 | Viewed by 19086

Abstract

The Johnson–Holmquist-II(JH-2) model is introduced as the constitutive model for rock materials in tunnel smooth blasting. However, complicated and/or high-cost experiments need to be carried out to obtain the parameters of the JH-2 constitutive model. This study chooses Barre granite as an example to propose a quick and convenient determination method for the parameters of the JH-2 model using a series of computational and extrapolated methods. The validity of the parameters is verified via comparing the results of 3D numerical simulations with laboratory blast-loading experiments. Subsequently, the verified parameter determination method, together with the JH-2 damage constitutive model, is applied in the numerical simulation of smooth blasting in Zigaojian tunnel, Hangzhou–Huangshan high-speed railway. The overbreak/underbreak induced by rock blasting and joints/discontinuities is well estimated through comparing the damage contours resulting from the numerical study with the tunnel profiles measured from the tunnel site. The peak particle velocities (PPVs) of the near field are extracted to estimate the damage scope and damage degree for the surrounding rock mass of the tunnel on the basis of PPV damage criteria. This method can be used in the excavation of rock tunnels subjected to large strains, high strain rates, and high pressures, thereby reducing safety risk and economic losses. Full article

(This article belongs to the Section Mechanical Engineering)

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