Journal articles: 'Johnson Holmquist'

1

Xie, Beijing, Zheng Yan, Yujing Du, Zeming Zhao, and Xiaoqian Zhang. "Determination of Holmquist–Johnson–Cook Constitutive Parameters of Coal: Laboratory Study and Numerical Simulation." Processes 7, no. 6 (June 21, 2019): 386. http://dx.doi.org/10.3390/pr7060386.

Full text

Abstract:

The main sensitivity parameters of the Holmquist–Johnson–Cook constitutive model for coal were obtained from a variety of tests such as uniaxial compression, uniaxial cyclic loading, splitting and triaxial compression tests, as well as the indirect derivation equation of a briquette. The mechanical properties of briquettes under dynamic impact were investigated using a split Hopkinson pressure bar experiment. Based on the experimental measurement of the Holmquist–Johnson–Cook constitutive model, the numerical simulation of briquette was performed using ANSYS/LS-DYNA software. A comparison between experimental and simulation results verified the correctness of simulation parameters. This research concluded that the failure of briquette at different impact velocities started from an axial crack in the middle of the coal body, and the sample was swollen to some extent. By the increase of impact velocity, the severity of damage in the coal body was increased, while the size of the coal block was decreased. Moreover, there was good compliance between experimental and simulated stress wave curves in terms of coal sample failure and fracture morphology at different speeds. Finally, the parameters of the validated Holmquist–Johnson–Cook constitutive model were applied to the numerical simulation model of the impact damage of heading face and the process of coal seam damage in the roadway was visually displayed. The obtained results showed that the Holmquist–Johnson–Cook constitutive model parameters suitable for the prominent coal body were of great significance for the improvement and exploration of the occurrence mechanism of coal and rock dynamic disasters.

APA, Harvard, Vancouver, ISO, and other styles

2

Ren, Gen-Mao, Hao Wu, Qin Fang, and Xiang-Zhen Kong. "Parameters of Holmquist–Johnson–Cook model for high-strength concrete-like materials under projectile impact." International Journal of Protective Structures 8, no. 3 (August 2, 2017): 352–67. http://dx.doi.org/10.1177/2041419617721552.

Full text

Abstract:

Holmquist–Johnson–Cook constitutive model has been widely used in analyzing the dynamic responses of concrete-like materials under projectile impact and explosive loadings, the constitutive parameters of which were always referred from the original documents and only applied to the normal strength concrete with the compressive strength of 48 MPa. Aiming to confirm the Holmquist–Johnson–Cook model parameters for high-strength concrete-like materials (compressive strength ≥60 MPa), based on the available test data from the quasi-static uniaxial compression, triaxial compression, Split-Hopkinson pressure bar, as well as the Hugoniot experiments, the strength parameters, the strain rate parameter, and the equation of state parameters of Holmquist–Johnson–Cook model for high-strength concrete-like materials are determined. Using the finite element program LS-DYNA, total eight sets of projectile penetration and perforation tests on high-strength concrete (uniaxial compressive strengths of 67.5–157 MPa) and high-strength rock targets (uniaxial compressive strengths of 60 and 154 MPa) are numerically simulated, respectively. By comparisons with the test data of penetration depths and residual velocities of the projectiles, the verifications of the proposed parameters are validated, which provides the reference for the design of protective structures.

APA, Harvard, Vancouver, ISO, and other styles

3

ISLAM, M. J., S. SWADDIWUDHIPONG, and Z. S. LIU. "PENETRATION OF CONCRETE TARGETS USING A MODIFIED HOLMQUIST–JOHNSON–COOK MATERIAL MODEL." International Journal of Computational Methods 09, no. 04 (December 2012): 1250056. http://dx.doi.org/10.1142/s0219876212500569.

Full text

Abstract:

For concrete target penetration and/or perforation simulation, the Holmquist–Johnson–Cook (HJC) material model is widely used as concrete material model. However, the strain rate expression of the model has failed to explain the sudden increase in concrete strength at high strain rates. The pressure-volume relationship of the HJC model is complex and requires a large number of material constants. In this study, a modified Holmquist–Johnson–Cook (HJC) model is proposed for concrete material under high velocity impact. The modification involves simplification and improvement of the strain rate expression and pressure-volume relationship. Material parameters identification procedure for the MHJC model is also elaborated. The numerical simulations using the proposed model show a good agreement with experimental observations, especially, on the residual velocities, penetration depths and failure patterns of the target plates. These validate the applicability of the MHJC model for high velocity projectile impact studies for concrete.

APA, Harvard, Vancouver, ISO, and other styles

4

Ruggiero, A., G. Iannitti, N. Bonora, and M. Ferraro. "Determination of Johnson-holmquist constitutive model parameters for fused silica." EPJ Web of Conferences 26 (2012): 04011. http://dx.doi.org/10.1051/epjconf/20122604011.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Gurevich, Leonid Moiseevich, Victor Georgievich Shmorgun, Dmitriy Vladimirovich Pronichev, and Roman Evgenyevich Novikov. "The Simulation of Titanium-Aluminium Composite with Intermetallic Inclusions Behavior under Compression." Key Engineering Materials 743 (July 2017): 176–80. http://dx.doi.org/10.4028/www.scientific.net/kem.743.176.

Full text

Abstract:

3D finite element simulation of behavior of composite VT6-AD1-D20 with the intermetallic layer at axial compression was carried out. The properties of the intermetallic interlayer were described using the model of Johnson-Holmquist. The effect of the aluminum layer thickness on failure deformation was defined.

APA, Harvard, Vancouver, ISO, and other styles

6

Kurnenkov, Anton, Alexei Shurigin, and Vladimir Glebov. "Finite element analysis of the dynamic interaction between a single abrasive grain and a glass surface." MATEC Web of Conferences 298 (2019): 00068. http://dx.doi.org/10.1051/matecconf/201929800068.

Full text

Abstract:

The article presents the results of 2D and 3D formulation finite element analysis of glass surface scratching process using single abrasive grain. Johnson-Holmquist model JH-2 was chosen to describe the brittle behavior of the glass material. The cracked layer depth for a given depth penetration of grain and scratching speed were obtained.

APA, Harvard, Vancouver, ISO, and other styles

7

Yuan, Yi Chu, Bei Zhi Li, Zhen Xin Zhou, and Qiang Zhang. "Study on the Simulation Model and Characteristics of High-Speed Grinding for Ceramics." Applied Mechanics and Materials 138-139 (November 2011): 662–67. http://dx.doi.org/10.4028/www.scientific.net/amm.138-139.662.

Full text

Abstract:

Engineering ceramic machining would bring out several kinds of surface damage owing to its hard and brittle nature. In this paper, a simulation model of single-grit grinding for silicon carbide (Sic) was established to explore the high-speed grinding mechanism. The material behavior was described with the Johnson-Holmquist Ⅱ (JH-2) model. According to the simulation experiment results, the optimal grinding parameters to achieve ductile grinding for Sic has been analyzed, which would provide theoretical basis and take surface damage under control.

APA, Harvard, Vancouver, ISO, and other styles

8

Chen, Yu Feng, and Guang Xiang Yi. "Dynamic Response Analysis of the Reinforced Concrete Column under the Effect of Explosive Impact Load." Advanced Materials Research 681 (April 2013): 99–104. http://dx.doi.org/10.4028/www.scientific.net/amr.681.99.

Full text

Abstract:

This paper does the data simulation analysis by using the large-scale finite element nonlinear ANSYS/LS-DYNA software. It chooses the MAT111(MAT-JOHNSON-HOLMQUIST -CONCRETE）concrete materials and the MAT3 (MAT-PLASTIC-KINEMATIC) reinforcement material model in ANSYS/LS-DYNA finite element software, builds the separating RC column finite element model, dynamically simulates the hurting process of RC column under the effect of explosive impact load, and mainly does research into the damage degree of RC column under different effects of explosive load of different peak pressures.

APA, Harvard, Vancouver, ISO, and other styles

9

Huang, Hongxin, Wenbin Li, and Zhenyu Lu. "Determination of Parameters of Johnson-Holmquist-II (JH-2) Constitutive Model for Red Sandstone." Journal of Physics: Conference Series 2002, no. 1 (August 1, 2021): 012071. http://dx.doi.org/10.1088/1742-6596/2002/1/012071.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Gertsik, S. M., and Yu V. Novozhilov. "NUMERICAL SIMULATION OF A MASSIVE IMPACTOR FALLING ONTO A REINFORCED CONCRETE BEAM." Problems of strenght and plasticity 82, no. 1 (2020): 5–15. http://dx.doi.org/10.32326/1814-9146-2020-82-1-5-15.

Full text

Abstract:

The paper presents the results of numerically modeling the dynamics of a concrete beam reinforced by longitudinal rods and transversal frames of rods under the effect of a falling massive impactor. The dynamic behavior of the material of concrete is described using the Holmquist - Johnson - Cook model. The reinforcement of the beam is modeled by beam elements, using the bilinear model of elastoplastic material with isotropic hardening. Binding between the reinforcement and concrete is described by introducing additional kinematic equations that couple degrees of freedom of the related nods of the beam and volumetric finite elements. The mathematical model makes it possible to introduce additional failure criteria to predict propagation of tensile cracking. Pressure lower than the minimal one (failure only in the tension zone) and volumetric strain higher than the threshold value are taken as a criterion of tensile failure. Failure is modeled by removing elements from the computational pattern, when the above failure criteria are satisfied. The effect of accounting for failure on the response of the beam is analyzed. Numerical modeling is done using the finite-element method with explicit time integration in the LOGOS and LS-DYNA systems. Concrete is modeled using linear four-node finite elements with one integration point. The impactor is modeled as an absolutely solid body with a detailed description of the impacting end. The obtained results are compared with experimental data. It is demonstrated that the Holmquist - Johnson - Cook material model developed for analyzing high-velocity impacts can also be applied to problems of low-velocity impact.

APA, Harvard, Vancouver, ISO, and other styles

11

Zhang, Yu Wu, Lu Hui Yan, and Ling Feng Li. "Numerical Simulation of Projectile Penetration into UHMWPE Fiber Reinforced Concrete." Applied Mechanics and Materials 716-717 (December 2014): 513–16. http://dx.doi.org/10.4028/www.scientific.net/amm.716-717.513.

Full text

Abstract:

Based on LS-DYNA 3D finite element program and Holmquist Johnson Cook (HJC) model, a numerical simulation research on a new type of fiber concrete reinforced by UHMWPE fiber against 12.7 mm Armor Piercing ammunition was conducted. The results show that the simulated results to penetration depth have a good agreement with experiment data. An ACE modified formula both considering promoted tensile strength and toughness reinforced by UHMWPE fiber is proposed, whose theoretical results are very close to that of experiment and numerical simulation and can predict the penetration depth of UHMWPE fiber concrete (UFRC) well.

APA, Harvard, Vancouver, ISO, and other styles

12

Liu, Li Sheng, Dong Feng Cao, Jiang Tao Zhang, and Qing Jie Zhang. "Numerical Simulation of SHPB Experiment on Dynamic Behaviour of Ceramic Particle Reinforced MMCs." Key Engineering Materials 326-328 (December 2006): 1539–42. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.1539.

Full text

Abstract:

The dynamic behaviour of ceramic particle reinforced metal matrix composites (MMCs) is a key to its application. In this paper, the computational micro-mechanics method (CMM) is used to simulate SHPB experiment of MMCs. The numerical SHPB’s specimen of MMCs is firstly generated by CMM. Then, for verifying the correction of numerical experiment, the Al2O3/6061- T6Al composite is used to carry out numerical experiment, and the Johnson-Holmquist (JH-2) damage model is used to describe the ceramic mechanics behaviour, and a comparison between this numerical method and Unit Cell analytical model is carried out. Lastly, the dynamic behaviour of T6061Al/Al2O3 is investigated by this method.

APA, Harvard, Vancouver, ISO, and other styles

13

Thamburaj, Priya, Michael H. Santare, and George A. Gazonas. "The Effect of Graded Strength on Damage Propagation in Continuously Nonhomogeneous Materials." Journal of Engineering Materials and Technology 125, no. 4 (September 22, 2003): 412–17. http://dx.doi.org/10.1115/1.1605116.

Full text

Abstract:

A damage model developed by Johnson and Holmquist is implemented into a dynamic finite element code. This is then used to study the effect of grading of the phenomenological damage parameters on the propagation of damage through the material. The numerical results for two one-dimensional example problems with different boundary conditions are presented, wherein the effect of a gradient in the intact strength of the material on damage propagation is studied. The results show that introducing different strength gradients can alter the location of the site of maximum damage. This may have important implications in the design of impact resistant materials and structures.

APA, Harvard, Vancouver, ISO, and other styles

14

Abdulhamid, Hakim, Kevin Delabre, Fabien Plassard, Pierre Héreil, Jérôme Mespoulet, and Paul Deconinck. "Kinetic Energy Penetrator (KEP) impact on confined concrete." EPJ Web of Conferences 250 (2021): 06015. http://dx.doi.org/10.1051/epjconf/202125006015.

Full text

Abstract:

Understanding concrete response facing warheads threats is important for both the design of strategic infrastructure protection and the prediction of warhead performances. This ongoing study aims at building a robust approach for the characterisation of concrete behaviour under ballistic impact of Kinetic Energy Penetrator (KEP). A set of tests has been developed and performed to fit the main parameters of the Holmquist Johnson Cook Concrete material model. Highly instrumented tests are conducted to improve the model prediction capability and to identify its limits. After a brief description of the test configuration, the paper focuses on the analysis of an impact test and presents preliminary simulation results.

APA, Harvard, Vancouver, ISO, and other styles

15

Xiong, Yi Bo, Lu Peng, Jin Xu, and Liang Ma. "Triaxial Compressive Behavior of Two Types of Concrete with Curing Conditions of Construction Site." Advanced Materials Research 261-263 (May 2011): 38–42. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.38.

Full text

Abstract:

Based on an extensive experimental program under uniaxial and triaxial compression, this paper studies the mechanical behavior of two types of concrete with the same raw materials and the same curing conditions of the construction site. Stress-strain relations and strengths are obtained under triaxial compression with confining pressures from 10MPa to 120MPa. Material constants of different types of failure criterion are determined by the statistical method with the data from this study and public literature, including linear Mohr-Coulomb model, parabolic Willam-Warnke failure criterion and power functional Johnson-Holmquist model. The results indicate that the modulus of both types of concrete decrease as an exponential decay law with the increase of confining pressures in triaxial compression.

APA, Harvard, Vancouver, ISO, and other styles

16

Jaulin, Vincent, David Hébert, Bertrand Aubert, Jean-Luc Rullier, Frédéric Malaise, and Emilien Lescoute. "Laser-induced cratering of a 3DCC material at mesoscale: Experiments and simulations." EPJ Web of Conferences 183 (2018): 01028. http://dx.doi.org/10.1051/epjconf/201818301028.

Full text

Abstract:

This study concerns the damaging of a 3-Dimension Carbon/Carbon (3DCC) composite material under dynamic loading. Experiments were performed with a laser facility delivering energies between 13 and 40 J with 100 nanoseconds pulse duration. The focal spot diameter was 250 μm, leading to dynamic pressure up to 10 GPa. The focal spot being smaller than the size of the composite components, it allows us to study the dynamic behaviour of the material at mesoscopic scale. The dynamic process of this cratering is then investigated via 3D numerical simulations, and a Johnson-Holmquist model is proposed. It appears that comparison of simulations with experimental results is useful to identify the dynamic strength of individual components of composite materials.

APA, Harvard, Vancouver, ISO, and other styles

17

Kristoffersen, Martin, Oda Lunde Toreskås, Sumita Dey, and Tore Børvik. "Ballistic impact on concrete slabs: An experimental and numerical study." EPJ Web of Conferences 250 (2021): 02001. http://dx.doi.org/10.1051/epjconf/202125002001.

Full text

Abstract:

The ballistic perforation resistance of 50 mm thick concrete slabs impacted by 20 mm diameter ogive-nose steel projectiles is investigated experimentally and numerically. Three commercially produced concretes with nominal unconfined compressive strengths of 35, 75 and 110 MPa were used to cast material test specimens and slabs. After curing, ballistic impact tests were carried out to determine the ballistic limit curve and velocity for each slab quality. Material tests instrumented with digital image correlation (DIC) were conducted along the ballistic impact tests. DIC measurements were used to establish engineering stress-strain curves for calibration of a modified version of the Holmquist-Johnson-Cook concrete model. Finite element simulations of the impact tests gave good conservative predictions.

APA, Harvard, Vancouver, ISO, and other styles

18

Zhang, Xiu Hua, Yan Yan Wu, and Jun Wang. "Numerical Simulation for Failure Modes of Reinforced Concrete Beams under Blast Loading." Advanced Materials Research 163-167 (December 2010): 1359–63. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.1359.

Full text

Abstract:

The reinforced concrete (RC) beams have three failure modes using large-scale finite element procedure LS-DYNA to simulate dynamic responses and failure modes of RC beams under blast loading. Holmquist-Johnson-Cook material model was used in concrete, the damage and strain rate effects were considered the kinematic hardening plasticity material model was used in reinforcing bars. With different rebar ratios and charges of weight TNT equivalent and stand-off distance were investigated and discussed. The numerical simulation can predict responses and flexure, flexure-shear and direct shear of the RC beams under different blast loading. The influence of the several factors have been identified and provided a theoretical basis for blast resistant design and retrofitting of the RC beam.

APA, Harvard, Vancouver, ISO, and other styles

19

Wei, Li, and Zhang. "Simulation Study of Low-Velocity Impact on Polyvinyl Butyral Laminated Glass Based on the Combined TCK-JH2 Model." Applied Sciences 9, no. 15 (August 6, 2019): 3204. http://dx.doi.org/10.3390/app9153204.

Full text

Abstract:

In this paper, both experimental tests and numerical simulations of Polyvinyl Butyral (PVB) laminated glass pane under low-speed impact were carried out. In order to accurately predict the responses of annealed glass under low-speed impact, a constitutive model combined of the Taylor–Chen–Kuszmaul (TCK) model and the Johnson-Holmquist Ceramic (JH2) model is proposed. In order to describe the tensile damage characteristic of annealed glass, a rate-dependent TCK model is employed. The JH2 model is adopted when the glass material is under compression. The velocity and force of impactor, deflection of central point of glass pane, and the cracking pattern are studied to verify the combined TCK-JH2 model. Furthermore, the effects of the thickness of glass layer and PVB interlayer are investigated.

APA, Harvard, Vancouver, ISO, and other styles

20

Pashmforoush, Farzad, and Amir Esmaeilzare. "Experimentally validated finite element analysis for evaluating subsurface damage depth in glass grinding using Johnson-Holmquist model." International Journal of Precision Engineering and Manufacturing 18, no. 12 (December 2017): 1841–47. http://dx.doi.org/10.1007/s12541-017-0213-2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Miedzińska, Danuta. "Influence of Grains Shape Irregularity in Porous Ceramics—Numerical Study." Materials 13, no. 8 (April 21, 2020): 1944. http://dx.doi.org/10.3390/ma13081944.

Full text

Abstract:

The presented study deals with the analysis of the stochastic geometry of grains on ceramic foam strength behavior. A microstructural finite element (FE) model of a grainy structure of such a material was developed and stochastic changes to the grain geometry (initially of a regular cubic shape) were introduced. The numerical compression test of a series of finite element models was carried out with the use of LS Dyna computer code. To consider the ceramic specific behavior, the Johnson Holmquist constitutive model was implemented with parameters for alumina. The influence of the stochastic irregularities on the ceramic foam strength was observed—the geometry changes caused an increase in the maximum stress, which could be the basis for the indication that the production of the energy absorbing material should be based on mostly irregular grains.

APA, Harvard, Vancouver, ISO, and other styles

22

Salman, H. Anıl, and R. Orhan Yıldırım. "Investigation of rain erosion on a brittle material by means of numerical simulation." Journal of Defense Modeling and Simulation: Applications, Methodology, Technology 9, no. 4 (July 5, 2011): 327–34. http://dx.doi.org/10.1177/1548512911411330.

Full text

Abstract:

In this work, the resistance and deformation characteristics of a brittle material against rain erosion are examined by using the non-linear, explicit software LS-DYNA. The water jet with varying speeds impinges at 90° on silica float glass plates with different thicknesses. In the simulations, the Arbitrary Lagrangian Eulerian method is used for modelling of the water. In order to analyse the deformations on the brittle material Johnson–Holmquist–Ceramics (JH-2) is used as the material model. Minimum plate thickness (for constant water jet speed) and maximum water speed (for constant plate thickness), which do not cause any damage to the target, are determined depending on the geometry, boundary conditions and assumed failure strain value for erosion. The results are compared with the water-hammer pressure.

APA, Harvard, Vancouver, ISO, and other styles

23

Zhang, Dan, Zhiwu Zhu, and Zhijie Liu. "Dynamic Mechanical Behavior and Numerical Simulation of Frozen Soil under Impact Loading." Shock and Vibration 2016 (2016): 1–16. http://dx.doi.org/10.1155/2016/3049097.

Full text

Abstract:

Split Hopkinson pressure bars (SHBP) were used to perform impact experiments on frozen soil under various impact velocities and temperatures to analyze the effect of these parameters on the mechanical behavior of the soil. Based on the Holmquist-Johnson-Cook constitutive model, the dynamic mechanical properties under impact loading were analyzed. The SHPB experiments of frozen soil were also simulated using the finite element analysis software LS-DYNA, and the simulation results were similar to the experimental results. The temperature effect, strain rate effect, and the destruction process of the frozen soil as well as the propagation process of stress waves in the incident bar, transmission bar, and frozen soil specimen were investigated. This work provides a good theoretical basis and technical support for frozen soil engineering applications.

APA, Harvard, Vancouver, ISO, and other styles

24

Kędzierski, P., A. Morka, G. Sławiński, and T. Niezgoda. "Optimization of two-component armour." Bulletin of the Polish Academy of Sciences Technical Sciences 63, no. 1 (March 1, 2015): 173–79. http://dx.doi.org/10.1515/bpasts-2015-0020.

Full text

Abstract:

Abstract The paper presents research on optimization of two-layer armour subjected to the normal impact of the 7.62x54 B32 armour piercing (AP) projectile. There were analysed two cases in which alumina Al2O3 was supported by aluminium alloy AA2024-T3 or armour steel Armox 500T. The thicknesses of layers were determined to minimize the panel areal density whilst satisfying the constraint, which was the maximum projectile velocity after panel perforation. The problem was solved through the utilization of LS-DYNA, LS-OPT and HyperMorph engineering software. The axisymmetric model was applied to the calculation in order to provide sufficient discretization. The response of the aluminium alloy, armour steel and projectile material was described with the Johnson-Cook model, while the one of the alumina with the Johnson-Holmquist model. The study resulted in the development of a panel optimization methodology, which allows the layer thicknesses of the panel with minimum areal density to be determined. The optimization process demonstrated that the areal density of the lightest panel is 71.07 and 71.82 kg/m2 for Al2O3-Armox 500T and Al2O3-AA2024-T3, respectively. The results of optimization process were confirmed during the experimental investigation.

APA, Harvard, Vancouver, ISO, and other styles

25

Khazraiyan, N., GH Liaghat, H. Khodarahmi, and N. Dashtian-Gerami. "Analysis of perforation process into concrete/metal targets by rigid projectiles." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 227, no. 7 (November 7, 2012): 1454–68. http://dx.doi.org/10.1177/0954406212462198.

Full text

Abstract:

In this article, a semi-analytical model has been developed for perforation of a hard projectile into a single- and two-layer concrete targets. The model is based on the dynamic cavity expansion theory and the reflection of compressive waves from the end of the concrete targets. The effect of friction coefficient is also investigated in the analysis. Numerical modeling of the problem has been performed in LS-DYNA code. Holmquist–Johnson–Cook, plastic kinematic, and rigid material models have been employed for the concrete, the backing plate, and the projectile, respectively. The impact velocity range, considered in this study, is between 300 and 800 m/s. No projectile erosion is considered in this velocity range. The analytical results of the investigation for both single- and two-layer concrete targets are in a good agreement with numerical simulations and experimental data.

APA, Harvard, Vancouver, ISO, and other styles

26

Wu, Hai-Jun. "Mechanism of High-velocity Projectile Penetration into Concrete." International Journal of Nonlinear Sciences and Numerical Simulation 13, no. 2 (April 1, 2012): 137–43. http://dx.doi.org/10.1515/ijnsns.2011.122.

Full text

Abstract:

Abstract The penetration depth of rigid projectiles is investigated using the modified spherical cavity expansion theory and the Holmquist–Johnson–Cook (HJC) model for the concrete targets, in which the model parameters used in the Mohr–Coulomb Tresca-limit yield criterion are obtained by the triaxial compression tests. By comparing the cavity expansion pressures of the concrete samples with two different types of aggregate, the influence of the aggregate hardness on the penetration processes is discussed. With the analysis of the tractions acted on the projectile nose, the influences of the projectile and target material properties as well as the projectile structure on the transition impact velocity are also discussed. By comparing the theoretical results with the experimental data, two penetration mechanisms are demonstrated for the ogive-nose projectile penetration into concrete with the striking velocities up to 2.0 km/s.

APA, Harvard, Vancouver, ISO, and other styles

27

Wang, Jianxiu, Yao Yin, and Chuanwen Luo. "Johnson–Holmquist-II(JH-2) Constitutive Model for Rock Materials: Parameter Determination and Application in Tunnel Smooth Blasting." Applied Sciences 8, no. 9 (September 16, 2018): 1675. http://dx.doi.org/10.3390/app8091675.

Full text

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.

APA, Harvard, Vancouver, ISO, and other styles

28

Wan, Wenzheng, Jian Yang, Guoji Xu, and Yikang Liu. "Determination and evaluation of Holmquist-Johnson-Cook constitutive model parameters for ultra-high-performance concrete with steel fibers." International Journal of Impact Engineering 156 (October 2021): 103966. http://dx.doi.org/10.1016/j.ijimpeng.2021.103966.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Alebooyeh, M., H. R. Baharvandi, and C. Aghanajafi. "Two-Dimensional FE Simulation of Impact Loading on Alumina Matrix Nanocomposite Reinforced by Dyneema® HB25 Laminates." Journal of Mechanics 33, no. 1 (April 15, 2016): 1–11. http://dx.doi.org/10.1017/jmech.2016.26.

Full text

Abstract:

AbstractPerforation process of a novel ceramic/composite panel including alumina-silicon carbide (Al2O3-SiC) nanocomposite as the front plate and ultra-high molecular weight polyethylene laminated composite (Dyneema® HB25) as the back-up impacted by a tip tapered penetrator has been analyzed based on LS-Dyna and HyperMesh codes. In order to balance the competing requirements posed by thickness, weight, cost and performance, a finite element (FE) simulation has been developed with well-developed material models. A two-dimensional, dynamic-explicit and Lagrangian model has been considered. The perforation process has been investigated for three different thicknesses of the ceramic plate. The Johnson-Cook, Johnson-Holmquist and Orthotropic-Elastic material models have been used for the penetrator, ceramic, and composite, respectively. The FE results, which have a good agreement with available experimental data, show that with the increase in the ceramic thickness, ceramic's fracture conoid as well as elasto-plastic deformation of fibers increase while fiber breakage and dishing of the composite layers diminish. In addition to saving cost and time, the FE simulation results can be useful as a fairly accurate prediction tool for the designing of lightweight body protective panels with desired impact resistance performance and eligible blunt trauma of the back-up.

APA, Harvard, Vancouver, ISO, and other styles

30

Xiong, Yi Bo, Jian Jie Chen, Yong Le Hu, and Feng Chao Wang. "Numerical Simulation Using FE-SPH Method for Concrete Slabs Penetrated and Perforated by Steel Projectiles." Advanced Materials Research 378-379 (October 2011): 143–46. http://dx.doi.org/10.4028/www.scientific.net/amr.378-379.143.

Full text

Abstract:

The explicit dynamic code LS-DYNA3D is used to simulate limited-thickness concrete slabs penetrated and perforated by steel projectiles with velocities from 381 m/s to 1058 m/s. The concrete slab is modeled with Smooth Particle Hydrodynamics (SPH) elements near the trajectory while Finite Element Method (FEM) elements in the others of the target, which is called FE-SPH method. The elastic-plastic model and Johnson-Holmquist concrete model are used to describe the mechanical behaviors of the projectiles and target slabs, respectively. The residual velocities computed by both FEM and FE-SPH method agree well with those of experimental results. For brittle concrete, the penetration and perforation phenomenon modeled by FE-SPH are in closer agreement with the experimental results than those modeled by FEM. Simulation of penetration and perforation by FEM require artificial element erosion set, which would lead to distortion of modeled results.

APA, Harvard, Vancouver, ISO, and other styles

31

Baranowski, Paweł, Łukasz Mazurkiewicz, Jerzy Małachowski, and Mateusz Pytlik. "Experimental testing and numerical simulations of blast-induced fracture of dolomite rock." Meccanica 55, no. 12 (August 18, 2020): 2337–52. http://dx.doi.org/10.1007/s11012-020-01223-0.

Full text

Abstract:

AbstractIn this paper, the Johnson-Holmquist II (JH-2) model with parameters for a dolomite rock was used for simulating rock fragmentation. The numerical simulations were followed by experimental tests. Blast holes were drilled in two different samples of the dolomite, and an emulsion high explosive was inserted. The first sample was used to measure acceleration histories, and the cracking pattern was analyzed to perform a detailed study of the blast-induced fracture to validate the proposed method of modelling and to analyze the capability of the JH-2 model for the dolomite. The second sample was used for further validation by scanning the fragments obtained after blasting. The geometries of the fragments were compared with numerical simulations to further validate the proposed method of modelling and the implemented material model. The outcomes are promising, and further study is planned for simulating and optimizing parallel cut-hole blasting.

APA, Harvard, Vancouver, ISO, and other styles

32

An, H. M., and L. Liu. "Numerical Study of Dynamic Behaviors of Concrete Under Various Strain Rates." Archives of Civil Engineering 65, no. 4 (December 1, 2019): 21–36. http://dx.doi.org/10.2478/ace-2019-0044.

Full text

Abstract:

AbstractAs the dynamic behavior of the concrete is different from that under static load, this research focuses on the study of dynamic responses of concrete by simulating the split Hopkinson pressure bar (SHPB) test. Finite element code LS-DYNA is used for modeling the dynamic behaviors of concrete. Three continuous models are reviewed and the Holmquist-Johnson-Cook model (HJC) is introduced in detail. The HJC model which has been implemented in LS-DYNA is used to represent the concrete properties. The SHPB test model is established and a few stress waves are applied to the incident bar to simulate the dynamic concrete behaviors. The stress-strain curves are obtained. The stress distributions are analyzed. The crack initiation and propagation process are described. It is concluded that: the HJC model can modeling the entire process of the fracture initiation and fragmentation; the compressive of the concrete is significantly influenced by the strain rates.

APA, Harvard, Vancouver, ISO, and other styles

33

Long, Xiaohong, Ahmed Turgun, Rong Yue, Yongtao Ma, and Hui Luo. "Influence Factors Analysis of RC Beams under Falling Weight Impact Based on HJC Model." Shock and Vibration 2018 (October 21, 2018): 1–16. http://dx.doi.org/10.1155/2018/4731863.

Full text

Abstract:

Impact loads may cause serious or even fatal damage to the structure (component), in most existing specifications in China, and there are no special terms that take impact load into consideration. So, the response analysis of the structure (component) under impact loads is very important. In this paper, the sensitivity analysis was conducted for the 22 parameters of the Holmquist–Johnson concrete (HJC) constitutive model of concrete, and the sensitive parameters of the HJC model are identified with A, B, G, Pl, μl, and fc respectively. LS-DYNA nonlinear transient finite element analysis code was used for this paper. Based on the validation of finite element modeling and choosing midspan deflection of RC beams and impact loads as response indices, some influencing factors on RC beams under falling weight impact were investigated, such as the mass and speed of falling weight, impact position, the strength of concrete and rebar, longitudinal reinforcement ratio, and the span of the beam.

APA, Harvard, Vancouver, ISO, and other styles

34

Trung, Phan Thành, Nguyễn Quốc Bảo, and Vũ Đức Hiếu. "Đánh giá sự phá hủy cấu kiện cột bê tông cốt thép dưới tác dụng tải trọng nổ tiếp xúc bằng mô phỏng số và thực nghiệm tại hiện trường." Tạp chí Khoa học Công nghệ Xây dựng (KHCNXD) - ĐHXD 14, no. 5V (November 9, 2020): 180–96. http://dx.doi.org/10.31814/stce.nuce2020-14(5v)-15.

Full text

Abstract:

Đánh giá tác động và phá hủy của lượng nổ tiếp xúc với các cấu kiện là bài toán rất phức tạp và có sai số lớn. Ở Việt nam, tính toán này hiện nay chủ yếu sử dụng một số công thức thực nghiệm tham khảo đã có. Kết quả thực nghiệm chỉ phù hợp trong phạm vi thực nghiệm đề ra và còn có nhiều sai lệch đáng kể so với thực tế tại hiện trường. Bài báo tập trung vào nghiên cứu và đánh giá sự phá hủy của tải trọng nổ tiếp xúc đối với bê tông cốt thép theo phương pháp thực nghiệm tại hiện trường và mô phỏng số. Để phục vụ mô phỏng số, tác giả đã lựa chọn mô hình vật liệu phù hợp với bài toán nổ và tiến hành thực nghiệm để xác định các tham số trên. Kết quả so sánh nhằm đánh giá mức độ tin cậy của mô phỏng, lựa chọn mô hình tính và mô hình vật liệu trong mô phỏng kết cấu chịu tác dụng của tải trọng nổ bằng phần mềm ABAQUS. Từ khóa: nổ tiếp xúc; phá hủy bê tông cốt thép; phân tích động tường minh theo thời gian; mô hình Holmquist - Johnson - Cook; mô hình Johnson - Cook.

APA, Harvard, Vancouver, ISO, and other styles

35

Stanislawek, S., A. Morka, and T. Niezgoda. "Pyramidal ceramic armor ability to defeat projectile threat by changing its trajectory." Bulletin of the Polish Academy of Sciences Technical Sciences 63, no. 4 (December 1, 2015): 843–49. http://dx.doi.org/10.1515/bpasts-2015-0096.

Full text

Abstract:

Abstract This paper presents a numerical study of a multilayer composite panel impacted by an AP (Armor Piercing) 14.5×114 mm B32 projectile. The composite consists of alternating layers of hard ceramic and a ductile aluminum alloy. While the alloy layer consists of typical plate, ceramics confront projectiles in the form of ceramic pyramids. The studied models are compared with a reference structure, which is a standard double layer panel. The problem has been solved with the usage of modeling and simulation methods as well as a finite elements method implemented in LS-DYNA software. Space discretization for each option was built with three dimensional elements ensuring satisfying accuracy of the calculations. For material behavior simulation, specific models including the influence of the strain rate and temperature changes were considered. A steel projectile and aluminum plate material were described by the Johnson-Cook model and a ceramic target by the Johnson-Holmquist model. The obtained results indicate that examined structures can be utilized as a lightweight ballistic armor in certain conditions. However, panels consisting of sets of ceramic prisms are a little easier to penetrate. Despite this fact, a ceramic layer is much less susceptible to overall destruction, making it more applicable for the armor usage. What is most important in this study is that significant projectile trajectory deviation is detected, depending on the impact point. Such an effect may be utilized in solutions, where a target is situated relatively far from an armor.

APA, Harvard, Vancouver, ISO, and other styles

36

Luo, Dong. "Dynamic Constitutive Model Analysis of High Parameter Steel Fiber Reinforced Concrete." Symmetry 11, no. 3 (March 14, 2019): 377. http://dx.doi.org/10.3390/sym11030377.

Full text

Abstract:

The traditional Holmquist-Johnson-Cook (HJC) constitutive model does not consider the effect of crack resistance, reinforcement and toughening effect of high parameter steel fiber on original concrete. The causes of the analysis effect of the high parameter reinforced concrete is not obvious. To address this problem, a dynamic constitutive model of high parameter steel fiber reinforced concrete is built in this paper. Based on the static constitutive model built by static force, a dynamic constitutive model is built based on the similarity between static and dynamic stress-strain curve. On this basis, the yield surface equation, state equation, and damage evolution equation of HJC constitutive model are constructed. An improved HJC constitutive model for high parameter steel fiber reinforced concrete is obtained by introducing the modification of the steel fiber reinforced, toughened, and strain rate effects into the HJC constitutive model. Dynamic analysis of high parameter steel fiber reinforced concrete is achieved by using the improved model. Experimental results show that the proposed model is effective in analyzing high parameter concrete and has strong applicability.

APA, Harvard, Vancouver, ISO, and other styles

37

Lian, Xiao Qing, Xiu Mei Feng, and Ming Xue Jiang. "Stress and System Energy in Erosion Process for Brittle Materials." Advanced Materials Research 239-242 (May 2011): 1165–70. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.1165.

Full text

Abstract:

Erosion tests on high strengh refractory castables were carried out using SiC grains at impact angles of 30°,45°,60°,and 90° with the velocity of 5m/s.In order to study the variation in stress and system energy with impact angles during solid particle erosion process,a single particle erosion model was designed by means of three-dimensional explicit dynamic software ANSYS/LS-DYNA according to experiment parameters. The Johnson-Holmquist brittle ceramic model was employed to model the failure of target material. The impact angles varied from 15° to 90° in increments of 15°.The simulation results were compared with erosion rate values from experiments. The results show that the variation trends of both the maximum stress of targets and system total energy loss are in a good agreement with experiment data,which increaes with increasing impact angle. The variation of erosion rate as a function of impact angle can be explained by the variation of the maximum stress of target material. The rule “the maximum erosion of typical brittle material occurs at 90°” is confirmed by the view of energy analysis.

APA, Harvard, Vancouver, ISO, and other styles

38

Yu, Zhi Xiang, Lan Yan Zhang, Ya Na Zhao, and Tao Wei. "Effectiveness Analysis on the Protection Measures for the Mountain Bridge Piers against Rockfall." Applied Mechanics and Materials 226-228 (November 2012): 1683–88. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.1683.

Full text

Abstract:

In order to study effectiveness of measures taken to protect mountain bridge piers against rockfall in the upper reaches of the Minjiang River in Sichuan, based on non-linear explicit dynamic analysis, a numerical model was established to analyze the effectiveness using Holmquist–Johnson –Cook(HJC) damage constitutive model .And the numerical stability of calculation was tested in accordance with energy conservation principle. Four working conditions of bridge pier, namely ordinary non-protection, encryption stirrups, thickening plain concrete protection layer, being wrapped in steel tube, had been analyzed.Then by studying the response characteristics of the pier including the maximum damage depth of concrete, stress of longitudinal rebar, failure volume of concrete, different effectiveness of the three protective measures was compared . The rationality of analysis was verified by comparing with experimental results.The study shows that the HJC constitutive model can simulate the behavior of concrete under impact load well, and respectively protective effect of being wrapped in steel tube , thickening plain concrete protection layer, encryption stirrups, is weaker than the previous one.

APA, Harvard, Vancouver, ISO, and other styles

39

Yang, Yuezong, Zhushan Shao, Junfeng Mi, and Xiaofeng Xiong. "Effect of Adjacent Hole on the Blast-Induced Stress Concentration in Rock Blasting." Advances in Civil Engineering 2018 (November 15, 2018): 1–13. http://dx.doi.org/10.1155/2018/5172878.

Full text

Abstract:

To investigate the effect of an adjacent hole on the blast-induced stress concentration in rock blasting, a rock blasting model with an adjacent hole is explored through theoretical analysis and numerical simulation. The commercial software LS-DYNA is utilized to simulate adjacent hole effect in rock blasting, in which the Johnson–Holmquist concrete material model is used to simulate rock and the high-explosive-burn-explosive and the equation of state of JWL are used to simulate explosive. Influences of the key parameters of adjacent hole effect in rock blasting, pitch of holes, adjacent hole diameter, and uncoupled medium in a blasting hole are extensively explored. According to the simulation results, when the explosion stress wave spreads to the adjacent hole wall, the tangential stress on the adjacent hole wall induced by the explosion stress wave is always greater than the radial stress. Adjacent hole diameter has a major effect on stress concentration, but with the adjacent hole diameter increasing, the stress concentration phenomenon weakens and the free surface effect of the adjacent hole plays a more important role.

APA, Harvard, Vancouver, ISO, and other styles

40

Mysin, Alexey, and Vladimir Kovalevskiy. "Creation and Verification of Numerical Model of Explosive Charge Blast in The Ansys Software System, for the Purpose of Substantiating the Optimal Parameters of Drilling and Blasting Operations." E3S Web of Conferences 174 (2020): 01046. http://dx.doi.org/10.1051/e3sconf/202017401046.

Full text

Abstract:

The purpose of this paper was to create a numerical model of explosive destruction of a rock slab by exploding a cylindrical explosive charge. The paper considers the features of solving the problem of explosive charge using the finite element method in a three-dimensional setting. The equations of state of materials used for calculations are given. The results of the laboratory experiment carried out on the basis of the laboratory: “Physical and technological processes of rock destruction” and “Physics of rock destruction by explosive energy” of the Department of Blasting works of the Mining University are presented. The comparison of the results of the laboratory experiment and the numerical modeling performed using the ANSYS software system is presented. Experimental research has shown that having clarified the constants in the polynomial equation of state of the material and the Johnson–Holmquist strength model, the results of numerical modeling, in general, are similar to the experimental ones. The obtained and verified numerical model of the cylindrical explosive charge blast is considered as the basis for choosing the optimal parameters of drilling and blasting works.

APA, Harvard, Vancouver, ISO, and other styles

41

Gharehdash, Saba, Lu Ming Shen, Yi Xiang Gan, and E. A. Flores-Johnson. "Numerical Investigation on Fracturing of Rock under Blast Using Coupled Finite Element Method and Smoothed Particle Hydrodynamics." Applied Mechanics and Materials 846 (July 2016): 102–7. http://dx.doi.org/10.4028/www.scientific.net/amm.846.102.

Full text

Abstract:

This paper aims to provide a coupled finite element method (FEM) and smoothed particle hydrodynamics (SPH) approach capable of reproducing the blast response in rock. In the proposed approach, SPH is used to simulate large deformation and fracture of rock at the near detonation zone, while the FEM is adopted to capture the far field response of the rock. The explosive is modelled explicitly using SPH. The numerical simulations are carried out using LS-DYNA. The interaction of the SPH particles and FEM elements was modelled by the node to surface contact, and for the interactions between explosive and rock SPH parts node to node penalty based contact was used. In the present study, the Johnson and Holmquist constitutive model is used for rock. Jones–Wilkins–Lee model is used for TNT explosive. It is found that the preliminary numerical simulation reproduces some of the well-known phenomena observed experimentally by other researchers. The numerical results indicate that the coupled SPH-FEM approach used in this work can be applied to simulate effectively both compressive and tensile damage of rock subjected to blast loading.

APA, Harvard, Vancouver, ISO, and other styles

42

Peng, Kang, Ke Gao, Jian Liu, Yujiao Liu, Zhenyu Zhang, Xiang Fan, Xuyan Yin, Yongliang Zhang, and Gun Huang. "Experimental and Numerical Evaluation of Rock Dynamic Test with Split-Hopkinson Pressure Bar." Advances in Materials Science and Engineering 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/2048591.

Full text

Abstract:

Feasibility of rock dynamic properties by split-Hopkinson pressure bar (SHPB) was experimentally and numerically evaluated with ANSYS/LS-DYNA. The effects of different diameters, different loading rates, and different propagation distances on wave dispersion of input bars in SHPB with rectangle and half-sine wave loadings were analyzed. The results show that the dispersion effect on the diameter of input bar, loading rate, and propagation distance under half-sine waveform loading is ignorable compared with the rectangle wave loading. Moreover, the degrees of stress uniformity under rectangle and half-sine input wave loadings are compared in SHPB tests, and the time required for stress uniformity is calculated under different above-mentioned loadings. It is confirmed that the stress uniformity can be realized more easily using the half-sine pulse loading compared to the rectangle pulse loading, and this has significant advantages in the dynamic test of rock-like materials. Finally, the Holmquist-Johnson-Concrete constitutive model is introduced to simulate the failure mechanism and failure and fragmentation characteristics of rock under different strain rates. And the numerical results agree with that obtained from the experiment, which confirms the effectiveness of the model and the method.

APA, Harvard, Vancouver, ISO, and other styles

43

Liang, Ninghui, Ru Yan, Xinrong Liu, Peng Yang, and Zuliang Zhong. "A Study of Impact Response and Its Numerical Study of Hybrid Polypropylene Fiber-Reinforced Concrete with Different Sizes." Advances in Materials Science and Engineering 2020 (October 8, 2020): 1–15. http://dx.doi.org/10.1155/2020/6534080.

Full text

Abstract:

Compressive properties of hybrid polypropylene fiber-reinforced concrete (HPFRC) with different sizes of polypropylene fibers (PPFs) under the impact load (101∼102/s) were tested by using a 74 mm diameter various cross-section split-Hopkinson pressure bar (SHPB), in which the fiber content of fine PPFs was 0.9 kg/m3 and that of coarse PPFs was 6.0 kg/m3. The effect of strain rate and PPF hybridization on the impact characteristics of HPFRC was analyzed. It is found that dynamic compressive properties, including dynamic compressive strength, dynamic compressive strength increase factor (DCF), ultimate strain, and impact toughness, increased with the increase of strain rate. Meanwhile, both fine PPFs and coarse PPFs can enhance the impact strength of concrete, and an appropriate hybridization of two sizes of PPFs in concrete was more effective than the concrete reinforced with one size of PPF. Moreover, a modified constitutive model for HPFRC was proposed based on the Holmquist–Johnson–Cook (HJC) constitutive model. Then, the numerical study of SHPB tests for HPFRC was conducted based on the modified model, which showed that the modified HJC constitutive model could well describe the dynamic stress-strain relationship of HPFRC.

APA, Harvard, Vancouver, ISO, and other styles

44

Stanislawek, Sebastian, Andrzej Morka, and Tadeusz Niezgoda. "A Composite Consisting of a Set of Hexagonal Ceramic Bars - The Numerical Study of the Ballistic Resistance." Key Engineering Materials 471-472 (February 2011): 1142–46. http://dx.doi.org/10.4028/www.scientific.net/kem.471-472.1142.

Full text

Abstract:

The paper presents a numerical study of a double layer composite panels impacted by a AP (Armor Piercing) 51WC projectile. The standard panel is built with aluminum and Al2O3 ceramic continuum layers while the studied model consists of the same aluminum plate but the front one is built with a set of hexagonal ceramic bars. The bar width and the impact position influence on the ballistic resistance are analyzed and compared with the reference solution. The problem has been solved with the usage of the modeling and simulation methods as well as finite elements method implemented in LS-DYNA software. Space discretization for each option was built by three dimension elements guarantying satisfying accuracy of the calculations. For material behavior simulation specific models including the influence of the strain rate and temperature changes were considered. Projectile Tungsten Curbide and aluminum plate material were described by Johnson-Cook model and ceramic target by Johnson-Holmquist model. In the studied panels the area surrounding back edges was supported by a rigid wall. The obtained results show interesting properties of the examined structures considering their ballistic resistance. All tests has given clear results about ballistic protection panel response under WC projectile impact. Panels consisting of sets of hexagonal ceramic bars are slightly easier to penetrate, reference model is stronger by 19% for smaller bars and by only 7% for bigger rods. Despite this fact, the ceramic layer is much less susceptible to overall destruction what makes it more applicable for the armor usage. Furthermore, little influence of the projectile impact point and consequently a part of the bar which is first destroyed is proved.

APA, Harvard, Vancouver, ISO, and other styles

45

Hu, Feng, Hao Wu, Qin Fang, and Jinchun Liu. "Numerical simulations of shaped charge jet penetration into concrete-like targets." International Journal of Protective Structures 8, no. 2 (June 2017): 237–59. http://dx.doi.org/10.1177/2041419617706863.

Full text

Abstract:

Shaped charge jet has been widely applied in the military and energy sources’ extraction fields; while the related investigations on the shaped charge jet penetration into concrete-like target are still limited, a series of numerical simulation works are conducted in this article. Holmquist–Johnson–Cook and Johnson–Cook models are used to describe the concrete-like targets and metal liner/casing of the shaped charge, respectively. The whole process including the formation, elongation in the air, and penetration into concrete-like target of shaped charge jet is reproduced using the multi-material arbitrary Lagrange–Euler algorithm and fluid–structure interaction method implemented in LS-DYNA. Simultaneously, the striking velocities of the jet (both tip and tail) and the damage of target (diameter and depth of penetration borehole) are derived. The above constitutive models, the corresponding material parameters, and the finite element algorithms are validated by comparing with the available tests’ data. The analyses of parametric influences are further performed. It indicates that for the unfragmented shaped charge jet, the penetration depth increases and the average penetration borehole diameter decreases with the standoff distance increasing, respectively; the compressive strength of concrete target has slight influence on the penetration depth of shaped charge jet; the diameter of shaped charge jet penetration borehole with aluminum liner is larger, while that with copper liner has a deeper penetration depth. It can also be found that the influence of explosive type on the penetration performance of shaped charge jet is negligible at small standoff distance, while the explosive LX-14 performs better than explosives Octol, B, and 8701 at larger standoff distance.

APA, Harvard, Vancouver, ISO, and other styles

46

Wang, Chao, Ran Song, Gaohui Wang, Sherong Zhang, Xuexing Cao, and Peiyong Wei. "Modifications of the HJC (Holmquist–Johnson–Cook) Model for an Improved Numerical Simulation of Roller Compacted Concrete (RCC) Structures Subjected to Impact Loadings." Materials 13, no. 6 (March 17, 2020): 1361. http://dx.doi.org/10.3390/ma13061361.

Full text

Abstract:

Structures made of Roller Compacted Concrete (RCC) may be subjected to dynamic loads during their service life. Understanding the dynamic material properties of RCC and the performance of RCC structures is essential for better analysis and design of RCC structures. As full-scale tests are often unaffordable, numerical simulation methods are continuously employed. However, in numerical simulations, determining a reasonable constitutive relationship for RCC materials is still limited due to the complexity of the composite and the special rolling and compacting construction technology. In this paper, the triaxial compressive test and split Hopkinson pressure bar (SHPB) experimental results for RCC are introduced as an experimental foundation. Parameter calibrations and modifications in terms of the strength yield surface, the strain rate effect and the failure criterion for the RCC materials are presented. Numerical verification is illustrated for simulating the SHPB experiment and predicting the dynamic compressive characteristics of RCC specimens with a modified HJC model. The results reveal that the simulation results for the modified model have better agreement with the test data than those with the model before modification and have better simulation results. Sensitivity studies of the key parameters on the yield surface of the modified HJC model are conducted to improve the simulation effect for numerically predicting the performance of RCC structures exposed to explosive and impact loads.

APA, Harvard, Vancouver, ISO, and other styles

47

Fourmeau, Marion, Alexandre Kane, and Mikko Hokka. "Experimental and numerical study of drill bit drop tests on Kuru granite." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 375, no. 2085 (January 28, 2017): 20160176. http://dx.doi.org/10.1098/rsta.2016.0176.

Full text

Abstract:

This paper presents an experimental and numerical study of Kuru grey granite impacted with a seven-buttons drill bit mounted on an instrumented drop test machine. The force versus displacement curves during the impact, so-called bit–rock interaction (BRI) curves, were obtained using strain gauge measurements for two levels of impact energy. Moreover, the volume of removed rock after each drop test was evaluated by stereo-lithography (three-dimensional surface reconstruction). A modified version of the Holmquist–Johnson–Cook (MHJC) material model was calibrated using Kuru granite test results available from the literature. Numerical simulations of the single drop tests were carried out using the MHJC model available in the LS-DYNA explicit finite-element solver. The influence of the impact energy and additional confining pressure on the BRI curves and the volume of the removed rock is discussed. In addition, the influence of the rock surface shape before impact was evaluated using two different mesh geometries: a flat surface and a hyperbolic surface. The experimental and numerical results are compared and discussed in terms of drilling efficiency through the mechanical specific energy. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’.

APA, Harvard, Vancouver, ISO, and other styles

48

Mai, Viet-Chinh, Xuan-Bach Luu, Cong-Binh Dao, and Dinh-Viet Le. "Investigate the Structural Response of Ultra High Performance Concrete Column under the High Explosion." Defence Science Journal 71, no. 2 (March 10, 2021): 256–64. http://dx.doi.org/10.14429/dsj.71.16427.

Full text

Abstract:

Most of the structures that are damaged by an explosion are not initially designed to resist this kind of load. In the overall structure of any building, columns play an important role to prevent the collapse of frame structure under blast impact. Hence, the main concept in the blast resistance design of the structure is to improve the blast load capacity of the column. In this study, dynamic analysis and numerical model of Ultra High Performance Concrete (UHPC) column under high explosive load, is presented. Based on the Johnson Holmquist 2 damage model and the subroutine in the ABAQUS platform, a total of twenty UHPC model of the column were calculated. The objective of the article is to investigate the structural response of the UHPC column and locate the most vulnerable scenarios to propose necessary recommendations for the UHPC column in the blast loading resistance design. The input parameters, including the effect of various shapes of cross-section, scaled distance, steel reinforcement ratio, and cross-section area, are analyzed to clarify the dynamic behavior of the UHPC column subjected to blast loading. Details of the numerical data, and the discussion on the important obtained results, are also provided in this paper.

APA, Harvard, Vancouver, ISO, and other styles

49

Kojima, Tomohisa, Masahiro Suzuki, and Mitsuo Notomi. "Numerical Simulation on Dynamic Fracture of Glass Plate Fitted with Polymeric Film." Advanced Materials Research 1166 (September 27, 2021): 57–64. http://dx.doi.org/10.4028/www.scientific.net/amr.1166.57.

Full text

Abstract:

The impact resistance improvement is important for window glass to protect people from injury. Although it has been proved that the impact resistance of a glass plate can be improved easily by fitting a thin polymeric film, its mechanism has not been clarified yet. The purpose of this study is to clarify the reinforcing mechanism of the impact resistance of a glass plate by fitting a polymeric film. To clarify it, a numerical simulation model was built using ANSYS Autodyn to simulate the dynamic fracture of a glass plate fitted with a polymeric film. The simulation model and results were examined by comparing them to the experimental result in the previous study. The Johnson-Holmquist (JH2) damage model was used for the constitutive law of the glass plate. A polymeric film with 0.2 mm thickness (3% with the glass plate) was modeled at the non-impact surface of the glass plate. The nodes of the glass plate at the interface with the film connected the nodes of the film by perfect bonding. By comparing the simulation results to the experiment, it was indicated the importance of modeling the remaining fragments of the glass plate and the adhesive layer of the film in simulating the dynamic fracture of the glass plate fitted with polymeric film.

APA, Harvard, Vancouver, ISO, and other styles

50

Stanislawek, Sebastian, Andrzej Morka, and Tadeusz Niezgoda. "Multisphere Ceramic Composite Concept and its Numerical Study of the Ballistic Response." Key Engineering Materials 471-472 (February 2011): 1136–41. http://dx.doi.org/10.4028/www.scientific.net/kem.471-472.1136.

Full text

Abstract:

Numerical investigations were performed to determine the influence of the spherical convex shape ceramic - alumina composite in reference to the standard double layer panel. All versions of the target were verified in an impact test including influence upon the position of the AP (Armor Piercing) 7,62x51HHS impact. The crucial parameter which was used for this verification was change in time of the PROJECTILE kinetic energy. The problem has been solved with the usage of the modeling and simulation methods as well as finite elements method implemented in LS-DYNA software. Space discretization for each option was built by three dimension elements guarantying satisfying accuracy of the calculations. For material behavior simulation specific models including the influence of the strain rate and temperature changes were considered. Projectile’s core made of HHS and aluminum plate material were described by Johnson-Cook model and ceramic target with Johnson-Holmquist model. In the studied panels the area surrounding back edges was supported by rigid wall. The obtained results show interesting properties of the new structures considering their ballistic resistance. However only certain places were chosen for tests, the protection ability against projectile attack is in general higher than the reference model. What is particularly interesting during the 6.6mm from the sphere center impact the sphere surface trajectory deviation effect is present. A projectile is not stopped here by material strength but the front layer shape. Moreover it can be assumed that this phenomenon will take place on majority of points on the sphere surface. Despite this fact, a ceramic multi sphere layer is less susceptible to overall destruction, depending on the impact point. The results of those numerical simulations can be used for designing of modern armor protection systems against hard kinetic projectiles.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Johnson Holmquist'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles