scholarly journals Impact Perforation of aluminum Cymat Foam

2018 ◽  
Vol 183 ◽  
pp. 01003
Author(s):  
Ibrahim Elnasri ◽  
Han Zhao
Keyword(s):  
Impact Loading ◽  
Failure Strain ◽  
Failure Criteria ◽  
Tensile Failure ◽  
Static Test ◽  
System A ◽  
Split Hopkinson ◽  
Clamping System ◽  
Split Hopkinson Pressure Bars ◽  
Force Displacement

The behavior of aluminum Cymat foam under impact perforation loading was studied using experiments and simulations. Measurements at 40 m/s were performed with an inverse perforation setup using a Split Hopkinson Pressure Bars system. Such measurement is missing in a classical free-flying penetrator–immobile–target scheme under impact loading and makes it possible to directly compare impact the perforation force–displacement curves with the static ones. Compared with quasi-static test perforation forces obtained under the same geometry and clamping system, a significantly enhanced perforation force was found under impact loading. Numerical simulations of the perforation test were developed using LS-DYNAfinite element code to provide the local information necessary to understand the unexpected enhancement in perforation force. The shock effect was found to be responsible for enhancement of the perforation force and revealed that the honeycomb model with appropriate tensile failure criteria was more suitable for model perforation of the foam than the Deshpande and Fleck model with volumetric failure strain criteria

Effect of Material Composition on Impact Energy Absorbing Capability of Composite Laminates

2016 ◽  
Vol 715 ◽  
pp. 147-152
Author(s):  
Ryota Haruna ◽  
Takayuki Kusaka ◽  
Ryota Tanegashima ◽  
Junpei Takahashi
Keyword(s):  
Impact Loading ◽  
Composite Laminates ◽  
Fiber Type ◽  
Material Composition ◽  
Control Technique ◽  
Dynamic Stress Field ◽  
Split Hopkinson ◽  
Split Hopkinson Pressure Bars ◽  
Crushing Behavior ◽  
Energy Absorbing

A novel experimental method was proposed for characterizing the energy absorbing capability of composite materials during the progressive crushing process under impact loading. A split Hopkinson pressure bars system was employed to carry out the progressive crushing tests under impact loading. The stress wave control technique was used to avoid the inhomogeneity of dynamic stress field in the specimen. The progressive crushing behavior was successfully achieved by using a coupon specimen and anti-buckling fixtures. With increasing strain rate, the absorbed energy during the crushing process slightly decreased, whereas the volume of the damaged part clearly increased regardless of material type. Consequently, the energy absorbing capability decreased with increasing loading rate. The effects of material composition, such as fiber type, matrix type and fabric pattern, on energy absorbing capability were also investigated by using the proposed method.

scholarly journals Impact Testing of 3D Re-Entrant Honeycomb Polyamide Structure Using Split Hopkinson Pressure Bar

2021 ◽  
Vol 11 (21) ◽  
pp. 9882
Author(s):  
Jiangping Chen ◽  
Weijun Tao ◽  
Shumeng Pang
Keyword(s):  
Energy Absorption ◽  
Impact Velocity ◽  
Impact Loading ◽  
Split Hopkinson Pressure Bar ◽  
Impact Testing ◽  
Hopkinson Pressure Bar ◽  
Static Test ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
The Impact

In this study, a total of 30 3D re-entrant honeycomb specimens made of polyamide were fabricated with various configurations by using the additive manufacturing (AM) technique. Split Hopkinson Pressure Bar (SHPB) tests were conducted on the RH specimens at different impact velocities. The incident, reflected and transmitted waveforms can well explain the wave propagation and energy absorption characteristics of the specimens, which can help us to understand and analyse the process of impact loading. The stress–strain curves, energy absorption ability and failure modes of SHPB tests with different impact velocities and quasi-static compression tests were analysed and compared, and it was found that the flow stress and energy absorption ability of the specimens subjected to impact load were much improved. Among the tested specimens, specimen C2, with a smaller re-entrant angle θ, displayed the best energy absorption ability, which was 1.701 J/cm3 at the impact velocity of 22 m/s and was 5.1 times that in the quasi-static test. Specimen C5 had the longest horizontal length of the diagonal bar L0, and its energy absorption was 1.222 J/cm3 at the impact velocity of 22 m/s and was 15.7 times that in the quasi-static test, reflecting the superiority of a structurally stable specimen in energy absorption under impact loading. The test results can provide a reference for the optimization of the design of the same or similar structures.

Modified split Hopkinson pressure bars for dynamic bending and shear tests

2006 ◽  
Vol 134 ◽  
pp. 725-730 ◽  
Author(s):  
A. Pignon ◽  
G. Mathieu ◽  
S. Richomme ◽  
J. M. Margot ◽  
F. Delvare
Keyword(s):  
Shear Tests ◽  
Split Hopkinson ◽  
Split Hopkinson Pressure Bars ◽  
Dynamic Bending

Experimental and Numerical Study on the Dynamic Buckling of Ping-pong Balls under Impact Loading

2012 ◽  
Vol 13 (1) ◽  
Author(s):  
X. W. Zhang ◽  
T. X. Yu
Keyword(s):  
Impact Loading ◽  
Numerical Study ◽  
Digital Camera ◽  
Dynamic Buckling ◽  
Spherical Shells ◽  
Static Tests ◽  
Air Gun ◽  
Ping Pong ◽  
The Impact ◽  
Force Displacement

AbstractBy means of ping-pong balls, the dynamic buckling behaviours of thin-walled spherical shells under impact loading are studied both experimentally and numerically. First, the quasi-static tests were conducted on an MTS tester, in which the ball was compressed onto a PMMA plate. Apart from the force-displacement relationship, the evolution of the contact zone between the ball and the plate was obtained by a digital camera. In the impact tests, ping-pong balls were accelerated by an air-gun and then impinged onto a rigid plate with the velocity ranging 10–45 m

scholarly journals Development of a True-Biaxial Split Hopkinson Pressure Bar Device and Its Application

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7298
Author(s):  
Shumeng Pang ◽  
Weijun Tao ◽  
Yingjing Liang ◽  
Shi Huan ◽  
Yijie Liu ◽  
...  
Keyword(s):  
Stress Wave ◽  
Impact Loading ◽  
Split Hopkinson Pressure Bar ◽  
Axial Stress ◽  
Dynamic Mechanical Properties ◽  
Stress Waves ◽  
Hopkinson Pressure Bar ◽  
Dynamic Mechanical ◽  
Split Hopkinson ◽  
Pressure Bar

Although highly desirable, the experimental technology of the dynamic mechanical properties of materials under multiaxial impact loading is rarely explored. In this study, a true-biaxial split Hopkinson pressure bar device is developed to achieve the biaxial synchronous impact loading of a specimen. A symmetrical wedge-shaped, dual-wave bar is designed to decompose a single stress wave into two independent and symmetric stress waves that eventually form an orthogonal system and load the specimen synchronously. Furthermore, a combination of ground gaskets and lubricant is employed to eliminate the shear stress wave and separate the coupling of the shear and axial stress waves propagating in bars. Some confirmatory and applied tests are carried out, and the results show not only the feasibility of this modified device but also the dynamic mechanical characteristics of specimens under biaxial impact loading. This novel technique is readily implementable and also has good application potential in material mechanics testing.

scholarly journals NUMERICAL SIMULATION OF A MASSIVE IMPACTOR FALLING ONTO A REINFORCED CONCRETE BEAM

2020 ◽  
Vol 82 (1) ◽  
pp. 5-15
Author(s):  
S.M. Gertsik ◽  
Yu.V. Novozhilov
Keyword(s):  
Finite Elements ◽  
Concrete Beam ◽  
Time Integration ◽  
Volumetric Strain ◽  
Failure Criteria ◽  
Tensile Failure ◽  
Low Velocity Impact ◽  
Isotropic Hardening ◽  
Elastoplastic Material ◽  
Low Velocity

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.

Impact tensile behavior analysis of Twaron fiber tows from fast Fourier transform

2018 ◽  
Vol 89 (8) ◽  
pp. 1363-1370
Author(s):  
Lvtao Zhu ◽  
Guocheng Zhu ◽  
Jianyong Feng ◽  
Limin Jin ◽  
Pibo Ma
Keyword(s):  
Fourier Transform ◽  
Strain Rate ◽  
Fast Fourier Transform ◽  
Failure Strain ◽  
Amplitude Spectrum ◽  
Strain Rates ◽  
Transform Method ◽  
Fast Fourier Transform Method ◽  
Split Hopkinson ◽  
Specific Frequency

In this study, tensile experiments of Twaron fiber tows under different strain rates (quasi-static: 0.001 s−1, dynamic: 800–2400 s−1) were tested with an MTS materials tester (MTS 810.23) and a split Hopkinson tension bar, respectively. The results showed that the mechanical properties of the Twaron fiber tows were sensitive to strain rate: the stiffness and failure stress of the fiber tows increased distinctly as the strain rate increased, while the failure strain decreased. From scanning electron microscope photographs of the fracture surface, it is evident that the Twaron fiber tows failed in a tougher mode and the axial split became more severe as the strain rate increased. The tensile behaviors of the Twaron fiber tows were analyzed in the frequency domain using the fast Fourier transform method. The amplitude spectrum and power of energy absorption of the Twaron tows were concentrated in a specific frequency range and increased with strain rate.

Micromechanics Analysis of the Tensile Behavior of Twaron Fiber Tows at Various Strain Rates

2011 ◽  
Vol 181-182 ◽  
pp. 749-753
Author(s):  
Lv Tao Zhu ◽  
Bao Zhong Sun
Keyword(s):  
Mechanical Properties ◽  
Fracture Surface ◽  
Strain Rate ◽  
Failure Strain ◽  
Tensile Behavior ◽  
Failure Stress ◽  
Strain Rates ◽  
Split Hopkinson ◽  
Electronic Microscope ◽  
Split Hopkinson Tension Bar

In this study, tensile experiments of Twaron fiber tows under different strain rates (quasi-static:0.001s-1, dynamic: 800s-1~2400s-1) were carried out with MTS 810.23 materials tester and split Hopkinson tension bar (SHTB) respectively. The results showed that the mechanical properties of the Twaron fiber tows were sensitive to strain rate: the stiffness and failure stress of the fiber tows increased distinctly as the strain rate increased, while the failure strain decreased. From scanning electronic microscope (SEM) photographs of the fracture surface, it is indicated that the Twaron fiber tows failed in a more tough mode and the axial split will become more severe as the strain rate increases.

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