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.

scholarly journals Wave Attenuation and Dispersion in a 6 mm Diameter Viscoelastic Split Hopkinson Pressure Bar and Its Correction Method

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Haotian Zhang ◽  
Linjian Ma ◽  
Zongmu Luo ◽  
Ning Zhang
Keyword(s):  
Impact Velocity ◽  
Wave Attenuation ◽  
Split Hopkinson Pressure Bar ◽  
Small Diameter ◽  
Correction Method ◽  
Hopkinson Pressure Bar ◽  
Amplitude Attenuation ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
The Impact

The propagation characteristics of viscoelastic waves have been investigated with a 6 mm diameter split Hopkinson pressure bar (SHPB) made of polymethyl methacrylate (PMMA). The strain signals in SHPB tests were improved by the pulse shaping technique. Based on the experimentally determined propagation coefficients, the amplitude attenuation and wave dispersion induced by viscoelastic effects at different impact velocities were quantitatively analyzed. The results indicate that the high-frequency harmonics attenuate faster in a higher phase velocity. With an increase in the impact velocity, the amplitude attenuation of the viscoelastic wave changes slightly during propagation, while the waveform dispersion gradually intensifies. A feasible method by waveform prediction was proposed to verify the validity and applicability of the propagation coefficient. The results indicate that the strain obtained from the small diameter viscoelastic SHPB can be effectively modified by utilizing the propagation coefficient. Furthermore, it is preferred to adopt the propagation coefficient obtained at low impact velocity for correction when the impact velocity varies. Moreover, the PMMA-steel bar impact test was performed to further illustrate the accuracy of the propagation coefficient and the effectiveness of the correction method.

scholarly journals Impact Tensile Properties of Notched Titanium Alloy Bolt for Fairing Separation of Launch Vehicle

2018 ◽  
Vol 183 ◽  
pp. 04006
Author(s):  
Hiroto Shimanuki ◽  
Hiroyuki Yamada ◽  
Tsuyoshi Kami ◽  
Yoshihiro Yamasaki ◽  
Hiroshi Ikaida ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Maximum Load ◽  
Displacement Rate ◽  
Hopkinson Pressure Bar ◽  
Static Test ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
The Impact

The payload fairing in Japan is fixed by a lot of notched bolts. These notched bolts were fractured by axial impact tensile using the explosive devices to separate the fairing. In this case, the stress waves and the oscillations propagate, which may seriously damage the satellites. In this study, the impact deformation and the fracture behavior of notched titanium alloy bolt was investigated using a split Hopkinson pressure bar method. The notched bolt specimen was made of commercial Ti-6Al-4V alloy. The maximum load value was increased with increasing the displacement rate. It can be said that the strain rate dependence of strength for Ti-6Al-4V alloy appeared. From the observation of fracture surface using a scanning electron microscope, compared with the quasi-static test, it was clear that the irregularities of the fractured surface at the impact tensile test became rough. Therefore, it was found that the brittle fracture was mainly observed due to the increase in displacement rate, which may mean that the mode of fracture changes from the transgranular to the intergranular. It was surmised that this change of fracture mode was caused by the high strain rate due to stress concentration of the notched part.

Analysis of the Impact of the Frequency Range of the Tensometer Bridge and Projectile Geometry on the Results of Measurements by the Split Hopkinson Pressure Bar Method

2013 ◽  
Vol 20 (4) ◽  
pp. 555-564 ◽  
Author(s):  
Wojciech Moćko
Keyword(s):  
Test Bench ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Deformation ◽  
Spectral Width ◽  
Hopkinson Pressure Bar ◽  
Computing Environment ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
The Impact ◽  
Bench Model

Abstract The paper presents the results of the analysis of the striker shape impact on the shape of the mechanical elastic wave generated in the Hopkinson bar. The influence of the tensometer amplifier bandwidth on the stress-strain characteristics obtained in this method was analyzed too. For the purposes of analyzing under the computing environment ABAQUS / Explicit the test bench model was created, and then the analysis of the process of dynamic deformation of the specimen with specific mechanical parameters was carried out. Based on those tests, it was found that the geometry of the end of the striker has an effect on the form of the loading wave and the spectral width of the signal of that wave. Reduction of the striker end diameter reduces unwanted oscillations, however, adversely affects the time of strain rate stabilization. It was determined for the assumed test bench configuration that a tensometric measurement system with a bandwidth equal to 50 kHz is sufficient

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 Impact Testing of Polymer-filled Auxetics Using Split Hopkinson Pressure Bar

2017 ◽  
Vol 19 (10) ◽  
pp. 1700076 ◽  
Author(s):  
Tomáš Fíla ◽  
Petr Zlámal ◽  
Ondřej Jiroušek ◽  
Jan Falta ◽  
Petr Koudelka ◽  
...  
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Impact Testing ◽  
Hopkinson Pressure Bar ◽  
Split Hopkinson ◽  
Pressure Bar

New Impact Testing Methods for Sheet Metals Based on SHPB Technique

2007 ◽  
Vol 566 ◽  
pp. 255-260
Author(s):  
Tadashi Hasebe ◽  
Yutaka Imaida
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Impact Testing ◽  
Sheet Metals ◽  
Hopkinson Pressure Bar ◽  
Testing Methods ◽  
Tension And Compression ◽  
Die Set ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Explicit Dynamic

This paper proposes new impact testing methods applicable to sheet metals both under tension and compression based on widely used split Hopkinson pressure bar (SHPB) technique. Explicit dynamic finite element simulations by using LS-DYNA 3D are systematically conducted for several specimen clamping conditions to seek the appropriate methodologies to realize the two tests. For the tensile test, a method which can reduce stress oscillations that usually appear in the measured stress-strain curves is proposed and is devised to be used with SHPB technique. For the compression test, a candidate which can restrict buckling of the specimen is proposed. The method uses a special die-set sandwiching the sheet metal specimen which is simultaneously compressed without disturbing the planar stress wave to be propagated.

Experimental Study of Impact Strength of Al-6063 Alloy Processed by Equal Channel Angular Extrusion

2014 ◽  
Vol 911 ◽  
pp. 158-162 ◽  
Author(s):  
Shamsuddin Sulaiman ◽  
J. Nemati ◽  
Hani Mizhir Magid ◽  
B.T.H.T. Baharudin ◽  
G.H. Majzoobi ◽  
...  
Keyword(s):  
Impact Strength ◽  
Equal Channel Angular Extrusion ◽  
Split Hopkinson Pressure Bar ◽  
Hopkinson Pressure Bar ◽  
Angular Extrusion ◽  
Split Hopkinson ◽  
Ram Speed ◽  
Pressure Bar ◽  
The Impact ◽  
Strength Improvement

In the present study, the impact strength of annealed Al-6063 alloy developed by equal channel angular extrusion (ECAE), up to 6 passes at a temperature of 200°C following route A with a constant ram speed of 30 mm/min through a die angle of 90° between the die channels was investigated. The impact strength of extruded specimens is evaluated for different passes at a strain rate of 1800 s-1 using Split-Hopkinson pressure bar techniques. The results indicate that the major strength improvement occurs in the 5th and 6th passes while in primary passes, the strength improved but at a considerably lower rate. A total increasing in ultimate strength (UTS) and yield strength (YS) are 127% and 65% respectively and observed for the extruded material after 6 passes. Optical microscopic examinations show a grain refinement from 45 μm to 2.8 μm.

Impact Compressive Properties of Foamed Film with Closed Cell

2014 ◽  
Vol 566 ◽  
pp. 134-139 ◽  
Author(s):  
Hiroyuki Yamada ◽  
Ryo Okui ◽  
Nagahisa Ogasawara ◽  
Hidetoshi Kobayashi ◽  
Kinya Ogawa
Keyword(s):  
Strain Rate ◽  
Impact Test ◽  
Split Hopkinson Pressure Bar ◽  
Rate Dependency ◽  
Hopkinson Pressure Bar ◽  
Compressive Properties ◽  
Static Test ◽  
Closed Cell ◽  
Pressure Bar ◽  
The Impact

The compressive properties of foamed polyethylene (PE) film with a closed cell for electronic devices have been investigated. A commercial closed cell foamed PE film with a density of 330 kg/m3 was used. Quasi-static testing was carried out at strain rates of 10−3 to 10−1 s−1. The strain rate of the impact test was approximately 105 s−1 by means of split Hopkinson pressure bar method. Within the set of experiments, the compressive stress increased with the strain rate in both the quasi-static and impact test. In particular, the flow stress increased substantially with the increasing strain rate in the impact deformation. At strains of less than 0.4, the trapped air was locally compressed within the cells, which led to the strain rate dependency of strength in the quasi-static test and the impact test.

scholarly journals Analisis Numerik Penyerapan Energi pada Sabot untuk Pengujian Bird Strike

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Riskha Agustianingsih
Keyword(s):  
Energy Absorption ◽  
Split Hopkinson Pressure Bar ◽  
Bird Strike ◽  
Hopkinson Pressure Bar ◽  
Crushing Force ◽  
Split Hopkinson ◽  
Pressure Bar

abstrak - Pengujian Bird Strike dilakukan menggunakan alat SHPB (Split Hopkinson Pressure Bar) yang menembakkan sabot (wadah burung). Pada ujung alat SHPB, sabot akan dihentikan oleh stopper sehingga burung akan terlepas dan meluncur dengan bebas hingga mengalami tumbukan dengan komponen uji. Sabot harus memaksimalkan kecepatan burung ketika keluar (terlepas dari sabot). Berdasarkan persamaan impuls dan momentum, hal ini dapat diperoleh dengan meminimalkan waktu tumbukan sehingga gaya impulsnya akan meningkat. Tujuan penelitian ini adalah mengetahui waktu tumbukan, pola grafik Energy Absorption (EA), Peak Crushing Force (PCF), dan Mean Crushing Force (MCF). Dari parameter tersebut, maka diperoleh sabot yang diinginkan berdasarkan waktu tumbukan tersingkat, PCF dan MCF tertinggi, serta EA terendah. Simulasi dilakukan menggunakan perangkat lunak elemen hingga (Abaqus CAE) berdasarkan variasi material (AA6061-T6, S355, dan AISI 1340) sabot. Berdasarkan hasil dan pembahasan, diperoleh bahwa waktu tumbukan paling singkat dimiliki variasi material AISI 1340 dengan nilai 0.00071 s. EA terendah untuk variasi material dimiliki oleh AISI 1340, yaitu sebesar 2.51 kJ. PCF tertinggi untuk variasi material dimiliki oleh material AISI 1340, yaitu 466 kN. Ditentukan bahwa berdasarkan nilai waktu (t) paling singkat, PCF, MCF paling tinggi, dan EA paling rendah, maka diperoleh material AISI 1340 sebagai material yang diinginkan karena paling berpengaruh terhadap peningkatan kecepatan burung setelah keluar dari sabot.

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