scholarly journals Influence of Crack Geometry on Dynamic Damage of Cracked Rock: Crack Number and Filling Material

2020 ◽  
Vol 11 (1) ◽  
pp. 250
Author(s):  
Feili Wang ◽  
Shuhong Wang ◽  
Zhanguo Xiu
Keyword(s):  
Energy Absorption ◽  
Split Hopkinson Pressure Bar ◽  
Mineral Exploration ◽  
Damage Variable ◽  
Filling Material ◽  
Hopkinson Pressure Bar ◽  
Filling Materials ◽  
The Stability ◽  
Pressure Bar ◽  
Dynamic Damage

The dynamic damage of cracked rock threatens the stability of rock structures in rock engineering applications such as underground excavation, mineral exploration and rock slopes. In this study, the dynamic damage of cracked rock with different spatial geometry was investigated in an experimental method. Approximately 54 sandstone specimens with different numbers of joints and different filling materials were tested using the split Hopkinson pressure bar (SHPB) apparatus. The energy absorption in this process was analyzed, and the damage variable was obtained. The experimental results revealed that the dynamic damage of cracked rock is obviously influenced by the number of cracks; the larger the number, the higher the energy absorption and the bigger the dynamic damage variable. Moreover, it was observed from the dynamic compressive experiments that the energy absorption and the dynamic variable decreased with the strength and cohesion of the filling material, indicating that the filling material of crack has considerate influence on the dynamic damage of cracked rock.

scholarly journals Stress Attenuation and Energy Absorption of the Coral Sand with Different Particle Sizes under Impacts

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 545
Author(s):  
Xiao Yu ◽  
Li Chen ◽  
Qin fang ◽  
Wuzheng Chen
Keyword(s):  
Energy Absorption ◽  
Stress Wave ◽  
Wave Attenuation ◽  
Split Hopkinson Pressure Bar ◽  
Particle Size Effect ◽  
Particle Sizes ◽  
Hopkinson Pressure Bar ◽  
Coral Sand ◽  
Stress Zone ◽  
Pressure Bar

The stress wave attenuation and energy absorption in the coral sand were respectively investigated. A series of experiments were carried out by using a new methodology with an improved split Hopkinson pressure bar (SHPB). Four types of coral sand, i.e., particle sizes of 1.18–0.60 mm, 0.60–0.30 mm, 0.30–0.15 mm, and 0.15–0.075 mm, were carefully sieved and tested. Significant effects of coral sand on stress wave attenuation and energy absorption were observed. Correlation between stress wave attenuation and energy absorption of coral sand was validated. Conclusions on particle size effect of stress wave attenuation and energy absorption, which support each other, were drawn. There existed a common critical stress zone for coral sand with different particle sizes. When the stress below this zone, sand with small particle sizes attenuates stress wave better and absorb energy more; when the stress beyond this zone, sand with larger particle sizes behave better on stress wave attenuation and energy absorption.

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.

Study of dynamic compressive behaviour of aramid and ultrahigh molecular weight polyethylene composites using Split Hopkinson Pressure Bar

2016 ◽  
Vol 51 (1) ◽  
pp. 81-94 ◽  
Author(s):  
Khubab Shaker ◽  
Abdul Jabbar ◽  
Mehmet Karahan ◽  
Nevin Karahan ◽  
Yasir Nawab
Keyword(s):  
Molecular Weight ◽  
Strain Rate ◽  
Energy Absorption ◽  
Split Hopkinson Pressure Bar ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Hopkinson Pressure Bar ◽  
Ultrahigh Molecular Weight ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Polyethylene Composites

In this paper, high strain rate compression properties of aramid and ultrahigh molecular weight polyethylene composites in the out-of-plane direction are tested at room temperature on a Split Hopkinson Pressure Bar apparatus. Tests were conducted on composites reinforced with woven or Uni-Directional (UD) fabrics made from aramid or ultrahigh molecular weight polyethylene as well as on composites reinforced with hybrid reinforcement. The strain rate is varied in the tests by changing the projectile shooting pressure. Four different pressures 2, 4, 6 and 8 bar were selected to change the strain rate. Stress–strain and energy absorption behaviour of eight type of samples were noted. Hybrid samples showed better performance in the energy absorption compared with other samples.

scholarly journals Constitutive Parameters Identification of AZ31B-H24 Magnesium Alloy and Energy-Absorption Analysis in Structural Panel Use

2018 ◽  
Vol 153 ◽  
pp. 01004
Author(s):  
Yuedong Yang ◽  
Jiqing Chen ◽  
Fengchong Lan ◽  
Wu Zeng ◽  
Zhengwei Ma
Keyword(s):  
Magnesium Alloy ◽  
Constitutive Model ◽  
Energy Absorption ◽  
Split Hopkinson Pressure Bar ◽  
Parametric Identification ◽  
Hopkinson Pressure Bar ◽  
Curve Fit ◽  
Wide Range ◽  
Pressure Bar ◽  
Constitutive Parameters

As a novel lightweight material, AZ31B magnesium alloy is considered as the most potential material to instead baseline steel in some automotive parts. However, their structural use is quite limited and so far proper numerical modeling has not been developed to represent magnesium alloy. In present study, the Split Hopkinson Pressure Bar (SHPB) test is utilized to investigate material dynamic mechanism for AZ31B-H24 over a wide range of strain rates from 1389 s-1 to 7296 s-1. Parametric identification for Johnson-Cook (J-C) constitutive model available in the commercial finite element package LS-DYNA is carried out. Proper parameters are obtained by curve fit using genetic algorithm with experimental results. Constitutive model after parametric identification is applied to automotive outer panels for crashworthiness analysis. Energy absorption with magnesium alloy substituted baseline steel under lightweight 51.18% is obtained and the key problem of thin-walled magnesium alloy applied in automotive structure is advanced.

A Methodology for Evaluation of Shockwave Absorption by Blast Energy-Absorption Materials

2015 ◽  
Vol 1124 ◽  
pp. 243-248
Author(s):  
Ondřej Koutný ◽  
Josef Krátký ◽  
Miloslav Popovič ◽  
Martina Drdlová
Keyword(s):  
Energy Absorption ◽  
Split Hopkinson Pressure Bar ◽  
Second Step ◽  
Sample Material ◽  
Hopkinson Pressure Bar ◽  
Testing Method ◽  
Blast Energy ◽  
Split Hopkinson ◽  
Pressure Bar

This article presents a new direct testing method and device for evaluation of response of blast-absorption materials against direct blast wave and its ability to absorb energy generated during this type of loading. This is a second step of characterization of blast energy absorption materials which take place after standard and most common characterization using Split-Hopkinson pressure bar. The principle of the method is an assessment of longitudinal stress process in standard rod after the explosion of testing blast charge. Stress amplitude reduction in standard rod caused due to energy-absorption of sample material will directly lead to absorption capability of tested sample material.

scholarly journals High strain-rate dynamic compressive behavior and energy absorption of distiller’s dried grains and soluble composites with paulownia and pine wood using a split Hopkinson pressure bar technique

BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 9444-9461
Author(s):  
Damian Stoddard ◽  
Suman Babu Ukyam ◽  
Brent Tisserat ◽  
Ivy Turner ◽  
Rowan Baird ◽  
...  
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Energy Absorption ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Rate Sensitivity ◽  
Hopkinson Pressure Bar ◽  
Split Hopkinson ◽  
Pressure Bar

Novel bio-based composite wood panels (CWPs) that consisted of distiller’s dried grains and solubles (DDGS) flour adhesive bound to a wood filler/reinforcement were subjected to high strain-rate compression loading, and their behavior was investigated. Specimens of DDGS-Paulownia wood (PW) or DDGS-pinewood (Pine) composites made using DDGS with fractions of 10%, 15%, 25%, and 50% were tested at high strain-rates using a modified compression Split Hopkinson Pressure Bar (SHPB). Both DDGS-PW and DDGS-Pine composites displayed strain-rate sensitivity, and DDGS-PW had a 25% fraction, which showed the highest ultimate compressive strength of 655 MPa at approximately 1600/s. The 90%-PW had the highest specific energy of 19.24 kJ/kg at approximately 1600/s when loaded via dynamic compression. The CWPs constructed of DDGS-PW had higher strength and energy absorption than DDGS-Pine with the exception of the 50% DDGS composites.

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.

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

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