scholarly journals Dynamic Behavior of PET FRP and Its Preliminary Application in Impact Strengthening of Concrete Columns

2019 ◽  
Vol 9 (23) ◽  
pp. 4987 ◽  
Author(s):  
Yu-Lei Bai ◽  
Zhi-Wei Yan ◽  
Togay Ozbakkaloglu ◽  
Jian-Guo Dai ◽  
Jun-Feng Jia ◽  
...  
Keyword(s):  
Impact Loading ◽  
Split Hopkinson Pressure Bar ◽  
Concrete Columns ◽  
Fiber Bundles ◽  
Hopkinson Pressure Bar ◽  
Strain Property ◽  
Frp Composites ◽  
Drop Weight ◽  
The Impact ◽  
Rupture Strain

Polyethylene terephthalate (PET) fiber has attracted significant attention for reinforced concrete (RC) structure rehabilitation due to its large rupture strain (LRS; more than 7%) characteristic and recyclability from waste plastic bottles. This study presents a dynamic tensile test of PET fiber bundles performed using a drop-weight impact system. Results showed that the tensile strength and the elastic modulus of the PET fiber bundles increased, whereas the failure strain and the toughness decreased with the increasing strain rate from 1/600 to 160 s−1. In addition, the performance of concrete confined with the PET fiber-reinforced polymer (FRP) under impact loading was investigated based on a 75 mm-diameter split Hopkinson pressure bar (SHPB) device and a drop-weight apparatus. For the SHPB test, owing to the large rupture strain property of PET FRP, the PET FRP-confined concrete exhibited significantly better performance under impact loading compared to its counterpart confined with carbon FRPs (CFRPs). During the drop-weight test, the confinement of the PET FRP composites to the concrete columns as external jackets not only improved the peak impact force, but also prolonged the impact process.

Dynamic Mechanical Properties of Porous Rock under Impact Loading

2011 ◽  
Vol 228-229 ◽  
pp. 5-9
Author(s):  
Yong Xiang Dong ◽  
Chang Jing Xia ◽  
Li Xing Xiao ◽  
Shun Shan Feng
Keyword(s):  
Mechanical Behavior ◽  
Impact Loading ◽  
Split Hopkinson Pressure Bar ◽  
Rock Fracture ◽  
Wave Theory ◽  
Hopkinson Pressure Bar ◽  
Dynamic Mechanical ◽  
Dynamic Mechanical Behavior ◽  
Rock Porosity ◽  
The Impact

Dynamic impact experiments of man-made rock were carried out with the Split Hopkinson Pressure Bar (SHPB) apparatus in this paper. The impact process was analyzed and the influence of rock porosity on dynamic mechanical behavior was investigated. The stress-strain curves in rock were obtained by the one-dimensional stress wave theory. The curve lays foundation for numeric simulation of rock fracture under impact loading. The damage profiles of rock specimen under the impact loading show that the man-made rock exhibits obvious shear damage under the impact loading because it is a typical porous medium containing large quantities of defects such as pores, cracks and grain boundaries at the microscale. The experimental results also indicated that rock porosity plays an important role in dynamic mechanical behavior.

scholarly journals Behaviour of Foam Concrete under Impact Loading Based on SHPB Experiments

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Yongliang He ◽  
Mingshi Gao ◽  
Hongchao Zhao ◽  
Yichao Zhao
Keyword(s):  
Impact Velocity ◽  
Impact Loading ◽  
Split Hopkinson Pressure Bar ◽  
Coal Mines ◽  
Strain Curve ◽  
Hopkinson Pressure Bar ◽  
Foam Concrete ◽  
Absorption Increase ◽  
Underground Coal Mines ◽  
The Impact

This paper presents an innovative method for using foam concrete as a typical building material for soft structures in underground coal mines subjected to dynamic loading. To understand the behaviour of foam concrete under impact loading, a total of 30 specimens with a diameter of 50 mm and a height of 50 mm were experimentally tested using a 75 mm diameter split Hopkinson pressure bar (SHPB) device. The key parameters investigated in the present study included the type of foam concrete (fly ash and sand), the density of foam concrete (1000, 1200 and 1400 kg/m3), and the impact velocity (3.0, 4.0, 5.0, 6.0, and 7.0 m/s). Six specimens were also tested under static loading for comparison. The stress-strain curve of foam concrete under impact loading showed three stages, started with a linear elastic stage, followed by a yield stage and ended with a pore wall destruction stage. The test results also indicated that the dynamic increase factor, ultimate compressive strength, tenacity, and specific energy absorption increase with the strain rate under the same density. In particular, both the failure model and the behaviour of foam concrete were affected by the impact velocity. The findings of this research provide a reference for further research on the application of foam concrete in underground coal mines.

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

scholarly journals Application and Development of an Environmentally Friendly Blast Hole Plug for Underground Coal Mines

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Donghui Yang ◽  
Yixin Zhao ◽  
Zhangxuan Ning ◽  
Zhaoheng Lv ◽  
Huafeng Luo
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Low Cost ◽  
Blast Hole ◽  
Environmentally Friendly ◽  
Test System ◽  
Industrial Test ◽  
Labor Intensity ◽  
Rock Blasting ◽  
Hopkinson Pressure Bar ◽  
The Impact

Drilling and blasting technology is one of the main methods for pressure relief in deep mining. The traditional method for blasting hole blockage with clay stemming has many problems, which include a large volume of transportation, excess loading time, and high labor intensity. An environmentally friendly blast hole plug was designed and developed. This method is cheap, closely blocks the hole, is quickly loaded, and is convenient for transportation. The impact test on the plug was carried out using an improved split Hopkinson pressure bar test system, and the industrial test was carried out in underground tunnel of coal mine. The tests results showed that, compared with clay stemming, the new method proposed in this paper could prolong the action time of the detonation gas, prevent premature detonation gas emissions, reduce the unit consumption of explosives, improve the utilization ratio, reduce the labor intensity of workers, and improve the effect of rock blasting with low cost of rock breaking.

Experimental Calibration of ISV Damage Model Constants for Pure Copper for High-Speed Impact Simulation

2016 ◽  
Author(s):  
Yangqing Dou ◽  
Yucheng Liu ◽  
Wilburn Whittington ◽  
Jonathan Miller
Keyword(s):  
High Speed ◽  
Impact Analysis ◽  
Split Hopkinson Pressure Bar ◽  
Internal State ◽  
Pure Copper ◽  
Damage Model ◽  
Hopkinson Pressure Bar ◽  
Experimental Calibration ◽  
High Speed Impact ◽  
The Impact

Coefficients and constants of a microstructure-based internal state variable (ISV) plasticity damage model for pure copper have been calibrated and used for damage modeling and simulation. Experimental stress-strain curves obtained from Cu samples at different strain rate and temperature levels provide a benchmark for the calibration work. Instron quasi-static tester and split-Hopkinson pressure bar are used to obtain low-to-high strain rates. Calibration process and techniques are described in this paper. The calibrated material model is used for high-speed impact analysis to predict the impact properties of Cu. In the numerical impact scenario, a 100 mm by 100 mm Cu plate with a thickness of 10 mm will be penetrated by a 50 mm-long Ni rod with a diameter of 10mm. The thickness of 10 mm was selected for the Cu plate so that the Ni-Cu penetration through the thickness can be well observed through the simulations and the effects of the ductility of Cu on its plasticity deformation during the penetration can be displayed. Also, that thickness had been used by some researchers when investigating penetration mechanics of other materials. Therefore the penetration resistance of Cu can be compared to that of other metallic materials based on the simulation results obtained from this study. Through this study, the efficiency of this ISV model in simulating high-speed impact process is verified. Functions and roles of each of material constant in that model are also demonstrated.

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 Surface Interactions of Transonic Shock Waves with Graphene-Like Nanoribbons

Surfaces ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 505-515
Author(s):  
Shamal L. Chinke ◽  
Inderpal Singh Sandhu ◽  
Tejashree M. Bhave ◽  
Prashant S. Alegaonkar
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Interaction Mechanism ◽  
Chemical Vapor ◽  
Biomass Combustion ◽  
Structure Property ◽  
Hopkinson Pressure Bar ◽  
Blast Energy ◽  
Impulse Duration ◽  
Vapor Deposition Technique ◽  
The Impact

Graphene-like nanoribbons (GLNRs) were fabricated (length—20 μm; width—2 μm) and subjected to blast-like pulsed pressure >1.5 GPa (pulse speed ≈1 Mach, impulse duration, ≈µs) to examine the amount of absorption. GLNRs prepared by the chemical vapor deposition technique via controlled biomass combustion were subjected to investigate the structure–property characteristics using microspectroscopic techniques. Following this, GLNRs were employed to high strain rate (HSR) studies with the help of the technique known as split Hopkinson pressure bar (SHPB) to evaluate numerous dynamic parameters. The parameters were extracted from variations in the stress and strain rates. Their analysis provided insight into the damping response of blast energy within GLNRs. By and large, the impact generated modified the microstructure, exhibiting modifications in the number of layers, conjugated loops, and dynamic disorder. Signal processing analysis carried out for incident and transmitted impulse pressure revealed an interaction mechanism of shock wave with GLNR. Details are presented.

scholarly journals Dynamic Characteristics of Deep Dolomite Under One-Dimensional Static and Dynamic Loads

2019 ◽  
Vol 101 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Jianguo Wang ◽  
Yang Liu ◽  
Kegang Li
Keyword(s):  
Strain Rate ◽  
Axial Compression ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Strength ◽  
Strong Positive Correlation ◽  
Hopkinson Pressure Bar ◽  
Irreversible Damage ◽  
One Dimensional ◽  
Rock Structure ◽  
The Impact

AbstractThe failure characteristics of rock subjected to impact disturbance under one-dimensional static axial compression are helpful for studying the problems of pillar instability and rock burst in deep, high geostress surrounding rock under blasting disturbances. Improved split Hopkinson pressure bar equipment was used for one-dimensional dynamic–static combined impact tests of deep-seated dolomite specimens under axial compression levels of 0, 12, 24, and 36 MPa. The experimental results demonstrate that the dolomite specimens exhibit strong brittleness. The dynamic strength always maintains a strong positive correlation with the strain rate when the axial compression is fixed; when the strain rate is close, the dynamic elasticity modulus and peak strength of the specimens first increase and then decrease with the increase in axial compression, and the peak value appears at 24 MPa. The impact resistance of specimens can be enhanced when the axial compression is 12 or 24 MPa, but when it increases to 36 MPa, the damage inside the specimen begins to cause damage to the dynamic rock strength. Prior to the rock macroscopic failure, the axial static load changes the rock structure state, and it can store strain energy or cause irreversible damage.

Improving the Impact Resistance of Reinforced Concrete

2014 ◽  
Vol 919-921 ◽  
pp. 1924-1929 ◽  
Author(s):  
Husain Abbas ◽  
Tarek Almusallam ◽  
Yousef Al-Salloum
Keyword(s):  
Reinforced Concrete ◽  
Split Hopkinson Pressure Bar ◽  
Impact Resistance ◽  
Concrete Structures ◽  
Material Behavior ◽  
Analytical Models ◽  
Impact Loads ◽  
Hopkinson Pressure Bar ◽  
Hybrid Fibers ◽  
The Impact

The strategic concrete structures are often required to resist impact loads arising from the projectile strike, falling weight, blast generated missile etc. The existing structures found deficient in resisting these loads are required to be retrofitted whereas the upcoming structures are required to be designed for expected impact loads. This paper explores the ways of strengthening existing reinforced concrete (RC) structures using externally bonded carbon fiber reinforced polymer (CFRP) sheets and improving the impact resistance of concrete by mixing hybrid fibers in its production. The impact response of concrete structures is assessed using experiments involving the impact of projectiles of different nose shapes on slab specimens. The material behavior at high strain rate is established using split Hopkinson pressure bar (SHPB) testing at varying strain rates. Analytical models are developed for predicting penetration depth, scabbing thickness, ballistic limit velocity and ejected mass. The experimental results were also validated through numerical modeling using LS-DYNA.

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