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

Moćko, W.

doi:10.2478/mms-2013-0047

Cited by 14 publications

(7 citation statements)

References 5 publications

(5 reference statements)

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“…Quasi-static tests were carried out at strain rate equal to 0.005 1/s whereas dynamic tests were performed at strain rate equal to 800/s. Split Hopkinson Pressure Bar [3][4][5][6][7][8][9], presented in Fig. 1, was equipped with incident and transmitter bars 20 mm in diameter and 2000 mm in length, which were made of high strength maraging steel, σ y = 2100 MPa.…”

Section: Experimental Methodsmentioning

confidence: 99%

Comparative experimental study of dynamic compressive strength of mortar with glass and basalt fibres

Kruszka

Moćko

Fenu

et al. 2015

EPJ Web of Conferences

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Abstract. Specimen reinforced with glass and basalt fibers were prepared using Standard Portland cement (CEM I, 52.5 R as prescribed by EN 197-1) and standard sand, in accordance with EN 196-1. From this cementitious mixture, a reference cement mortar without fibers was first prepared. Compressive strength, modulus of elasticity, and mod of fracture were determined for all specimens. Static and dynamic properties were investigated using Instron testing machine and split Hopkinson pressure bar, respectively. Content of the glass fibers in the mortar does not influence the fracture stress at static loading conditions in a clearly observed way. Moreover at dynamic range 5% content of the fiber results in a significant drop of fracture stress. Analysis of the basalt fibers influence on the fracture stress shows that optimal content of this reinforcement is equal to 3% for both static and dynamic loading conditions. Further increase of the fiber share gives the opposite effect, i.e. drop of the fracture stress.

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Section: Experimental Methodsmentioning

confidence: 99%

Comparative experimental study of dynamic compressive strength of mortar with glass and basalt fibres

Kruszka

Moćko

Fenu

et al. 2015

EPJ Web of Conferences

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“…The length of the transmission bar is 1800 mm. The history of elastic wave in the bars is determined using tensometers, which is then amplified at the broad-band bridge [4] and finally recorded by a digital oscilloscope.…”

Section: Constitutive Modellingmentioning

confidence: 99%

Energy absorbing properties of a steel profile made of dual phase steel

Moćko

Brodecki

2018

EPJ Web Conf.

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“…The Thorlabs detectors work with bandwidth equal to 1 MHz. It should be noted that this bandwidth is sufficient and recommended for the split Hopkinson compression bar experiments [1,25]. Detectors worked with 20 dB gain and typical noise ratio equal 0.25 mV.…”

Section: Laser Extensometer -Accuracy Analysismentioning

confidence: 99%

Strain measuring accuracy with splitting-beam laser extensometer technique at split Hopkinson compression bar experiment

Panowicz¹,

Janiszewski²,

Traczyk³

2017

Bulletin of the Polish Academy of Sciences Technical Sciences

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Abstract. An accuracy problem of strain measurement at compression split Hopkinson compression bar experiments with a splitting-beam laser extensometer was considered. The splitting-beam laser extensometer technique was developed by Nie et al. to measure strain of a specimen during its tension under a high strain rate loading condition. This novel concept was an inspiration for the authors to develop own laser extensometer system, which allows for simultaneous and independent measurement of displacement of bar ends between which a compressed material specimen is placed. In order to assess a metrological property of this measuring system, a wide range of high strain rate experiments were performed, including tests with various sample materials (Al 5251, Cu OFE) with different rate of strain, and with the use of two bars material. A high accuracy of the developed laser extensometer was found in measurement of specimen strain, for which uncertainty is not greater than 0.1% and, for a typical specimen dimension, the maximum permissible error is 4.5 μm.Key words: SHPB test, strain rates, non-contact strain measurement, laser extensometer. The simplest approach is to use a high speed digital camera to photograph the specimen deformation [10,11]. The camera is focused on the entire gauge section and part of the nongauge section at both ends to achieve a sufficient image with the highest resolution possible. Due to motion analysis of the selected characteristic points, defining the strain gage length, a strain-time relationship can be determined. However, due to the limited frame rate and its corresponding resolution of a contemporary high speed camera, the obtained results did not provide sufficient data points to construct a full stress-strain curve [8]. Strain measuring accuracy with splitting-beam laserThe high-rate digital image correlation (DIC) is a further development of the above described techniques [12,13]. In this case, information about specimen deformation is given by motion analysis of a large number of points (speckle) spreading over the surface of the specimen gauge length [14,15]. A random speckle pattern is generated by a spraying black paint and a white base layer directly onto the surface of the specimen. Thus, DIC provides highly valuable information on dynamic full-field strain measurements in the specimen, however, the above-mentioned limitations resulting from the usage of a contemporary high speed camera and an extreme difficulty in acquiring a large quantity of high-resolution images at very high frame rates do not allow for constructing a precise stressstrain curve [8].Another strain measuring technique is the interferometric-strain-gauge method, which is one of the first diagnostic techniques applied to straightforward non-contact measurement of specimen strain in SHPB testing. Sharpe et al. [16] used this method for evaluation of strain uniformity in the compressed specimen by comparison of surface strain at the specimen midpoint to the average strain calculated from the conventional Kolsk...

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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

Cited by 14 publications

References 5 publications

Comparative experimental study of dynamic compressive strength of mortar with glass and basalt fibres

Comparative experimental study of dynamic compressive strength of mortar with glass and basalt fibres

Energy absorbing properties of a steel profile made of dual phase steel

Strain measuring accuracy with splitting-beam laser extensometer technique at split Hopkinson compression bar experiment

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