Normal and Transverse Displacement Interferometers Applied to Small Diameter Kolsky Bars

Casem, Daniel; Grunschel, Stephen; Schuster, Brian E.

doi:10.1007/s11340-011-9524-x

Cited by 63 publications

(24 citation statements)

References 16 publications

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“…Although a number of techniques have been developed to measure material properties at high strain rates, the splitHopkinson pressure bar [55][56][57][58], or Kolsky bar, has now become ubiquitous for materials characterization between 500 and 10 4 s -1 , or even higher if miniaturized systems are used [59,60]. A schematic of the split Hopkinson pressure bar system at the Air Force Research Laboratory, Eglin AFB, FL is shown in Fig.…”

Section: Dynamic Loading: Split Hopkinson Pressure Barmentioning

confidence: 99%

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High Strain Rate Mechanics of Polymers: A Review

Siviour

Jordan

2016

J. dynamic behavior mater.

272

121

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The mechanical properties of polymers are becoming increasingly important as they are used in structural applications, both on their own and as matrix materials for composites. It has long been known that these mechanical properties are dependent on strain rate, temperature, and pressure. In this paper, the methods for dynamic loading of polymers will be briefly reviewed. The high strain rate mechanical properties of several classes of polymers, i.e. glassy and rubbery amorphous polymers and semi-crystalline polymers will be reviewed. Additionally, time-temperature superposition for rate dependent large strain properties and pressure dependence in polymers will be discussed. Constitutive modeling and shock properties of polymers will not be discussed in this review.

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Section: Dynamic Loading: Split Hopkinson Pressure Barmentioning

confidence: 99%

“…2a, respectively. Typically, all three waves are measured using strain gauges mounted on the incident and transmitted bars; although quartz gauges [62][63][64] and interferometric techniques [59,65] have been used. Representative voltage-time curves are shown in Fig.…”

Section: Dynamic Loading: Split Hopkinson Pressure Barmentioning

confidence: 99%

High Strain Rate Mechanics of Polymers: A Review

Siviour

Jordan

2016

J. dynamic behavior mater.

272

121

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“…This lower limit could be increased by reducing the cross section of the bars, or by increasing the sample cross section dimensions. Other diagnostic methods such as quartz force transducers [7] and optical interferometers [13] could be employed if finer force resolution is required.…”

Section: Discussion Of System Range Of Operationsmentioning

confidence: 99%

“…The strain pulses in the incident and transmitted bars are typically measured using metal foil strain gages. The small size of miniature Kolsky bar systems and the low force levels associated with small samples often precludes the use of metal foil gages, forcing researchers to use alternatives such as optical interferometer techniques [13], quartz stress gages/load cells [7], or semiconductor strain gages to measure the strain (or equivalent) in the incident and transmitted bars. Our system utilizes semiconductor strain gages to measure the bar strains allowing for the traditional Kolsky bar analysis to be utilized.…”

Section: Description Of Experimental Set-upmentioning

confidence: 99%

A Desktop Tensile Kolsky Bar for the Dynamic Testing of Metallic Foils

Paul

Kimberley

2015

J. dynamic behavior mater.

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A miniature tension Kolsky (split-Hopkinson) bar has been developed to facilitate measurement of the uniaxial stress-strain constitutive response of metallic foils at strain rates on the order of 10 4 s -1 . The system utilizes a cylindrical launch tube with an internal striker to generate the loading pulse. This launch tube set-up allows for the use of traditional disk shaped pulse shapers which may be required to ensure that the specimen in deformed under force equilibrium and at a nearly constant strain rate. Unlike most traditional Kolsky bar systems, incident and transmitted bars with rectangular cross-section are used to facilitate specimen and strain gage mounting. The rectangular bar cross-section also provides a reduced cross sectional bar area when compared to an equivalent diameter circular section which increases the system sensitivity. The system was used to perform dynamic tests on 99.9 % magnesium specimens, illustrating the ability to measure the high-rate response of ductile metals under equilibrium and constant strain rate conditions.

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“…Non-contact measuring methods are an alternative for the conventional specimen strain calculation with the reflected pulse. R. Panowicz, J. Janiszewski, and M. Traczyk applied an interferometric technique to measure the displacement of the incident and transmitted bars in the small diameter SHPB arrangement, which allowed investigating Al 6061-T6 alloy with a very high strain rate (order of 10 5 1/s) [17,18]. Another non-contact method used for measuring strain is the laser extensometer.…”

Section: Introductionmentioning

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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Normal and Transverse Displacement Interferometers Applied to Small Diameter Kolsky Bars

Cited by 63 publications

References 16 publications

High Strain Rate Mechanics of Polymers: A Review

High Strain Rate Mechanics of Polymers: A Review

A Desktop Tensile Kolsky Bar for the Dynamic Testing of Metallic Foils

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

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