A Novel Splitting-Beam Laser Extensometer Technique for Kolsky Tension Bar Experiment

Nie, Xu; Song, Bo; Loeffler, Colin

doi:10.1007/s40870-015-0005-7

Cited by 35 publications

(16 citation statements)

References 14 publications

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“…The journal is highly international, publishing experimental and theoretical studies of metals [57], polymers [58], glasses [59], composites [60], granular materials [61], explosives [62], biological materials [63], geological materials [64], phase transitions [65], and structural response [66]. The journal includes application and development of techniques including split Hopkinson pressure bar/Kolsky bar [67], plate impact with light gas guns and powder guns [68], Taylor Anvil [69], Dynamic-TensileExtrusion [70], spectroscopy-and pyrometry-based shock temperature measurements [71], optical and X-ray imaging methods [72], interferometry and velocimetry techniques [73], dynamic fracture [74], laser based dynamic drivers [75], penetration and ballistics [76], equation of state [77], and spall failure [78].…”

Section: Members Of the Photoelasticity Conference And Guestsmentioning

confidence: 99%

Celebrating 75 Years of the Society for Experimental Mechanics and the Study of Dynamic Behavior of Materials

Brown

2018

J. dynamic behavior mater.

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Section: Members Of the Photoelasticity Conference And Guestsmentioning

confidence: 99%

Celebrating 75 Years of the Society for Experimental Mechanics and the Study of Dynamic Behavior of Materials

Brown

2018

J. dynamic behavior mater.

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“…Based on the concept of an optical extensometer described in [21,24], the system for measuring the displacements of bars' ends is shown in Fig. 3.…”

Section: Laser Extensometer -Accuracy Analysismentioning

confidence: 99%

“…However, a slight variation in laser intensity along the measurement gauge section may induce a significant error, particularly in the case of tests at small strains. Recently, therefore, Nie et al [21] have proposed a novel measuring technique called splitting-beam laser extensometer, which allowed for measuring the motions of the incident and transmission bar ends independently, thus offering better chances to improve the accuracy of strain determination. This innovative measuring idea was an inspiration for the authors to develop their own measuring system, based on which the accuracy problem of specimen strain measurement with a splitting-beam laser extensometer technique in compression SHPB experiments was considered.…”

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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“…A laser extensometer system was used on the transmission bar to accurately determine the amount of prestrain applied to the specimen prior to dynamic loading [11]. The laser system consisted of a uniform line laser as a light source and a highly sensitive photodetector.…”

Section: Kolsky Compression Bar With Pre-load Capabilitymentioning

confidence: 99%

Pre-strain Effect on Frequency-Based Impact Energy Dissipation through a Silicone Foam Pad for Shock Mitigation

Sanborn

Song

Smith

2015

J. dynamic behavior mater.

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Silicone foams have been used in a variety of applications from gaskets to cushioning pads over a wide range of environments. Particularly, silicone foams are used as a shock mitigation material for shock and vibration applications. Understanding the shock mitigation response, particularly in the frequency domain, is critical for optimal designs to protect internal devices and components more effectively and efficiently. The silicone foams may be subjected to pre-strains during the assembly process which may consequently influence the frequency response with respect to shock mitigation performance. A Kolsky compression bar was modified with pre-compression capabilities to characterize the shock mitigation response of silicone foam in the frequency domain to determine the effect of pre-strain. A silicone sample was also intentionally subjected to repeated pre-strain and dynamic loadings to explore the effect of repeated loading on the frequency response of shock mitigation.

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A Novel Splitting-Beam Laser Extensometer Technique for Kolsky Tension Bar Experiment

Cited by 35 publications

References 14 publications

Celebrating 75 Years of the Society for Experimental Mechanics and the Study of Dynamic Behavior of Materials

Celebrating 75 Years of the Society for Experimental Mechanics and the Study of Dynamic Behavior of Materials

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

Pre-strain Effect on Frequency-Based Impact Energy Dissipation through a Silicone Foam Pad for Shock Mitigation

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