Dynamic characterization of micro scale samples using the Hopkinson tensile bar technique

Leung, Mei‐yung; Yu, Tao

doi:10.14711/thesis-b989005

Cited by 2 publications

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“…Using incident and reflected pulse signals from S 2 together with the transmitted pulse signal from S 4 , the stressstrain curves and the corresponding strain rates of Lincoln wool fibers were calculated by using a program specially developed for this mSHTB [23,24]. The resultant impact stress-strain curves at various strain rates, together with the quasi-static stress-strain curve, are shown in Figure 7.…”

Section: Resultsmentioning

confidence: 99%

“…Secondly, the use of these visco-elastic bars overcame the mechanical impedance mismatch problem that existed in the conventional SHPB. However, the elastic wave theory is no longer applicable in PMMA bars, and hence visco-elastic wave propagation analysis was established [23,24] and used here for analysis. The visco-elastic wave propagation analysis method was validated by a simple compression impact test [23].…”

Section: Impact Experimental Equipmentmini Split Hopkinson Tensile Barmentioning

confidence: 99%

“…The impact tests were conducted in the Impact Laboratory at Hong Kong University of Science and Technology. A mSHTB system (Figures 1 and 2) was designed and developed there to characterize the dynamic tensile behavior of small-scaled specimens [23,24]. Modifications were made to the conventional SHPB in order to obtain the tensile stress-strain curves efficiently and effectively.…”

Section: Impact Experimental Equipment -Mini Split Hopkinson Tensile Barmentioning

confidence: 99%

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Impact Tests on Lincoln Wool Fibers Using a Mini Split Hopkinson Tensile Bar

Ruan

Leung

et al. 2009

Textile Research Journal

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Wool's mechanical properties have been a subject of extensive research since the 1920s because wool fibers are normally subjected to both static and impact tensile loadings in their manufacturing processes and applications.Tensile behavior of wool fibers under quasi-static loads has been thoroughly studied both experimentally and analytically. The effects of moisture, temperature, non-uniformity, and the extent of crystallization and amorphous orientation in wool fibers have been previously investigated [1][2][3][4]. Various theoretical models have been proposed to explain the tensile behavior of wool fibers in terms of their microstructures [5][6][7][8][9].In spite of the advances of research on the mechanical properties of wool fibers under quasi-static loadings, few reports can be found in the open literature describing their impact response. Wool fibers are subjected to impact loadings in textile processing and in the service life of the finished wool products. A good understanding of the impact behavior of wool fibers is essential for their manufacturing and applications. Impact behavior has been experimentally studied and results have been published for textile fibers subjected to impact loadings at strain rates up to the order of 10 2 s -1 by using the apparatus of both Meredith and Holden, discussed in Lyons [10]. These fibers included polypropylene monofils, Orlon 42 acrylic fibers, cellulose acetate fibers, high-tenacity viscose fibers, polyethylene fibers [11], and nylon 66 fibers [10]. Few papers report on the impact response of wool fibers. Therefore, there is a need to develop a new laboratory set-up to obtain experimental data on how wool fibers respond to impact loading.In this study, a mini split Hopkinson tensile bar (mSHTB) was employed to obtain stress-strain curves of Lincoln wool fibers subjected to impact loadings at strain rates in the order of 10 2 s -1 . This method is different from the traditional method adopted by Meredith, discussed in Lyons [10]. * The split Hopkinson pressure bar (SHPB) is named after Bertram Hopkinson [12], who first used the stress wave propagation in a long metal bar to measure the pressures in impact events. In the 1940s, Davies [13] and Kolsky [14] modified and used two Hopkinson bars in series to measure the dynamic stress-strain response of materials, which were sandwiched in-between bars. To date, the SHPB has been widely used in the measurement of the stress-strain curves of various materials such as metals, polymers, concrete, metal foams, polymer foams, and nano-materials subjected to compressive loadings. Moreover, the traditional split Hopkinson bar has been modified and used to measure the impact response of materials subjected to uniaxial tension [15-18], torsion [19, 20], and combined torsion and compression [21,22].Abstract A new testing method using a mini split Hopkinson tensile bar was employed in the impact tests of Lincoln wool fibers. Stress-strain curves of Lincoln wool fibers subjected to impact loadings at strain rates in the order of 1...

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Section: Resultsmentioning

confidence: 99%

Section: Impact Experimental Equipmentmini Split Hopkinson Tensile Barmentioning

confidence: 99%

Section: Impact Experimental Equipment -Mini Split Hopkinson Tensile Barmentioning

confidence: 99%

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Impact Tests on Lincoln Wool Fibers Using a Mini Split Hopkinson Tensile Bar

Ruan

Leung

et al. 2009

Textile Research Journal

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“…Leung and Yu (2008) developed a mini-Split Hopkinson tensile bar and tested the plastic behavior under strain-rate 100-1000 (1/s), but it was not accurate enough to obtain the dynamic modulus of the material. For the measurement of linear visco-elastic parameters of polymer materials, DMA (i.e., dynamic mechanical analysis) method is usually applied (Lakes, 2004).…”

Section: Impact Tests Of the Ping-pong Ballsmentioning

confidence: 99%

Dynamic behaviors of visco-elastic thin-walled spherical shells impact onto a rigid plate

Zhang

2014

Lat. Am. j. solids struct.

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As a representative structure, ping-pong balls are usually used to study the mechanical properties of thin-walled spherical shells. In a previous study, the dynamic behaviors of ping-pong balls impinged onto a rigid plate were investigated. It was found that the dynamic deformation energy of the balls could be several times higher than that under quasi-static compression, which could not be completely explained by elastic-plastic material property, strain-rate and inertial effects. In this paper, more impact tests were conducted and the details including the contact time, deformation and rebound behaviors with different impact velocities were reinvestigated. Based on the experimental results, visco-elastic material model is applied and the numerical simulation of thin-walled spherical shells impact onto a plate is performed, in which the influences of the visco-elastic parameters and the impact velocity on the dynamic behaviors are studied. By adjusting the visco-elastic parameters, the contact time, deformation, and the coefficient of restitution agree well with the experimental results. Keywords Impact; visco-elastic; coefficient of restitution; spherical shell.Dynamic behaviors of visco-elastic thin-walled spherical shells impact onto a rigid plate INTRODUCTIONDue to high load-carrying efficiency and good aerodynamic properties, thin-walled spherical shells are extensively applied not only in engineering structures, but also for sports facilities, such as aircraft, submarine, pressure vessels, oil containers, footballs, tennis balls and so on. Considering loading conditions, their large deformation and buckling behaviors compressed against a rigid plate attract great attentions of researchers.In earlier decades, theoretical and experimental studies about the deformation modes and contact force of elastic and rigid-plastic spherical shells have been done by Updike and Kalnins (1970;1972), Kitching et al (1975), De Olivera andWierzbicki (1982), Gupta et al (1999), most of which focused on the quasi-static cases and the dynamic effects were not considered. To examine the ener- gy absorption of metal hollow sphere (MHS) materials, Ruan et al (2006) investigated the dynamic crushing of 1D and 2D ping-pong ball arrays under in-plane impacts and found that a single ball's load-deformation relation can be used to predict the ball-array's load deformation behavior. Hubbard and Stronge (2001) conducted the impact tests for ping-pong balls onto a flat plate with velocity 0-20m/s, and obtained the contact time and coefficient of restitution. However, in their analytical modeling, they considered the balls to be pure elastic. As a result, the predictions for the contact time and coefficient of restitution were both higher than the experiments, while the predicted energy dissipation was too little. Besides, Stronge and Achsoft (2007), and Arakawa et al (2007Arakawa et al ( , 2009) studied the impact behaviors of basketballs and golf balls, respectively. Bao and Yu (2012) conducted numerical simulations about the dy...

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Dynamic characterization of micro scale samples using the Hopkinson tensile bar technique

Cited by 2 publications

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Impact Tests on Lincoln Wool Fibers Using a Mini Split Hopkinson Tensile Bar

Impact Tests on Lincoln Wool Fibers Using a Mini Split Hopkinson Tensile Bar

Dynamic behaviors of visco-elastic thin-walled spherical shells impact onto a rigid plate

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