Compressive strain rate sensitivity of ballistic gelatin

Kwon, Jong Bum; Subhash, Ghatu

doi:10.1016/j.jbiomech.2009.10.008

Cited by 100 publications

(64 citation statements)

References 35 publications

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“…In previous studies (Kwon and Subhash (2010)), the increasing stiffness with strain rate was attributed to mechanisms like internal energy dissipation (related to underlying crosslinking/bond-structure of the gelatin) and hydrocluster formation (related to the microstructure of the gelatin). Though these were hypothesised to account for changes observed up to dynamic loading rates (∼ 10 3 s −1 ), they may also be applicable at the quasi-static rates considered here.…”

Section: Discussionmentioning

confidence: 93%

“…The majority of past studies have focused on characterisation at 'dynamic' (∼ 1000 − 3000s −1 ) strain rates, reflecting its primary application area (Kwon and Subhash (2010); Subhash et al (2012); Salisbury and Cronin (2009)). Test configurations such as Hopkinson bar impact (Cronin and Falzon (2009)), uniaxial tension (Moy et al (2008)), indentation (Juliano et al (2006)), and others have been used for this purpose.…”

Section: Introductionmentioning

confidence: 99%

“…Test configurations such as Hopkinson bar impact (Cronin and Falzon (2009)), uniaxial tension (Moy et al (2008)), indentation (Juliano et al (2006)), and others have been used for this purpose. But, it is widely recognised that the material's constitutive behaviour is distinctly different under these two loading speed regimes, possibly due to microstructural re-organisation of the material at higher rates (Kwon and Subhash (2010)). Typically, the material appears much stiffer at higher speeds, though rate-dependence can indeed be observed across all speeds studied so far.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A constitutive model for ballistic gelatin at surgical strain rates

Ravikumar

Noble

Cramphorn

et al. 2015

Journal of the Mechanical Behavior of Biomedical Materials

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This paper describes a constitutive model for ballistic gelatin at the low strain rates experienced, for example, by soft tissues during surgery. While this material is most commonly associated with high speed projectile penetration and impact investigations, it has also been used extensively as a soft tissue simulant in validation studies for surgical technologies (e.g. surgical simulation and guidance systems), for which loading speeds and the corresponding mechanical response of the material are quite different. We conducted mechanical compression experiments on gelatin specimens at strain rates spanning two orders of magnitude (∼ 0.001 − 0.1s −1 ) and observed a nonlinear load-displacement history and strong strain rate-dependence. A compact and efficient visco-hyperelastic constitutive model was then formulated and found to fit the experimental data well. An Ogden type strain energy density function was employed for the elastic component. A single Prony exponential term was found to be adequate to capture the observed rate-dependence of the response over multiple strain rates. The model lends itself to immediate use within many commercial finite element packages.

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Section: Discussionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A constitutive model for ballistic gelatin at surgical strain rates

Ravikumar

Noble

Cramphorn

et al. 2015

Journal of the Mechanical Behavior of Biomedical Materials

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show abstract

“…Gelatin-based materials are commonly used to represent soft tissues and several studies have been performed to charactise the mechanical properties of such materials [6][7][8][9]. The work by Kwon and Subhash [7] shows that 11% concentrated gelatine results in a Young's modulus of 10.9kPa.…”

Section: Development Of a Surrogate Tissue Materialsmentioning

confidence: 99%

“…Photoelastic materials exhibit temporary birefringence, such that when loaded and viewed in polarised light, the doublerefraction effect results in the observation of interference fringes which relate directly to the shear strains in the material. Birefringent materials such as epoxy resins have been used to represent stiffer materials such as bone and dentine, and gelatine, also known as "ballistic gel", is often used as a surrogate to evaluate penetrating impacts or blast loading effects on soft tissues [6,7,8,9]. The use of photoelasticity for tissue analysis has been mainly limited to qualitative analysis since there are many issues which require consideration when developing flexible birefringent surrogate tissue materials for quantitative validation purposes.…”

Section: Introductionmentioning

confidence: 99%

Development of Tissue Surrogates for Photoelastic Strain Analysis of Needle Insertion

Tomlinson

Yong

Morton

et al. 2014

Mechanics of Biological Systems and Materials, Volume 7

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ABSTRACT:This paper focuses on the development of full-field experimental methods for validating computational models of needle insertion, and specifically the development of suitable tissue surrogate materials. Gelatine also known as "ballistic gel" is commonly used as a tissue surrogate since the modulus of elasticity matches that of tissue. Its birefringent properties also allow the visualisation of strains in polarised light. However, other characteristics of tissue are not well emulated by gelatine, for example the fibrous network of cells of tissue is not well represented by the granular microstructure of gelatine, which tears easily. A range of birefringent flexible materials were developed and calibrated for photoelastic analysis. The most suitable were then used to explore quantitatively the different strain distributions in tissue when subjected to a range of needles with different tip profiles.

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Impact Testing of Polymer‐filled Auxetics Using Split Hopkinson Pressure Bar

et al. 2017

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In this paper, impact testing of auxetic structures filled with strain rate sensitive material is presented. Two dimensional missing rib, 2D re-entrant honeycomb, and 3D re-entrant honeycomb lattices are investigated. Structures are divided into three groups according to type of filling: no filling, low expansion polyurethane foam, and ordnance gelatine. Samples from each group are tested under quasistatic loading and dynamic compression using Split Hopkinson Pressure Bar. Digital image correlation is used for assessment of in-plane displacement and strain fields. Ratios between quasistatic and dynamic results for plateau stresses and specific energy absorption in the plateau are calculated. It is found out that not only the manufactured structures, but also the wrought material exhibit strain rate dependent properties. Evaluation of influence of filling on mechanical properties shows that polyurethane increases specific absorbed energy by a factor of 1.05-1.4, whereas the effect of gelatine leads to increase of only 5-10%. Analysis of the Poisson's function reveals influence of filling on achievable (negative) values of Poisson's ratio, when compared to unfilled specimens. The results for the Poisson's function yielded apparently different values as the assessed minima of quasi-static Poisson's ratio in small deformations are constrained by a factor of 15.

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Compressive strain rate sensitivity of ballistic gelatin

Cited by 100 publications

References 35 publications

A constitutive model for ballistic gelatin at surgical strain rates

A constitutive model for ballistic gelatin at surgical strain rates

Development of Tissue Surrogates for Photoelastic Strain Analysis of Needle Insertion

Impact Testing of Polymer‐filled Auxetics Using Split Hopkinson Pressure Bar

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