Bulletin of the American Physical Society
17th Biennial International Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 56, Number 6
Sunday–Friday, June 26–July 1 2011; Chicago, Illinois
Session J5: Biological Materials |
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Chair: Horacio Espinosa, Northwestern University Room: Renaissance Ballroom D |
Tuesday, June 28, 2011 11:00AM - 11:15AM |
J5.00001: Prospects for studying how high-intensity compression waves cause damage in human blast injuries Katherine Brown, Chiara Bo, Arul Ramaswamy, Spiros Masouros, Nicolas Newell, Adam Hill, Jon Clasper, Anthony Bull, William Proud Blast injuries arising from improvised explosive devices are often complex leading to long-term disability in survivors. There is an urgent need to mitigate against the effects of blast that lead to these injuries, and to also improve post-traumatic therapeutic treatments related to problems associated with damage and healing processes and infections. We have initiated multidisciplinary studies to develop experimental facilities and strategies for analyzing the effects blast waves upon the human body, from cellular through to skeletal functions. [Preview Abstract] |
Tuesday, June 28, 2011 11:15AM - 11:30AM |
J5.00002: The pathogenesis of retinal damage in human eye under impact and blast load Luca Esposito, Nicola Bonora, Tommaso Rossi Human eye subjected to non penetrating impact (blunt-impact) may experience severe damage. The most common type is partial tearing of the retina at specific eye locations. In ophthalmology, based on impact experiment performed by Delori et al. (1967), it is commonly accepted that the mechanism responsible for retinal damage is the vitreous pull-traction action and the equatorial expansion of the sclera. Based on the evidence of a vitrectomized patient who reported retinal damage after blunt impact, an investigation on the possible role of shockwave dynamics in the retinal damage has been performed by means of hydrocode numerical simulation. A FEM model of the eye has been developed and the experiment of Delori et al. has been reproduced. Soft tissues constitutive response has been determined by means of reverse engineering approach. It has been demonstrated that release waves at the retina-choroid interface are generated in the early time of the blunt impact and can cause retina tearing when the eye bulb is still undeformed. This result has been also confirmed for the case of blast-load exposure [Preview Abstract] |
Tuesday, June 28, 2011 11:30AM - 11:45AM |
J5.00003: The Dynamic Behaviour and Shock Recovery of a Porcine Skeletal Muscle Tissue James Wilgeroth, Paul Hazell, Gareth Appleby-Thomas Modern-day ballistic armours provide a high degree of protection to the individual. However, the effects of non-penetrating projectiles, blast, and high-energy blunt impact events may still cause severe tissue trauma/remote injury. The energies corresponding to such events allow for the formation and transmission of shock waves within body tissues. Consequently, the nature of trauma inflicted upon such soft tissues is likely to be intimately linked to their interaction with the shock waves that propagate through them. Notably, relatively little is known about the effect of shock upon the structure of biological materials, such as skeletal muscle tissue. In this study plate-impact experiments have been used to interrogate the dynamic response of a porcine skeletal muscle tissue under one-dimensional shock loading conditions. Additionally, development of a soft-capture system that has allowed recovery of shocked skeletal muscle tissue specimens is discussed and comparison made between experimental diagnostics and hydrocode simulations of the experiment. [Preview Abstract] |
Tuesday, June 28, 2011 11:45AM - 12:00PM |
J5.00004: Dynamic Characterization of Porcine Lung Tissue Brett Sanborn, Xu Nie, Weinong Chen, Tusit Weerasooriya In this study, the dynamic shear and uniaxial compressive response of porcine lung tissue was examined using modified Kolsky bar techniques. High rate compression data was collected using a hollow transmission bar to amplify weak material response. Radial deformation of annular specimens was captured by a modified Kolsky bar and high speed camera. The images depicted inhomogeneous specimen deformation induced by radial inertia effects, which compromised the validity of such high rate compression test techniques. A novel torsion technique was developed to obtain dynamic pure shear behavior of lung tissue. The equivalent stress-strain behavior of lung tissue obtained from both methods was compared and the pure shear response was found to be an order of magnitude lower than the uniaxial compressive response. These results indicate the previously established annular specimen technique for the Kolsky bar soft materials characterization, targeted on reducing the influence of inertia stress, may still have underestimated the effects of radial inertia and the associated inhomogeneous deformation in materials as soft as lung tissues. [Preview Abstract] |
Tuesday, June 28, 2011 12:00PM - 12:30PM |
J5.00005: Toward Long-Time Simulation of Ballistic Gel Penetration Invited Speaker: Ballistic gelatin is used as a surrogate for tissue to study the performance of armor and ammunition. Numerical simulations of impact and penetration of ammunition into ballistic gelatin have the potential to complement experimental work. Ballistic gelatin is a nearly incompressible material with viscoelastic features, which can recover from very large strains. As a result, a bullet penetrating the gel forms a large temporary cavity behind it, which at long times collapses to a very small one. This is a marked difference with the behavior of a fluid under similar circumstances. This poses strenuous challenges to current numerical tools, since an imperfect ``memory'' of the material elasticity leads to abnormally large remaining cavities. Reaching these later times in a simulation ($\sim $10 ms) is challenging to do in a reasonable time frame of a few hours. In this presentation I will first showcase the phenomena we are trying to capture through experiments in Permagel. Among others, these show the bullet rebounding after fully stopping, the importance of the gases inside the created cavity in its long-term dynamics, and the apparent appearance of mild plastic deformations and local melting in the gel. I will then discuss about the numerical tools we are creating to simulate it. I will show a suite of variational time-integration strategies able to reach long-time simulations with reasonable accuracy. Then, I will comment on novel automatic remeshing strategies we are creating, needed to simulate the large shear deformations in the gel while retaining accurate elastic recoveries. I will illustrate these ideas with simulations in highly parallel computing environments, and discuss the challenges we face to qualitatively recover a number of the experimental observations. [Preview Abstract] |
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