Simulations of focused shear shock waves in soft solids and the brain

2014 ◽  
Vol 136 (4) ◽  
pp. 2279-2280
Author(s):  
Bruno Giammarinaro ◽  
François Coulouvrat ◽  
Gianmarco Pinton
Keyword(s):  
Shock Waves ◽  
Soft Solids ◽  
The Brain

scholarly journals Numerical Simulation of Focused Shock Shear Waves in Soft Solids and a Two-Dimensional Nonlinear Homogeneous Model of the Brain

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
B. Giammarinaro ◽  
F. Coulouvrat ◽  
G. Pinton
Keyword(s):  
Shock Wave ◽  
Numerical Methods ◽  
Shock Waves ◽  
Scaling Laws ◽  
Soft Tissues ◽  
Shear Waves ◽  
Homogeneous Model ◽  
Nonlinear Propagation ◽  
Soft Solids ◽  
The Brain

Shear waves that propagate in soft solids, such as the brain, are strongly nonlinear and can develop into shock waves in less than one wavelength. We hypothesize that these shear shock waves could be responsible for certain types of traumatic brain injuries (TBI) and that the spherical geometry of the skull bone could focus shear waves deep in the brain, generating diffuse axonal injuries. Theoretical models and numerical methods that describe nonlinear polarized shear waves in soft solids such as the brain are presented. They include the cubic nonlinearities that are characteristic of soft solids and the specific types of nonclassical attenuation and dispersion observed in soft tissues and the brain. The numerical methods are validated with analytical solutions, where possible, and with self-similar scaling laws where no known solutions exist. Initial conditions based on a human head X-ray microtomography (CT) were used to simulate focused shear shock waves in the brain. Three regimes are investigated with shock wave formation distances of 2.54 m, 0.018 m, and 0.0064 m. We demonstrate that under realistic loading scenarios, with nonlinear properties consistent with measurements in the brain, and when the shock wave propagation distance and focal distance coincide, nonlinear propagation can easily overcome attenuation to generate shear shocks deep inside the brain. Due to these effects, the accelerations in the focal are larger by a factor of 15 compared to acceleration at the skull surface. These results suggest that shock wave focusing could be responsible for diffuse axonal injuries.

Axonal damage and behavioral deficits in rats with repetitive exposure of the brain to laser-induced shock waves: Effects of inter-exposure time

2021 ◽  
Vol 749 ◽  
pp. 135722
Author(s):  
Kosuke Miyai ◽  
Satoko Kawauchi ◽  
Tamaki Kato ◽  
Tetsuo Yamamoto ◽  
Yasuo Mukai ◽  
...  
Keyword(s):  
Shock Waves ◽  
Exposure Time ◽  
Axonal Damage ◽  
Behavioral Deficits ◽  
Repetitive Exposure ◽  
The Brain

Adaptive ultrasonic displacement estimation for elastic shock waves in soft solids

2012 ◽  
Author(s):  
Gianmarco Pinton ◽  
Jean-Luc Gennisson ◽  
Mickael Tanter ◽  
Francois Coulouvrat
Keyword(s):  
Shock Waves ◽  
Displacement Estimation ◽  
Soft Solids ◽  
Elastic Shock

Modeling and simulations of two dimensional propagation of shear shock waves in relaxing soft solids

2019 ◽  
Vol 395 ◽  
pp. 205-222 ◽  
Author(s):  
Bharat B. Tripathi ◽  
David Espíndola ◽  
Gianmarco F. Pinton
Keyword(s):  
Shock Waves ◽  
Two Dimensional ◽  
Modeling And Simulations ◽  
Soft Solids

A Multi-Scale Finite Element Model for Shock Wave-Induced Axonal Brain Injury

2008 ◽  
Author(s):  
M. Sotudeh-Chafi ◽  
N. Abolfathi ◽  
A. Nick ◽  
V. Dirisala ◽  
G. Karami ◽  
...  
Keyword(s):  
Shock Wave ◽  
Brain Injury ◽  
Shock Waves ◽  
Brain Tissue ◽  
Scale Model ◽  
Micro Scale ◽  
Multi Scale ◽  
Injury Criteria ◽  
Wave Induced ◽  
The Brain

Traumatic brain injuries (TBIs) involve a significant portion of human injuries resulting from a wide range of civilian accidents as well as many military scenarios. Axonal damage is one of the most common and important pathologic features of traumatic brain injury. Axons become brittle when exposed to rapid deformations associated with brain trauma. Accordingly, rapid stretch of axons can damage the axonal cytoskeleton, resulting in a loss of elasticity and impairment of axoplasmic transport. Subsequent swelling of the axon occurs in discrete bulb formations or in elongated varicosities that accumulate organelles. Ultimately, swollen axons may become disconnected [1]. The shock waves generated by a blast, subject all the organs in the head to displacement, shearing and tearing forces. The brain is especially vulnerable to these forces — the fronts of compressed air waves cause rapid forward or backward movements of the head, so that the brain rattles against the inside of the skull. This can cause subdural hemorrhage and contusions. The forces exerted on the brain by shock waves are known to damage axons in the affected areas. This axonal damage begins within minutes of injury, and can continue for hours or days following the injury [2]. Shock waves are also known to damage the brain at the subcellular level, but exactly how remains unclear. Kato et al., [3] described the effects of a small controlled explosion on rats’ brain tissue. They found that high pressure shock waves led to contusions and hemorrhage in both cortical and subcortical brain regions. Based on their result, the threshold for shock wave-induced brain injury is speculated to be under 1 MPa. This is the first report to demonstrate the pressure-dependent effect of shock wave on the histological characteristics of brain tissue. An important step in understanding the primary blast injury mechanism due to explosion is to translate the global head loads to the loading conditions, and consequently damage, of the cells at the local level and to project cell level and tissue level injury criteria towards the level of the head. In order to reach this aim, we have developed a multi-scale non-linear finite element modeling to bridge the micro- and macroscopic scales and establish the connection between microstructure and effective behavior of brain tissue to develop acceptable injury threshold. Part of this effort has been focused on measuring the shock waves created from a blast, and studying the response of the brain model of a human head exposed to such an environment. The Arbitrary Lagrangian Eulerian (ALE) and Fluid/Solid Interactions (FSI) formulation have been used to model the brain-blast interactions. Another part has gone into developing a validated fiber-matrix based micro-scale model of a brain tissue to reproduce the effective response and to capturing local details of the tissue’s deformations causing axonal injury. The micro-model of the axon and matrix is characterized by a transversely isotropic viscoelastic material and the material model is formulated for numerical implementation. Model parameters are fit to experimental frequency response of the storage and loss modulus data obtained and determined using a genetic algorithm (GA) optimizing method. The results from macro-scale model are used in the micro-scale brain tissue to study the effective behavior of this tissue under injury-based loadings. The research involves the development of a tool providing a better understanding of the mechanical behavior of the brain tissue against blast loads and a rational multi-scale approach for driving injury criteria.

Study the Effects of Padding Materials on the Level of the Load in the Brain

2013 ◽  
Author(s):  
Mehdi Salimi Jazi ◽  
Asghar Rezaei ◽  
Ghodrat Karami ◽  
Fardad Azarmi ◽  
Mariusz Ziejewski
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Shock Waves ◽  
Military Service ◽  
Ballistic Impact ◽  
Motor Vehicles ◽  
Common Causes ◽  
The Military ◽  
The Brain

Experiencing a speedy strain or acceleration causes Traumatic Brain Injury (TBI) that can be classified into mild, moderate and severe, based on the level of the injury. Motor vehicles crashes; violence related injuries; collisions in sports; and falls are most common causes of TBI. Moreover in the military service TBI can be happened when soldiers are exposed to shock waves due to blasts or because of ballistic impact.

Nonlinear and von neumann reflection of elastic shock waves in soft solids

2009 ◽  
Author(s):  
Gianmarco F. Pinton ◽  
Francois Coulouvrat ◽  
Jean-Luc Gennisson ◽  
Mickael Tanter
Keyword(s):  
Shock Waves ◽  
Von Neumann ◽  
Soft Solids ◽  
Elastic Shock

scholarly journals Effects of retro-nasal aroma release on satiation

2008 ◽  
Vol 99 (5) ◽  
pp. 1140-1148 ◽  
Author(s):  
Rianne M. A. J. Ruijschop ◽  
Alexandra E. M. Boelrijk ◽  
Jacob A. de Ru ◽  
Cees de Graaf ◽  
Margriet S. Westerterp-Plantenga
Keyword(s):  
Sensory Stimulation ◽  
Physical Structure ◽  
Brain Response ◽  
Double Blind ◽  
Aroma Release ◽  
Soft Solids ◽  
Computer Controlled ◽  
Desire To Eat ◽  
Full Factorial ◽  
The Brain

It is suggested that the brain response of a food odour sensed retro-nasally is related to satiation. The extent of retro-nasal aroma release during consumption depends on the physical structure of a food, i.e. solid foods generate a longer, more pronounced retro-nasal aroma release than liquid foods. The aim of this study was to investigate if a beverage becomes more satiating when the retro-nasal aroma release profile coincides with the profile of a (soft) solid food. In a double-blind placebo-controlled randomised cross-over full factorial design, twenty-seven healthy subjects (fourteen males and thirteen females; aged 16–65 years; BMI 19–37 kg/m(2) were administered aroma profiles by a computer-controlled stimulator based on air dilution olfactometry. Profile A consisted of a profile that is obtained during consumption of normal beverages. Profile B is normally observed during consumption of (soft) solids. The two profiles were produced with strawberry aroma and administered in a retro-nasal fashion, while the subjects consumed a sweetened milk drink. Before, during and after the sensory stimulation, appetite profile measurements were performed. Subjects felt significantly more satiated if they were aroma stimulated with profile B (P = 0·04). After stimulation with sweet strawberry aroma, there was a significant decrease in desire to eat sweet products (P = 0·0001). In conclusion, perceived satiation was increased by altering the extent of retro-nasal aroma release.

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