Shock Wave Propagation as a Mechanism of Injury in Nonlinear Viscoelastic Soft Tissues

2011 ◽  
Author(s):  
Kaveh Laksari ◽  
Mehdi Shafieian ◽  
Kurosh Darvish ◽  
Keyanoush Sadeghipour
Keyword(s):  
Wave Propagation ◽  
Shock Waves ◽  
Brain Tissue ◽  
Soft Tissues ◽  
Material Model ◽  
High Rate ◽  
Loading Conditions ◽  
Mechanism Of Injury ◽  
Nonlinear Viscoelastic ◽  
Blast Induced Neurotrauma

This study investigates the propagation of shock waves and self-preserving waves in soft tissues such as brain as a mechanism of injury in high rate loading conditions as seen in blast-induced neurotrauma (BINT). The derived mathematical models indicate that whereas linear viscoelastic models predict only decaying waves, instances of such phenomena as shock can be achieved in nonlinear media. In this study, a nonlinear viscoelastic material model for brain tissue was developed in compression. Furthermore, nonlinear viscoelastic wave propagation in brain tissue was studied and a criterion for the development of shock waves was formulated. It was shown that discontinuities in the acceleration that happen in blast loading conditions may evolve to shock waves, resulting in large discontinuities in strain and stress at the wave front leading to tissue injuries.

Shock Wave as a Mechanism of Injury in Soft Tissues

2011 ◽  
Author(s):  
Kaveh Laksari ◽  
Kurosh Darvish ◽  
Keyanoush Sadeghipour
Keyword(s):  
Soft Tissues ◽  
Linear Models ◽  
Initial Conditions ◽  
Soft Tissue Injuries ◽  
High Rate ◽  
Loading Conditions ◽  
Mechanism Of Injury ◽  
Nonlinear Viscoelastic ◽  
Nonlinear Viscoelastic Materials ◽  
High Rate Loading

The aim of this study is to investigate the propagation of shock waves and self-preserving waves in soft tissues such as aorta and brain as a mechanism of injury in high rate loading conditions as seen in blunt trauma and blast-induced trauma (BIT). It is shown that such phenomena can only be seen in nonlinear viscoelastic materials and the existing linear and quasi-linear models predict only decaying waves. Based on the results of this study, it is shown that when studying such high-rate loading conditions as in a blast, it is critical to consider the discontinuities predicted in strain and stress in certain realistic initial conditions to accurately determine the extent of soft tissue injuries.

Comparing Predictive Accuracy and Computational Costs for Viscoelastic Modeling of Spinal Cord Tissues

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Nicole L. Ramo ◽  
Kevin L. Troyer ◽  
Christian M. Puttlitz
Keyword(s):  
Experimental Data ◽  
Spinal Cord ◽  
Mechanical Response ◽  
Predictive Accuracy ◽  
Material Model ◽  
Loading Conditions ◽  
Nonlinear Viscoelastic ◽  
Arbitrary Loading ◽  
Linear Viscoelastic ◽  
Viscoelastic Modeling

Abstract The constitutive equation used to characterize and model spinal tissues can significantly influence the conclusions from experimental and computational studies. Therefore, researchers must make critical judgments regarding the balance of computational efficiency and predictive accuracy necessary for their purposes. The objective of this study is to quantitatively compare the fitting and prediction accuracy of linear viscoelastic (LV), quasi-linear viscoelastic (QLV), and (fully) nonlinear viscoelastic (NLV) modeling of spinal-cord-pia-arachnoid-construct (SCPC), isolated cord parenchyma, and isolated pia-arachnoid-complex (PAC) mechanics in order to better inform these judgements. Experimental data collected during dynamic cyclic testing of each tissue condition were used to fit each viscoelastic formulation. These fitted models were then used to predict independent experimental data from stress-relaxation testing. Relative fitting accuracy was found not to directly reflect relative predictive accuracy, emphasizing the need for material model validation through predictions of independent data. For the SCPC and isolated cord, the NLV formulation best predicted the mechanical response to arbitrary loading conditions, but required significantly greater computational run time. The mechanical response of the PAC under arbitrary loading conditions was best predicted by the QLV formulation.

scholarly journals Dissemination of shock waves in thin isotropic plates

2019 ◽  
Vol 254 ◽  
pp. 05005
Author(s):  
František Klimenda ◽  
Josef Soukup ◽  
Milan Žmindák ◽  
Blanka Skočilasová
Keyword(s):  
Shock Wave ◽  
Wave Propagation ◽  
Shock Waves ◽  
Transverse Wave ◽  
Geometric Model ◽  
Material Model ◽  
Longitudinal Waves ◽  
Isotropic Plates ◽  
Matlab Program ◽  
The Impact

The article deals with the propagation of shock waves in thin isotropic plates. The solution is done analytically. The geometric model of Kirchhoff and Rayleigh was used for the solution. Material model was used Hook. The shock wave is induced by the impact of the punch into the centre of the plate. The longitudinal waves propagate in thexandyaxis, the transverse wave propagates in the axis. Comparison of the longitudinal and transverse wave propagation of both models at selected points is made. Comparisons are displacements, velocities and tensions inx, y andzaxis, depending on time. The rectangular plate is made of unidirectional rolled aluminium sheet of high purity. The plate is around the perimeter fixed. The MATLAB program was used to solve this problem.

scholarly journals Titanium Wear of Dental Implants from Placement, under Loading and Maintenance Protocols

2021 ◽  
Vol 22 (3) ◽  
pp. 1067
Author(s):  
Georgios Romanos ◽  
Gerard Fischer ◽  
Rafael Delgado-Ruiz
Keyword(s):  
Adverse Effects ◽  
Inflammatory Response ◽  
Dental Implants ◽  
Soft Tissues ◽  
Loading Conditions ◽  
Material Change ◽  
Implant Placement ◽  
Implant Abutment ◽  
Hard Tissues ◽  
Titanium Nanoparticles

The objective of this review was to analyze the process of wear of implants leading to the shedding of titanium particles into the peri-implant hard and soft tissues. Titanium is considered highly biocompatible with low corrosion and toxicity, but recent studies indicate that this understanding may be misleading as the properties of the material change drastically when titanium nanoparticles (NPs) are shed from implant surfaces. These NPs are immunogenic and are associated with a macrophage-mediated inflammatory response by the host. The literature discussed in this review indicates that titanium NPs may be shed from implant surfaces at the time of implant placement, under loading conditions, and during implant maintenance procedures. We also discuss the significance of the micro-gap at the implant-abutment interface and the effect of size of the titanium particles on their toxicology. These findings are significant as the titanium particles can have adverse effects on local soft and hard tissues surrounding implants, implant health and prognosis, and even the health of systemic tissues and organs.

Fall, Crush, Kick: Mechanisms and Outcomes in a Cohort of Equine-Related Injuries

2021 ◽  
pp. 000313482110488
Author(s):  
Pratik Bhade ◽  
Amelia Parsons ◽  
Abbey Smiley ◽  
Jacob Shreffler ◽  
Nick Nash ◽  
...  
Keyword(s):  
Traumatic Injury ◽  
The United States ◽  
Rib Fractures ◽  
High Rate ◽  
Protective Equipment ◽  
Solid Organ ◽  
Mechanism Of Injury ◽  
Severe Injuries ◽  
Protective Devices ◽  
Animal Size

Introduction The potential for significant traumatic injury to individuals who interact with horses remains high due to animal size, forces applied, and unpredictability. Despite an estimated 30 million riders in the United States annually, few recent publications have addressed this patient population. Objectives This study describes characteristics of patients injured in interactions with horses, focusing on mechanism of injury and use of protective equipment. Methods We queried our institution’s trauma registry for all patients admitted for equine-related injuries (ERI) between January 1, 2013 and December 31, 2017. We categorized by specific mechanism of injury (fall, crush, kick, fall + crush, and fall + kick) and presence or absence of protective devices. Results We discovered 143 patients admitted for injuries in equine-related accidents. Patients averaged 49.2 years old, and 62.2% were female. Crush injuries resulted in a high rate of rib fractures. Riders who were kicked had an increased chance of solid organ and facial injuries and falls most commonly led to rib fractures and extremity trauma. Despite lack of documentation on most subjects, protective devices were associated with less severe injuries in those with data (n = 36). Conclusions In this relatively large series of patients with ERI, we found mechanism differences within injury groups. Providers should more carefully document specific circumstances of ERIs. All individuals working with or around horses should exercise prudence and consider using protective equipment.

Development and Verification of a Dynamic TKR Model

2002 ◽  
Author(s):  
Jason P. Halloran ◽  
Anthony J. Petrella ◽  
Paul J. Rullkoetter
Keyword(s):  
Finite Element ◽  
Contact Mechanics ◽  
Dynamic Loading ◽  
Soft Tissues ◽  
Dynamic Models ◽  
Total Joint Replacement ◽  
Fe Model ◽  
Loading Conditions ◽  
Dynamic Loading Conditions

The success of current total knee replacement (TKR) devices is contingent on the kinematics and contact mechanics during in vivo activity. Indicators of potential clinical performance of total joint replacement devices include contact stress and area due to articulations, and tibio-femoral and patello-femoral kinematics. An effective way of evaluating these parameters during the design phase or before clinical use is via computationally efficient computer models. Previous finite element (FE) knee models have generally been used to determine contact stresses and/or areas during static or quasi-static loading conditions. The majority of knee models intended to predict relative kinematics have not been able to determine contact mechanics simultaneously. Recently, however, explicit dynamic finite element methods have been used to develop dynamic models of TKR able to efficiently determine joint and contact mechanics during dynamic loading conditions [1,2]. The objective of this research was to develop and validate an explicit FE model of a TKR which includes tibio-femoral and patello-femoral articulations and surrounding soft tissues. The six degree-of-freedom kinematics, kinetics and polyethylene contact mechanics during dynamic loading conditions were then predicted during gait simulation.

scholarly journals Massive Pseudotumor in a 28mm Ceramic-Polyethylene Revision THA: A Case Report

2014 ◽  
Vol 4 (1) ◽  
pp. 11-17 ◽  
Author(s):  
Edward McPherson, M.D., FACS ◽  
Matthew Dipane, BA ◽  
Sherif Sherif, MD
Keyword(s):  
Soft Tissues ◽  
Polyethylene Wear ◽  
Femoral Stem ◽  
High Rate ◽  
Zirconia Ceramic ◽  
Porous Coating ◽  
Metal Debris ◽  
Ultrafine Metal Particles ◽  
Revision Tha ◽  
Therapeutic Study

This report reviews the findings of a massive pseudotumor detected pre-operatively in a 13-year-old revision total hip arthroplasty. The case is unique in that the bearing involved was a 28mm zirconia ceramic head on a polyethylene liner. We propose that the pseudotumor arose from ultrafine titanium particles liberated from the proximal porous coating of the femoral stem. We suspect that the osteolysis produced from polyethylene wear exposed the proximal porous coating and, via a process of mechanical abrasion with the surrounding soft tissues, liberated ultrafine titanium particles. We believe the pseudotumor formed because the patient was pre-sensitized to metal debris based upon a pre-operative lymphocyte T-cell proliferation test (LTT). Based upon this unique case, we feel that pseudotumors more likely form when there is a high rate of ultrafine metal particles generated in a pre-sensitized patient. Finally, we introduce what we believe are the main biologic wear responses in THA. Further research is needed to validate this proposed model.Keywords: pseudotumor, ceramic, polyethylene, osteolysis, THA, bearing wear eesponse, titanium debrisLevel of Evidence:  AAOS Therapeutic Study Level IV

Hyperelastic Muscle Simulation

2007 ◽  
Vol 345-346 ◽  
pp. 1241-1244 ◽  
Author(s):  
Mohd. Zahid Ansari ◽  
Sang Kyo Lee ◽  
Chong Du Cho
Keyword(s):  
Skeletal Muscle ◽  
Silicone Rubber ◽  
Soft Tissues ◽  
Material Model ◽  
Incompressible Material ◽  
Material Behavior ◽  
Rubber Tube ◽  
Stress Strain ◽  
Element Analysis ◽  
Strain Behavior

Biological soft tissues like muscles and cartilages are anisotropic, inhomogeneous, and nearly incompressible. The incompressible material behavior may lead to some difficulties in numerical simulation, such as volumetric locking and solution divergence. Mixed u-P formulations can be used to overcome incompressible material problems. The hyperelastic materials can be used to describe the biological skeletal muscle behavior. In this study, experiments are conducted to obtain the stress-strain behavior of a solid silicone rubber tube. It is used to emulate the skeletal muscle tensile behavior. The stress-strain behavior of silicone is compared with that of muscles. A commercial finite element analysis package ABAQUS is used to simulate the stress-strain behavior of silicone rubber. Results show that mixed u-P formulations with hyperelastic material model can be used to successfully simulate the muscle material behavior. Such an analysis can be used to simulate and analyze other soft tissues that show similar behavior.

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