Validation of a Full Porcine Finite Element Model for Blast Induced TBI Using a Coupled Eulerian-Lagrangian Approach

2017 ◽  
Author(s):  
X. Gary Tan ◽  
Robert N. Saunders ◽  
Amit Bagchi
Keyword(s):  
Experimental Data ◽  
Shock Wave ◽  
Finite Element ◽  
Computational Models ◽  
Soft Tissues ◽  
Large Strain ◽  
Viscoelastic Model ◽  
The Body ◽  
Whole Body ◽  
Fe Model

Current understanding of blast induced traumatic brain injury (TBI) mechanisms is incomplete and limits the development of protective and therapeutic measures. Animal testing has been used as a surrogate for human testing. The correlation of animals to human responses is not well understood with a limited set of experimental data, because of ethical concerns and cost of live animal tests. The validated computational animal models can be used to supplement and improve the granularity of available data at a significantly reduced cost. A whole-body porcine high-fidelity computational model was developed based on the image data. The hyper-viscoelastic model was used for soft tissues to capture the rate dependence and large strain nonlinearity of the material. The shock wave interaction with a porcine subject in a shock tube was simulated using computational fluid dynamics (CFD) models, via a combination of 1-D, 2-D and 3-D numerical techniques. The shock wave loads were applied to the exterior of the porcine finite element (FE) model to simulate the pressure wave transmission through the body and capture its biomechanical response. The CFD and FE problems are solved using the explicit Eulerian and Lagrangian solvers, respectively, in the DoD Open Source code CoBi. The computational models were validated by comparing the simulation results with experimental data at specific instrumented locations. The predicted brain tissue stress-strain fields were used to determine the areas susceptible to blast induced TBI by using published mechanical injury thresholds. The validated porcine model can be used to better understand TBI and how injury in animals corresponds to injury in humans. The coupled Eurlerian and Lagrangian approaches developed in this paper can be extended to other simulations to improve the solution accuracy.

Computerized Tomography: A Perspective in the Pediatric Patient

PEDIATRICS ◽  
1977 ◽  
Vol 59 (2) ◽  
pp. 305-308
Author(s):  
Derek Harwood-Nash ◽  
Herman Grossman ◽  
Alvin Felman ◽  
John Kirkpatrick ◽  
Leonard Swischuk
Keyword(s):  
Computerized Tomography ◽  
Soft Tissues ◽  
Conventional Radiography ◽  
The United States ◽  
The Body ◽  
Whole Body ◽  
Central Research ◽  
X Ray ◽  
Whole Body Ct

Computerized tomography (CT), a technique conceptualized by Oldendorf in 19611 and developed by Hounsfield2 of EMI-Tronics Inc. (EMI) Central Research Laboratories, has proven to be a successful innovation in neuroradiology. Reviews by Ambrose3 in England and by Baker et al.4 and by New et al.5 in the United States have clearly demonstrated the value of this new modality in neuroradiological diagnosis. In 1975 Houser et al.6 and Harwood-Nash et al.7 provided the initial clinical and radiological data about CT in infants and children. More recently this technique has been extended to the study of tissues and organs in the body other than those in the head. This has been accomplished by modification of the original machine into a whole-body CT system. Early reviews by Ledley et al.8 and by Alfidi et al.9 suggest a significant potential for diagnosis of lesions in the abdomen, pelvis, and thorax. The advantages of CT are that it is less invasive than standard special diagnostic radiological procedures and that for the first time it provides in vivo information regarding the content and the characteristics of tissue composing organs and masses. DESCRIPTION OF EQUIPMENT In conventional radiography an image is made on radiographic film by an attenuated X-ray beam. In passing through a core of tissue, each ray of the beam is attenuated as it is absorbed and scattered by the tissue in its path. The intensity of the transmitted ray depends on the sum total of X-ray attenuation by all the different soft tissues in its path.

Age Dependent and Anisotropic Material Properties of Immature Porcine Sclera

2013 ◽  
Author(s):  
Jami M. Saffioti ◽  
Brittany Coats
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Anisotropic Material ◽  
Computational Models ◽  
Fe Model ◽  
Ocular Tissues ◽  
Load Bearing ◽  
Anisotropic Properties ◽  
Age Dependent ◽  
Testing Protocols

Current finite element (FE) models of the pediatric eye are based on adult material properties [2,3]. To date, there are no data characterizing the age dependent material properties of ocular tissues. The sclera is a major load bearing tissue and an essential component to most computational models of the eye. In preparation for the development of a pediatric FE model, age-dependent and anisotropic properties of sclera were evaluated in newborn (3–5 days) and toddler (4 weeks) pigs. Data from this study will guide future testing protocols for human pediatric specimens.

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.

Finite Element Simulation and Experimental Study on Blow Forming of Plastic Cups

2011 ◽  
Vol 148-149 ◽  
pp. 1319-1322
Author(s):  
Xiao Hu ◽  
Yi Sheng Zhang ◽  
Hong Qing Li ◽  
De Qun Li
Keyword(s):  
Finite Element ◽  
Thickness Distribution ◽  
Viscoelastic Model ◽  
Engineering Practice ◽  
Fe Model ◽  
Thin Wall ◽  
Forming Process ◽  
Element Simulation ◽  
Physically Based ◽  
Set Up

Blow forming process of plastic sheets is simple and easy to realize, thus, it is widely used for plastic thin-wall parts. In the practical production, an effective method is needed for the preliminary set-up of process parameters in order to achieve accurate control of thickness distribution. Thus, a finite element method (FEM) code is used to simulate blow forming process. For better description of complex material theological characteristics, a physically based viscoelastic model (VUMAT forms Buckley model) to model the complex constitutive behavior is used. Nonlinear FE analyses using ABAQUS were carried out to simulate the blow forming process of plastic cups. The actual values at different locations show a satisfactory agreement with the simulation results: as a matter of fact the error along the cell mid-section did not exceed 0.02 mm on average, corresponding to 5% of the initial thickness, thus the FE model this paper can meet the requirements of the engineering practice.

Development of Upper Extremity Finite Element Model for Elderly Female: Validated Against Dynamic Loading Conditions

2017 ◽  
Author(s):  
Anand Hammad ◽  
Anil Kalra ◽  
Prashant Khandelwal ◽  
Xin Jin ◽  
King H. Yang
Keyword(s):  
Finite Element ◽  
Upper Extremity ◽  
Injury Risk ◽  
Experimental Studies ◽  
Upper Extremities ◽  
Whole Body ◽  
Crash Test ◽  
Fe Model ◽  
Long Term Effects ◽  
Elderly Female

Injuries to the upper extremities that are caused by dynamic impacts in crashes, including contact with internal instrument panels, has been a major concern, especially for smaller female occupants, and the problem worsens with increasing age due to reduced strength of the bones. From the analysis of 1988–2010 CDS unweighted data, it was found that risk of AIS ≥ 2 level for the arm was 58.2±20.6 percent higher in females than males, and the injury risk for a 75-year-old female occupant relative to a 21-year-old subjected to a similar physical insult was 4.2 times higher. Although injuries to upper extremities are typically not fatal, they can have long-term effects on overall quality of life. Therefore, it is important to minimize risks of injuries related to upper extremities, especially for elderly females, who are most at risk. Current anthropomorphic surrogates, like crash-test dummies, cannot be directly used to study injury limits, as these dummies were developed mainly to represent the younger population. The current study is focused on the development of a finite element (FE) model representing the upper extremity of an elderly female. This can be further used to analyze the injury mechanisms and tolerance limits for this vulnerable population. The FE mesh was developed through Computer Tomography (CT) scanned images of an elderly female cadaver, and the data included for validation of the developed model were taken from the experimental studies published in scientific literature, but only the data directly representing elderly females were used. It was found that the developed model could predict fractures in the long bones of elderly female specimens and could be further used for analyzing injury tolerances for this population. Further, it was determined that the developed segmental model could be integrated with the whole body FE model of the elderly female.

Development and Preliminary Validation of a 50th Percentile Pedestrian Finite Element Model

2015 ◽  
Author(s):  
Costin D. Untaroiu ◽  
Jacob B. Putnam ◽  
Jeremy Schap ◽  
Matt L. Davis ◽  
F. Scott Gayzik
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Test Data ◽  
Element Model ◽  
Human Model ◽  
Whole Body ◽  
Fe Model ◽  
Pedestrian Protection ◽  
Bending Tests ◽  
Impact Tests

Pedestrians represent one of the most vulnerable road users and comprise nearly 22% of the road crash related fatalities in the world. Therefore, protection of pedestrians in the car-to-pedestrian collisions (CPC) has recently generated increased attention with regulations which involve three subsystem tests for adult pedestrian protection (leg, thigh and head impact tests). The development of a finite element (FE) pedestrian model could be a better alternative that characterizes the whole-body response of vehicle–pedestrian interactions and assesses the pedestrian injuries. The main goal of this study was to develop and to preliminarily validate a FE model corresponding to a 50th male pedestrian in standing posture. The FE model mesh and defined material properties are based on the Global Human Body Modeling (GHBMC) 50th percentile male occupant model. The lower limb-pelvis and lumbar spine regions of the human model were preliminarily validated against the post mortem human surrogate (PMHS) test data recorded in four-point lateral knee bending tests, pelvic impact tests, and lumbar spine bending tests. Then, pedestrian-to-vehicle impact simulations were performed using the whole pedestrian model and the results were compared to corresponding pedestrian PMHS tests. Overall, the preliminary simulation results showed that lower leg response is close to the upper boundaries of PMHS corridors. The pedestrian kinematics predicted by the model was also in the overall range of test data obtained with PMHS with various anthropometries. In addition, the model shows capability to predict the most common injuries observed in pedestrian accidents. Generally, the validated pedestrian model may be used by safety researchers in the design of front ends of new vehicles in order to increase pedestrian protection.

Fat, water and tissue solids of the whole body less its bone mineral

1959 ◽  
Vol 14 (6) ◽  
pp. 1009-1012 ◽  
Author(s):  
T. H. Allen ◽  
B. E. Welch ◽  
T. T. Trujillo ◽  
J. E. Roberts
Keyword(s):  
Bone Mineral ◽  
Soft Tissues ◽  
The Body ◽  
Whole Body ◽  
Water Density ◽  
Simultaneous Measurements ◽  
Free Body ◽  
Total Tissue ◽  
Isolated Tissues ◽  
Healthy Persons

Except for bone mineral, the body is shown to belong to the same water:fat:protein system as its soft tissues. Hence, an equation verified with a variety of freshly isolated tissues can be used to estimate the body fat and the so-called total tissue solids. On the average, there are 0.784 kg of water/kg of body weight less bone mineral and fat. However, this water content probably fluctuates between extremes of 0.816 and 0.752, in accordance with the time elapsing since imbibing much water. This causes the density of the tissues in the fat-free, bone mineral-free body to range from 1.050 to 1.071. Combined simultaneous measurements of water, density and bone mineral, therefore, are required for the estimation of fat and tissue solids. Bone mineral occurs in the proportion of about one part to three parts of tissue solids, irrespective of ranges in quantities of fat and water among 30 healthy persons. Submitted on June 15, 1959

scholarly journals On the Biomechanics of Cardiac S-Looping in the Chick: Insights From Modeling and Perturbation Studies

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Ashok Ramasubramanian ◽  
Xavier Capaldi ◽  
Sarah A. Bradner ◽  
Lianna Gangi
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
The Body ◽  
Congenital Defects ◽  
Finite Element Models ◽  
Heart Tube ◽  
Dorsal Wall ◽  
Embryonic Developmental Stage ◽  
Cervical Flexure ◽  
Shape Changes

Cardiac looping is an important embryonic developmental stage where the primitive heart tube (HT) twists into a configuration that more closely resembles the mature heart. Improper looping leads to congenital defects. Using the chick embryo as the experimental model, we study cardiac s-looping wherein the primitive ventricle, which lay superior to the atrium, now assumes its definitive position inferior to it. This process results in a heart loop that is no longer planar with the inflow and outflow tracts now lying in adjacent planes. We investigate the biomechanics of s-looping and use modeling to understand the nonlinear and time-variant morphogenetic shape changes. We developed physical and finite element models and validated the models using perturbation studies. The results from experiments and models show how force actuators such as bending of the embryonic dorsal wall (cervical flexure), rotation around the body axis (embryo torsion), and HT growth interact to produce the heart loop. Using model-based and experimental data, we present an improved hypothesis for early cardiac s-looping.

Development of Material Constants for Nonlinear Finite-Element Analysis

1988 ◽  
Vol 61 (5) ◽  
pp. 879-891 ◽  
Author(s):  
Robert H. Finney ◽  
Alok Kumar
Keyword(s):  
Experimental Data ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Large Strain ◽  
Strain Range ◽  
Nonlinear Finite Element ◽  
Element Analysis ◽  
Material Models ◽  
Tensile Data

Abstract The determination of the material coefficients for Ogden, Mooney-Rivlin, Peng, and Peng-Landel material models using simple ASTM D 412 tensile data is shown to be a manageable task. The application of the various material models are shown to be subject to the type and level of deformation expected, with Ogden showing the best correlation with experimental data over a large strain range for the three types of strain investigated. At low strains, all of the models showed reasonable correlation.

Decay and preservation of polychaetes: taphonomic thresholds in soft-bodied organisms

Paleobiology ◽  
1993 ◽  
Vol 19 (1) ◽  
pp. 107-135 ◽  
Author(s):  
Derek E. G. Briggs ◽  
Amanda J. Kear
Keyword(s):  
Chemical Composition ◽  
Soft Tissues ◽  
Lipid Fraction ◽  
Relative Proportion ◽  
Two Dimensions ◽  
The Body ◽  
Whole Body ◽  
Fluid Loss ◽  
Preservation Potential ◽  
Grès À Voltzia

A series of experiments was carried out to investigate the nature and controls (oxygen, microbial populations, agitation) on the degradation of soft tissues. Decay was monitored in terms of morphological change, weight loss, and change in chemical composition in the polychaete Nereis virens. Polychaetes include a range of tissue types of differing chemical composition and preservation potential: muscle, cuticle, setae, and jaws. Regardless of conditions, all the muscle had broken down and fluid loss through the ruptured cuticle had reduced the carcass to two dimensions within 8 days at 20°C. In most cases some cuticle, in addition to the jaws and setae, remained after 30 days. Where oxygen was completely eliminated, the rate of decay of the more volatile issues was significantly reduced. The degree of both osmotic uptake of water by the carcass and changes in water pH differed depending on whether the system was open or closed to oxygen diffusion. Autolytic and chemical processes are not sufficient to fully degrade the carcass in the absence of bacteria. Where internal bacteria are present, the presence or absence of water column bacteria made little difference to decay rate. Initial degradation (in the first 3 days) affects mainly the lipid fraction and the collagen of the cuticle. Later decay reduces the nonsoluble protein and increases the relative proportion of refractory structural components (tanned chitin and collagen) to more than 95% by day 30. Thus, only the sclerotized tissues are likely to survive beyond 30 days in the absence of early diagenetic mineralization. The sequence of degradation predicted from the relative decay resistance of macromolecules in the sedimentary record (protein → carbohydrate → lipid) is not, therefore, a consistent indicator of the preservation potential of structural tissues which incorporate them.The experiments reveal five stages in the decay of polychaete carcasses; whole/shriveled, flaccid, unsupported gut, cuticle sac, jaws and setae. All are represented in the fossil record. This allows an estimation of how far decay proceeded before it was halted by the fossilization process. The most complete preservations occur in the Cambrian where the Burgess Shale preserves evidence of muscle tissues. Traces of the gut and cuticle are more widely preserved, as at Mazon Creek, Grès à Voltzia, Solnhofen, and Hakel. Preservation varies within Konservat-Lagerstätten. The most common whole body preservation includes only the more recalcitrant tissues, jaws (where present) and setae, with an impression of the body outline. The stage of decay can be used as a taphonomic threshold, to provide an indication of how significantly the diversity of an exceptionally preserved biota is likely to have been reduced by taphonomic loss.

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