scholarly journals A comparison of head dynamic response and brain tissue stress and strain using accident reconstructions for concussion, concussion with persistent postconcussive symptoms, and subdural hematoma

2015 ◽  
Vol 123 (2) ◽  
pp. 415-422 ◽  
Author(s):  
R. Anna Oeur ◽  
Clara Karton ◽  
Andrew Post ◽  
Philippe Rousseau ◽  
T. Blaine Hoshizaki ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Brain Tissue ◽  
Subdural Hematoma ◽  
Von Mises Stress ◽  
Stress And Strain ◽  
Rotational Acceleration ◽  
Postconcussive Symptoms ◽  
Tissue Responses ◽  
Von Mises ◽  
Post Hoc

OBJECT Concussions typically resolve within several days, but in a few cases the symptoms last for a month or longer and are termed persistent postconcussive symptoms (PPCS). These persisting symptoms may also be associated with more serious brain trauma similar to subdural hematoma (SDH). The objective of this study was to investigate the head dynamic and brain tissue responses of injury reconstructions resulting in concussion, PPCS, and SDH. METHODS Reconstruction cases were obtained from sports medicine clinics and hospitals. All subjects received a direct blow to the head resulting in symptoms. Those symptoms that resolved in 9 days or fewer were defined as concussions (n = 3). Those with symptoms lasting longer than 18 months were defined as PPCS (n = 3), and 3 patients presented with SDHs (n = 3). A Hybrid III headform was used in reconstruction to obtain linear and rotational accelerations of the head. These dynamic response data were then input into the University College Dublin Brain Trauma Model to calculate maximum principal strain and von Mises stress. A Kruskal-Wallis test followed by Tukey post hoc tests were used to compare head dynamic and brain tissue responses between injury groups. Statistical significance was set at p < 0.05. RESULTS A significant difference was identified for peak resultant linear and rotational acceleration between injury groups. Post hoc analyses revealed the SDH group had higher linear and rotational acceleration responses (316 g and 23,181 rad/sec2, respectively) than the concussion group (149 g and 8111 rad/sec2, respectively; p < 0.05). No significant differences were found between groups for either brain tissue measures of maximum principal strain or von Mises stress. CONCLUSIONS The reconstruction of accidents resulting in a concussion with transient symptoms (low severity) and SDHs revealed a positive relationship between an increase in head dynamic response and the risk for more serious brain injury. This type of relationship was not found for brain tissue stress and strain results derived by finite element analysis. Future research should be undertaken using a larger sample size to confirm these initial findings. Understanding the relationship between the head dynamic and brain tissue response and the nature of the injury provides important information for developing strategies for injury prevention.

The influence of dynamic response and brain deformation metrics on the occurrence of subdural hematoma in different regions of the brain

2014 ◽  
Vol 120 (2) ◽  
pp. 453-461 ◽  
Author(s):  
Andrew Post ◽  
T. Blaine Hoshizaki ◽  
Michael D. Gilchrist ◽  
Susan Brien ◽  
Michael D. Cusimano ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Subdural Hematoma ◽  
Parietal Lobe ◽  
Linear Acceleration ◽  
Occipital Lobe ◽  
Von Mises Stress ◽  
Rotational Acceleration ◽  
Brain Deformation ◽  
Strain And Strain Rate ◽  
The Brain

Object The purpose of this study was to examine how the dynamic response and brain deformation of the head and brain—representing a series of injury reconstructions of which subdural hematoma (SDH) was the outcome—influence the location of the lesion in the lobes of the brain. Methods Sixteen cases of falls in which SDH was the outcome were reconstructed using a monorail drop rig and Hybrid III headform. The location of the SDH in 1 of the 4 lobes of the brain (frontal, parietal, temporal, and occipital) was confirmed by CT/MR scan examined by a neurosurgeon. Results The results indicated that there were minimal differences between locations of the SDH for linear acceleration. The peak resultant rotational acceleration and x-axis component were larger for the parietal lobe than for other lobes. There were also some differences between the parietal lobe and the other lobes in the z-axis component. Maximum principal strain, von Mises stress, shear strain, and product of strain and strain rate all had differences in magnitude depending on the lobe in which SDH was present. The parietal lobe consistently had the largest-magnitude response, followed by the frontal lobe and the occipital lobe. Conclusions The results indicated that there are differences in magnitude for rotational acceleration and brain deformation metrics that may identify the location of SDH in the brain.

scholarly journals Evaluation of Bone–Implant Interface Stress and Strain Using Heterogeneous Mandibular Bone Properties Based on Different Empirical Correlations

2021 ◽  
Author(s):  
Mostafa Omran Hussein ◽  
Mohammed Suliman Alruthea
Keyword(s):  
Finite Element ◽  
Group Iv ◽  
Von Mises Stress ◽  
Patient Specific ◽  
Dental Arch ◽  
Stress And Strain ◽  
Bone Implant ◽  
Bone Properties ◽  
Group I ◽  
Von Mises

Abstract Objective The purpose of this study was to compare methods used for calculating heterogeneous patient-specific bone properties used in finite element analysis (FEA), in the field of implant dentistry, with the method based on homogenous bone properties. Materials and Methods In this study, three-dimensional (3D) computed tomography data of an edentulous patient were processed to create a finite element model, and five identical 3D implant models were created and distributed throughout the dental arch. Based on the calculation methods used for bone material assignment, four groups—groups I to IV—were defined. Groups I to III relied on heterogeneous bone property assignment based on different equations, whereas group IV relied on homogenous bone properties. Finally, 150 N vertical and 60-degree-inclined forces were applied at the top of the implant abutments to calculate the von Mises stress and strain. Results Groups I and II presented the highest stress and strain values, respectively. Based on the implant location, differences were observed between the stress values of group I, II, and III compared with group IV; however, no clear order was noted. Accordingly, variable von Mises stress and strain reactions at the bone–implant interface were observed among the heterogeneous bone property groups when compared with the homogenous property group results at the same implant positions. Conclusion Although the use of heterogeneous bone properties as material assignments in FEA studies seem promising for patient-specific analysis, the variations between their results raise doubts about their reliability. The results were influenced by implants’ locations leading to misleading clinical simulations.

Simulation of Shock Wave Assisted Free and Shape Forming of Metallic Plates in a Shock Tube

2015 ◽  
Vol 813-814 ◽  
pp. 586-591 ◽  
Author(s):  
Kottakota Kalasagarreddi ◽  
Prem Sai Koppuravuri Sobhan ◽  
Vinay Kumar Gundu ◽  
S.R. Nagaraja
Keyword(s):  
Shock Wave ◽  
Shock Tube ◽  
Metal Forming ◽  
Von Mises Stress ◽  
Stress And Strain ◽  
Shock Strength ◽  
Engineering Problems ◽  
Experimental Values ◽  
Von Mises ◽  
Metallic Plates

Due to their complexity, certain engineering problems like finding shock strength, Mach number etc. and the interaction of shock wave with a structure in free and restricted metal forming techniques cannot be achieved in a single experimentation, these can be obtained only through a number of trials and that leads to increase in cost and time. In such cases both cost and time can be reduced by adopting numerical simulations. In this projectcommercial software ANSYS is used to simulate the propagation shock wave through a shock tube, free and shape forming of metallic plates subjected to this shock wave. Shock Mach numbers up to 2.12 have been generated by varying the driver to driven pressure ratios. Thin copper plates of diameter 60mm and thickness of 0.5mm and 0.3mm are subjected to shock wave loadingin order to form into dies.These dies,madeof structural steel are modelled with pre-defined shapes. The plate peakoverpressures ranging from 9 to 20bar have been generated.The midpoint deflection, Von Mises stress and strain are calculated for free forming copper plates. The simulated results are compared with the experimental values available in literature. The simulated results match well with the experimental values.

Simulation of Brain Response to Noncontact Impacts Using Coupled Eulerian–Lagrangian Method

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Miao Na ◽  
Timothy J. Beavers ◽  
Abhijit Chandra ◽  
Sarah A. Bentil
Keyword(s):  
Brain Tissue ◽  
Mechanical Response ◽  
Brain Regions ◽  
Von Mises Stress ◽  
Fe Model ◽  
Brain Response ◽  
Fe Method ◽  
Angular Velocities ◽  
Von Mises ◽  
The Brain

Abstract Finite element (FE) method has been widely used for gaining insights into the mechanical response of brain tissue during impacts. In this study, a coupled Eulerian−Lagrangian (CEL) formulation is implemented in impact simulations of a head system to overcome the mesh distortion difficulties due to large deformation in the cerebrospinal fluid (CSF) region and provide a biofidelic model of the interaction between the brain and skull. The head system used in our FE model is constructed from the transverse section of the human brain, with CSF modeled by Eulerian elements. Spring connectors are applied to represent the pia-arachnoid connection between the brain and skull. Validations of the CEL formulation and the FE model are performed using the experimental results. The dynamic response of brain tissue under noncontact impacts and the brain regions susceptible to injury are evaluated based on the intracranial pressure (ICP), maximum principal strain (MPS), and von Mises stress. While tracking the critical MPS location on the brain, higher likelihood of contrecoup injury than coup injury is found when sudden brain−skull motion takes place. The accumulation effect of CSF in the ventricle system, under large relative brain−skull motion, is also identified. The FE results show that adding relative angular velocities, to the translational impact model, not only causes a diffuse high strain area, but also cause the temporal lobes to be susceptible to cerebral contusions since the protecting CSF is prone to be squeezed away at the temporal sites due to the head rotations.

Shear Ram Height Characterization for Copper Wire Bond Shear Test

2012 ◽  
Vol 229-231 ◽  
pp. 674-677 ◽  
Author(s):  
Z. Sauli ◽  
V. Retnasamy ◽  
A. H. M. Shapri ◽  
N. A. Z. Rahman ◽  
W.M.W. Norhaimi ◽  
...  
Keyword(s):  
Shear Test ◽  
Copper Wire ◽  
Equivalent Strain ◽  
Von Mises Stress ◽  
Stress And Strain ◽  
Strain Response ◽  
Element Analysis ◽  
Ball Bond ◽  
Wire Bond ◽  
Von Mises

The work here investigates the height effect during a shearing process of a copper ball bond in a wire bond. Finite element analysis was used to investigate this analysis.The effects of the shear ram height on the stress and strain response of the copper ball bond were investigated. The results obtained hows there is a significant effect of the shear height to the Von Mises stress and equivalent strain response to the copper ball bond during the shearing simulation.

scholarly journals Porosity Structure Offering Improved Biomechanical Stress Distribution and Enhanced Pain-Relieving Potential

2020 ◽  
Vol 10 (9) ◽  
pp. 3026
Author(s):  
Chia-Cheng Lin ◽  
Chia-Yu Wu ◽  
Mao-Suan Huang ◽  
Bai-Hung Huang ◽  
Hsin-Hua Chou ◽  
...  
Keyword(s):  
Human Body ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
Stress And Strain ◽  
The Finite Element Method ◽  
Human Body Model ◽  
Biomechanical Stress ◽  
Porosity Structure ◽  
Von Mises ◽  
Stress Variations

In this study, we developed a three-dimensional (3D) human body model and a body sculpting clothing (BSC) which was fitted onto that body to simulate the biomechanical stress variations of the BSC with different porosity structures using the finite element method. The mechanical properties of the BSC with different porosity structures were also examined through the tensile testing. Analytical results indicated that the Von Mises stress of the BSC with a porosity structure of 10.28% varied from 0.076 MPa to 337.79 MPa. As compared with a porosity structure of 35.18%, the von Mises stress varied from 0.067 MPa to 207.30 MPa. The von Mises stress decreased as the porosity increasing. Based on the statistical analysis findings, we obtained a formula to predict the biomechanical relationships (von Mises stress and strain) between the human body and porosity of the BSC. Therefore, these findings could offer potential information in the modification of BSC for pain-relieving applications.

The Proportional Anisotropic Elastic Invariants

1991 ◽  
Vol 58 (1) ◽  
pp. 50-57 ◽  
Author(s):  
A. M. Sadegh ◽  
S. C. Cowin
Keyword(s):  
Elastic Material ◽  
Hydrostatic Stress ◽  
Von Mises Stress ◽  
Stress And Strain ◽  
Fracture Criteria ◽  
Linear Elastic Material ◽  
Linear Elastic ◽  
Isotropic Elasticity ◽  
Anisotropic Elastic ◽  
Von Mises

There are two proportional invariants for a linear isotropic material, the hydrostatic invariant, and the deviatoric invariant. The former is proportional to the trace of the tensor and the latter is proportional to the trace of the square of the associated deviatoric tensor. The hydrostatic stress and strain and the von Mises stress and strain are directly related to the hydrostatic and deviatoric proportional invariants, respectively, for an isotropic, linear elastic material. For each anisotropic linear elastic material symmetry there are up to six proportional invariants. In this paper we illustrate the six proportional invariants of an orthotropic elastic material using the elastic constants for spruce as the numerical example. The proportional elastic invariants play a role in anisotropic linear elasticity similar to the roles played by the hydrostatic stress and strain and the von Mises stress and strain in isotropic elasticity. They are the unique parameters whose contours represent both the stress and the strain distributions. They also have potential for representing failure or fracture criteria.

scholarly journals Effect of material selection on tibial post stresses in posterior-stabilized knee prosthesis

2020 ◽  
Vol 9 (11) ◽  
pp. 768-777
Author(s):  
Chang-Hung Huang ◽  
Yung-Chang Lu ◽  
Lin-I Hsu ◽  
Jiann-Jong Liau ◽  
Ting-Kuo Chang ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Material Selection ◽  
Equivalent Plastic Strain ◽  
Mobile Bearing ◽  
Von Mises Stress ◽  
Stress And Strain ◽  
Fixed Bearing ◽  
Bearing Design ◽  
Tibial Post ◽  
Von Mises

Aims The material and design of knee components can have a considerable effect on the contact characteristics of the tibial post. This study aimed to analyze the stress distribution on the tibial post when using different grades of polyethylene for the tibial inserts. In addition, the contact properties of fixed-bearing and mobile-bearing inserts were evaluated. Methods Three different grades of polyethylene were compared in this study; conventional ultra high molecular weight polyethylene (UHMWPE), highly cross-linked polyethylene (HXLPE), and vitamin E-stabilized polyethylene (VEPE). In addition, tibial baseplates with a fixed-bearing and a mobile-bearing insert were evaluated to understand differences in the contact properties. The inserts were implanted in neutral alignment and with a 10° internal malrotation. The contact stress, von Mises stress, and equivalent plastic strain (PEEQ) on the tibial posts were extracted for comparison. Results The stress and strain on the tibial post for the three polyethylenes greatly increased when the insert was placed in malrotation, showing a 38% to 56% increase in von Mises stress and a 335% to 434% increase in PEEQ. The VEPE insert had the lowest PEEQ among the three materials. The mobile-bearing design exhibited a lower increase in stress and strain around the tibial posts than the fixed-bearing design. Conclusion Using VEPE for the tibial component potentially eliminates the risk of material permanent deformation. The mobile-bearing insert can help to avoid a dramatic increase in plastic strain around the tibial post in cases of malrotation. The mobility allows the pressure to be distributed on the tibial post and demonstrated lower stresses with all three polyethylenes simulated. Cite this article: Bone Joint Res 2020;9(11):768–777.

scholarly journals Effects on the Various Aluminum Foam Fenders of a Tripod Offshore Wind Turbine Collision Due to a Ship

2020 ◽  
Vol 54 (1) ◽  
pp. 79-96
Author(s):  
Zhiwei Han ◽  
Xinlei Zhao ◽  
Chun Li ◽  
Qinwei Ding
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Dynamic Response ◽  
Contact Force ◽  
Aluminum Foam ◽  
Offshore Wind ◽  
Von Mises Stress ◽  
Offshore Wind Turbine ◽  
Structural Dynamic ◽  
Von Mises

AbstractThe interest in offshore wind energy is growing all over the world. Increasingly, offshore wind turbines (OWTs) are being installed close to shipping lanes, which puts them at risk of potential collisions with ships during their service period. This article aims to investigate the structural dynamic response of OWTs to a ship collision. Considering the structure size of the fender as well as the nonlinear characteristics of the structural materials, a finite element model of a 5,000-ton ship colliding with a 4-MW tripod OWT has been developed using the explicit finite element code LS-DYNA. By observing the collision energy conversion, contact force, fender performance, Von Mises stress on the tripod, shear stress, and dynamic response of a nacelle in differently sized fender collision scenarios, it was observed that when the thickness of the fender surpasses 1.1 m, it can protect the OWT from a collision more effectively than with no fender case. Otherwise, the local contact force is cushioned by aluminum foam materials, whose contact force leads to a whole movement of the bearing tripod. The tripod with the aforementioned 1.1-m fender generates a contact force, Von Mises stress, and a shear stress, as well as the anticollision characteristics of a fender and the dynamic responses of a nacelle in 15 scenarios. Therefore, the structural design of the fender is essential in the safety of a tripod foundation in a collision. This article will provide a better understanding of the collision characteristics of the fender in the future.

Biomechanics effect of two implant system with different bone height under axial and non–axial loading conditions

2021 ◽  
Vol 2 (1) ◽  
pp. 11913
Author(s):  
Carlos Eduardo Datte ◽  
Fabiana Barbi Datte ◽  
Vinícius Anéas Rodrigues ◽  
Alexandre Luiz Souto Borges ◽  
Júlio Ferraz Campos ◽  
...  
Keyword(s):  
Bone Loss ◽  
Axial Loading ◽  
Von Mises Stress ◽  
Stress And Strain ◽  
Element Analysis ◽  
Bone Level ◽  
Strain Magnitude ◽  
Von Mises ◽  
Implant System ◽  
Bone Height

The objective of this current in silico study was to evaluate the influence of axial and non-axial loads on unitary implant-supported implants, with external hexagon or Morse-taper connection in two different bone level, using finite element analysis. Two implant models with the same length (13 x 3.75 mm) were analyzed according to the prosthetic connection (external hexagon or morse Taper) and bone height (bone level or 5 mm of bone loss). Both implant systems received screw-retained metallic crowns in chromium-cobalt. The peri-implant tissue was simulated as an isotropic material (polyurethane resin). The polyurethane block has been fixed and a load of 300 N was applied on the occlusal surface in two different directions (Axial or Non-axial) for each implant model and bone condition. The results were analyzed in terms of von-Mises stress and bone microstrain. The materials were considered isotropic, homogeneous, linear and elastic. The results showed that there is no difference regarding the prosthetic connection for the generated stress and strain under the same load incidence. However, bone loss and non-axial loadings increased the stress and strain magnitude regardless the prosthetic connections. In conclusion, the load incidence is more prone to modify the implant stress and bone microstrain than the prosthethic connection. In addition, the higher the bone loss the higher the stress and strain magnitude generated, regardless the loading condition.

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