Biomechanical Evaluation of the Axial Compressive Responses of the Human Cadaveric and Manikin Necks

1989 ◽  
Vol 111 (3) ◽  
pp. 250-255 ◽  
Author(s):  
N. Yoganandan ◽  
A. Sances ◽  
F. Pintar
Keyword(s):  
Human Head ◽  
Axial Stiffness ◽  
Axial Loads ◽  
Anatomic Structure ◽  
Clinical Prognosis ◽  
Cervical Spine Injuries ◽  
Compressive Response ◽  
Hybrid Iii ◽  
Human Cadavers ◽  
Head Neck

Cervical spine injuries such as wedge, burst, and tear drop fractures are often associated with compressive axial loads delivered to the human head-neck complex. Understanding the injury mechanisms, the kinematics of the anatomic structure, and the tissue tolerances can improve clinical prognosis and facilitate a better design for anthropomorphic devices. The axial compressive response of human cadaveric preparations was compared with the 50th percentile anthropomorphic Hybrid III manikin under various loading rates. Ten fresh human cadavers were used in the study. Intact cadaver torsos, head-cervical spines, and ligamentous cervical columns were tested. The head-neck structure and the neck (without head) of the Hybrid III manikin were also tested. Responses of the human cadaveric preparations and manikin structures were nonlinear at all rates of loading. However, axial stiffness, a measure of the ability of the structure to withstand external force, was higher under all rates of loading for manikin preparations when compared with the human cadaveric tissues.

The Influence of Neck Kinematics on Brain Pressures and Strains Under Blast Loading

2013 ◽  
Author(s):  
J. C. Roberts ◽  
T. P. Harrigan ◽  
E. E. Ward ◽  
D. Nicolella ◽  
L. Francis ◽  
...  
Keyword(s):  
Shock Tube ◽  
Blast Loading ◽  
Human Head ◽  
Pressure Response ◽  
System Level ◽  
Hybrid Iii ◽  
Head Rotations ◽  
The Brain ◽  
Head Neck

Strains and pressures in the brain are known to be influenced by rotation of the head in response to loading. This brain rotation is governed by the motion of the head, as permitted by the neck, due to loading conditions. In order to better understand the effect neck characteristics have on pressures and strains in the brain, a human head finite element model (HHFEM) was attached to two neck FEMs: a standard, well characterized Hybrid III Anthropometric Test Device neck FEM; and a high fidelity parametric probabilistic human FEM neck that has been hierarchically validated. The Hybrid III neck is well-established in automotive injury prevention studies, but is known to be much stiffer than in vivo human necks. The parametric FEM is based on CT scans and anatomic data, and the components of the model are validated against biomechanical tests at the component and system level. Both integrated head-neck models were loaded using pressure histories based on shock tube exposures. The shock tube loading applied to these head models were obtained using a computational fluid dynamics (CFD) model of the HHFEM surface in front of a 6 inch diameter shock tube. The calculated pressure-time histories were then applied to the head-neck models. The global head rotations, pressures, brain displacements, and brain strains of both head-neck models were compared for shock tube driver pressures from 517 to 862 kPa. The intracranial pressure response occurred in the first 1 to 5 msec, after blast impact, prior to a significant kinematic response, and was very similar between the two models. The global head rotations and the strains in the brain occurred at 20 to 100 msec after blast impact, and both were approximately two times higher in the model using the head parametric probabilistic neck FEM (H2PN), as compared to the model using the head Hybrid III neck FEM (H3N). It was also discovered that the H2PN exhibited an initial backward and small downward motion in the first 10 ms not seen in the H3N. The increased displacements and strains were the primary difference between the two combined models, indicating that neck constraints are a significant factor in the strains induced by blast loading to the head. Therefore neck constraints should be carefully controlled in studies of brain strain due to blast, but neck constraints are less important if pressure response is the only response parameter of primary interest.

A destructible headform for the assessment of sports impacts

2021 ◽  
pp. 175433712110559
Author(s):  
Ben Stone ◽  
Sean Mitchell ◽  
Yusuke Miyazaki ◽  
Nicholas Peirce ◽  
Andy Harland
Keyword(s):  
Human Subjects ◽  
Permanent Deformation ◽  
Human Head ◽  
Local Deformation ◽  
Resonance Excitation ◽  
Destructive Testing ◽  
Head Impacts ◽  
Resonance Frequencies ◽  
Hybrid Iii ◽  
Athletic Equipment

Commercially available headforms, such as the Hybrid-III and EN 960 headforms, have been used effectively to investigate the mechanics of head impacts. These headforms may result in accelerations that are unrepresentative of a human head in some impact scenarios. This may be important when considering impacts that produce areas of high pressure, since skull deformation and resonance excitation may influence the dynamic response. The National Operating Committee on Standards for Athletic Equipment (NOCSAE) headform may produce a more suitable response during these types of impacts due to the more representative skull component. However, permanent deformation may occur in some unprotected impact scenarios, resulting in the entire headform needing to be replaced. This paper outlines the development of a novel, modular and destructible headform (LU headform) that can be used in potentially destructive testing, where individual components can be replaced. The LU headform was modelled after a UK 50th percentile male. The inertial properties of the LU headform were within 6% of those observed in humans. The skull simulant properties were within the range of values reported for human tissue in two build orientations, but lower in one build orientation. The lowest and highest resonance frequencies observed in the headform model were within 5% of those observed in humans. Drop and projectile tests were conducted in line with previous cadaver tests with the observed accelerations within the range reported for post-mortem human subjects. The LU headform offers a practical means of simulating head dynamics during localised unprotected impacts or in protected impacts where local deformation and/or resonance frequency excitation remains possible.

scholarly journals Frequency spectrum of the human head–neck to mechanical vibrations

2017 ◽  
Vol 37 (3) ◽  
pp. 611-618 ◽  
Author(s):  
Bin Yang ◽  
Zheng Shi ◽  
Qun Wang ◽  
Feng Xiao ◽  
Tong-Tong Gu ◽  
...  
Keyword(s):  
Finite Element ◽  
Frequency Spectrum ◽  
Mechanical Vibration ◽  
Three Dimensional ◽  
Human Head ◽  
Element Model ◽  
Mode Shapes ◽  
Joint Disorder ◽  
Biomechanical Responses ◽  
Head Neck

This study is based on a real finite element human head–neck model and concentrates on its numerical vibration characteristic. Frequency spectrum and mode shapes of the finite element model of human head–neck under mechanical vibration have been calculated. These vibration characteristics are in good agreement with the previous studies. The simulated fundamental frequency of 35.25 Hz is fairly similar to the published documents, and rarely reported modal responses such as “mastication” and flipping of nasal lateral cartilages modes, however, are introduced by our three-dimensional modal analysis. These additional modes may be of interest to surgeons or clinicians who are specialized in temporomandibular or rhinoplasty joint disorder. Modal validation in terms of modal shapes proposes a necessity for elaborate modeling to identify each individual part’s extra frequencies. Furthermore, it also studies the influence of damping on resonant frequencies and biomechanical responses. It is discovered that damping has an inverse proportionality between damping effect on natural frequency and that on biomechanical responses.

Head Impact Modeling to Support a Rotational Combat Helmet Drop Test

2021 ◽  
Author(s):  
Ryan Terpsma ◽  
Rika Wright Carlsen ◽  
Ron Szalkowski ◽  
Sushant Malave ◽  
Alice Lux Fawzi ◽  
...  
Keyword(s):  
Human Head ◽  
Mechanical Stimulus ◽  
Scientific Basis ◽  
Test Method ◽  
Drop Test ◽  
Head Impacts ◽  
Digital Twin ◽  
Brain Deformation ◽  
Acceleration Time Histories ◽  
Hybrid Iii

ABSTRACT Introduction The Advanced Combat Helmet (ACH) military specification (mil-spec) provides blunt impact acceleration criteria that must be met before use by the U.S. warfighter. The specification, which requires a helmeted magnesium Department of Transportation (DOT) headform to be dropped onto a steel hemispherical target, results in a translational headform impact response. Relative to translations, rotations of the head generate higher brain tissue strains. Excessive strain has been implicated as a mechanical stimulus leading to traumatic brain injury (TBI). We hypothesized that the linear constrained drop test method of the ACH specification underreports the potential for TBI. Materials and Methods To establish a baseline of translational acceleration time histories, we conducted linear constrained drop tests based on the ACH specification and then performed simulations of the same to verify agreement between experiment and simulation. We then produced a high-fidelity human head digital twin and verified that biological tissue responses matched experimental results. Next, we altered the ACH experimental configuration to use a helmeted Hybrid III headform, a freefall cradle, and an inclined anvil target. This new, modified configuration allowed both a translational and a rotational headform response. We applied this experimental rotation response to the skull of our human digital twin and compared brain deformation relative to the translational baseline. Results The modified configuration produced brain strains that were 4.3 times the brain strains from the linear constrained configuration. Conclusions We provide a scientific basis to motivate revision of the ACH mil-spec to include a rotational component, which would enhance the test’s relevance to TBI arising from severe head impacts.

The Plantar Plate of the Lesser Toes: An Anatomical Study in Human Cadavers

1994 ◽  
Vol 15 (5) ◽  
pp. 276-282 ◽  
Author(s):  
Richard B. Johnston ◽  
Judith Smith ◽  
Timothy Daniels
Keyword(s):  
Metatarsophalangeal Joint ◽  
Anatomical Study ◽  
Volar Plate ◽  
Anatomic Structure ◽  
Joint Dislocation ◽  
Plantar Plate ◽  
Adjacent Structures ◽  
Fresh Frozen ◽  
Human Cadavers ◽  
Second Toe

The purpose of this study was to evaluate the anatomic structure and biochemical composition of the plantar plate of the lesser toes. Fresh frozen-human cadaveric feet were used to study 20 metatarsophalangeal and proximal interphalangeal plantar plates. The observations of foot dissections were compared with the finger volar plate. The plantar plate of the toe is a rectangular structure with a stout distal insertion and relatively flimsy proximal origin. The anatomic relationships to adjacent structures and composition are similar between the volar plates of the fingers and plantar plates of the toes. The plantar plate is known to experience extension forces that the volar plate does not experience. The weightbearing nature of the foot and forces imposed by toe-off may create chronic hyperextension of the metatarsophalangeal joint and predispose the plantar plate to attenuation or rupture, thus leading to instability of the metatarsophalangeal joint. These findings may explain in part the clinical condition of spontaneous metatarsophalangeal joint dislocation, most commonly found in the second toe.

Abstract 3672: Semaphorin 4D in human head & neck cancer: A promising predictive biomarker for the peri-tumoral stromal phenotype

2017 ◽  
Author(s):  
Rania H. Younis ◽  
Roshanak Derakhshandeh ◽  
Ahmed Sultan ◽  
Haiyan Chen ◽  
Kyu Lee Han ◽  
...  
Keyword(s):  
Neck Cancer ◽  
Human Head ◽  
Predictive Biomarker ◽  
Head Neck Cancer ◽  
Semaphorin 4D ◽  
Head Neck

The Influence of Hard Hat Design Features on Head Acceleration Attenuation

2020 ◽  
pp. 1-7
Author(s):  
Arthur Alves Dos Santos ◽  
James Sorce ◽  
Alexandra Schonning ◽  
Grant Bevill
Keyword(s):  
Lead Shot ◽  
Construction Site ◽  
Head Acceleration ◽  
Protective Capacity ◽  
Design Features ◽  
Shell Design ◽  
Hybrid Iii ◽  
Hard Hat ◽  
Head Neck

This study evaluated the performance of 6 commercially available hard hat designs—differentiated by shell design, number of suspension points, and suspension tightening system—in regard to their ability to attenuate accelerations during vertical impacts to the head. Tests were conducted with impactor materials of steel, wood, and lead shot (resembling commonly seen materials in a construction site), weighing 1.8 and 3.6 kg and dropped from 1.83 m onto a Hybrid III head/neck assembly. All hard hats appreciably reduced head acceleration to the unprotected condition. However, neither the addition of extra suspension points nor variations in suspension tightening mechanism appreciably influenced performance. Therefore, these results indicate that additional features available in current hard hat designs do not improve protective capacity as related to head acceleration metrics.

Mechanisms controlling human head stabilization. I. Head-neck dynamics during random rotations in the horizontal plane

1995 ◽  
Vol 73 (6) ◽  
pp. 2293-2301 ◽  
Author(s):  
F. A. Keshner ◽  
B. W. Peterson
Keyword(s):  
Visual Feedback ◽  
Horizontal Plane ◽  
Mental Arithmetic ◽  
Human Head ◽  
The Body ◽  
Myoelectric Activity ◽  
Head Tracking ◽  
Arithmetic Task ◽  
Head Velocity ◽  
Head Neck

1. Potential mechanisms for controlling stabilization of the head and neck include voluntary movements, vestibular (VCR) and proprioceptive (CCR) neck reflexes, and system mechanics. In this study we have tested the hypothesis that the relative importance of those mechanisms in producing compensatory actions of the head-neck motor system depends on the frequency of an externally applied perturbation. Angular velocity of the head with respect to the trunk (neck) and myoelectric activity of three neck muscles were recorded in seven seated subjects during pseudorandom rotations of the trunk in the horizontal plane. Subjects were externally perturbed with a random sum-of-sines stimulus at frequencies ranging from 0.185 to 4.11 Hz. Four instructional sets were presented. Voluntary mechanisms were examined by having the subjects actively stabilize the head in the presence of visual feedback as the body was rotated (VS). Visual feedback was then removed, and the subjects attempted to stabilize the head in the dark as the body was rotated (NV). Reflex mechanisms were examined when subjects performed a mental arithmetic task during body rotations in the dark (MA). Finally, subjects performed a voluntary head tracking task while the body was kept stationary (VT). 2. Gains and phases of head velocity indicated good compensation to the stimulus in VS and NV at frequencies < 1 Hz. Gains dropped and phases advanced between 1 and 2 Hz, suggesting interference between neural and mechanical components. Above 3 Hz, the gains of head velocity increased steeply and exceeded unity, suggesting the emergence of mechanical resonance.(ABSTRACT TRUNCATED AT 250 WORDS)

Response of a Realistic Human Head-Neck Model to Impact

1978 ◽  
Vol 100 (1) ◽  
pp. 25-33 ◽  
Author(s):  
W. Goldsmith ◽  
J. L. Sackman ◽  
G. Ouligian ◽  
M. Kabo
Keyword(s):  
Human Head ◽  
Realistic Model ◽  
Impulsive Loading ◽  
Head Model ◽  
Steel Sphere ◽  
Pressure Transducers ◽  
Response Characteristics ◽  
System A ◽  
The Impact ◽  
Head Neck

A structurally realistic model of the human head-neck system, consisting of a water-filled human cadaver skull and an artificial neck was subjected to pendulum impact under nondestructive conditions. The neck consisted of a series of neoprene and aluminum rings fabricated so as to faithfully reproduce the head motion of living persons in the saggital plane. Both an aluminum spherical shell and a solid steel sphere were employed to produce contact durations of the order of 1–6 ms and 0.2–1 ms, respectively, depending upon whether the impact occurred against the bare skull or against one of several scalp simulators used. Both frontal and occipital blows were produced on the system. A series of pressure transducers were suspended along the impact axis that measured the history of this parameter for the various conditions employed, and a crystal transducer arrangement ascertained the force input to the system. A displacement gage was utilized to record the excursion of the head-neck junction. Significant differences in pressure response were noted between frontal and occipital blows without protective covers that disappeared when scalp simulators were employed. The response characteristics in the present tests were much simpler than in corresponding tests using an acrylic shell for the head model, where pressures under similar impulsive loading conditions were at least an order of magnitude larger; this difference is attributed to the layering effect of the real skull relative to the homogeneous shell previously used.

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