Repeatability Evaluation of the Pre-Prototype NHTSA Advanced Dummy Compared to the Hybrid III

Xu, Lan; Agaram, Venkatesh; Rouhana, Stephen W.; Hultman, Robert W.; Kostyniuk, Gregory; McCleary, Joseph D.; Mertz, Harold J.; Nusholtz, Guy S.; Scherer, Risa

doi:10.4271/2000-01-0165

Cited by 16 publications

(4 citation statements)

References 2 publications

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“…18,22,37,41,47,55 To measure the deviation of our model from the SD corridors we have introduced percent of load range deviation to show the amount of the loading range in which the model is within the corridors. It is apparent from Figs.…”

Section: Discussionmentioning

confidence: 99%

Validation of a Finite Element Model of the Young Normal Lower Cervical Spine

et al. 2008

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A Finite Element Model (FEM) of the young adult human cervical spine has been developed as a first step in studying the process of spondylotic degeneration. The model was developed using normal geometry and material properties for the lower cervical spine. The model used a three-zone composite disc annulus to reflect the different material properties of the anterior, posterior, and lateral regions of the annulus. Nonlinear ligaments were implemented with a toe region to help the model achieve greater flexibility at low loads. The model was validated against experimental data for normal, nondegenerated cervical spines tested in flexion and extension, right and left lateral bending, and right and left axial rotation at loads of 0.33, 0.5, 1.0, 1.5, and 2.0 Nm. The model was within in vitro experimental standard deviation corridors 100% of the load range for right and left lateral bending. The model was within 80% of the load response corridors for extension and flexion with a deviation <0.3 degrees from the SD corridors. For axial rotation, the model was within 70% of the SD corridors for left axial rotation within 83% of right axial rotation responses. The deviation from SD corridors for axial rotation was generally <0.2 degrees.

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Section: Discussionmentioning

confidence: 99%

Validation of a Finite Element Model of the Young Normal Lower Cervical Spine

et al. 2008

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“…The model response compared to volunteer corridors was quantified through a correlation analysis as a linear combination of a corridor method and a cross-correlation method (Gehre et al 2009;Panzer et al 2011;Xu et al 2000). The corridor method quantified how well the model response fit within the volunteer corridors and resulted in a score of one if the model fit within the one standard deviation corridor, a value of zero if the model fell outside the 2 standard deviation corridor, and a linear transition between one and zero.…”

Section: Validation Against Low-speed Frontal Impactmentioning

confidence: 99%

Importance of Muscle Activations for Biofidelic Pediatric Neck Response in Computational Models

Dibb¹,

Cox²,

Nightingale³

et al. 2013

Traffic Injury Prevention

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Objective: During dynamic injury scenarios, such as motor vehicle crashes, neck biomechanics contribute to head excursion and acceleration, influencing head injuries. One important tool in understanding head and neck dynamics is computational modeling. However, realistic and stable muscle activations for major muscles are required to realize meaningful kinematic responses. The objective was to determine cervical muscle activation states for 6-year-old, 10-year-old, and adult 50th percentile male computational head and neck models. Currently, pediatric models including muscle activations are unable to maintain the head in an equilibrium position, forcing models to begin from nonphysiologic conditions. Recent work has realized a stationary initial geometry and cervical muscle activations by first optimizing responses against gravity. Accordingly, our goal was to apply these methods to Duke University's head-neck model validated using living muscle response and pediatric cadaveric data.Methods: Activation schemes maintaining an upright, stable head for 22 muscle pairs were found using LS-OPT. Two optimization problems were investigated: a relaxed state, which minimized muscle fatigue, and a tensed activation state, which maximized total muscle force. The model's biofidelity was evaluated by the kinematic response to gravitational and frontal impact loading conditions. Model sensitivity and uncertainty analyses were performed to assess important parameters for pediatric muscle response. Sensitivity analysis was conducted using multiple activation time histories. These included constant activations and an optimal muscle activation time history, which varied the activation level of flexor and extensor groups, and activation initiation and termination times.Results: Relaxed muscle activations decreased with increasing age, maintaining upright posture primarily through extensor activation. Tensed musculature maintained upright posture through coactivation of flexors and extensors, producing up to 32 times the force of the relaxed state. Without muscle activation, the models fell into flexion due to gravitational loading. Relaxed musculature produced 28.6-35.8 N of force to the head, whereas tensed musculature produced 450-1023 N. Pediatric model stiffnesses were most sensitive to muscle physiological cross-sectional area.Conclusions: Though muscular loads were not large enough to cause vertebral compressive failure, they would provide a prestressed state that could protect the vertebrae during tensile loading but might exacerbate risk during compressive loading. For example, in the 10-year-old, a load of 602 N was produced, though estimated compressive failure tolerance is only 2.8 kN. Including muscles and time-variant activation schemes is vital for producing biofidelic models because both vary by age. The pediatric activations developed represent physiologically appropriate sets of initial conditions and are based on validated adult cadaveric data.

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“…Select time-dependent responses of the THUMS-for example, resultant head CG acceleration-resulting from the simulated experimental conditions were quantitatively compared to the physical test results, where available, via cross-correlation analysis. The methodology (Appendix B, see online supplement), which has previously been used to evaluate the biofidelity and repeatability of anthropomorphic test devices (ATDs) and test devices (Gehre et al 2009;Kerrigan et al 2011;Nusholtz et al 1997;Xu et al 2000), assesses the similarity between 2 curves based on their magnitude, shape, and phase. The signal deviation with respect to a defined corridor, where available, was also calculated.…”

Section: Experiments Reconstruction With Thumsmentioning

confidence: 99%

Sensitivity of Head and Cervical Spine Injury Measures to Impact Factors Relevant to Rollover Crashes

Mattos

McIntosh

Grzebieta

et al. 2015

Traffic Injury Prevention

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Objective: Serious head and cervical spine injuries have been shown to occur mostly independent of one another in pure rollover crashes. In an attempt to define a dynamic rollover crash test protocol that can replicate serious injuries to the head and cervical spine, it is important to understand the conditions that are likely to produce serious injuries to these 2 body regions. The objective of this research is to analyze the effect that impact factors relevant to a rollover crash have on the injury metrics of the head and cervical spine, with a specific interest in the differentiation between independent injuries and those that are predicted to occur concomitantly.Methods: A series of head impacts was simulated using a detailed finite element model of the human body, the Total HUman Model for Safety (THUMS), in which the impactor velocity, displacement, and direction were varied. The performance of the model was assessed against available experimental tests performed under comparable conditions. Indirect, kinematic-based, and direct, tissue-level, injury metrics were used to assess the likelihood of serious injuries to the head and cervical spine.Results: The performance of the THUMS head and spine in reconstructed experimental impacts compared well to reported values. All impact factors were significantly associated with injury measures for both the head and cervical spine. Increases in impact velocity and displacement resulted in increases in nearly all injury measures, whereas impactor orientation had opposite effects on brain and cervical spine injury metrics. The greatest cervical spine injury measures were recorded in an impact with a 15• anterior orientation. The greatest brain injury measures occurred when the impactor was at its maximum (45 • ) angle. Conclusions:The overall kinetic and kinematic response of the THUMS head and cervical spine in reconstructed experiment conditions compare well with reported values, although the occurrence of fractures was overpredicted. The trends in predicted head and cervical spine injury measures were analyzed for 90 simulated impact conditions. Impactor orientation was the only factor that could potentially explain the isolated nature of serious head and spine injuries under rollover crash conditions. The opposing trends of injury measures for the brain and cervical spine indicate that it is unlikely to reproduce the injuries simultaneously in a dynamic rollover test.

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Repeatability Evaluation of the Pre-Prototype NHTSA Advanced Dummy Compared to the Hybrid III

Cited by 16 publications

References 2 publications

Validation of a Finite Element Model of the Young Normal Lower Cervical Spine

Validation of a Finite Element Model of the Young Normal Lower Cervical Spine

Importance of Muscle Activations for Biofidelic Pediatric Neck Response in Computational Models

Sensitivity of Head and Cervical Spine Injury Measures to Impact Factors Relevant to Rollover Crashes

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