Traumatic brain injury in pedestrian–vehicle collisions: Convexity and suitability of some functionals used as injury metrics

Sánchez-Molina, David; Arregui‐Dalmases, Carlos; Velázquez-Ameijide, Juan; Angelini, Marco; Kerrigan, Jason; Crandall, Jeffrey Richard

doi:10.1016/j.cmpb.2016.08.007

Cited by 5 publications

(9 citation statements)

References 11 publications

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“…Moreover, in the Appendix A it is justified that, for

, it is also a convex function, under some reasonable assumptions. All these properties make BVDM a mathematically suitable metric in the sense of [ 15 ]. As for the suitability of RMDM, it was previously discussed in the same reference.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, there are some mathematical properties that make a metric suitable, which we will examine for the three metrics. As a mathematical functional, the suitable properties of an injury metric are scalability, continuity and convexity [ 15 ] (see Appendix A ). Scalability and continuity are intuitive, while convexity is required for the existence of an acceleration curve which minimizes the damage under specific conditions and, therefore, the value of the injury metric.…”

Section: Methodsmentioning

confidence: 99%

“…This metric has been extensively used in many subsequent empirical and theoretical studies which showed the usefulness of RMDM for assessing traumatic events [ 15 , 18 , 19 , 20 , 21 ]. The basic idea of this metric was to calculate the strain value of the CBVs and compare the obtained value with the value Löwenhielm–Takhounts failure function at the instantaneous strain rate.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Injury Metrics for Assessing the Risk of Acute Subdural Hematoma in Traumatic Events

García-Vilana

Sánchez-Molina

Velázquez-Ameijide

et al. 2021

IJERPH

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Worldwide, the ocurrence of acute subdural hematomas (ASDHs) in road traffic crashes is a major public health problem. ASDHs are usually produced by loss of structural integrity of one of the cerebral bridging veins (CBVs) linking the parasagittal sinus to the brain. Therefore, to assess the risk of ASDH it is important to know the mechanical conditions to which the CBVs are subjected during a potentially traumatic event (such as a traffic accident or a fall from height). Recently, new studies on CBVs have been published allowing much more accurate prediction of the likelihood of mechanical failure of CBVs. These new data can be used to propose new damage metrics, which make more accurate predictions about the probability of occurrence of ASDH in road crashes. This would allow a better assessement of the effects of passive safety countermeasures and, consequently, to improve vehicle restraint systems. Currently, some widely used damage metrics are based on partially obsolete data and measurements of the mechanical behavior of CBVs that have not been confirmed by subsequent studies. This paper proposes a revision of some existing metrics and constructs a new metric based on more accurate recent data on the mechanical failure of human CBVs.

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“…Moreover, in the Appendix A it is justified that, for

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Injury Metrics for Assessing the Risk of Acute Subdural Hematoma in Traumatic Events

García-Vilana

Sánchez-Molina

Velázquez-Ameijide

et al. 2021

IJERPH

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“…With respect to nonlinear stress–strain response, it is interesting to note that some widely used computational models, such as early versions of SIMon, created by NHTSA, modeled CBVs as linear elastic cables rather than as cables with a nonlinear elastic response [ 39 , 40 ]. This would have a direct bearing on the estimation made in the injury metric called relative motion damage measure (RMDM) [ 41 ] used to predict the probability of SDH due to mechanical failure of some CBV [ 42 , 43 ]. Similarly, other human head computational models, among which are the UDS FEHM (Université de Strasbourg) [ 44 ], the KTH FEHM (S. Kleiven) [ 45 ], the UCDBTM (University College Dublin) [ 46 , 47 ], the WSUBIM (Wayne State University) [ 48 ], or the G/LHM [ 49 ], also model CBVs as elastic beams with a linear stress–strain response [ 16 ].…”

Section: Discussionmentioning

confidence: 99%

Mechanical Behavior of Blood Vessels: Elastic and Viscoelastic Contributions

Sánchez-Molina

García-Vilana

Llumà

et al. 2021

Biology

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The mechanical properties of the cerebral bridging veins (CBVs) were studied using advanced microtensile equipment. Detailed high-quality curves were obtained at different strain rates, showing a clearly nonlinear stress–strain response. In addition, the tissue of the CBVs exhibits stress relaxation and a preconditioning effect under cyclic loading, unequivocal indications of viscoelastic behavior. Interestingly, most previous literature that conducts uniaxial tensile tests had not found significant viscoelastic effects in CBVs, but the use of more sensitive tests allowed to observe the viscoelastic effects. For that reason, a careful mathematical analysis is presented, clarifying why in uniaxial tests with moderate strain rates, it is difficult to observe any viscoelastic effect. The analysis provides a theoretical explanation as to why many recent studies that investigated mechanical properties did not find a significant viscoelastic effect, even though in other circumstances, the CBV tissue would clearly exhibit viscoelastic behavior. Finally, this study provides reference values for the usual mechanical properties, as well as calculations of constitutive parameters for nonlinear elastic and viscoelastic models that would allow more accurate numerical simulation of CBVs in Finite Element-based computational models in future works.

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“…The improvement of injury metrics used to assess restraint systems in vehicles or the design of other preventive elements against head trauma. Currently, the estimation is often done by the injury metric called "relative motion damage measure" (RMDM) [40,41], used to predict the probability of a SDH due to the failure of PSBVs [42,43]. However, that metric was developed based on obsolete data [26], and the data from this study can be used to update that injury metric.…”

mentioning

confidence: 99%

Viscoelastic Characterization of Parasagittal Bridging Veins and Implications for Traumatic Brain Injury: A Pilot Study

et al. 2021

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Many previous studies on the mechanical properties of Parasagittal Bridging Veins (PSBVs) found that strain rate had a significant effect on some mechanical properties, but did not extensively study the viscoelastic effects, which are difficult to detect with uniaxial simple tensile tests. In this study, relaxation tests and tests under cyclic loading were performed, and it was found that PSBVs do indeed exhibit clear viscoelastic effects. In addition, a complete viscoelastic model for the PSBVs is proposed and data from relaxation, cyclic load and load-unload tests for triangular loads are used to find reference values that characterize the viscoelastic behavior of the PSBVs. Although such models have been proposed for other types of blood vessels, this is the first study that clearly demonstrates the existence of viscoelastic effects from an experimental point of view and also proposes a specific model to explain the data obtained. Finally, this study provides reference values for the usual viscoelastic properties, which would allow more accurate numerical simulation of PSBVs by means of computational models.

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Traumatic brain injury in pedestrian–vehicle collisions: Convexity and suitability of some functionals used as injury metrics

Cited by 5 publications

References 11 publications

Injury Metrics for Assessing the Risk of Acute Subdural Hematoma in Traumatic Events

Injury Metrics for Assessing the Risk of Acute Subdural Hematoma in Traumatic Events

Mechanical Behavior of Blood Vessels: Elastic and Viscoelastic Contributions

Viscoelastic Characterization of Parasagittal Bridging Veins and Implications for Traumatic Brain Injury: A Pilot Study

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