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Biomechanical Engineering

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Addressing a Critical Need

Injury biomechanics research at the Center is conducted to fill critical gaps in quantitative data on the response of children to crash or other injury forces. Research into the biomechanics of pediatric injury and children’s tolerance for withstanding forces of impact has been extremely limited to date.

The need for this type of data is heightened by recent federal legislation and rulemaking, due-care efforts by the automotive industry, and increasing consumer demand for safety.

Our biomechanical engineering research enhances our understanding of the mechanisms of pediatric injury, and provides a solid experimental foundation for the development of improved injury prevention technology. Specifically, the objectives of this research are to:

• Develop improved injury assessment devices and techniques
• Facilitate the design of technical interventions to prevent or reduce the severity of injury
• Determine mechanisms of injury so that diagnoses and treatment can be enhanced

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Engineering Resources at the Center

Housed in a children’s hospital, our research team has access to extensive, non-invasive radiological data, and uses it to understand the geometric structure of children’s developing bodies. In particular, the significant material and structural changes that occur throughout the body during normal human development are well documented by advanced Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) scans performed at The Children’s Hospital of Philadelphia, and these developmental changes are what likely cause a child’s response to injury to be different than that of the adult.

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Methodology

While understanding the geometric aspects of the child is important, biomechanical experiments are necessary to understand how the developmental changes in the body influence traumatic injury. Since social and ethical considerations preclude conducting crash tests with actual children, the Center conducts kinematics tests to determine how children’s bodies respond to sub-injurious forces, based upon children’s everyday athletic and amusement activities. Current research includes quantifying the shoulder-belt-to-torso interaction in frontal crashes towards the improvement of the anthropomorphic test dummy’s (ATD) shoulder-thorax complex; and understanding the pediatric cervical spine range of motion.

Pediatric tissue property research forms the third element of our research. Such properties define the mechanical response of tissue to injury-inducing loads. This tissue data provides the material characteristics for computational models of child subjects, together with radiological data, which provides the geometry of the model; and the biomechanical testing data, which provides important insights into how well models can replicate the human crash experience. Such models are validated tools for safety system design and development of crash test dummy design requirements.

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Biomechanics Projects

Improving Pediatric Crash Test Dummies

• Bumper Car Project- Frontal kinematics of the child’s head and spine

  Traumatic brain and skull injuries are the most common serious injuries sustained by children in motor vehicle crashes regardless of age group, crash direction, or restraint type. To accurately evaluate head injury risk and robustly assess the performance of a restraint concept intended to mitigate head injury risk, head and spinal kinematics must be accurately predicted. Current ATD's contain critical differences in spinal kinematics compared to humans in the same restraint system due to the compliance in the human thoracic and cervical spine. The human spine is a relatively mobile, multi-segmented system, while the Hybrid III ATD's thoracic spine is essentially rigid. These differences in spinal compliance generate vast differences in the head trajectory of the ATD relative to a human and are particularly poorly understood in the child. The objective of this project is to quantify the frontal kinematics of the restrained 6 and 10-year-old child's head and spine, evaluate the interaction of the child with several restraints, and thus more accurately predict the likelihood of injury and associated injury mechanisms.

  Experimentally, this project will use pediatric and adult human volunteer testing coupled with a novel scaling procedure. Low-speed impact tests will be conducted using human child volunteers (age 6-12 years), in which the acceleration pulse imparted to the child is similar in magnitude and duration to that imparted in a bumper-car impact. The head and spine kinematics will be measured optically using an advanced motion tracking system. Adult volunteers (age 25-40 years) will then be subject to analogous impacts to the child volunteers. The response of the child at a higher severity impact will be predicted through a novel scaling procedure. Collaborators include University of Virginia and TNO. Funding is provided by Takata Corporation.

• Abdominal insert for 6-year-old anthropomorphic test dummy (ATD)

  Abdominal injuries, along with lumbar spine fractures, are part of a constellation of injuries referred to as "seat belt syndrome". Geometrical characteristics of the pelvis and abdomen of younger children place them at higher risk for these injuries. Efforts to design restraints that mitigate these injuries are limited as no current pediatric anthropomorphic dummy (ATD) can accurately quantify the abdominal response to belt loading. This research project addresses this gap through a four-phase effort involving pediatric anthropometrics, real-world abdominal injury risk, abdominal biomechanical structural response and injury tolerance from a porcine model, and development of an abdominal insert for the 6-year-old ATD based on these data. Collaborators include University of Virginia and Ford Motor Company. Funding was provided by Takata Corporation and Ford Motor Company.