In Situ Strain Measurements Within Helmet Padding During Linear Impact Testing.

Drop and Impact testing of helmets are used extensively in the design process and eventual certification of helmets. These techniques have traditionally relied heavily on the measurement of the kinematic response to impact, which provides an indirect measurement of the liner response that is subject to interpretation during the design process. In the present work, we introduce an in situ experimental technique that provides a time-resolved measurement of the deformation of the helmet and its components during an impact event.

The influence of the tertiary bronchi on dynamic lung deformation.

Finite element models of thoracic injury often treat the lung as a bulk homogeneous and isotropic material, which reduces the computational costs associated with such investigations. Ignoring the heterogeneous structure of the lung may be computationally expedient, but this simplification may inadvertently fail to capture the true lung strain dynamics. In the present work, a series of direct impact experiments were performed on porcine lungs, inflated to a relevant expiratory pressure, and monitored using high-speed X-ray imaging.

A Parametric Analysis of Embedded Tissue Marker Properties and Their Effect on the Accuracy of Displacement Measurements.

Datasets obtained from cadaveric experimentation are broadly used in validating finite element models of head injury. Due to the complexity of such measurements in soft tissues, experimentalists have relied on tissue-embedded radiographic or sonomicrometry tracking markers to resolve tissue motion caused by impulsive loads. Dynamic coupling of markers with the surrounding tissue has been a previous concern, yet a thorough sensitivity investigation of marker influences on tissue deformation has not been broadly discussed.