Response Ratio Development for Lateral Pendulum Impact with Porcine Thorax and Abdomen Surrogate Equivalents

There has been recent progress over the past 10 years in research comparing 6-year-old thoracic and abdominal response of pediatric volunteers, pediatric post mortem human subjects (PMHS), animal surrogates, and 6-year-old ATDs. Although progress has been made to guide scaling laws of adult to pediatric thorax and abdomen data for use in ATD design and development of finite element models, further effort is needed, particularly with respect to lateral impacts. The objective of the current study was to use the impact response data of age equivalent swine from Yaek et al. (2018) to assess the validity of scaling laws used to develop lateral impact response corridors from adult porcine surrogate equivalents (PSE) to the 3-year-old, 6-year-old, and 10-year-old for the thorax and abdominal body regions. Lateral impact response corridors were created from 50th adult male PSE pendulum lateral impact T1, T14, and L6 accelerations and pendulum impact force time histories for the thorax and abdomen testing performed. The ISO 9790 scaling technique using length, mass, and elastic modulus scale factor formulas were used in conjunction with measured swine parameters to calculate scale factors for the PSE. In addition to calculation of pertinent test scale factors, response ratios for the pendulum impact tests were calculated. The scaling factors and response ratios determined for the porcine surrogates were compared to the already established ISO human lateral pendulum impact response ratios to determine whether a consistent pattern over the age levels described for the two sets of data (human and swine) exists. The actual lateral impact pendulum data, for both thoracic and abdominal regions, increases in magnitude and time duration from the 3-year-old PSE up to the 50th male PSE. This increase in magnitude and time duration is comparable to the human response corridors developed based on an impulse-momentum analysis and the elastic bending modulus derived from human skull bone. This pattern in the human impact response corridors was observed in the response ratio values and the swine response data. Based on the current study's findings, when utilizing the elastic modulus of human skull bone presented previously in research, thoracic and abdominal lateral pendulum impact response of PSE follows the general scaling laws, based on the impulse-momentum spring-mass model. The thoracic and abdominal lateral pendulum force impact response of PSE also follows the human scaled impact response corridors for lateral pendulum impact testing presented in previous research. The overall findings of the current study confirm, through actual swine testing of appropriate weight porcine surrogates, that scaling laws are applicable from the midsized-male adult down to the 3-year-old age level using human skull elastic modulus values established in previous research.