BIOPHYSICAL MECHANISMS AND SCALING PROCEDURES APPLICABLE IN ASSESSING RESPONSES OF THE THORAX ENERGIZED BY AIR‐BLAST OVERPRESSURES OR BY NONPENETRATING MISSILES*

Abstract : A mathematical model was devised to study the dynamic response of the thorax of mammals to rapid changes in environmental pressure and to non- penetrating missiles impacting the rib cage near the mid-lateral point of the right or left thorax. Scaling procedures are presented for similar animals relating, for a given degree of damage, the body mass of the animal to various parameters describing the exposure 'dose'. Internal pressures computed with the model for a dog exposed at the end plate of a shock-tube are compared to those measured with a pressure transducer inserted in the esophagus down to the level of the heart. Computed time-displacement histories of missiles following impact with the right side of the thorax are compared to those obtained experimentally by means of high-speed motion picture photography. High internal pressures predicted with the model for non-penetrating impact are compared to those obtained experimentally and theoretically for exposure to air blast. Experimental data are presented arbitrarily assessing lung damage in animals struck by non-penetrating missiles (constant impact area) as a function of missile mass and impact velocity. These data are compared for several missile mass-velocity combinations with those computed using the mathematical model. Similarities in the dynamic responses of the thorax to air blast and to non- penetrating missiles are discussed.