Defining blast loading ‘zones of relevance’ for primary blast injury research: A consensus of injury criteria for idealised explosive scenarios

Abstract

Blast injuries remain a serious threat to defence and civilian populations around the world. ‘Primary’ blast injuries (PBIs) are caused by direct blast wave interaction with the human body, particularly affecting air-containing organs. Despite development of blast injury criteria since the 1960s, work to define blast loading conditions for safety limits, protective design and injury research has received relatively little attention. With a continued experimental focus on PBI mechanisms and idealised blast assumptions, meaningful test outcomes rely on appropriate simulated conditions. This paper critically evaluates existing predictive criteria for PBIs (grouped into those affecting the auditory system, pulmonary injuries and brain trauma) as a function of incident blast wave parameters, assuming idealised air blast scenarios. Analysis of the multi-injury criteria reveals new insights and understanding. It showed that blast conditions of relevance to realistic explosive threats are limited and they should be an important consideration in the design of clinical trials simulating blast injury. Zones of relevance for PBI research are proposed to guide experimental designs and compare future data. This work will prove valuable to blast protection engineers and clinical researchers seeking to determine blast loading conditions for safety limits, protective design requirements and injury investigations.

Guidelines to inform the generation of clinically relevant and realistic blast loading conditions for primary blast injury research

“…For this study, PBI criteria take the form of blast overpressure thresholds and overpressure-duration curves assuming human exposure to idealised blast waves. PBI criteria selected for this study were informed by a separate review, [13] and grouped into: (1) auditory system; (2) pulmonary injury & lethality; and (3) brain-related PBI (Table 1). Pulmonary injury criteria utilise the Bowen overpressure-time curves, [17] including the threshold (onset) and probabilities (1%, 50% and 99%) of fatality (Table 1; Fig.…”

“…Overpressure levels for lung injury and lethality have been proposed by some researchers although these were not included as dependence on the blast duration has been demonstrated [17,19,20]. Due to a lack of consensus on how to extend Bowen's pulmonary injury criteria to an open-field scenario, [13] this analysis considered a 70kg person stood near a reflective wall (Table 1; Fig. 1, red lines).…”

“…While multiple combinations are possible, current guidance does not specify appropriate ranges of blast wave parameters for PBI research. Existing criteria to predict injury and fatality from PBIs are fragmented, contested, [13] and limited to specific anatomical regions. This makes it challenging to understand the range of blast conditions responsible for the full spectrum of possible PBIs (e.g.…”