Separation characteristics study of ridge-cut explosive bolts

Explosive bolts are one type of reliable and efficient pyrotechnic release devices used for many applications. Although numerous explosive bolts have been designed and utilized, most design processes rely on experience based on repetitive experiments. In order to provide a better understanding of the separation behavior of explosive bolts, separation behavior analysis environments for the ridge-cut explosive bolts are established. Ridge-cut explosive bolts, which are separated by ridge-cut mechanism or spallation, are analyzed using AUTODYN. From the behavior analysis of explosive bolts whose design was based on the author's prior experience, the numerical analysis method is verified, including appropriate failure criteria. Utilizing the proposed methodology, the separation characteristics of ridge-cut explosive bolts according to confinement conditions, and especially the gap distance between the bolt body and the fixture, are studied. A degradation in separation reliability due to tight gap distance is observed in separation experiments. This separation phenomenon is specifically clarified by the separation behavior analysis. Based on the numerical study of separation characteristics, some design improvements considering manufacturing tolerance are proposed here.