Study of Separation Mechanism and Characteristics of Ridge-Cut Explosive Bolts Using Numerical Analysis

Abstract

Ridge-cut explosive bolts are a type of pyrotechnic release devices in which two connected structures are separated by explosives. They are designed such that shock waves can interact with and cut their body. Furthermore, they provide a clean separation surface and require a smaller explosive amount compared with other types of explosive bolts. In this study, ridge-cut explosive bolts of various diameters and with an exploding bridge wire (EBW) detonator were developed for use in sled testing. Their initial shapes were designed using an established procedure. Initial separation tests for the initial designs of the explosive bolts showed that considerable debris was produced for some models and that the explosive amount should be reduced. For the minimization of the number of experiments, the appropriate explosive amount was determined in advance through numerical analysis, which was performed using Autodyn, a commercial hydrocode. The numerical analysis technique used was improved to analyze the complete separation phenomena. The numerical results clearly revealed the separation mechanism and characteristics of the explosive bolts and helped determine an appropriate explosive amount for achieving a small amount of debris. Verification tests confirmed that explosive amounts determined using the numerical results were appropriate for separation and generated a small amount of debris.