Numerical study on separation shock characteristics of pyrotechnic separation nuts

• Published in: Acta astronautica Vol. 151; pp. 893 - 903
• Main Authors: Zhao, Hongda, Liu, Wei, Ding, Jifeng, Sun, Yi, Li, Xiao, Liu, Yizhi
• Format: Journal Article
• Language: English
• Published: Elmsford Elsevier Ltd 01.10.2018; Elsevier BV
• Subjects: Aerospace engineering; ALE algorithm; Computer simulation; Energy; Fasteners; Finite element method; Mathematical models; Nuts; Prestress; Prestressing; Pyrotechnic separation nuts; Separation; Separation shock; Shock response spectrum; Spacecraft; Vibration analysis; Shock response spectrum; Prestress; ALE algorithm; Separation shock; Pyrotechnic separation nuts
• ISSN: 0094-5765; 1879-2030
• DOI: 10.1016/j.actaastro.2018.07.040

This paper establishes a finite element model of pyrotechnic separation nuts and simulates the whole separation process based on the explicit dynamic codes LS-dyna with Arbitrary Lagrange-Euler (ALE) algorithm. The separation shock generated in the unlocking process is analyzed in detail and the results reveal that the pyrotechnic explosion shock and strain energy shock are two sources for the whole separation shock. Besides that, the influence of prestress on the separation shock and its two shock sources is also researched. The results show that the prestress could strengthen all three shocks, especially the strain energy release shock. This paper also compares the shock response spectrum (SRS) of the three shocks and finds that the SRS of separation shock is equal to the envelope of the SRS of pyrotechnic explosion shock and strain energy release shock. In the model of this paper, the pyrotechnic explosion shock plays a dominant role in the frequency range of 100 Hz to 10 KHz. The conclusions got in this work are helpful to insight the mechanism of separation shock and can provide a reference for the design of separation nuts. •Pyrotechnic explosion shock and strain energy release shock are the shock sources.•The two shock sources of separation shock are divided by separation time.•Prestress can strengthen the separation shock and its two shock sources.•Prestress has a larger effect on strain energy release shock than others.•The SRS of separation shock equals the envelope of the SRS of its two sources.