Numerical Techniques for Predicting Pyroshock Responses of Aerospace Structures

The use of pyrodevices in the aerospace industry has been increasing because of their ability to implement separation missions with a small weight, for example, space launchers, spacecrafts, and missiles. During operation, pyrodevices generate pyroshock, which causes failures of electronic devices. Recently, a pyroshock simulation method using laser shock has been developed to evaluate the risk of pyroshock before flight mission. However, depending on the structure, the laser shock showed some difficulty simulating pyroshock in the low-frequency regime accompanying vibration. Therefore, in this study, we developed a hybrid method of numerical modal analysis and laser shock-based experimental simulation to visualize the pyroshock propagation in all the relevant frequency regimes. For the proof of concept of the proposed method, we performed experiments of explosive bolt-induced shock and pyrolock-induced shock in the open-box-type tension joint and compared the hybrid simulation results with actual pyroshock. From the results, we obtained the simulated time-domain signal with an averaged peak-to-peak acceleration difference (PAD) of 11.2% and the shock response spectrum (SRS) with an averaged mean acceleration difference (MAD) of 28.5%. In addition, we were able to visualize the simulation results in the temporal and spectral domains to compare the pyroshock induced by each pyrodevice. A comparison of the simulations showed that the pyrolock had an impulse level of 1/12 compared to the explosion bolt. In particular, it was confirmed that the pyrolock-induced shock at the near field can cause damage to the electronic equipment despite a smaller impulse than that of the explosive bolt-induced shock. The hybrid method developed in this paper demonstrates that it is possible to simulate pyroshock for all the frequency regimes in complex specimens and to evaluate the risk in the time and frequency domain.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hybrid Method of Modal Analysis and Laser Shock Scanning to Visualize the Pyroshock Propagation in a Tension Joint

Kim

Jang

Lee

et al. 2019

“…This high-acceleration, high frequency pyroshock can induce malfunction of electrical components of a launch vehicle or a satellite, resulting in a catastrophic mission failure [1]. Therefore prediction of the shock induced responses of structures is an essential work when pyro devices are employed [2]. For this practical purpose, an empirical method based on the measurement data of heritage programs used to be applied just to obtain an approximated level of shock that would be induced in structural parts of interest [3,4].…”

Section: Introductionmentioning

confidence: 99%

Mid Frequency Shock Response Determination by Using Energy Flow Method and Time Domain Correction

Woo

Han

2013

Shock induced vibration can be more crucial in the mid frequency range where the dynamic couplings with structural parts and components play important roles. To estimate the behavior of structures in this frequency range where conventional analytical schemes, such as statistical energy analysis (SEA) and finite element analysis (FEA) methods may become inaccurate, many alternative methodologies have been tried up to date. This study presents an effective and practical method to accurately predict transient responses in the mid frequency range without having to resort to the large computational efforts. Specifically, the present study employs the more realistic frequency response functions (FRFs) from the energy flow method (EFM) which is a hybrid method combining the pseudo SEA equation (or SEA-Like equation) and modal information obtained by the finite element analysis (FEA). Furthermore, to obtain the time responses synthesized with modal characteristics, a time domain correction is practiced with the input force signal and the reference FRF on a position of the response subsystem. A numerical simulation is performed for a simple five plate model to show its suitability and effectiveness over the standard analytical schemes.

“…Among them, recent research into Hydro-code-based pyroshock simulation has been reported as suitable for simulating highly dynamic phenomena such as pyroshock [13][14][15]. However, most of these numerical techniques required accurate knowledge of all parameters of the structure to obtain reliable simulation results, and computational time and cost limitations emerged when applied to complex structures [16,17].…”

Section: Shock and Vibrationmentioning

confidence: 99%

“…In this section, pyroshock data in ref [16] was secured to verify and compare the performance of the developed algorithm ( Table 1). The pyroshock data were obtained by exploding the linear pyrotechnical device in the quasi-isotropic CFRP sandwich panel.…”

Section: Reconstruction Of Linear Explosive Induced Pyroshock In Cfrpmentioning

confidence: 99%

Pyroshock Acceleration Field Reconstruction in Temporal and Spectral Domains Based on Laser Shock Scanning and Iterative Decomposition and Synthesis Considering Stop Band Effects

Kim

Jang

Lee

2017

Pyrotechnic devices are used to separate substructures from main structures. Pyroshock can cause failure in electronic components that are sensitive to high frequency shock. Most of the existing methods to analyze pyroshock have limitations for high frequency simulations and are only available for simulation of point explosive-induced pyroshock. To solve the problem of existing methods, we developed a laser shock-based pyroshock reconstruction algorithm covering high frequency range that can predict linear explosive-induced pyroshock, as well as point explosive-induced ones. The developed algorithm reconstructs pyroshock from laser shock test in both temporal and spectral domains using an iterative signal decomposition and synthesis method. In the signal decomposition and synthesis process, unremoved signals in the stopbands occurred and were compensated by iteration to improve the results. At the end of this paper, various types of pyroshock were processed through the proposed method. Pyroshock wave propagation images and shock response spectrum images were presented as a result. To verify the algorithm, we compared the obtained result with a real pyroshock. The time domain signal was reconstructed with an averaged peak to peak acceleration difference of 20.21%, and the shock response spectrum was reconstructed with an average mean acceleration difference of 25.86%.