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Dynamic analysis of laser shock response: Experimental and numerical studies
摘要： Laser is an excellent shock source with the advantages of non-contact, high controllability and broadband frequency, which has great potential to replace traditional mechanical impact and simulate pyroshock. In this paper, the dynamic response induced by laser shock is studied both experimentally and numerically. Firstly, laser shock tests are conducted. The general characteristics of laser shock response are experimentally investigated, where the effects of transparent overlays and absorbent coatings are evaluated in terms of shock response spectrum. Furthermore, a finite element (FE) model is developed and validated by comparing simulation and experimental results. Based on FE model, the effects of power density, pulse duration, and spot size of laser on the dynamic response are evaluated. The results demonstrate that laser shock response has fantastic high-frequency and broadband-frequency characteristics and shock response spectrum amplitude of laser shock can be obviously improved by adding transparent overlays and absorbent coatings. The amplitude of shock response spectrum is in quadratic correlation with laser power density. Laser pulse duration significantly influences the slope of shock response spectrum, but power density and spot size of laser have little effect on the slope.
关键词： Laser shock,Dynamic response,Shock response spectrum,Pyroshock
更新于2025-09-12 10:27:22
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Hybrid Method of Modal Analysis and Laser Shock Scanning to Visualize the Pyroshock Propagation in a Tension Joint
摘要： 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.
关键词： pyroshock,shock response spectrum,modal analysis,pyrodevices,laser shock,hybrid method
更新于2025-09-11 14:15:04