scholarly journals Shock Response Spectra Reconstruction of Pointwise Explosive-Induced Pyroshock Based on Signal Processing of Laser Shocks

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
S. Y. Chong ◽  
J. R. Lee ◽  
C. W. Kong
Keyword(s):  
Signal Processing ◽  
Response Spectrum ◽  
Arbitrary Point ◽  
Response Spectra ◽  
Industrial Applications ◽  
Reconstruction Method ◽  
Laser Shock ◽  
Signal Processing Algorithm ◽  
Magnetic Components ◽  
Shock Response

Pyroshock has been an issue of great concern for aerospace and defense industrial applications. When pyroshock devices are detonated, they can easily cause failures in electronic, optical, relay, and magnetic components generally in mid- and far-fields which is not avoidable at the design level. Thus, many numerical and experimental pyroshock simulations have been widely studied to predict explosive-induced pyroshock effect quantitatively, especially the shock response spectrum (SRS). In this study, a laser shock-based pyroshock reconstruction method is proposed to simulate a pointwise explosive-induced pyroshock signal. The signal processing algorithm for the laser shock-based pyroshock reconstruction is developed in a LabVIEW platform and consists of subbands decomposition, SRS matching in decomposed bands, and wave synthesizing. Then, two experimental setups are configured to obtain pyroshock signals and laser shock signals at four points in an aluminum plate. The reconstructed pyroshock signals synthesized according to the signal processing of the laser shocks demonstrate high similarity to the real pyroshock signals, where the similarity is evaluated by the mean acceleration difference between the SRS curves. The optimized settings of the subband decomposition were obtained and can be in the future used in a pyroshock simulator based on laser shock for pyroshock simulation at any arbitrary point.

Analytical Determination of Shock Response Spectra for an Impulse-Loaded Proportionally Damped System

Volume 1 ◽  
2004 ◽  
Author(s):  
R. David Hampton ◽  
Nathan S. Wiedenman ◽  
Ting H. Li
Keyword(s):  
Transient Response ◽  
Shock Loading ◽  
Response Spectrum ◽  
Response Spectra ◽  
Analytical Determination ◽  
System Response ◽  
Mechanical Shock ◽  
Shock Response ◽  
Mass Spring ◽  
The Impact

Many military systems must be capable of sustained operation in the face of mechanical shocks due to projectile or other impacts. The most widely used method of quantifying a system’s vibratory transient response to shock loading is called the shock response spectrum (SRS). The system response for which the SRS is to be determined can be due, physically, either to a collocated or to a noncollocated shock loading. Taking into account both possibilities, one can define the SRS as follows: the SRS presents graphically the maximum transient response (output) of an imaginary ideal mass-spring-damper system at one point on a flexible structure, to a particular mechanical shock (input) applied to an arbitrary (perhaps noncollocated) point on the structure, as a function of the natural frequency of the imaginary mass-spring-damper system. For a response point sufficiently distant from the impact area, many Army platforms (such as vehicles) can be accurately treated as linear systems with proportional damping. In such cases the output due to an impulsive mechanical-shock input can be decomposed into exponentially decaying sinusoidal components, using normal-mode orthogonalization. Given a shock-induced loading comprising such components, this paper provides analytical expressions for the various common SRS forms. The analytical approach to SRS-determination can serve as a verification of, or an alternative to, the numerical approaches in current use for such systems. No numerical convolution is required, because the convolution integrals have already been accomplished analytically (and exactly), with the results incorporated into the algebraic expressions for the respective SRS forms.

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

2017 ◽  
Vol 2017 ◽  
pp. 1-19 ◽  
Author(s):  
Yong-Woon Kim ◽  
Jae-Kyeong Jang ◽  
Jung-Ryul Lee
Keyword(s):  
High Frequency ◽  
Response Spectrum ◽  
Stop Band ◽  
Synthesis Method ◽  
Reconstruction Algorithm ◽  
Signal Decomposition ◽  
Synthesis Process ◽  
Laser Shock ◽  
Shock Response ◽  
Shock Response Spectrum

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%.

scholarly journals Comparison of Shock Response Spectrum for Different Gun Tests

2013 ◽  
Vol 20 (3) ◽  
pp. 481-491 ◽  
Author(s):  
J.A. Cordes ◽  
P. Vo ◽  
J.R. Lee ◽  
D.W. Geissler ◽  
J.D. Metz ◽  
...  
Keyword(s):  
Response Spectrum ◽  
Response Spectra ◽  
Tolerance Limit ◽  
Accelerometer Data ◽  
Test Results ◽  
Discussion Section ◽  
Component Testing ◽  
Shock Response ◽  
Shock Response Spectrum ◽  
Acceptance Tests

The Soft Catch Gun at Picatinny Arsenal is regularly used for component testing. Most shots contain accelerometers which record accelerations as a function of time. Statistics of accelerometer data indicate that the muzzle exit accelerations are, on average, higher than tactical firings. For that reason, Soft Catch Gun tests with unusually high accelerations may not be scored for Lot Acceptance Tests (LAT) by some customers. The 95/50 Normal Tolerance Limit (NTL) is proposed as a means of determining which test results should be scored. This paper presents comparisons of Shock Response Spectra (SRS) used for the 95/50 scoring criteria. The paper also provides a Discussion Section outlining some concerns with scoring LAT results based on test results outside of the proposed 95/50 criteria.

Prediction of the Dynamic Behaviour of Electromagnetic Relays Submitted to Mechanical Shocks

2006 ◽  
Author(s):  
D. Wattiaux ◽  
C. Conti ◽  
O. Verlinden
Keyword(s):  
Shock Waves ◽  
Dynamic Behaviour ◽  
Response Spectrum ◽  
Response Spectra ◽  
Electronic Equipment ◽  
Computational Techniques ◽  
Experimental Frequency ◽  
Mechanical Shocks ◽  
Shock Response ◽  
Electromagnetic Relays

During space flights, pyrotechnic devices are widely used to separate structural subsystems, to unfold solar panels or to activate propellant valves. The firing of these pyrotechnic devices generates severe shock waves (so-called pyroshocks) with high intensity and wide frequency range, which can damage the surrounding electronic equipment. Common observed damages more especially concern relay chatter and transfer, as well as failure of magnetic components. There is a lack of failure criteria for electronic equipment as well as computational techniques able to predict the dynamic behaviour of complex structures subjected to high frequency shock waves. The pyrotechnic shock behaviour is checked experimentally: test specifications imposed through embarked electronic devices are generally defined as a maximum limit imposed to the Shock Response Spectrum (SRS). This paper describes a methodology to check the electrical and mechanical behaviours of some electromagnetic relays submitted to severe mechanical shocks. Experimental results obtained when checking the perturbations induced by shocks on the electrical behaviour of some relays, such as the latching GP250 relay are also presented. Microswitches levels have been correlated with the magnitude and shape of different Shock Response Spectra. This paper presents also a simplified model of electromagnetic relays allowing to predict the electrical dysfunctions such as the micro-openings. The model has been updated using experimental frequency and modal analysis.

scholarly journals Aspects of Strength Testing of Tank Containers in Compliance with the Requirements of the UN Navigation Rules and Regulations

2021 ◽  
Vol 9 (3) ◽  
pp. 349
Author(s):  
Andrii Sulym ◽  
Pavlo Khozia ◽  
Eduard Tretiak ◽  
Václav Píštěk ◽  
Oleksij Fomin ◽  
...  
Keyword(s):  
Natural Frequencies ◽  
Response Spectrum ◽  
Experimental Curve ◽  
Bulk Liquid ◽  
Frequency Range ◽  
Test Configuration ◽  
Shock Response ◽  
Shock Response Spectrum ◽  
Spectrum Curve ◽  
The Impact

This article deals with the method of computer-aided studies of the results of tank container impact tests to confirm the ability of portable tanks and multi-element gas containers to withstand the impact in the longitudinal direction on a specially equipped test rig or using a railway flat car by impacting a flat car with a striking car, in compliance with the requirements of the UN Navigation Rules and Regulations. It is shown that the main assessed characteristic of the UN requirements is the spectrum of the shock response (accelerations) for the interval natural frequencies of the shock pulse. The calculation of the points of the shock response spectrum curve based on the test results is reproduced in four stages. A test configuration of the impact testing of the railway flat car with a tank container is presented, and the impact is performed in such a way that, under a single impact, the shock spectrum curve obtained during the tests for both fittings subjected to impact repeats or exceeds the minimum shock spectrum curve for all frequencies in the range of 2 Hz to 100 Hz. Formulas for determining the relative displacements and accelerations for the interval natural frequencies of the shock wave are given. The research results are presented in graphical form, indicating that the experimental values of the shock response spectrum exceed the minimum permissible values; the equation of the experimental curve of the shock response spectrum in the frequency range 0–100 Hz is described by power-law dependence. The coefficients of the equation were determined by the statistical method of maximum likelihood with the determination factor being 0.897, which is a satisfactory value; a comparative analysis showed that the experimental curve of the impact response spectrum in the frequency range 0–100 Hz exceeds the normalized curve, which confirms compliance with regulatory requirements. A new test configuration is proposed using a tank car with a bulk liquid, the processes in which upon impact differ significantly from other freight wagons under longitudinal impact loads of the tank container. The hydraulic impact resulting from the impact on the tank container and the platform creates an overturning moment that causes the rear fittings to be unloaded.

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