Advances in Shock Testing Facilities for Naval Shipboard Equipments

2011 ◽  
Vol 301-303 ◽  
pp. 1220-1225 ◽  
Author(s):  
Gong Xian Wang ◽  
Yong Hu
Keyword(s):  
Shock Wave ◽  
Test Methods ◽  
Shock Pulse ◽  
Shock Trial ◽  
Shock Test ◽  
Underwater Explosions ◽  
Shock Testing ◽  
New Concepts ◽  
Negative Shock ◽  
Shock Pulses

The capability to withstand non-contact underwater explosions (UNDEX) is an important aspect to be emphasized in the design of modern warships, and shock testing is one of the efficient methods to qualify the ability. A brief history on the research of shock testing of naval shipboard equipment as well as major means in evaluating anti-shock performance of warship equipment is introduced first in this paper. Three prevailing shock test methods: UNDEX testing, virtual shock trial and land-based test with shock test machines are presented with the focus on the advances in shock test machines in US and Europe. Comparison of current shock testing facilities is also given. Moreover, some new concepts of shock test machines are reviewed as well, and three major directions of the development of shock test machines are concluded. The first trend is that shock testing machines are required to generate positive and negative shock pulse to simulate real UNDEX environment made up of shock wave followed by bubble pulse and structural whipping. The second is that shock test machines can test heavy equipments, and the last is that shock pulses can be controlled and customized conveniently.

scholarly journals Shock Pulse Shaping in a Small-Form Factor Velocity Amplifier

2010 ◽  
Vol 17 (6) ◽  
pp. 787-802 ◽  
Author(s):  
Gerard Kelly ◽  
Jeff Punch ◽  
Suresh Goyal ◽  
Michael Sheehy
Keyword(s):  
Pulse Shaping ◽  
Vertical Axis ◽  
Mechanical Shock ◽  
Practical Applications ◽  
Shock Testing ◽  
Acceleration Signal ◽  
High Acceleration ◽  
Component Assembly ◽  
Small Form Factor ◽  
Shock Pulses

This theme of this paper is the design and characterisation of a velocity amplifier (VAMP) machine for high-acceleration shock testing of micro-scale devices. The VAMP applies multiple sequential impacts to amplify velocity through a system of three progressively smaller masses constrained to move in the vertical axis. Repeatable, controlled, mechanical shock pulses are created through the metal-on-metal impact between pulse shaping test rods, which form part of the penultimate and ultimate masses. The objectives are to investigate the controllable parameters that affect the shock pulses induced on collision, namely; striker and incident test rod material; test rod length; pulse shaping mechanisms; and impact velocity. The optimum VAMP configuration was established as a 60 mm long titanium striker test rod and a 120 mm long titanium incident rod. This configuration exhibited an acceleration magnitude and a primary pulse duration range of 5,800–23,400 g and 28.0–44.0μs respectively. It was illustrated that the acceleration spectral content can be manipulated through control of the test rod material and length. This is critical in the context of practical applications, where it is postulated that the acceleration signal can be controlled to effectively excite specific components in a multi-component assembly affixed to the VAMP incident test rod.

EMISSION BY UNDERWATER EXPLOSIONS

Geophysics ◽  
1970 ◽  
Vol 35 (3) ◽  
pp. 419-435 ◽  
Author(s):  
M. Lavergne
Keyword(s):  
Shock Wave ◽  
Frequency Band ◽  
Experimental Investigations ◽  
Water Interface ◽  
Single Charge ◽  
Seismic Effects ◽  
Underwater Explosions ◽  
Seismic Efficiency ◽  
Marine Life ◽  
Air Water Interface

Theoretical and experimental investigations of the seismic effects of underwater explosions of dynamite charges are described. We investigate the acoustic efficiency in a broad frequency band and in the seismic frequency band, the partition of energy between the shock wave and bubble pulses, the seismic effects of cavitation due to ghost reflection at the air‐water interface, and the damage caused to marine life. Results concerning the variation of the seismic efficiency with shot conditions are given: the conclusion is that the seismic efficiency of charges of the order of 100 gm can be considerably increased by dividing the charges and by shooting at depth. Experiments show that two or three properly spaced 50 gm charges of dynamite, shot at a depth of about 12 m, give the same result as a single charge of about 5 to 15 kg shot at a depth of 1 m. CDP marine sections comparing caged charge shooting with conventional shooting in the same area are shown.

Shock Test and Acceleration Analysis Methods of Marine Diesel Engines to Underwater Explosions

2013 ◽  
Vol 345 ◽  
pp. 64-67
Author(s):  
Jian Hua Zhao ◽  
Rui Bo Zhang ◽  
De Bin Zhu ◽  
Hong Bin Gao
Keyword(s):  
Diesel Engine ◽  
Low Frequency ◽  
Vibration Signal ◽  
Test Methods ◽  
Shock Acceleration ◽  
Test Results ◽  
Shock Test ◽  
Marine Diesel ◽  
Reduction Methods ◽  
Acceleration Analysis

Shock test of marine diesel engine is the important content for ship anti-shock research. Plentiful shock tests of equipments have been carried out abroad, but there is no detailed test methods of diesel engine. According to simulation results, 8-channel acceleration test points are determined. Because diesel engine is working, the measured shock acceleration is interfered by vibration signal. Orthogonal wavelet decomposition and wavelet noise reduction methods are used to separate shock component from test results. The seperated shock component consists of two parts. One is the low-frequency part caused by the shock from diesel foundation and then attenuation through the isolator, the other is the high-frequency part caused by the secondary shock of the retainer.

scholarly journals Segregation of the bulk cargo on a belt conveyor under the vibro-pulse impact

2021 ◽  
Vol 303 ◽  
pp. 01044
Author(s):  
Alexander Zakharov ◽  
Natalya Erofeeva
Keyword(s):  
Negative Impact ◽  
Conveyor Belt ◽  
Shock Pulse ◽  
Belt Conveyor ◽  
Lower Face ◽  
Rotation Direction ◽  
Impact Device ◽  
Characteristic Points ◽  
Linear Sections ◽  
Shock Pulses

The dynamics of interaction of the large lumps of the bulk cargo with a conveyor belt while passing through roller supports of the conveyor linear sections is often a cause of damage on the conveyor belt. In order to reduce the negative impact it is proposed to isolate the conveyor belt surface from the large lumps by filling small fractions of the bulk cargo by means of adding a shock device to the conveyor structure that causes increased segregation of the bulk cargo. A mathematical model of the segregation of the bulk cargo located on the conveyor belt and in zone of impact of the shock pulses has been developed. The model considers a change in the rotation direction of the large lump when applying shock pulses to the characteristic points of the lump lower face. Herewith it takes into consideration weakening of the shock pulse by a layer of the bulk cargo small fractions. The presented model has received experimental confirmation. Analytically and experimentally the height of filling of the bulk cargo small fractions under a large lump when passing the vibrating impact device located on the conveyor belt has been determined.

Design and Control of a High Velocity, High Force Hydraulic Shock Test Machine

1986 ◽  
Vol 29 (2) ◽  
pp. 54-57
Author(s):  
John Favour
Keyword(s):  
System Performance ◽  
System Response ◽  
Test Machine ◽  
Testing Device ◽  
Concept Design ◽  
Hydraulic Shock ◽  
Shock Test ◽  
Shock Testing ◽  
Shock Test Machine ◽  
And Control

This paper discusses the design and control of a large hydraulic shock testing device. The system is capable of peak velocities up to 10.2 m/s (400 in/sec) and peak forces up to 801 kN (180,000 lbs). The major challenges discussed are: 1) the concept design, 2) the specification and procurement of two very large (2500 gpm) electro-hydraulic servovalves and 3) the failsafe control of the servovalves and system response. The system performance is briefly discussed.

Shock environment design for space equipment testing

2016 ◽  
Vol 231 (6) ◽  
pp. 1154-1167 ◽  
Author(s):  
OMF Morais ◽  
CMA Vasques
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Test System ◽  
Test Apparatus ◽  
Shock Test ◽  
Shock Testing ◽  
Test Parameters ◽  
Shock Environment ◽  
Definition Of

The main specification in the verification by testing of space hardware vulnerability to shock excitations is the shock response spectrum. Although it compiles the most relevant information needed to describe the overall shock environment characteristics, shock testing still poses various difficulties and uncertainties concerning the suitability and operation of the shock test system used, and the adequate definition of the underlying test parameters. The approach followed from the interpretation of typical shock testing specifications to the development, validation, and characterization of the developed shock test system, including the definition and design of the relevant parameters influencing the attained shock environment, is described in this paper. The shock testing method here presented consists of a pendular in-plane resonant mono-plate shock test apparatus where the structural response of the ringing plate depends upon well-defined controllable parameters (e.g. impact velocity, striker shape, mass, and contact stiffness), which are parametrically determined to achieve the target shock environment specification. The concept and analytical model of two impacting bodies are used in a preliminary analysis to perform a rigid body motion analysis and contact assessment. A detailed finite element model is developed for the definition of the ringing plate dimensions, analysis of the plate dynamics and virtual shock testing. The assembled experimental apparatus is described and a test campaign is undertaken in order to properly characterize and assess the design and test parameters of the system. The developed shock test apparatus and corresponding finite element model are experimentally verified and validated. As a result of this study, a reliable finite element modeling methodology available for future shock test simulation and prediction of the experimental results was created, being an important tool for the adjustment of the shock test input parameters for future works. The developed shock test system was well characterized and is readily available to be used for shock testing of space equipment with varying specifications.

Pressure Load on Rigid Structure Induced by Double Underwater Explosions

2016 ◽  
Author(s):  
Rui Han ◽  
Aman Zhang ◽  
Shiping Wang
Keyword(s):  
Shock Wave ◽  
Underwater Explosion ◽  
Time Difference ◽  
Wave Load ◽  
Underwater Explosions ◽  
Rigid Structure ◽  
Pressure Load ◽  
Adjacent Structures ◽  
Explosive Source ◽  
Source Case

Underwater explosion is a severe threat to nearby ocean structures, such as underwater construction, floating vessels. The pressure load produced by underwater explosion of explosives consists of shock wave load and the explosion bubble pulsation pressure load. After the detonation, there will be a shock wave propagating radially outwards and it’s followed by a large oscillating bubble. The shock wave has the first damaging effect on adjacent structures. Then, the collapse and high-speed jet of oscillating bubbles will cause the second damage to structures. When there are double explosive sources near a rigid structure, the mutual superposition of shock waves and the interaction between two bubbles may improve the explosive damage. If the distance between one explosive source and the rigid structure is fixed, the damage force produced by double underwater explosions is related to many factors, like the detonation time difference and the distance between two explosive sources. At first, the pressure field in single explosive source case is numerically simulated by using the AUTODYN in this paper. Next, pressure fields of underwater explosion detonated by double sources at the same time and with time difference are calculated, respectively. The flow fields in double explosive sources case are compared with that in single explosive source case. The effect of the detonation time difference and the distance between explosive sources on the damage force is investigated and analysed in detail.

Effective Data Validation Methodology for Pyrotechnic Shock Testing

2010 ◽  
Vol 53 (1) ◽  
pp. 9-30 ◽  
Author(s):  
Charles Wright
Keyword(s):  
Shock Wave ◽  
Measurement System ◽  
Response Spectra ◽  
Data Validation ◽  
Shock Test ◽  
Acceleration Time ◽  
Acceleration Time Histories ◽  
Shock Response ◽  
Time Histories ◽  
Wave Shapes

Valid test data from explosively or ordnance-initiated pyrotechnic shock tests are difficult to acquire. Measurement of these frequency-rich acceleration time histories, a prerequisite to calculation of a valid shock response spectrum, drives the measurement system to its performance limits. Successful acquisition of demonstrably valid acceleration time histories requires a series of performance compromises that must be made with a depth of measurements expertise. Such expertise may not be available from vendors of the various data acquisition systems sold for these tests. All measurement system performance characteristics (transducer mount dynamics, gain, frequency response, phase response, linearity, lead wire effects, sampling rate, etc.) require compromise. It takes professional-level knowledge and experience to make the proper compromises to assure data validity for the measured wave shape. These measurements should never be taken for granted, as often and unfortunately happens. Data validation methods should be used by a test organization to prove the validity of the experimental shock wave shapes and subsequent shock response spectra (SRS). Recent events in the explosively driven, pyrotechnic shock test community show that methods for effective data validation are not in general use. This situation can lead to the problem of invalid shock test acceleration time histories causing invalid shock response spectra with both entering the design verification cycle. This paper defines the requirements for the measurement of valid shock wave shapes. It then defines an ordered series of validity tests that will both identify and quantify a number of detrimental effects in the acquisition of these frequency rich time histories, and resultant shock response spectra. Use of this set of validity checking methods assures the objective identification of invalid shock data to customers of pyrotechnic shock tests.

Mars Exploration Rover (MER) Airbag Retraction Actuator (ARA) Pyroshock Test Results

2005 ◽  
Vol 48 (1) ◽  
pp. 114-126 ◽  
Author(s):  
Kurng Chang
Keyword(s):  
Test Methods ◽  
Test Results ◽  
Mars Exploration ◽  
Flight System ◽  
Shock Test ◽  
Mars Exploration Rover ◽  
Alternate Test ◽  
Explosive Charges ◽  
Test Requirements

This paper presents the shock test results achieved in the Mars Exploration Rover (MER) airbag retraction actuator (ARA)/brush motor pyroshock qualification. The results of MER flight system pyrofiring tests are compared with ARA shock test requirements. Alternate test methods were developed in an effort to qualify critical MER equipment for adequate performance under actual flight pyroshock conditions. Simulated pyroshock qualification tests were conducted using shakers, mechanical impacts, and explosive charges for excitation. Comparisons of excitation and responses of an ARA subjected to different shock tests are presented.

Rarefaction shock wave near the critical liquid–vapour point

1983 ◽  
Vol 126 ◽  
pp. 59-73 ◽  
Author(s):  
A. A. Borisov ◽  
Al. A. Borisov ◽  
S. S. Kutateladze ◽  
V. E. Nakoryakov
Keyword(s):  
Shock Wave ◽  
Shock Tube ◽  
Critical Point ◽  
Wave Front ◽  
Propagation Velocity ◽  
Test Substance ◽  
Unperturbed State ◽  
Long Wave ◽  
Rarefaction Shock ◽  
Negative Shock

The existence of a rarefaction shock wave or negative shock wave in a substance whose unperturbed state is close to the thermodynamic critical liquid–vapour point has been demonstrated experimentally. Its evolution and propagation velocity in a shock tube with Freon-13 as the test substance are described. It is shown that the steepness of the wave front does not diminish as the wave evolves. An equation is derived that describes the evolution of long-wave perturbations near the critical point.

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