Present invention is based on a chemical reaction, which converts the original material namely, the explosive into
gaseous product at very high temperature and pressure in relatively short time to generate shock wave.
BACKGROUND
This equipment is developed for testing of Protected Memory Module (PMM) that is a data storing device required
for storing the recorded data transmitted from Solid State Flight data Recorder (SSFDR) fitted on the platform into
solid state non‐volatile memory. It can store the aircraft audio & parameter data. The stored data is protected
against stipulated crash conditions to enable its subsequent retrieval and decoding by Ground Replay Equipment.
The stipulated crash conditions are based on ED‐112 and TSO‐c‐124(a).
SUMMARY OF PRESENT INVENTION
In accordance with one aspect of present invention, the said equipment generates 4000 ’g’ impact shock.
In accordance with second aspect of present invention, the said equipment generates impact shock for
6.5milisecond.
In accordance with third aspect of present invention, the said equipment can be used for testing the test piece of
size approximately 124mmX134mmX196mm.
In accordance with another aspect of present invention, the said equipment can be used for Impact testing of test
piece in aircraft application.
In accordance with another aspect of present invention, the said equipment can be used for Impact testing of test
piece in marine application.
DETAIL DESCRIPTION
Fig.1 shows the details of all components for the present invention. It consists of a shock Tube assembly cladded
with visco ‐ elastic layers ,shock pulse expander, accelerometers, signal conditioner units, Data Acquisition
System/CAT analyzer and explosion Fire Control System etc. The test table assembly cladding with visco‐elastic
layers and pulse expander system are specially designed and calibrated to simulate shock pulse duration of the
order to 6.5msec. Shock tube assembly and other sub‐systems using CFD/FEM analysis technique are designed to
withstand very high explosive shock. Items as shown in fig1 are cone(1),impact table (2),throat
extension(3),charge holder(4),baseplate(5), push suspension(6), bolt(8,11), Nut(9) and washer (10).
Fig.2 shows Impact table.
Annexure‐II
Fig.3 shows throat extension.
The desired shock environment can be achieved through underwater explosion using a suitable shock tube. The
radiating pressure wave propagates in the radial direction as a compressive wave which is generally termed as the
shock wave. The design parameters are selected so as to create directional propagation of wave and eliminate high
frequency reflections .The shock wave front travels across the axis of the tube and excites the shock tube with
sufficient forces so as to create crash condition.
The sequence of events associated with an underwater explosion can broadly be categorized into five
phases,namely;
1. Primary shock wave
2. Gas bubble oscillation and secondary shock wave
3. Gas bubble migration and surface phenomena
4. Boundary effects
5. Fluid‐structure interaction
A submerged spherical explosive charge causes a cavity of its own shape and size in water medium. It is acted upon
by normal hydrostatic pressure at the interface between the charge and water. This explosive changes
instantaneously into gaseous products at very high pressure and temperature (of order of 50,000 atmospheres and
3000 deg C). This process takes place very rapidly within a short period and evolving a great deal of heat. This high
– pressure gas bubble then tries to expand, compressing the spherical layer of water immediately surrounding the
charge. Because of compression and outward motion of the water medium, the disturbance generated in water
propagates radially outwardfrom the source as shock wave. The pressure rise in the shock front is extremely rapid
and decay is nearly exponential.
Water being a compressible medium, the wave generated at the region near the explosion is transmitted as a
wave disturbance with finite velocity involving local motion of water and varying pressure. The underwater shock
wave pressure generated by the explosion is superimposed on the hydrostatic pressure.
Because of the spherical spreading nature of the shock wave, it will be reaching different locations at different
times, i.e. there is time delay. The time delay of the pressure pulse at different locations is essential for response
predictions.
In the vicinity of the charge, the pressure in the shock wave falls off more rapidly with distance than the inverse
first power low of acoustic wave propagation. At other distance, the pressure pulse follows the usual acoustic law
and the very large distances the pulse becomes noise. As the wave travels away from the explosion, the profile of
the shock wave broadens and the amplitude reduces.
The shock wave generated due to underwater explosion travels with a velocity several times that of the limiting
acoustic velocity (1500 m/sec for water) near the charge and reaches the acoustic velocity as the wave advances.
The velocity in the vicinity of the explosion depends on the peak pressure of the shock wave and the acoustic
velocity.

WE CLIAMS:-
Accordingly, the description of the present invention is to be considered as illustrative only and is for the purpose of teaching those skilled in the art of the best mode of carrying out the invention. The details may be varied substantially without departing from the spirit of the invention, and exclusive use of all modifications which are within the scope of the appended claims is reserved. We Claim that

1. The Equipment for generating shock, comprising
- shock Tube assembly cladded with visco - elastic layers,
- shock pulse expander,
- accelerometers,
- signal conditioner units,
- Data Acquisition System/CAT analyzer &
- Explosion Fire Control System
2. The equipment according to claim 1, capable of generation of impact shock in the range of 1000g to 4000g for atleast 6.5milliseconds.
3. The equipment according to claim 1, capable of testing test piece with a maximum dimension of 124mmX134mmX196mm.
4. The equipment according to claim 1, capable of fulfilling atleast the requirements as set for Aircraft and marine applications.
5. The equipment according to claim 1, based on a chemical reaction, which converts the original material namely, the explosive into gaseous product at very high temperature and pressure in relatively short time to generate shock wave.
6. The equipment according to claim 1, the explosive housing material is capable of sustaining atleast one shock wave of upto 4000g without any damage; capable of withstanding heat generated too.
7. The equipment according to claim 1 & 2, capable of generating impact shock in atleast one known direction with minimal frequency reflections.
8. The equipment according to claim 1, capable of recording atleast one impact shock generated for future reference, calibration etc.
9. The equipment according to claim 1, uses relevant sensors for sensing the subject impact shock. ,TagSPECI:As per Annexure-II