Pressure impulse

Figure B-1. Pressure impulse diagrams for damage to brick houses. Line 1 Threshold for light damage. Line 2 Threshold or moderate damage partial collapse of roof some bearing wall failures. Line 3 Threshold for severe damage 50 to 75 percent of bearing wall destruction. P, side-on overpressure. /, side-on impulse (Baker et al. 1983).

Most of the criteria found in literature are extracted from Bowen et al. (1968). Diagrams of pressure versus duration are presented for various body positions in relation to the blast wave, from which the chance of survivability can be calculated. Those diagrams were combined in a pressure-impulse diagram, which is depicted in Figure C-1. The scaled overpressure P equals Plp, in which P is the actual pressure acting on the body, and po is the ambient pressure. The scaled impulse i equals ... 

Figure C-1. Pressure-impulse diagram for lung injury. P scaled overpressure. / scaled impulse. (Bowen et al. 1968).

Refiected pressure Impulse or pressure experienced by an object facing a blast. 

The Lovelace work was later converted in Ref. 46 to scaled curves for combinations of peak incident overpressure and positive phase specific impulse. These curves are reproduced here as Fig. 40. Hirsch s work (Ref. 44) can also be given as pressure-impulse combinations for ear injury, and this also was done in Ref. 46. 

Another graphical method which is sometimes used in the evaluation of SDOF structural elements for blast loading is the Pressure-Impulse, or P-I, method. The P-I method combines both dynamic analysis and design evaluation into a single procedure... 

Attenuators may be used to reduce both peak pressure impulse. They act as momentum traps ... 

Active sites created by an electric discharge method were being used for graft copolymerization by Akutin et al. (130). When a solution of a polymer in a suitable monomer is subjected to high voltage electric discharge polymerization of monomer is initiated as a result of the pressure impulses acting on the system. The authors studied the copolymerization of methyl methacrylate onto polyvinyl chloride, and of vinyl chloride onto ethylcellulose. 

Gas Motion Under the Action of Short-Duration Pressure (Impulse) 107... 

This solution is related to the problem of an instantaneous pressure impulse (r — 0) obviously, any extended application of pressure and any delay in the pressure decrease at the piston can only diminish the rate of the shock wave pressure decrease. 

After the pressure at the piston returns to zero, the gas is not acted upon by any external forces since the pressure in the cold gas is equal to zero both at x — —oo (in the limit at the boundary of dispersion), and at x — oo (x > X is sufficient) in the cold gas. In the motion, therefore, the total momentum of the gas, f pudx, is conserved. This momentum is equal to the pressure impulse of the piston,... 

We consider the problem of motion of a gas adjacent to a vacuum under the influence of a short pressure impulse. 

The problem considered in this paper of a self-sustaining propagation wave of flame is closely related to self-similar solutions of the second kind, considered by Ya.B. in his paper, Gas Motion Under the Action of Short-Duration Pressure (Impulse) (see article 9 of the present volume) nearly twenty years later. Indeed, we are dealing here with wave-like solutions, for instance,... 

Shock sensitive materials react exothermally when subject to a pressure impulse. The impulse may come from a hammer-like blow, such as used in the standard drop-weight test, or a compression, such as might be experienced in a deadheaded plant compressor or valve slamming shut. Normally, shock sensitivity increases with an increase in temperature. Materials that do not show an exotherm on the DSC are seldom shock sensitive. 

DETERMINE EXPLOSIVE OUTPUT (PEAK PRESSURE IMPULSE)... 

A hot fan (Fi) in Figure 2 acts in a push-pull mode to suck gases from the reactor and pressurize them to move through the circuits. The volume of recirculated gas through the heat exchanger-reactor loop is set by valve V2. The off-gas valve vy operates automatically in response to a pressure impulse line in the top of the reactor above the wood feed. This line provides a pressure signal referenced to ambient barometric pressure for adjusting to accomplish the desired pressure differential. Typically this is set at zero or minus 3.0 Pa to prevent wood gas escape... 

In Eq. (13), the duration of a pressure impulse of a compressing cavitation bubble, t, is significantly less than the sound period, i.e. t T. The actual values for the frequency of 18 kHz are the following T= 56 ps and t = 1 (T2 ps. Due to such rapid occurrence of cavitation phenomena, the process of fine filtration in an ultrasonic field starts just after 10 to 60 s after pouring (when a liquid metal enters a filter). 

To determine the effect of a pressure field, resulting from cavitation bubbles compressing, on the penetration of a melt into a capillary channel of a filter, one should estimate the character of the pressure impulse propagation through the capillary. The mechanism of the flow is somewhat different under conditions of fine filtration of a melt through a porous medium (a filter from multilayer fiberglass with a cell of 0.6 x 0.6 or 0.4 x 0.4 mm in size) with rather short (about several mm) but complexly curved channels, but the main conditions remain. 

We should note that acoustic cavitation eliminates some restrictions stipulated by capillaries. The dynamics of a cavitation bubble—collapse and generation of a pressure impulse of Pmix > 102 MPa or high-speed cumulative jets—provides accelerated filling of capillaries of submicroscopic sizes. 

Distance (feet) Value of "Z" (feet/lb r b Reflected Properties Pressure Impulse (psig) (psig-ms) Personal Injury Property Damage... 

The profile of the impulse as a function of the pressure inside the PDF tube (more specifically at the closed-end) provides a useful check on the potential for impulse maximization. As shown in Fig. 14.3 for a uniform mixture ( = 0.5), the pressure-impulse combination evolves from the lower-right corner towards the higher-left corner, at which time the maximum impulse is achieved. The point then enters a tightening spiral until steady state is achieved. If the pressure at the top-left corner is sufficiently low, one could initiate injection sufficiently early to avoid the start of the spiral, which results in lowering of the impulse and cycling frequency. According to Fig. 14.3, optimization can be achieved if the reservoir pressure is higher than 1 atm. 

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