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DennyDevHE77
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What does brisance depend on besides detonation velocity?
What does brisance depend on besides detonation velocity?
Looking through various reference books on explosives, I noticed these things:
1. Why C4 (and especially its British analog PE-4) having detonation velocities of 8000-8150 m/s are so much inferior to ordinary molten ETN (with
velocity of 8000 m/s)? On the forum someone even posted the results of detonation of plastic explosives and molded ETN on a sewer manhole, and if the
plastic only bent it, the ETN penetrated through.
2. Why such explosive as dinitroguanidine with density and detonation rate similar to HMX is similar to RDX in brisance?
3. Or such an explosive as NTO (nitrotriazolone) has a density higher than that of HMX and detonation velocity like that of ETN, but is similar in
power to TNT.
4. Or picric acid has a density of 1.813 (RDX has 1.816), but pressed to 1.8 it is not even superior to tetryl. Is this due to the low presence of
nitro groups?
I was thinking what else influences, saw such a parameter as heat of explosion (MJ/kg), it was very different between aromatic explosives and
nitramines and even more so nitroesters.
But then why EGDN (which has a heat of explosion of 6.8-7 MJ and a detonation velocity of 8200 m/s) is only 15% breezier than TNT. The same PETN is
45% more powerful, although its heat of explosion is lower.
Can you explain in a simple way what is the matter? And, if you can, can you throw the literature that will sort it all out?
[Edited on 20-8-2023 by DennyDevHE77]
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Etanol
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1. These data are correct for industrial plastic explosives with a high content HMX or RDX. Homemade plastic explosives is not equal to industrial.
Its density and percentage are much lower.
2. The detonation pressure = density * VoD^2 / (k +1)
Politropic indicator "k" is individual for each substance and its density.
3. Politropic indicator "k" is individual for each substance and density. Brisance is not equal to power. Power (throwing ability) is determined by
the heat of the explosion to a large extent.
4. Politropic indicator from bad composition of detonation products
Yes
EGDN density is lower.
Look for books about the theory of detonation.
[Edited on 20-8-2023 by Etanol]
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Microtek
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Brisance itself is not super well defined. It is the ability of an explosive to shatter a hard target, but how exactly this should be measured is a
bit ambiguous. It depends on how rapidly the explosive can transfer the largest amount of momentum to the target, or accelerate parts of the target.
This is a function of at least explosion energy, density, VOD, detonation pressure, gas volume and gas composition.
Several methods of generating estimates from easily tabulated properties exist, but you are bound to find inconsistencies in any one of them.
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PLSHY
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In my book, the intensity is not equal to the detonation pressure, but the intensity is the comprehensive value of the detonation pressure, various
charges and constraints, and the detonation velocity is approximately equal to the detonation pressure. What needs to be corrected is that if the
actual detonation speed of c4 can reach the same as that of casting etn, then their violentness should also be the same. The same is true for egdn.
Someone on youtube has tested the comparison between egdn, etn and petn. Because egdn is a liquid, it is easy to reach the maximum detonation
velocity, while etn can be cast, and it is easier to achieve the maximum detonation velocity. Petn needs to be suppressed, and it is extremely
difficult to achieve the maximum detonation velocity. The maximum detonation velocity of the three is almost the same, so the result is
egdn>etn>>petn, which also proves from the side that under the same bottom area, mass, and detonation velocity, the density has almost no
effect on the jerk, while the density measured in ordinary times has little effect on the explosion velocity. The impact of the jerk is because more
explosives are packed in the same volume, so the specific impulse (jerk) is increased. Therefore, it is concluded that the jerk is affected by the
detonation velocity and the charging method, and is affected by the density under certain conditions.
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PLSHY
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My translation software is very bad, I am considering whether to use Chinese dialogue directly in the future, and you can use better translation
software for translation
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PLSHY
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猛度与做功能力有关系，但是不是强关系，最终还要看爆速才行
My evaluation of egdn is very high, because after I read the books about pyrotechnics, I found that the force is closely related to the workmanship
ability, and the workmanship ability of egdn is the strongest, there is no one, although the density is relatively high Low, but due to the
characteristics of the liquid, its maximum detonation velocity is extremely high, so the violence is very strong, especially in the shaped charge, and
the strong constraints can further improve the acceleration efficiency of the metal jet! Resulting in perfect formation of the shaped jet. And its
biggest advantage is that it is not sensitive, which is about 10 times more insensitive than NG!
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OneEyedPyro
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Quote: Originally posted by PLSHY  | | In my book, the intensity is not equal to the detonation pressure, but the intensity is the comprehensive value of the detonation pressure, various
charges and constraints, and the detonation velocity is approximately equal to the detonation pressure. What needs to be corrected is that if the
actual detonation speed of c4 can reach the same as that of casting etn, then their violentness should also be the same. The same is true for egdn.
Someone on youtube has tested the comparison between egdn, etn and petn. Because egdn is a liquid, it is easy to reach the maximum detonation
velocity, while etn can be cast, and it is easier to achieve the maximum detonation velocity. Petn needs to be suppressed, and it is extremely
difficult to achieve the maximum detonation velocity. The maximum detonation velocity of the three is almost the same, so the result is
egdn>etn>>petn, which also proves from the side that under the same bottom area, mass, and detonation velocity, the density has almost no
effect on the jerk, while the density measured in ordinary times has little effect on the explosion velocity. The impact of the jerk is because more
explosives are packed in the same volume, so the specific impulse (jerk) is increased. Therefore, it is concluded that the jerk is affected by the
detonation velocity and the charging method, and is affected by the density under certain conditions. |
Brisance is essentially the peak pressure generated at the detonation wave front.
The pressure generated can be estimated by the VoD, the amount of gasses liberated per volume of explosive, the heat of those gasses and the ratio of
different gasses based on the elemental composition of the molecule. Typically N2, H2O, CO2 and CO are the primary gasses we would be interested in.
EGDN is very powerful by mass and so is methyl nitrate for example but by volume they are not quite as impressive and their brisance suffers as a
result. Regarding the sensitivity of EGDN, I believe it's similar to NG and borders on if not exhibits primary levels of sensitivity to impact. It's
certainly not something to handle carelessly.
[Edited on 22-8-2023 by OneEyedPyro]
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PLSHY
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This is the source of egdn sensitivity data
[Edited on 22-8-2023 by PLSHY]
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PLSHY
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I just reviewed the concept of jerk, and the following is my conclusion after simplifying the content in the book: jerk is actually related to three
points, we need to talk about the definition of jerk first, jerk refers to the impulse per unit area , and the calculation method of impulse is I=FT,
which is force multiplied by time, and the calculation of jerk is actually very simple. The jerk can be calculated by burst pressure (force per unit
area)*charge length/detonation velocity, so because of the burst pressure *Square of detonation velocity*Density, so the formula can be simplified
into violent force=density*Charge length*Detonation velocity, and because of density*Charge length*Detonation wave area (area of the bottom of
the charge column)=Charge mass, so the final formula It can be simplified as violent =detonation velocity multiplied by charge mass *detonation wave
area. Note that the above conditions are valid for the detonation on the surface of a rigid body without external constraints. According to my
detailed elaboration on the force in the paragraph above, I hope you have a better understanding of the force. What I said yesterday is correct. The
force is determined by the detonation velocity, the quality of the charge and the method of charge. The same quality The downward force has nothing
to do with the density! But under the same volume, the intensity is proportional to the density (the detonation velocity is equal)
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Microtek
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No, what you are describing here as "jerk" is, as far as I can tell, more akin to heaving power. Impulse per unit area would give pressure multiplied
by time, which is an important metric for thermobaric devices, but not for evaluating brisance. Brisance requires a shock (which is what I assume you
mean when you introduce the non-technical term "jerk") which means that there must be a large pressure rise in a very short amount of time. Thus it
would be better to divide by the overpressure duration than to multiply by it.
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PLSHY
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| Quote: Originally posted by Microtek | | No, what you are describing here as "jerk" is, as far as I can tell, more akin to heaving power. Impulse per unit area would give pressure multiplied
by time, which is an important metric for thermobaric devices, but not for evaluating brisance. Brisance requires a shock (which is what I assume you
mean when you introduce the non-technical term "jerk") which means that there must be a large pressure rise in a very short amount of time. Thus it
would be better to divide by the overpressure duration than to multiply by it. |
In fact, the shorter the
time, the higher the intensity, because the calculation method of the time is the charge length divided by the detonation velocity, and the detonation
pressure is equal to the density multiplied by the square of the detonation velocity, so when the charge length is fixed, the detonation velocity
increases, and the intensity does not change. will decrease, but increase. This is an area that is easily misunderstood. It seems that this formula
shows that the lower the detonation velocity, the higher the force, but in fact it is the opposite
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OneEyedPyro
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| Quote: Originally posted by PLSHY | | Quote: Originally posted by Microtek | | No, what you are describing here as "jerk" is, as far as I can tell, more akin to heaving power. Impulse per unit area would give pressure multiplied
by time, which is an important metric for thermobaric devices, but not for evaluating brisance. Brisance requires a shock (which is what I assume you
mean when you introduce the non-technical term "jerk") which means that there must be a large pressure rise in a very short amount of time. Thus it
would be better to divide by the overpressure duration than to multiply by it. |
In fact, the shorter the
time, the higher the intensity, because the calculation method of the time is the charge length divided by the detonation velocity, and the detonation
pressure is equal to the density multiplied by the square of the detonation velocity, so when the charge length is fixed, the detonation velocity
increases, and the intensity does not change. will decrease, but increase. This is an area that is easily misunderstood. It seems that this formula
shows that the lower the detonation velocity, the higher the force, but in fact it is the opposite |
The density and VoD of a given explosive cannot be used as constant values since brisance and useful heaving power don't scale up in a linear manner.
As density and VoD increases so does the reaction rates between the detonation products such as with hydrogen and oxygen for example.
ETN at 1.6 g/cc as a cast charge will not have 60% more brisance than a charge pressed to 1 g/cc.
It's a complex thing with no exact universal formula. There are different models that disagree with each other, but they tend to give a reasonably
close approximation.
[Edited on 23-8-2023 by OneEyedPyro]
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PLSHY
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| Quote: Originally posted by OneEyedPyro | | Quote: Originally posted by PLSHY | | Quote: Originally posted by Microtek | | No, what you are describing here as "jerk" is, as far as I can tell, more akin to heaving power. Impulse per unit area would give pressure multiplied
by time, which is an important metric for thermobaric devices, but not for evaluating brisance. Brisance requires a shock (which is what I assume you
mean when you introduce the non-technical term "jerk") which means that there must be a large pressure rise in a very short amount of time. Thus it
would be better to divide by the overpressure duration than to multiply by it. |
In fact, the shorter the
time, the higher the intensity, because the calculation method of the time is the charge length divided by the detonation velocity, and the detonation
pressure is equal to the density multiplied by the square of the detonation velocity, so when the charge length is fixed, the detonation velocity
increases, and the intensity does not change. will decrease, but increase. This is an area that is easily misunderstood. It seems that this formula
shows that the lower the detonation velocity, the higher the force, but in fact it is the opposite |
The density and VoD of a given explosive cannot be used as constant values since brisance and useful heaving power don't scale up in a linear manner.
As density and VoD increases so does the reaction rates between the detonation products such as with hydrogen and oxygen for example.
ETN at 1.6 g/cc as a cast charge will not have 60% more brisance than a charge pressed to 1 g/cc.
It's a complex thing with no exact universal formula. There are different models that disagree with each other, but they tend to give a reasonably
close approximation.
[Edited on 23-8-2023 by OneEyedPyro] |
Yes, what I am discussing is the detonation wave formed by the
detonation products flying to one dimension under ideal conditions. The actual detonation products are flying to the surroundings, so it is necessary
to introduce a concept of effective charge quality. My formula is correct when the drug quality is low or in an ideal state, but if you need to
discuss the actual state, you need to introduce calculus, which is very complicated, so I won’t elaborate
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OneEyedPyro
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PLSHY
As density changes so do the fundamental dynamics of the detonation.
At higher densities the atoms are closer to each other and moving at higher speeds as the molecules break apart upon detonation. This results in more
nitrogen bonding and oxidization of fuels near the detonation wavefront meaning significantly higher peak detonation pressure than your idea of
density and VoD working as fixed values would suggest.
At lower density more unbonded nitrogen and oxygen and fuel are left to react later behind the detonation wave. This effects brisance much more than
heaving power generally speaking.
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Microtek
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| Quote: |
In fact, the shorter the time, the higher the intensity |
This is true, but not what you are getting from multplying by time, which is what my critique was about.
Much of what you are saying is contradictory or doesn't make sense, possibly because of language barriers. I think you should go into the calculus if
you can, that way the language will be less of a problem.
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PLSHY
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| Quote: Originally posted by PLSHY | | Quote: Originally posted by Microtek |
| Quote: |
In fact, the shorter the time, the higher the intensity |
This is true, but not what you are getting from multplying by time, which is what my critique was about.
Much of what you are saying is contradictory or doesn't make sense, possibly because of language barriers. I think you should go into the calculus if
you can, that way the language will be less of a problem. |
Very simple reason, due to the formula "detonation
pressure is equal to density multiplied by the square of detonation velocity". Notice! square! Therefore, every time the time is doubled, the
detonation speed will be doubled, and the detonation pressure will become 1/4 of the original!Twice the time, half the brisance！I still hope that
you can read my previous speech and try my best to understand it before replying, because I have never objected to your point of view from beginning
to end! |
[Edited on 24-8-2023 by PLSHY]
[Edited on 24-8-2023 by PLSHY]
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PLSHY
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I think I know the problem, google translate keeps translating "double the time, half the force" to "double the time, double the force"
[Edited on 24-8-2023 by PLSHY]
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PLSHY
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| Quote: Originally posted by OneEyedPyro | PLSHY
As density changes so do the fundamental dynamics of the detonation.
At higher densities the atoms are closer to each other and moving at higher speeds as the molecules break apart upon detonation. This results in more
nitrogen bonding and oxidization of fuels near the detonation wavefront meaning significantly higher peak detonation pressure than your idea of
density and VoD working as fixed values would suggest.
At lower density more unbonded nitrogen and oxygen and fuel are left to react later behind the detonation wave. This effects brisance much more than
heaving power generally speaking. |
You are right, but in the case of the same detonation velocity, the
density is not important, but most charges with different densities have different detonation velocities, so I just want to explain the root cause,
that is, the violentness ultimately depends on the detonation velocity Instead of density, if the density is low but the detonation velocity is high,
then the brisance will be high (under the same mass). Also, I will try my best to check whether the translation is correct in the future, so as not
to cause misunderstandings. I am very sorry for the misunderstandings just caused.
[Edited on 24-8-2023 by PLSHY]
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PLSHY
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| Quote: Originally posted by Microtek |
| Quote: |
In fact, the shorter the time, the higher the intensity |
This is true, but not what you are getting from multplying by time, which is what my critique was about.
Much of what you are saying is contradictory or doesn't make sense, possibly because of language barriers. I think you should go into the calculus if
you can, that way the language will be less of a problem. |
If you agree, I will delete a few replies with
unclear meaning, but I will keep a few excellent and clear replies. Although the derivation of the formula makes people drowsy, it is very helpful for
understanding the fundamental concept of brisance , again apologizing for the misunderstanding I caused and criticizing the hateful Google Translate
[Edited on 24-8-2023 by PLSHY]
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PLSHY
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I just found out that Google has translated "brisance" into strange words such as "VoD" and violence. It would be too difficult to correct them one by
one. Sorry everyone, my foreign language level is very average, and I will try to reduce the use of professional words in the future
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PLSHY
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I will give the original version of my most painstaking reply, I hope you can use a better translator for translation, I spent about an hour reading
and rewriting this text, he can really help you understand brisance which is a good teaching material in China:
我刚刚复习了一下关于猛度的概念，以下是我将书中内容简化后的结论：猛度其实关乎到三个点，我们需要先讲到
猛度的定义，猛度是指单位面积的冲量，而冲量的计算方式是I=FT，就是力乘以时间，而计算猛度实际非常简单，
压（单位面积的力）*装药长度/爆速即可计算出猛度，那么因为爆压=爆速的平方*密度，所以式子可以化简成猛度=
密度*装药长度*爆速，又因为密度*装药长度*爆轰波面积（药柱底面积）=装药质量，所以最终式子可以简化成猛度=
爆速乘以装药质量*爆轰波面积。注意，以上条件是在刚体表面爆轰，并且没有外在束缚的情况下成立。根据我上
这一段对猛度的详细阐述，希望你对猛度有更好的理解，我昨天说的并没错，猛度是由爆速，装药质量以及装药
式而决定的，同等质量下猛度与密度无关系！但是同等体积下，猛度与密度成正比例（爆速相等）
[Edited on 24-8-2023 by PLSHY]
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Microtek
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OK, when I plug your post into the best translation software I can find, I get this:
"jerk is actually related to three points. The calculation method is I=FT, which is force multiplied by time, and the calculation of the intensity is
actually very simple, the intensity can be calculated by pressure (force per unit area)*charge length/detonation velocity, then because the explosion
pressure = the explosion velocity Square*Density, so the formula can be simplified into Violence=Density*Charge Length*Detonation Velocity, and
because Density*Charge Length*Detonation Wave Area (Collum Bottom Area)=Charge Mass, so the final formula can be simplified as Violence = detonation
velocity multiplied by charge mass * detonation wave area."
I tried a few different translators, but apart from translating brisance as either "jerk" or "sharpness", there wasn't much difference.
There are still major problems however:
Is the "I" in your formula supposed to be impulse or intensity (you state both)? If you mean intensity, you are simply wrong in stating that it is
calculated as force multiplied by time. If you mean impulse, you are using the correct formula, but using it here does not make sense. Impulse is not
related to brisance!
Then you say that "intensity" is calculated as I=P*L/VOD, but that will give a quantity with units of newton times seconds over square meters. This is
the units for viscosity, not intensity.
Also, the explosion pressure is not equal to the square of the VOD times density, though it can be approximately proportional to it.
Finally, IF brisance could be expressed as density*charge length*VOD, your formula would simplify to VOD*mass DIVIDED by the cross sectional area, not
multiplied by it as you say.
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PLSHY
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| Quote: Originally posted by Microtek | OK, when I plug your post into the best translation software I can find, I get this:
"jerk is actually related to three points. The calculation method is I=FT, which is force multiplied by time, and the calculation of the intensity is
actually very simple, the intensity can be calculated by pressure (force per unit area)*charge length/detonation velocity, then because the explosion
pressure = the explosion velocity Square*Density, so the formula can be simplified into Violence=Density*Charge Length*Detonation Velocity, and
because Density*Charge Length*Detonation Wave Area (Collum Bottom Area)=Charge Mass, so the final formula can be simplified as Violence = detonation
velocity multiplied by charge mass * detonation wave area."
I tried a few different translators, but apart from translating brisance as either "jerk" or "sharpness", there wasn't much difference.
There are still major problems however:
Is the "I" in your formula supposed to be impulse or intensity (you state both)? If you mean intensity, you are simply wrong in stating that it is
calculated as force multiplied by time. If you mean impulse, you are using the correct formula, but using it here does not make sense. Impulse is not
related to brisance!
Then you say that "intensity" is calculated as I=P*L/VOD, but that will give a quantity with units of newton times seconds over square meters. This is
the units for viscosity, not intensity.
Also, the explosion pressure is not equal to the square of the VOD times density, though it can be approximately proportional to it.
Finally, IF brisance could be expressed as density*charge length*VOD, your formula would simplify to VOD*mass DIVIDED by the cross sectional area, not
multiplied by it as you say.
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I'm glad our discussion is finally back on track, I'll explain: i refers to brisance, and L refers to length, so L/VoD=time, explosion
pressure*time=i, which is a unit of impulse, It is not a viscosity unit, I=FT is an expression of impulse. Because explosion pressure=F/area, so
i=I/area, which also fits the Chinese definition of brisance: brisance is the impulse per unit area. Then there is the problem of simplification, I
think you and I simplify the same, and they are all simplified as: VoD*quality/cross-sectional area, I think I may have copied it wrong, because my
initial version is by Special characters, so I copied it again before posting it on the website. The last is explosion pressure=VoD squared*density,
I will give a picture of Uehara's formula below. And attach the derivation process of the original book.
 
[Edited on 25-8-2023 by PLSHY]
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DennyDevHE77
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In one thread here on the forum, I was advised to use DeepL to translate from Chinese.
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Etanol
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This is an approximate detonation pressure formula for k=3. It is valid only for similar CHNO-substances at a density of about 1.0 g/cm3.
In general
P=ro*D^2/(K+1)
K is not a constant.
There is an active charge length "La". At L>La pulse does not grow.
[Edited on 25-8-2023 by Etanol]
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