I'm just wondering what JWL parameters are the appropriate ones for TNT? Especially the internal energy (per unit volume or per unit mass) varies a lot in literature. You can find values for the energy per unit volume between 6 and 7.1. By using these values you find also a significant difference in the blast wave results.
Yes.
You can find the standard material properties of TNT, Air and .... in AUTODYN library.
Hi Martin,
I'm using the parameters given in the Dobratz from Levermore.
Bertrand
I am aware of the parameters from the AUTODYN Material library. But I doubt that espiacily these values are correct. You will find the same values in Dobratz 1981 but in a newer version of his book 1985 the value for example for the internal energy increased from 6 to 7 MJ.
I always use the the AUTODYN material library for my researches. But if you cant trust to that, you may use the parameters in journal papers. However i still suggest you to use AUTODYN library.
I am using the values in Dobratz 81. I was not aware of changes in these values (specially for tnt). I will have a look again.
Hi martin,
you can find many JWL parameter in this publicayion:
JWL EQUATION OF STATE COEFFICIENTS FOR HIGH EXPLOSIVES
LAWRENCE UVERMORE LABORATORY
E. Lee, M. Finger, W. Collins, 1973
http://www.osti.gov/scitech/servlets/purl/4479737
http://www.osti.gov/scitech/servlets/purl/4479737
An Another interesting bool is :
Dobratz, B. M., "LLNL Explosives Handbook. Properties of Chemical Explosives
and Explosive Simulants", UCRL-52997, Lawrence Livermore National
Laboratory, March 1981. UNCLASSIFIED
A previous version is avalaible at
Pascal Galon
http://www.osti.gov/scitech/servlets/purl/4285272
Hi Martin,
We usually use 7. This is probably an over estimation but for security applications gives some reserves.
Isabelle Sochet published some nice articles with lots of data:
Blast Wave Parameters for Spherical Explosives
Detonation in Free Air, 2011
and, Blast effects of external explosions, https://hal.archives-ouvertes.fr/hal-00629253/document
I guess this also depends on your problem size and a possible confinement as the oxygene balance has a large influence on the overall released energy.
Did you do comparisons of numerical calulations with measured data?
Best regards,
Achim
a = 371.2GPa; b = 3.231GPa; r1 = 4.15; r2 = 0.95; Omega = 0.30; E0 = 7.0GPa -m3/m3
they strongly depend on the initial density of the considered TNT and there is no standard for this value, it actually dépends on the process.
The most given reference is the one said by Gayan above. But if you change the initial density of the explosive, then you have to reconsider it. Then you need a Thermochemical code like EXPLO5, CHEETAH ...
@Gayan Wijesundara
Hi
When I used 7 for detonation energy density for TNT properties in Abaqus, the error like speed ration above 1 reported.why?
for common explosive charge, the value of constants available in autodyn or ansys engineering data library
Dear friends,
I need the departure functions of JWL to add this equation of state to openFoam liberaries. How can I find them?
Thanks
Dear friends,
There are different JWL parameter sets for TNT explosive published through the years, derived mainly through iterative numerical simulations to fit experimental tests such as the cylinder expansion test. The following research article provides a comparison of the blast wave characteristics of the various published JWL parameter sets for different scaled distances. Hope this helps!
Article Numerical review of JWL parameters for TNT explosive in free-air blast
With regards to the choice of TNT parameters, a conservative choice might be the most appropriate for blast effects analysis. This would mean placing priority on the parameter sets that provide higher impulse and over-pressures.
@Hamid Moaieri , you can restrict your stable time increment and introduce flux limit ratio to ensure numerical stability.