Modeling Software for EHS Professionals

How does ExDAM account for shielding effects?

The shielding algorithm in ExDAM involves the use of finite line doublets from potential theory. Each structure/component is characterized by its three dimensions and orientation. For shielding effects, the direction of the blast wave is taken into account relative to the orientation of the shielding structure/component. The shielding factor is computed from potential functions based on the finite line doublets, and the pressure reduction is further computed from the shielding factor.

Does ExDAM compute secondary explosions?

Yes. Each structure component is considered a source of a secondary explosion if it is damaged above a certain threshold. Secondary explosions produce collateral effects in the form of increased damage levels to nearby structures.

How does ExDAM account for pulse duration effects from high explosive?

As the explosive yield increases, the corresponding pulse duration also increases. For a specified overpressure or dynamic pressure level, the longer the pulse duration the greater the damage. For a fixed scaled distance, (distance/yield)1/3, the overpressure or dynamic pressure is essentially independent of yield. Because of the effect of pulse duration, however, the damage level remains dependent on yield and will increase as yield increases. Structures/components which are classified as "Q" type are more sensitive to this effect than are "P" type structures/components. For each structure/component, two pulse duration factors (with values ranging from 0 to 10) are assigned, corresponding to moderate and severe damage. For "P" type structures/components the pulse duration factors are on the order of 2.5 while for "Q" type structures/components the factors are on the order of 8. Each structure component is also assigned levels of overpressure (Pm and Ps), or dynamic pressure (Qm and Qs), corresponding to moderate and severe damage, along with a fixed reference yield.

The actual yield used in an individual test case is an input variable, and will generally differ from the fixed reference yield. The pulse duration factor, the yield, and the reference yield determine the R-factor which connects the moderate and severe damages with this difference in yield.

How does ExDAM compute damage/injury levels due to high explosives?

Damage/injury level computations are based on the incident pressure, either peak overpressure or peak dynamic pressure, which would occur at a distance from the burst point corresponding to the centroid of each structure/component, as projected into the horizontal plane at ground level. Such pressures are adjusted to take into account shielding and collateral effects. The dimensions and orientations of the structures/components do not directly affect the calculations.

How does ExDAM predict damage/injury levels due to a vapor cloud explosion?

The damage/injury to each structure/component is based on the maximum peak overpressure, combined with the accumulated impulse, reduced by shielding, and supplemented by secondary explosions. The adjusted values for peak overpressure and impulse are used as inputs to a pressure-impulse diagram characteristic of the structure.

How does ExDAM predict overpressure and pulse duration for a vapor cloud explosion?

Peak overpressure and pulse duration of the positive phase produced by vapor cloud explosion are calculated based on the TNO multi-energy method, and they are functions of the participating combustion energy, the explosive strength, atmospheric pressure and temperature and the ambient speed of sound. Both overpressure and positive phase duration are stored in dimensionless form as a function of dimensionless range for various explosive strengths.

How does ExDAM predict impulse due to a vapor cloud explosion?

ExDAM predicts impulse due to vapor cloud explosion by integrating overpressure over the pulse duration.

How do I setup blast characteristics? Is there any pre-defined module to put together an explosion scenario?

Users can specify vapor cloud explosion and high explosive parameters in corresponding tabs within BREEZE ExDAM software. For high explosive, users need to specify the TNT-equivalent yield (mass) and location; for vapor cloud explosion, users need to specify the fuel type, vapor cloud size and location, atmospheric temperature and pressure, and explosion strength (1-10). If the fuel type is user-defined, users need to specify molecular weight, stoichiometric mixing ratio (by volume), and net combustion energy.

BREEZE ExDAM has a fuel type database which contains molecular weight, stoichiometric mixing ratio and net combustion energy for common materials; it provides three high explosive examples and three vapor cloud explosion example. With little training and practice, users will be able to do a full explosion scenario easily.

Can ExDAM handle detonation vs deflagration modeling?

BREEZE ExDAM uses the TNO Multi-Energy method for vapor cloud explosions. This involves selecting an ‘Explosion Strength’ which distinguishes a deflagration from a detonation. The method is based on a numerical simulation of a blast wave from a centrally ignited spherical cloud with constant velocity flames.

For a detonating cloud, explosion strength 10 can be used. For explosion strengths 1-9, the pressure profile is a deflagration. For explosion strengths 6-9 as the blast propagates away from the centre of the explosion, the gradient at the front will steepen and eventually become a shock wave, like the blast from a TNT charge.

How complete are the fuel air mixture options for vapor cloud explosion?

There are 15 pre-defined fuels with fuel-air mixture volume ratio corresponding to stoichiometric composition. Users can choose a user-defined fuel type by specifying molecular weight, fuel-air mixing ratio, and the net combustion energy.

What kinds of construction material options are available in library? Can we add more?

BREEZE ExDAM includes 123 master structure materials and 19 human body component materials. Users can also create custom materials.

Where can I get P-I data?

Contact BREEZE at +1 (972) 661-8881 or for a quote on P-I data.

Pricing from $10,995

ExDAM® has two available modules. Discount provided for the purchase of both.

  • HExDAM - $10,995
  • VExDAM - $10,995
  • HExDAM, VExDAM - $19,995

ExDAM® extensions include:

  • 3D Extend - $5,995
  • HExFRAG - $7,995

Includes one year of maintenance with purchase.

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