Run a blast analysis

A charge goes off some distance from a part, and you want to know what the blast wave does to it: how far it bends, where it yields, how much of the deformation stays. That is explicit dynamics with a pressure load rather than an impact — the part is standing still when the charge detonates.

Solved by OpenRadioss. The free tier caps the event at 10 ms, which is long enough for the wave to arrive, load the part and leave it ringing.

Pick the analysis

Press + New simulation.
Choose Explicit dynamics, then Blast.

Mesh the part

As every solid family does, with the same restriction the rest of this family has: first-order tetrahedra only, because an explicit code carries no mid-side nodes.

The mesh also decides how finely the load is applied. The pressure is worked out for each triangle of the struck face separately, at that triangle’s own distance and angle to the charge, so a coarse face gets a coarse picture of the wave — which matters when the charge is close enough that one end of the face is much nearer than the other.

Set the material

The same elastoplastic Johnson-Cook material as the rest of the family; see Run a drop test for what each number means. A yield stress is required.

Blast loading is fast — pressures rise in microseconds — so if you have strain-rate constants for your steel from the same source as its yield stress, this is a case where they earn their place.

State the charge

On the Models step, under CHARGE:

Face struck — the side of the part that looks toward the charge. Only this face is loaded.
Charge — the mass in kilograms of equivalent TNT. For another explosive, convert first by its TNT equivalence factor. That factor is published separately for pressure and for impulse and the two differ; use the one for whichever governs the damage you care about.
Charge X, Y, Z — where the charge is, in the part’s own coordinates. The pane prints the part’s extent above these fields so you can see which way its coordinates run.
Burst — Free air for a charge with nothing near it, Surface burst for one sitting on the ground. A surface burst reflects the wave straight back up and behaves like a free-air charge of roughly 1.7 to 1.8 times the mass.

Hold the part somewhere. Under RESTRAINT, pick a fixed face. A part with nothing holding it is not wrong — it simply flies away, carrying the blast’s impulse as momentum, and barely deforms. What bends a part is being held while it is pushed.

What the pane refuses, and why

The pane checks the charge against the part as you set it up, and says so before you press RUN. Each of these would otherwise run and give an answer that looks reasonable:

It says	What it means
the face looks away from the charge	The blast would strike its back. The part would be pushed toward the charge, not away — pick the face that sees it
closer than the blast data covers	The charge is so close it is still a fireball at the part. The published data does not go there, and the solver would extrapolate it
farther than the blast data covers	Past 40 m per cube-root kilogram, where the data stops
a surface burst below its own ground	A charge on the ground loads what stands above it. Part of your face is at or below the charge, and would get nothing

Run it, and read it

Press RUN. The starter checks the deck, the engine advances it, and a third program converts the last animation state for the viewport.

The result carries von Mises stress and plastic strain. Plastic strain is the one to read for permanent damage: it is what did not spring back.

Remember that the state shown is the end of the event, not its worst moment. The peak stress during the wave’s passage is in the earlier states in the run folder.

What this build does not do

Not possible	Why
Fragments, casing or debris	The load is the air blast alone
A charge inside a room or tunnel	Reflections off walls add to the load; this is the open-air wave
A blast that tears the part open	Elements can be deleted at a stated failure strain — set one on the Materials step under FAILURE — but nothing here has been checked against a measured breach, so read a torn result as an illustration and not as an answer

How far to trust it

The load itself is checked against the published blast data — Kingery and Bulmash’s 1984 report, the source the TM5-1300 and UFC 3-340-02 charts come from — and agrees to 0.02% for a free plate, square-on and at an angle, for two charge sizes and both burst types. What the part then does with that load is ordinary explicit dynamics, with the same element-technology caveats as the rest of the family: first-order tetrahedra are stiff in bending, so a thin panel wants several elements through its thickness before its deflection means much.

See the verification page for the measurements.

Run a drop test — the same family, an impact instead of a pressure load.
Explicit analysis and Explicit material — every control on the two panes.