Bulletproof.

[Scorpio64 5,180]

Hopefully there are some engineers here that can answer this for me.  Which would have a greater effect in stopping or slowing a bullet?  A solid 1 inch thick steel plate or four 1/4 inch steel plates clamped together or spaced apart.

 

 

 

[NYMetsFan86 9]

I don't have an answer but am very curious  what the project is

[High Exposure 5,673]

What kind of steel?

 

What kind of bullet? Velocity? Composition? Construction?

 

Are you worried about spall?

 

Is backface deformation a concern?

 

Does the energy need to be dissipated or simply stopped by the steel?

[checko 180]

I have no idea but all other variables being equal I would think a solid steel plate would give less

 

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[maintenanceguy 510]

solid steel - unless there's some unseen condition.

 

Consider that 1" plate as 4 1/4" plates all stacked together and bonded to each other with bonds as strong as steel.  The first 1/4" plate will be supported by 3 other identical plates that will strengthen it.   The same is true for plates 2 and 3. 

 

If you have 4 separate plates, none of the plates are supported.  Even if the plates are stacked tight against each other, there is more opportunity for each plate to deform independent of the others and each plate restrains the others less than if they were one piece.

[djg0770 481]

It's not like plywood, so solid is better in this case unless you're able to closely control the grain structure within the steel.

[Scorpio64 5,180]

I don't have an answer but am very curious  what the project is

 

No project.  I just have an amazing talent for conjuring up ridiculous questions.  I was thinking about energy and the way it is transferred and distributed through systems.

 

What kind of steel?

 

What kind of bullet? Velocity? Composition? Construction?

 

Are you worried about spall?

 

Is backface deformation a concern?

 

Does the energy need to be dissipated or simply stopped by the steel?

 

No specific kind of steel.  I'm not actually trying to make something bulletproof so I'm not looking for material recommendations.  You could just as easily substitute plexiglass or 2x4s.

 

Lets say you have a 6x6 post and three 2x4s, same volume of material but three surfaces to penetrate vs one.

[High Exposure 5,673]

Still depends what round you are trying to stop.

 

But generally, one solid piece of a material will be more effective than 3 seperate pieces if the mass, volume, and density are the same.

 

That being said, soft body armor is constructed in overlapping sheets for a reason. It is more flexible - you can shape it to wrap around 3D objects (like a torso) and you can move (breath, bend, etc...) in it. It also helps "catch" the bullet spreading the forces of the impact throughout the armor and preventing backface deformation and blunt trauma.

[Golf battery 1,223]

Multiple plates of course. Just like bullet proof glass. Where i worked we had 1.75" with 7 layers if ican remember would stop almost all the way a 223. Correct me if im wrong.

[JohnnyB 4,330]

Multiple plates of course. Just like bullet proof glass. Where i worked we had 1.75" with 7 layers if ican remember would stop almost all the way a 223. Correct me if im wrong.

With glass as with soft body armor, the layers are bonded together to in effect for a single, solid barrier!  OP is talking about separate layers clamped together or with a space between the layers!

[Golf battery 1,223]

Ok. I still cant envision it. Ill sleep on it.

[JackDaWack 2,895]

Glass is a bit different since its layers of 2 different materials.

 

Anything stacked will not be as rigid in comparison to a solid piece. Even though they may be tightly held together they are not technically bonded and work independently from one another.

[mipafox 438]

Multiple. The bullet will will start to yaw and deflect after each challenge.

 

Composite armor is more practical, though.

 

Small caliber bullets actually penetrate RHA steel because the impact heats the steel and softens it. That's why it looks like a meteor crater. Why the heck would steel splash out like a strobe image of a drop of water falling into a dish of water?

 

Also, formerly, the most effective rounds had a tiny bit of lead in the tip to settle the bullet and yaw. It would preheat the steel only slightly, but would settle the yaw of the penetrator core to do its job.

 

Nowadays, most AP rounds have incendiary in the tip, which is a very complicated subject.

 

Bottom line, it matters how your bullet meets the challenge, and after a couple most will have less penetration on an equivalent basis.

[JohnnyB 4,330]

Multiple. The bullet will will start to yaw and deflect after each challenge.

 

Composite armor is more practical, though.

 

Small caliber bullets actually penetrate RHA steel because the impact heats the steel and softens it. That's why it looks like a meteor crater. Why the heck would steel splash out like a strobe image of a drop of water falling into a dish of water?

 

Also, formerly, the most effective rounds had a tiny bit of lead in the tip to settle the bullet and yaw. It would preheat the steel only slightly, but would settle the yaw of the penetrator core to do its job.

 

Nowadays, most AP rounds have incendiary in the tip, which is a very complicated subject.

 

Bottom line, it matters how your bullet meets the challenge, and after a couple most will have less penetration on an equivalent basis.

Depleted Uranium is still the best armor piercing round! That's what the Navy taught me anyway! I remember the instructor passing just the projectile around the class. That sucker was black and very heavy

for its size! .55 cal I seem to remember! That was 38 years ago!!!!

[Shocker 151]

Small caliber bullets actually penetrate RHA steel because the impact heats the steel and softens it. That's why it looks like a meteor crater. Why the heck would steel splash out like a strobe image of a drop of water falling into a dish of water?

 

Because the stresses at the strain rate of a ballistic impact so far overwhelm the yield strength of the material that it the driving physics are better modeled by hydrodynamics where viscosity is more important. In the shock physics regime almost all materials act like a compressible fluid.

 

Yes, the material heats but a phase change from melting is an after effect. Even shaped charges don't melt their targets at a primary defeat mechanism.

[mipafox 438]

Because the stresses at the strain rate of a ballistic impact so far overwhelm the yield strength of the material that it the driving physics are better modeled by hydrodynamics where viscosity is more important. In the shock physics regime almost all materials act like a compressible fluid.

 

Yes, the material heats but a phase change from melting is an after effect. Even shaped charges don't melt their targets at a primary defeat mechanism.

Phase change is not an after effect. It has been known as one of the primary means of armor penetration since before WWII.

 

http://hrcak.srce.hr/file/209302

 

Skip AP bullets for a moment, and read up on AT kinetic penetrators and the aforementioned change to adding incendiary/explosive combination to the tips of API ammo. It took me years to believe that could possibly enhance penetration based on the speed of the attack but the data are indisputable.

[JackDaWack 2,895]

Reminds me of shape charges.