A laser-powered journey into projectile resistance
In the world of protective materials, scientists are always looking for ways to make things that can resist high-speed projectiles like bullets or even jellyfish stings. But it’s hard to figure out how well a new material will work in real life just by looking at it under a microscope.
To solve this problem, a group of researchers at the National Institute of Standards and Technology (NIST) developed a cool new method. They use a powerful laser to shoot tiny projectiles at materials and see how they react. By studying this micro-level interaction, they can predict how well the material will resist projectiles like bullets. This new method saves time and money because they can do fewer extensive experiments with real bullets.
Katherine Evans, a chemist at NIST, explained why this is important. When scientists want to test new material for protection, they want to save resources if it won’t work. With this new method, they can figure out early on if material is worth investigating further.
“When you’re investigating a new material for its protective applications, you don’t want to waste time, money and energy in scaling up your tests if the material doesn’t pan out,” Evans said. “With our new method we can see earlier if it’s worth looking into a material for its protective properties.”
In the lab, scientists can easily make small amounts of new material, but it’s much harder to make enough of it to do the big tests. This is especially true for new synthetic materials. Scaling up production to make a lot of testing material is difficult.
Christopher Soles, a materials research engineer at NIST, talked about the challenge of making and testing new materials.
“The problem with ballistic tests is that you must take two steps when making new materials,” Soles said. “You need to synthesize a new polymer that you think will be better, and then scale it up to kilogram size. That is a big jump. The biggest accomplishment of this work is that we surprisingly show that the micro-ballistic tests can be scaled and linked to real-world large-scale tests.”
During their study, the researchers tested different materials using their method. They looked at a compound used in bulletproof glass, a new type of material called a nanocomposite, and a super-strong material called graphene.
Their method, called Laser-Induced Projectile Impact Testing (LIPIT), involves shooting tiny projectiles made of glass or silica at a thin layer of the material they want to test. The laser creates a powerful wave that pushes the projectile into the material.
One of the materials they tested was a nanocomposite called polymer-grafted nanoparticle polymethacrylate (npPMA). It has tiny particles that could be used for body armor. They shot the projectiles at the material and used a camera to see what happened. By combining their results with existing data and doing some math, they could predict how the material would perform against bigger projectiles.
They found that a material’s ability to resist punctures is related to its failure stress, which is how much stress it can handle before breaking. This challenges what scientists used to think about how materials work against projectiles.
This new method helps scientists choose which materials to use for different applications. They can even study things like graphene, which is really thin but super strong, to see how well it can protect against impacts.
The researchers are excited about the possibilities this opens up. They can study new materials for many applications, like making better protective gear, protecting spacecraft, or even developing new ways to deliver medicine. They also want to connect their experimental results with computer simulations to learn even more about how materials work.
Ultimately, this new method could produce stronger and safer materials in various fields. It’s an exciting step forward in understanding how materials behave under high-speed impacts.
Their study was published in ACS Applied Materials & Interfaces.
