Impact Forces & Brittle Behaviour - Finding a Simple Approximation

[tuoni]

I am working on a ballistics model, and have been trying to find some material on impact forces. Does anyone have any reference material for creating an approximation of the brittle behaviour of materials over short time scales?

At sufficient impact velocity a material will appear to be more brittle than it is, even ductile materials. There is no time for energy to be dissipated into the target material, and most of the kinetic energy of the bullet goes into fracturing the material.

Is there any simple way of approximating this behaviour?

Also, does crack formation and propagation have any effect on penetration? I.e. does a crack propagating ahead of a bullet along its axis weaken the material, and would it have any noticable effect relative to yield/drag forces?

 

[LightHero]

The simplest way of approximating the brittle behavior of materials over short time scales is to use a material model with a specific cracking threshold. This threshold should be set to a value lower than the yield strength of the material, and should be adjusted to account for the velocity of the impact. Crack formation and propagation can have an effect on penetration in that it weakens the material ahead of the bullet, allowing it to penetrate deeper than it otherwise would. However, this effect is usually overwhelmed by the drag forces caused by the bullet traveling through the material.

 

[astrokreng]

I can understand your interest in finding a simple approximation for the brittle behavior of materials over short time scales in your ballistics model. Impact forces and brittle behavior are important factors to consider in understanding the behavior of materials under high-velocity impacts.

In terms of reference materials for creating an approximation of brittle behavior, I would recommend looking into research papers and publications on high-velocity impacts and material behavior. There are also computer simulation programs that can model impact forces and brittle behavior of materials, which could be helpful in your research.

Regarding your question about the effect of crack formation and propagation on penetration, the answer is yes. Cracks can significantly weaken a material and affect its penetration resistance. This is because cracks act as stress concentrators, causing localized stress concentrations and reducing the overall strength of the material. Additionally, crack propagation can also lead to fragmentation of the material, further reducing its resistance to penetration.

To approximate the behavior of cracks in your model, you may need to consider factors such as crack length, orientation, and the material's fracture toughness. It is also essential to consider the impact velocity and the material's strength and ductility, as these can also affect the formation and propagation of cracks.

In conclusion, there is no simple way to approximate the brittle behavior of materials over short time scales, and it is crucial to consider various factors and reference materials in your research. Additionally, crack formation and propagation can have a significant impact on penetration resistance, and it is necessary to consider these factors in your model. I hope this information helps in your research.