Projectile impact contact time

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Discussion Overview

The discussion revolves around determining the contact time of a projectile colliding with a plate, with the aim of calculating the pressure exerted on the plate based on material properties and impact dynamics. The scope includes theoretical considerations and practical applications related to impact mechanics and material strength.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant inquires about calculating contact time during a collision to determine pressure using force and area, given specific material properties of both the projectile and the plate.
  • Another participant suggests that knowledge of the geometry and elastic properties of both the projectile and the plate is necessary to accurately assess pressure.
  • A participant mentions having the dimensions of the bullet and plate, as well as the potential to find elastic properties, and emphasizes the need for a method to calculate contact time for pressure calculations.
  • One reply highlights the complexity of collisions and suggests that simple formulas may not suffice, recommending finite element software for non-destructive scenarios, while noting challenges for destructive impacts.
  • A participant acknowledges the complexity of the subject and expresses a desire to find a way to calculate contact time based on material properties to evaluate whether the plate can withstand the pressure from a bullet, outlining three potential impact scenarios.

Areas of Agreement / Disagreement

Participants express varying degrees of understanding regarding the complexity of calculating contact time and pressure in impact scenarios. While there is agreement on the need for material properties and geometry, no consensus exists on a specific method or formula to achieve the desired calculations.

Contextual Notes

Limitations include the dependence on accurate material properties, the need for detailed geometric information, and the unresolved nature of how to approach the calculations for different impact scenarios.

AleksanderP90
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I am interested to know if there is possible to find out the contact time by a colliding object into a plate, given material properties? My object is to find out the pressure on a plate using force acting on an area.

What i know:

Mass of both projectile and target plate
Impact velocity of projectile
Density of both projectile and target plate
I also know yield strength, ultimate strength.. for the plate.
 
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If the object is really to know the pressure then I think you will need to know the geometry and elastic properties of the plate and also that of the projectile.
 
Well I know the dimensions of the bullet and plate, like radius, length and width, height of the plate. I could also know some elastic properties of the plate if I find a table that would give me those properties as a material.

The main thing I want to know if there is some way to calculate the contact time. That way I can calculate the Pressure with Force/Area. (I need the time in the force calculations)
 
AleksanderP90 said:
Well I know the dimensions of the bullet and plate, like radius, length and width, height of the plate. I could also know some elastic properties of the plate if I find a table that would give me those properties as a material.

Check out all the complicated stuff that goes on in such collisions:

https://www.youtube.com/watch?v=QfDoQwIAaXg

You can't seriously expect a simple formula for pressure, based on some basic parameters. For non destructive collisions you could use FE-software. But the destructive stuff would be a challenge even with that.
 
I know that this subject is very complicated, and that is why I want to know a way to calculate contact given material properties, that way I can find out if the plate will withstand the pressure from a bullet. There are three different scenarios: No indentation and bullet does not leave a mark, indentation where bullet hits, and last the bullet will penetrate the target.
I have watched that video a lot, and to decide what scenario a bullet will do, I only need to check pressure against the Yield strength and ultimate Strength for the plate. I don't want to simulate the complete process, only first find out what scenario I am dealing with.
 

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