- #1
berty_g
- 4
- 0
Hello!
At the moment, my collegues and myself have been asked to test some materials for their crush strengths. Unfortunately our dept. doesn't have a decent method for impact/crush testing, so we've come up with a modification to a Charpy Impact test.
If you're unfamiliar, it's basically a known weight/hammer on the end of a pendulum which swings into a material sample. Usually the quantitative result is read from a gauge mounted on the inside of the swing arm. However, in the case of 'crush' testing the sample isn't broken in two, but rather compressed. So we've attached a back plate so the pendulum swing arm hits a rigid wall. We've encountered some problems though, and I thought I could benefit from a lesson or two in mechanics as it's been a while since a-level physics.
We need to record 3 different sets of data: Velocity (of the hammer), Time and G (althought this can be calculated from velocity and stroke - the change in length of the crushed sample). I.e: We have a known maximum for Peak G and Average G, hence a range of materials are being tested. The variable in the experiment is the Material, all we need is a decent way to set up the data logger or something else, so that we can record everything we test.
We're thinking about using a data logger and potentiometer and using the gradients of the (time, potential) graph gradients to assosciate with velocity.
Any help, ideas or other ways of doing it entirely would be greatly appreciated. Note that if you help, you will be helping a real-life project involving the materials selection of an Impact Attenuator (crash box) for a formula one car.
Thanks for reading!
Bert
Ps: The attatched document is not my own and is the produce of Hexweb, the basic ideas are explained far better then I ever could. It also includes the basic mathematical elements. Note: we cannot do a weighted-trolley-impact-at-known-speed-type test due to H&S regulations in the dept.
At the moment, my collegues and myself have been asked to test some materials for their crush strengths. Unfortunately our dept. doesn't have a decent method for impact/crush testing, so we've come up with a modification to a Charpy Impact test.
If you're unfamiliar, it's basically a known weight/hammer on the end of a pendulum which swings into a material sample. Usually the quantitative result is read from a gauge mounted on the inside of the swing arm. However, in the case of 'crush' testing the sample isn't broken in two, but rather compressed. So we've attached a back plate so the pendulum swing arm hits a rigid wall. We've encountered some problems though, and I thought I could benefit from a lesson or two in mechanics as it's been a while since a-level physics.
We need to record 3 different sets of data: Velocity (of the hammer), Time and G (althought this can be calculated from velocity and stroke - the change in length of the crushed sample). I.e: We have a known maximum for Peak G and Average G, hence a range of materials are being tested. The variable in the experiment is the Material, all we need is a decent way to set up the data logger or something else, so that we can record everything we test.
We're thinking about using a data logger and potentiometer and using the gradients of the (time, potential) graph gradients to assosciate with velocity.
Any help, ideas or other ways of doing it entirely would be greatly appreciated. Note that if you help, you will be helping a real-life project involving the materials selection of an Impact Attenuator (crash box) for a formula one car.
Thanks for reading!
Bert
Ps: The attatched document is not my own and is the produce of Hexweb, the basic ideas are explained far better then I ever could. It also includes the basic mathematical elements. Note: we cannot do a weighted-trolley-impact-at-known-speed-type test due to H&S regulations in the dept.
