Three-point bend test fixture - with plans

3 Point Bend Test Report by phschemguy on Scribd

In the spring of 2015, Bob Hanlin, one of the ASM master teachers and a professor at University of Missouri-Kansas City, came to our spring training with a project that some of his students had developed. It was a three-point beam tester made on the cheap and designed to be cheaply made by high school teachers to more accurately and repeatedly test the cement composite beams that we make as part of the material science curriculum.

Bob had tasked his students with the following requirements, as found on page three of their final report - embedded above...

• Repeatable testing
• The new fixture and method of breaking the cement has to be able to be repeatable and provide similar results.
• Portable
• The fixture has to be compact and easy to transport since high school teachers will have to take the fixture to school and carry it around.
• Accurate
• The testing mechanism hast o prove similar test results when in use.
• Easy to make
• The new fixture design has to be simple and easy to make since high school teacher[s] will be building it to teach the students the importance of material science.
• Inexpensive
• The fixture has to be as low-cost as reasonably achievable since high school teachers have to function on a meager budget and sometimes [are] forced to spend their own money out-of-pocket.

Man, that's a set of requirements that screams understanding of the high school science/engineering teacher world. Cheap, easy to make, portable (storable, too), accurate, and repeatable...that's pretty spot on perfect for our world.

Bob showed off his students' creation at the training, and we were all amazed at the results. No, it's not a commercial beam tester, and the accuracy doesn't approach that level of precision and repeatability, but for $30, it's a brilliant bit of engineering.

I finally got permission from Bob (who actually had to get permission from the university) to publish the tester's plans here on my blog. The one stipulation was that credit had to be given to the students - Gabriella Baptistella, Zach Kellogg, Vincent Nolan, and Lee Seela - and to the University of Missouri-Kansas City. I'm happy to credit all of those folks because their product is just brilliant.

The students explored two fixtures and two methods of testing for each fixture. In the end, the best choice is the one they labeled fixture 2 - method 3. The exact plans for 2-3 can be found in the embedded document above in appendix B (p17). The fish scale that Bob used when he showed us was - I think - this one from Amazon. Everything else would be a Home Depot/Lowe's/local hardware store purchase.

Here are pics of the final product - along with Bob in the dark blue plaid.

 

By the way, in explaining how he'd gotten students to help design the tester, Bob mentioned that the funds for the design project came from the tuition that our ASM summer camp teachers have been paying for grad hours related to the teacher summer camps over the past few years. So it you - like I - have taken the grad hours, thank you for your contribution to this project.

So, go, make yourself some beams and get to testing them.

Oh, and if you want to see our old method for testing the beams, here's a pic from the UMKC website showing our pre-these-plans method from their ASM teacher summer camp.

Source - UMKC website