Hammer Handle vibration and failure analysis

[Glenn]

While looking for hammer handle materials I found the following




We designed and executed series of tests to compare and contrast three types of hammers--one with a hickory handle, another with an "unbreakable" fiberglass handle (or so claimed the marketing), and a final one with an ergonomic "anti-vibration" steel handle. Using data from tests performed with an Impact Tester, Instron Machine, and a custom setup with accelerometers, we compare and contrast the claims made my their packaging and their suitability for use.

Team Members: Oliver Haas, Leif Jentoft, Adam Kenvarg


Click here for the results

[Rich Hale]

Great idea. Sure wish I could read that page you linked us to: The print os too timy for me to read. And when I am on thqt page it makes my puters option to increase the size in percentages so I cannot do that. Any ideas?

[Glenn]

The PDF format has an option for enlargement. The pull down menu is about middle of the top bar. You can choose the size you want, from almost nothing to I think about 500%. You may be able to type in a specific size also. You may have to use the scroll bars bottom and to the side to locate the area of the chart you wish to read.

You can use the magnifying glass icon and drag it onto the area you want to enlarge. Click for additional enlargement. This is slower but works.

[Woodz]

You can also hold Ctrl and scroll your mouse wheel to increase size.


Interesting article, Glenn, thanks.

[son_of_bluegrass]

Terrible lay-out on the report. Yuck.

That aside, I wonder how hammer head hardness, shape and weight affected the results.

ron

[Glenn]

To eliminate the variables, use the same hammer head with different handles, one wood, one plastic, and one metal. You might have to wedge all three in place, and then glue all three in place, to get good results.

[Ferguson]

It looks like the students did a lot of testing, but they were weak in terms of usable conclusions. Others have commented how their presentation required magnification to read, but maybe their real goal was a large poster, not something internet friendly.

Are they saying that the wooden handle hammer had more vibrations than the other types of handles? And that the metal hammer had less harmful frequency vibrations? By superimposing the graphs it was almost impossible to read the accelerometer graph. The frequency distribution graph was more or less readable. Three graphs side by side would have been a lot more readable.

But other than criticizing the report and its format, what usable information can we get from this?

Richard

[thingmaker3]

"Examining the Young’s Modulus of each of the materials, we find that our experimental value is three orders of magnitude less than the expected value for the material."

Somebody needs to teach these kids about "tensile" versus "shear."

"The homopolymeric structure of polypropylene is shown to the right."

Somebody needs to teach these kids about "right" versus "left."

Somebody also needs to teach these kids about the effect of shape on vibration. And the difference made by rubber coating versus no rubber coating.

I'd give them an "F." But Harvard is known for making lawyers & doctors - NOT for making engineers.