chladni plate

This semester I had the pleasure of having a personalized course in which I had to do extensive investigations into visualization of frequency and waves. The course had to be completed by making a device that I thought would best communicate phenomena such as wave propagation and resonance and which would be used as a teaching tool in the engineering course dynamics & vibrations. Below you can see the final result of this process as well as a brief montage of images and text describing both the nature of the preliminary experiments and a behind the scenes look on how the final device was constructed.


Idea & conceptualization

For this project I had some different requirements than usual. Because the machine was going to be used for teaching purposes the design had to be all about functionality. The machine had to be designed in a way that offered a maximum amout of functionality settings in order to achieve the widest range of experimental options. In the some time I wanted the machine to appear immediately alluring to people how does not necessarily know what it is for. Thus, I chose to make the interface as simple as possible, and tried to give the machine qualities like those you'll found on arcade machines. Additionally, I wanted the machine to be constructed in a way that allowed for an effortless cleaning and replacement of the most vital parts and also make it so that the aluminium plate, on which the patterns emerge, would be easy to clean, replace or exchange to one of a different geometry.

Below you can see the very first CAD model that I made prior to the actual construction. The drawing is made in google sketchup which I find to be very useful when it comes to making quick 3D models that are not too organic in shape.




Experiments

As a part of the course I was asked to make several investigations into visualizing frequency and wave propagation. To accommodate this, I was trying everything from the schlieren photography technique to standing waves through ultrasonic mist out for its wave visualization portential. Though I did not get satisfactory results from all my experiments I still learned a bunch and espacially when it comes to the Schlieren technique I'm most definitely going to conduct many more experiments on. I think I have a really good idea for what that can be used for artistically.

Below you can see pictures of some of the experiments that I conducted. I have chosen to only let the investigations that led to the final concept appear as it would simply be too much if I showed all of the experiments. Though, don't feel that you missed out on something. I'm sure that a lot of what I found out during these investigations will be utilized in later projects.



Creation

Now, it was time for the construction of what would come to be a beefed up version of the chladni plate experiment. Consequently, the machine had three individually controllable vibration generators, a venturi effect based sand circulation system and a easy to replace vibration plate mechanism. The following is a short montage of images and text conveying the details about the building phase.


When trying to find different ways of getting the sand into an air stream I studied sandblaster designs as well as car carburetors which both utilizes the venturi effect to create a suction that pulls in sand or fuel. The problem that I had was that I wanted to feed stand into a pipe with a blowing fan attached to one of its ends. That meant, that if I drilled a hole in the pipe in order to let sand into the airstream the fan would simply blow all the sand back up insted of adding it to the stream. That sort of issues, it turns out, can be solved with a use of the venturi effect. I won't go into great detail about the venturi effect but if you are not familiar you should definitely look it up, personality I find it to be a really useful principle.

However, you will probably get a better idea of the effect of the venturi based system by taking a look at the illustration below. On the illustration you can see how a narrowing of the pipe increases airflow locally and allows for a suction effect if you drill a hole in that exatct region of the pipe.


I ended up making a sand circulation system that works as follows: When sand from the chladni plate, because of vibrations in the metal, falls off the sides of the plate iit is then directed into a huge funnel from where it is guided into a steel pipe for it only to be blown back up on the chladni plate when the user pushes a button and thereby activates a powerful centrifugal fan. The venturi effect comes into the picture in the part of the process where the sand has to be mixed with the airstream caused by the centrifugal fan. As I said, if I don't add a narrowing of the pipe where the sand and air are mixing, the air would blow all the sand back up causing this system to both accumulate a lot of sand in the funnel and create a lot of dust that eventually would damage mechanical and electronic components.



Conclusion

Looking back on this project I realize how many of my skills had to be used to construct a machine like this. I really appreciate to get to exercise so many of ones skills on just one project. If I had to do it all over, I would definitely put more attention into future maintenance of the machine and I would probably have experimented more with different types of sand and plate geometries.

As the very last thing I would like to thank associate Professors Jacob Hvidtved Lawaetz and Imad Abou-Hayt for getting in contact with me and giving me the opportunity, time and resources to make investigations into an area I have wanted to know much more about for an extensive period of time. It was a blast!