Early in my career as a Product Development Engineer, I developed a system to perform vibration analysis on the carbon fiber tubes we used to make our tripods. Later on as I was tasked with starting our in-house tube manufacturing, this process became critical to my R&D activities and determining how the tubes I was making performed compared to the tubes we were buying. # The setup ![[Pasted image 20250908215058.png]] ![[Pasted image 20250908215101.png]] I designed a V-block fixture for the tube specimens, and a process for ensuring repeatability between setups. I used a 3 DoF accelerometer affixed to the same point along the tube relative to the fixture. # Making Waves To test how the tubes responded to vibrations, I needed a controlled way to excite the tubes and ended up with two methods: ## The Ball Drop ![[Pasted image 20250908215111.png]] The first and most simple method was to drop a mass from a controlled height. I used a ball bearing that was held in place by a pin, and the drop height was controlled using a 123 block for reference. The pin was pulled allowing the ball to fall and impact the tube with the same energy every time. ## Surface Transducer ![[Pasted image 20250908215124.png]] Have you ever seen one of those devices that, when pressed against a surface (E.g. a wall, a box, a table etc...) turns that surface into a speaker?- Those are surface transducers. They are essentially speakers that vibrate surfaces directly, rather than using a diaphragm that modulates air pressure. ![[Pasted image 20250908215134.png]] The transducer would be hooked up to an amplifier, which allowed me to vibrate the transducer at using any waveform of my choosing. This signal could come from a traditional waveform generator, or any 3.5mm audio output. # Analyzing The Results The last piece of the puzzle was visualizing the results. I used an oscilloscope to read the output of the accelerometer. From there, I was able to quantify and compare natural frequency, impact force, resonant frequencies, and vibration dampening. ![[Pasted image 20250908215152.png]] ![[Pasted image 20250908215156.png]] ![[Pasted image 20250908215200.png]] In reality, vibrations are rarely one frequency. By applying a fast fourier transform in a spectral analyzer, I was able to break down any given impulse into it's frequency components ![[Pasted image 20250908215218.png]] ![[Pasted image 20250908215222.png]] ![[Pasted image 20250908215225.png]] # Results Because of this process, I was able to correlate the vibrational characteristics of our R&D carbon fiber tubes and lay the ground work for production, and the future development of vibration damping composite structures