Last week, I worked on a bunch of random stuff. Mostly I helped work on a new prototype for test bed 6. It is lighter and more compact than the old one. I am trying to help create a new ankle angle sensor also. But mostly just waiting for materials to get in.

Fun times with an Oildyne Pump

      This past week has been filled with a lot of reading. I received a 300 page book from Professor Durfee on O-ring materials, properties, fittings, etc. But I also had the chance to do some really fun things taking apart the miniature circuit that our lab uses to demonstrate the power density of compact fluid power machines.

Miniature Hydraulic Circuit

      This is the small hydraulic circuit that we use for demos. The entire thing is about the size of a sheet of paper. Although detached from the circuit in this picture, a small motor and pump contained in a manifold casing are attached to the two ports at the bottom right corner of the circuit. The small loop of metal wire (see top right corner of the circuit) is attached to the actuator and is used to attach a load to the actuator. Currently the system can lift a load of 300 pounds during actuation. Right now there's a minor problem with the reservoir not having a cap, making such tests very messy, but stay tuned for testing the circuit out to see if it can lift the other REUs at UMN! 

From left to right: motor, pump, manifold

     Now for fun times with the pump! first I had to take apart the motor, manifold, and pump. In the complete circuit, the pump fits snugly into the manifold which prevents the external pump casing from rotating when the motor is running. I decided to take them all apart and see what everything looked like on the inside, including figuring out how the inlet and outlet in the pump connected to the manifold and the rest of the circuit. Then Jicheng (a grad student in my lab) and I decided to have a little fun and tried to see if we could actually watch the pump displacing fluid out of the outlet.

Some serious struggle-bus moments and a LOT of spilled oil later, we ended up with this. Enjoy!

A Change of Scenery and A Change of Topic!

Hey everyone!

So far it has been an amazing, work-filled, and pretty insightful week. First, to begin, I found out on the  day after my return to Milwaukee that my research project would be changed from dealing with biodegradable fluids to working with reservoir sizing. Thus far the new name for my project is "Determining an Engineering Basis for Specifying the Size of a Hydraulic Reservoir"

After doing some initial digging on the criteria for reservoir sizing I was pretty shocked to figure out that there was no engineering or mathematical basis behind why the size of a hydraulics reservoir has to the size it is. I was able to determine that criteria used to size the reservoir include pump flow, cylinder displacement, slope, heat rejection, and aeration. One recommendation offered by many sources stated that the reservoir size should be 2-3 times your flow rate from the pump. What if there were a way to make it smaller?

My project will essentially revolve around the criteria used to size a hydraulic reservoir. I will stop here, but I just wanted to give you all a brief preview of what my project has become since leaving Purdue. I have a couple schematics and pictures of some of the equipment that I'll be working with, but that's for next time!

Thanks for reading!

Chris

A week already flew by?

Hey everyone! Hope everyone is doing alright!
So far I haven't done too much except read a lot of manuals and textbooks, and help out grad students here and there with their projects. During the first week I read papers on some previous students' work and had to read textbooks to get familiar with basic hydraulics and acoustics. The grad students taught me how to use the oil rig for testing and gave me a brief overview of how everything functions. In addition to working on my project, I am expected to help out other grad students with their projects. For example, I helped them test their hydraulic suppressors and collect data. I also had to make a fluid power schematic of the oil rig using all of those symbols learned at the boot camp. As far as my project goes, I'm still learning and researching on ways to optimize the device I'm creating and calculating the stresses that the device will undergo.

First update, for science

Hello all, hope you have all survived since the CCEFP meetup and have quickly assimilated to the REU sites.

I initially thought that I would be dealing with some direct involvement with Test Bed 6 (Human Assisted Ankle Foot Orthosis); my project title from the CCEFP website was as vague as they come, "Novel Fluid-Power Components through Additive Manufacturing". When I finally met with my advisor, he drew up some suggested routes to take the research project to, which I deduced to thermoelectric generators (TEGs)/energy harvesting or meso-scale steam turbines and actuators. I chose to continue the work on waste heat recovery from a previous REU participant from 2011 (Toni Borel) in seeing the impact that a TEG could have if implemented to any of the test beds, as they convert thermal energy and heat into electrical energy. Considering the project is listed under the compactness thrust, portability and size is definitely a consideration, as TEGs are mobile due to lack of moving parts. Additionally, the ability to extract excess heat from engines and convert it to useful energy would help improve efficiencies in most fluid power systems. I expect to fabricate my own miniature TEG and fully testing its capabilities for future use. Currently, we are using a demonstration kit from last year until a better commercial manufacturer is found; awaiting a soldering iron from McMaster to solder small contacts. 

The following short video demonstrates one of three effects (Peltier effect) that comprise of thermoelectricity theory. 

Your working on SimHydraulics! Oh wait, Just Kidding...

Thursday Professor Durfee returned to the University of Minnesota from vacation. We had a wonderful talk about my project, and we seemed to have settled on a topic. I would be responsible for modeling the refined AFO hydraulic circuit in SimHydraulics, a branch of Simulink in Matlab. The current generation of the AFO circuit is functional, but too heavy due to excess pipe fittings and an unnecessarily large cylinder. He explained the my goal would be to gain expertise in SimHydraulics and develop this model. Energized, I set out to master SimHydraulics through various tutorials and by reconstructing the existing models for the Generation 1 AFO circuit.

This is one of the sample circuits that you can find in the SimHydraulics tutorials. It's pretty simple, but it still took me a good hour to figure out how to put it together. 

I was modeling away happily, when Professor Durfee walked into the lab. He then informed me that I would be doing little to no modeling for the rest of the summer. Instead I would be responsible for machining a newly designed miniature cylinder, and running tests on the new hydraulic circuit to verify the theoretical values for circuit power and efficiency that one of Professor Durfee's grad students, Jicheng, has calculated. Honestly, I'm thrilled that I get to do some hands on machining and experiments instead of sitting in front of the computer all day! I've got to keep reading up on basic hydraulics for the next week, but soon Jicheng should be done designing the new cylinder and I can get started!

Hi everyone!

This first week has flown by! I have done a TON of reading on hydrostatic transmissions and wind turbines, and I am beginning to look at Matlab's Simhydraulics. This is all in preparation for my project which consists of modeling a split power system (between a planetary gear box and a hydrostatic transmission) for a 50 kW wind turbine. I am really excited to start the modeling process although my first interaction with the computers in the mechanical engineering computer cluster does not bode well for me- after logging into a Linux system for the very first time I discovered that not only was I incapable of finding or opening any programs but I didn't even know how to logout. I was completely stuck and ultimately needed a one-on-one tutoring session from the tech department. I definitely owe them some pastries now!