Development of a non-Newtonian latching device

Abstract

The objective of this project was to first evaluate the feasibility of developing a viscous damping device that used a Non-Newtonian Shear Thickening Fluid (STF) and incorporating it as a door latch into an existing commercial dryer unit. The device would keep the door closed during sudden large magnitude impact loads while still allowing the door to open normally when force is applied gradually at the door handle. The first phase of the project involved performing background research on the subject and performing preliminary analysis in order to determine if the concept was feasible enough to be worth constructing a physical prototype. This preliminary analysis consisted of a literature review of existing damping mechanisms and shear thickening fluids, rheometer testing of shear thickening suspensions to obtain viscosity data, and performing numerical simulations to determine if a damper that fit the size requirements could produce enough resistance force. The focus for the second phase of the project was to demonstrate a proof of concept in the form of a working model prototype. This prototype did not need be of identical shape and proportions as the finalized design, but would be developed to facilitate experimental testing and evaluation of performance under the desired operating conditions. It was also necessary to design and construct the test setup for the dynamic testing of the dryer door opening so that the opening displacement as well as the force applied to the door could be recorded as a function of time. The final phase of the project consisted of improving upon the original prototype in order to prove the validity of a viscous latch beyond the proof of concept phase in a form closer to what is desired for the commercial product. This required reducing the physical size of the new prototype latch so as to fit within the space available in a particular dryer, incorporate a one-way ratcheting device into the latch to allow unrestricted closing of the door, and increase the operational temperature range of the damper.