Some Friction at Home
Altair EmployeeIt’s crazy how we’ve been working from home for more than a year now. I do have to say that I am amazed at how well my partner and I adapted. We have definitely gotten our money’s worth with the espresso machine we splurged on pre-pandemic (not sure how I will ever be able to go back to office coffee) and I’m definitely not complaining about him now mastering sourdough bread baking. Working different schedules and navigating around the apartment “mission impossible-style” just to stay out of each other’s video calls have not really been an issue either. However, one thing was truly driving us insane… a squeaky door.
It was during an afternoon while recording a series of webinars (here) that at the same time my partner was moving around the apartment more than usual. I even think he was cleaning(!), hence opening and closing the door in question A LOT. Whereas I, with my noise cancelling headphones on, was blissfully unaware of him making all this noise. When I reviewed the recording a couple of days later, I noticed these annoying squeaky sounds in the background. As it turns out the recording microphone on my headset was very sensitive to the specific frequency of our door squeaking, so I then had to spend too much time editing that audio out of my videos.
As most of you know, the cause of this squeaky sound is friction in the door hinge, or more specifically stick-slip. Try dragging your finger across the table varying the pressure and you’ll experience the phenomena of stick-slip firsthand. Every transition from stick to slip can cause a noise. How often this occurs and how loud it sounds is highly dependent on the material pair and its characteristics such as surface graining and treatment as you can see and hear in the video below. In the case of my squeaky door, adding a surface treatment in the form of a lubricant quickly solved the issue.
Noises caused by incompatible material combinations are commonly considered very annoying and affects the perceived quality of a product. Besides unpleasant noises, the stick-slip phenomena can also lead to problems such as abrasion and wear so material compatibility becomes very important in product design.
Ziegler Instruments specializes in material pair testing, analyzing material compatibility, and touch haptics. The company has derived a reliable indicator, the risk priority number [RPN] to easily quantify material compatibility (i.e., the tendency a material pair have to emit a creaking or squeaking noise under certain conditions).
Through a collaboration between Ziegler and Altair, the data from more than 11,000 stick-slip tests (machine above) was gathered in the Ziegler stick-slip material database (below). This enables analysts and design engineers to explore different material combinations, take counter measures, and prevent issues at all stages of development. In the early development phase, the database provides a quick indication of the stick-slip behavior of the material combination using the RPN. Before building prototypes, the current material combinations can be checked and analyzed with the database. If incompatible pairs are found, the database can also help identify potential solutions since material combinations with different grain structures and coatings are also included. This makes it easy to check and analyze which coatings are helpful and will have a positive influence on the stick-slip behavior.
Ziegler Stick-Slip Material Database in Action:
The squeaky door in my home was an easy fix, but now we have moved to a new place and are instead struggling with a squeaky drag door to our patio. It’s only a problem when it’s hot outside (did I mention I live in California?). Why do you think that is?