Snap Fit Calculations 1

[Klaxon1]

Hi,

I have been looking into snap fit clips on plastic parts, and have been fine so far working with strieght and tapered beams. I am now trying to work out an 'L' shape clip, but the only formula I have found is confusing. I have attached it to this thread. I have no problem filling in the formula on Excel, but the 'Y' result for the maximun deflection is way too high. I noticed that on the example, the Flexural Modulus is stated as 1.31 (10 to power of 6) and the Moment of Inertia as 8.333(10 to power of -5). These figures seem to be messing me up. On material datasheets the Flexural Modulus should be 2200 Mpa. and I worked out the Moment of Inertia as 12.056.

Also, is there a formula for an 'L' or 'U' shaped clip that will tell me the maximum deflection after inputting the maximum yeild strain, or give me the maximum strain after inputting a deflection (similar to tapered beam equasions)?

 

[unclesyd]

Here are two sites that have information on snap fit calculations. There have been several threads on this site about this subject.

http://engr.bd.psu.edu/pkoch/plasticdesign/snap_calc.htm

http://www.sabic-ip.com/webtools/toolsHomePage.faces

 

[ShaggyPE]

Great links. A star for you.

-Dustin
Professional Engineer
Certified SolidWorks Professional
Certified COSMOSWorks Designer Specialist
Certified SolidWorks Advanced Sheet Metal Specialist