Fall 2012 ME 395 - GSI Josh Lacey

This is a discussion forum for Josh Lacey's lab sections of Fall 2012 ME 395.
HomeHome  CalendarCalendar  FAQFAQ  SearchSearch  MemberlistMemberlist  UsergroupsUsergroups  RegisterRegister  Log inLog in  

Share | 

 Calculating Error

Go down 

Posts : 5
Join date : 2012-10-07

PostSubject: Calculating Error   Tue Oct 09, 2012 12:31 am

I have a general question about calculating error.

Though it is an overestimate method that one of the technical professors mentioned where you can develop a range for error by simply using the most extreme values for equation inputs.

For example, if a = 1 +/- 0.1 and b = 1 +/- 0.1, then a x b would be 1, and would range from .9 x .9 to 1.1 x 1.1

This method is far less rigorous and could yield large overestimates, but it would be conservative (potentially a good thing) and would massively simply calculations. If we did the error calculations the proper way for a, w, PQ, B, Young's modulus, and yield strength for 3 different sections worth of data, it seems like we would be working on this report until December.
Back to top Go down
View user profile
GSI Overlord

Posts : 126
Join date : 2012-08-30

PostSubject: Re: Calculating Error   Tue Oct 09, 2012 3:56 pm

The problem is that doing the uncertainties that way will greatly exaggerate the uncertainties in Kq and your plot with error bars will look pretty bad.

The good news is that you don't really need to worry about the error from some of those quantities, because their uncertainties are so small and can probably be neglected (i.e. w and S). The dominant sources of uncertainty when finding Kq arise from the calculation of Pq and measurement of the crack length, a.

You definitely want to automate the uncertainty calculation process as much as you can by setting up nice formulae in your spreadsheet, Matlab script, etc. so you don't spend so much time on the uncertainty math. Really, once you have the post-processing for your section data set up, you should be able to chug the other two sections pretty quickly.
Back to top Go down
View user profile http://fall2012me395.forumotion.com
Calculating Error
Back to top 
Page 1 of 1
 Similar topics
» Error message at program startup
» error #268D3
» How to Fix Error # 268D3?
» pass word error Not login
» Admin error login

Permissions in this forum:You cannot reply to topics in this forum
Fall 2012 ME 395 - GSI Josh Lacey :: Lab Questions :: Lab 4-
Jump to: