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PostPosted: 04 Nov 2015, 03:49 
Sherlock User

Joined: 28 Dec 2014, 21:21
Posts: 10
Dear sir,
1. one quesiton for vibration need your support.
If the vibration PSD profile Freq range < board natural Freq, in sherlock, we can`t get any relibility result(such as TTF/Strain/Displacment/Score..), is it right by sherlock?

PSD Freq range:10-60Hz
Board natural: 70Hz
the RV analysis result is empty. see the pciture

2. another question for Natural Freq,
I was running assembly board(2 PCBs) NF analysis, but sherlock just got #1 &#2 NF result, what`s the problem for that? i was set the NF reuslt counter= 5

Capture.JPG [ 40.89 KiB | Viewed 4231 times ]
PostPosted: 08 Nov 2015, 19:42 
Site Admin
User avatar

Joined: 21 Mar 2013, 16:40
Posts: 121
Location: Beltsville, Maryland

This type of result is due the displacements being very small which generates generates a damage which is close to zero. These very small numbers cause a divide by zero result and prevents the computation. You can extend the random vibration profile slightly(with a small amplitude) to encompass the 1st natural frequency of the board it should work.

The number of natural frequencies returned are for the frequency range you specify. If only 2 are being returned there are only two results in that frequency range, make the range larger to get more NF results.

Best regards,

Nathan Blattau, PhD
Senior Vice President
DfR Solutions, LLC
9000 Virginia Manor Rd, Ste 290
Beltsville MD 20705

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