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Diagnosing VDDCSS Dynamic Test Control Issues

Owned by Diogo Teles (Deactivated)
Last updated: Nov 12, 2019
2 min read

Problem

Results from Dynamic stages on VDDCSS seem incorrect or the system encounters a control error during the test

Diagnosis

You will need to use a rubber sample. This can be a rubber disc with a similar shape and size to that of a VDDCSS sample or a rubber rectangular prism with at least a 2 to 1 ratio of width to height. Some of our customers used the rubber stopper of a sedimentation bottle for this purpose, which also worked well.

Once you find an adequate rubber sample please do the following steps and send the data and screenshots of the Load (kN) vs Displacement (mm) plots to a GDS support engineer.

 

  1. Align the pedestal with the top cap in both X and Y directions

  2. Place the rubber sample between the pedestal and top cap, with no membrane or rings.

  3. Apply a normal load of 0.1kN from Object Display, to dock the sample, then target 0.5kN normal load and keep that value constant

  4. Start a GDSLAB test, and run the following dynamic stages, after each stage return X and Y to the center position and then re-target 0.5kN on the vertical axis.

    1.  

    2.  

    3.  

    4.  

  5. Repeat the stage sequence using a frequency of 1Hz and 5 cycles

  6. All tests should behave correctly and hit the requested targets. If the load controlled stages seem to unstable retry them with a stiffness estimate of 3.

  7. During this procedure, you will be able to identify if one of the directions is not behaving as expected. If this happens, please create a support ticket using the GDS Support Centre and attach the following information:

    1. File (.gds) with the test data saved while following this guide,

    2. Station ini file used to create the test station,

    3. the version of GDSLAB (this can be found on the top left corner of the GDSLAB window