1 CTIS # Prepared By John Yurtin Updated Connection Systems Training Vibration & Fretting Corrosion Vibration

Delphi Confidential2 Having a good technical understanding of the expectations and performance of connections can help you properly apply them within the vehicle. Vibration performance should be clearly understood since it is one of the more significant issues in vehicle performance. This training help you understand vibration issues and how they apply to customer applications. Excellence Performance Goal: Do it right the first time, every time Method: Innovation and continuous improvement

Delphi Confidential3 Agenda u Most Important Comment u Terminology u Vibration Testing u Fretting Corrosion u Field Observations u Lab Variation u Lab Testing u Factors In Vibration Issues u Summary u Wish List

Delphi Confidential4  The vibration performance of a connector in a specific vehicle application may not be the same as its performance tested to a specification in the laboratory!  The following factors of application are of greater significance than the design of the terminal / connector system: –Wire harness design and routing –Connector and harness attachment methods –Harness coverings and wire types –Harness bundle size –Connector lock mechanisms –Damping effects of seals  The standard specifications are excellent for comparison, but really do not represent actual in vehicle performance! Very Important!

Delphi Confidential5 “ The best connection can fail in an application if improperly applied, and the worst connection can perform fine in an application if properly applied – John Yurtin” Very Important!

Delphi Confidential6 Terminology  Peak Force (g’s)  Frequency Range (Hz)  Displacement  Direction of Motion (Random or Sinusoidal)  Peak Acceleration  Peak Velocity  PSD (Power Spectral Density) (g 2 /Hz)

Delphi Confidential7  Specifications generally have a very specific “setup”. Test Setups

Delphi Confidential8  Numerous vibration profiles exist for testing connectors: –ESA 710 –USCAR –GMI –ISO –etc.  Some reasonable, some not  Each claims to be “The One”  Vibration tests have not been shown to correlate to field performance  A new test combines vibration with other environmental tests to correlate to “field” performance (called Field Correlated Life Test or FCLT)  FCLT test now specified by Delphi, Ford, and USCAR as an alternative connector validation test Vibration Testing

Delphi Confidential9  Inducing fretting corrosion inside connectors appears to be a black art  Common practice is to measure field vibration, then increase severity in the lab to shorten the test  These severe laboratory vibration schedules induce failures not seen in the field –Severe wear –Broken wires & early termination of test  Mild test schedules may not produce fretting in a poor design Vibration Testing

Delphi Confidential10  Lack of agreement among OEM’s causes suppliers to test to numerous vibration schedules  Industry agreement is urgently needed  Vibration specifications in progress: –GMW 3191 –USCAR PF-1 –ISO TC22//SC3/WG6  30 or more other standards organizations exist with similar interests  Tendency is for authors to guess at what the spec. should be. After it’s published, no one questions it. Vibration Testing

Are most connector troubles caused by vibration?  Severe Vibration can cause harmful wear of contact interfaces  Mild vibration can cause fretting corrosion  Thermal changes can cause movement and fretting Steps in the development of fretting corrosion on a tin ‑ plated terminal interface Fretting Corrosion

Delphi Confidential12 What about Plating and Lubricants? u Gold Plating will result in improved performance u Gold to Tin is not recommended by Delphi and other industry experts. (AMP clearly does not recommend tin to gold interfaces!) ( u Lubricants can reduce the effect of fretting u Thermal changes can cause movement and fretting Fretting Corrosion

This is fretting corrosion! Fretting Corrosion

Sensor terminal after GMI12590 Fretting corrosion can be caused by micro-movement from temperature changes as well as from mechanical vibration. Fretting Corrosion

 Symptoms of connections with fretting corrosion –Problem disappears after connector is bumped –Changing the device (sensor, computer, etc.) makes the problem go away temporarily –Problem appears when the weather changes Field Observations

 Other common troublemakers with similar symptoms –Fretting corrosion from thermal cycling –High resistance crimps –Damaged terminals –Corrosion –Cut Wires –Contaminants in contact area (flux, oil, etc)  Fretting corrosion from vibration is not the cause of most connector problems Field Observations

 Fretting corrosion found on a small percentage of field returns  Terminals with high contact force can still be functional when fretting debris is present  No relationship seen between mileage and degree of vibration-induced fretting wear  Worst looking fretting corrosion from actual vehicles looks milder than fretting corrosion from most lab vibration tests Field Observations

If a little vibration is good, is a lot of vibration better? Lab Variation

LAB VIBRATION – ACCELERATED TESTS  Acceleration techniques for structural components do not apply to electrical contacts (unless different material data is used) Lab Variation

Laboratory Fretting/Vibration Studies

Lab Vibration Tests

Lab Vibration  Most fretting degradation from vibration can be seen quickly (within minutes)  Additional vibration time can wear away the terminal substrate, but resistance may not increase  Some lab vibration test profiles cause cables to fracture and cause terminals to be ground into dust. Samples from field returns do not show the same failure modes  USCAR engine profile appears to match field performance better than most profiles

Lab Vibration – Resistance Monitoring  Connections with fretting wear can have extremely unstable resistance –Any movement of samples can “heal” the connections  Intermittency detection is helpful, but does not always detect fretting issues  Continuous voltage drop monitoring is useful, but “self-healing” will occur for high resistance connections  Continuous dry-circuit resistance monitoring is useful, but difficult

Lab Vibration Fixtures  Fixture design is a major test variable –Distance to nearest clamp –Cable size or cable bundle size –Slack in cable

Summary  “Accelerated” vibration tests may not be realistic  Longer vibration tests may not be any better than short-duration tests  End-of-test measurements may not be useful, once samples have been moved  Fixturing has a strong effect on vibration test results  Some vibration tests have different failure modes than field samples

Wish List For Vibration Testing  Documented relationship between existing lab profiles and field vibration performance  Documentation of acceleration factors used for vibration tests  More standardization of vibration profiles  Better methods for resistance monitoring  Standardization of fixturing methods