Electrical Connector Failure Rate Estimation Using Degraded Samples
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Solution Overview
Problem
Existing methods for determining the failure rate of electrical connectors are time-consuming, costly, and lack confidence in extrapolating results due to the difficulty in simulating sufficient operating hours without activating irrelevant degradation mechanisms.
Innovation Solution
A method involving degrading a sample connector to a reduced normal force, applying a vibration test, and calculating the failure rate by multiplying the sample's failure rate by its probability within the batch, using a normal distribution to select the threshold force and determine the probability of occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the vibration test duration is extended to simulate more operating hours, then the failure rate determination becomes more significant, but the time and cost required increase tremendously
Solution Approach 1:
The patent applies preliminary degradation (mechanical, vibratory, and/or thermal aging) to samples before the vibration test to reduce their normal contact force below the batch mean. This pre-conditioning creates samples that are more susceptible to failure during the vibration test, allowing significant failure rate determination in a shorter test duration while maintaining statistical significance
Solution Approach 2:
The patent changes the parameter of normal contact force by applying degradation treatments to create samples with reduced contact force. This parameter change accelerates the failure mechanism during vibration testing, enabling meaningful failure rate data to be obtained without extending the test duration to simulate millions of operating hours
2Loss of time
If the test conditions are made more severe to cause earlier failures, then the test duration is reduced, but other degradation mechanisms may be activated that are not correlated to reality
Solution Approach 1:
The patent applies degradation locally to specific samples rather than to the entire batch, creating a distribution of normal forces within the batch. This allows the vibration test to proceed under standard conditions that correlate to field experience, while the pre-degraded samples provide the necessary failures for statistical significance
Solution Approach 2:
The patent applies partial degradation to only some samples in the batch (those intended to fail during the test) rather than making all test conditions more severe. This selective approach maintains correlation to field experience for the overall batch while ensuring sufficient failures occur during the vibration test
3Reliability
If the quantity of samples in the test is increased to obtain significant failures, then the statistical significance improves, but the production cost increases
Solution Approach 1:
The patent uses preliminary degradation to create a subset of samples with reduced normal contact force that are pre-conditioned to fail during the vibration test. This allows significant statistical data to be obtained from a smaller total sample size, as the pre-degraded samples are guaranteed to fail while representing the lower end of the normal force distribution
4Ease of manufacture
If standard vibration testing is performed on new connectors, then the test setup is simple, but the contact resistance remains stable and no significant failures occur
Solution Approach 1:
The patent applies preliminary degradation treatments to samples before vibration testing to reduce their normal contact force. This maintains the simplicity of the vibration test setup while ensuring that failures occur during testing, as the pre-degraded samples have reduced contact force and are more susceptible to vibration-induced failures
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Accelerates the determination process, reduces costs, and increases confidence in the failure rate estimation by simulating failures closer to real-world conditions, thereby improving the accuracy of failure rate prediction.
Implementation Method 1
Applying a vibration test to at least one sample
Implementation Method 2
the possible micro-movement between the male and female terminals due to system vibrations or thermal expansion cycles
Implementation Method 3
the most contributing factor in the contact degradation, the contact degradation leading to a contact resistance increase
Data Source
AI summary
A method for determining the failure rate of a batch of electrical connectors involves degrading at least one sample connector to exhibit a normal contact force below a specified threshold, which is less than the batch's mean force. The method includes determining the probability of the sample's occurrence within the batch based on the threshold force, applying a vibration test to the sample, and obtaining its failure rate. The batch's failure rate is then calculated by multiplying the sample's failure rate by its probability of occurrence. This approach allows for an accurate estimation of the batch's overall reliability by assessing the performance of degraded samples under specified conditions.