Tools to Plan Reliability Testing

Accelerated Reliability Test

Plan reliability testing for your products, based on the Parametric Binomial Reliability Demonstration integrated with the Arrhenius Life-Stress model, using our calculator provided here. The calculation is done in 3 steps. The calculator helps you address two fundamental questions :
1) Number of samples for accelerated reliability test
2) Duration of the accelerated reliability test

Plan reliability testing for ceiling fans, to demonstrate the reliability of R90 C85 for 5-year warranty life:

Step 1: Calculate mission life
Mission life = No. of years x No. of days x Usage per day = 5 x 365 x 16 = 29200 hrs = 1216.67 days

Step 2: Acceleration parameter
The typical ambient operating temperature of a fan is 30o C, however, we will conduct the test in a thermal chamber at 45o C. We will use the Arrhenius model to calculate the acceleration factor. Let’s assume the activation energy to be 0.7 eV. Accordingly, we obtain the Acceleration Factor for the test.

Step 3: Distribution parameter
For the parametric binomial reliability test used here, an underlying distribution is to be assumed. This calculator uses the Weibull distribution which is widely used in industry. We must provide the shape parameter (beta) and allowable failures in test samples. For this example, we will assume beta=1 and set the number of samples allowed to fail during the test=0.

Result (a): Calculate the number of samples
Set the available test duration and obtain the number of samples required for the accelerated reliability test. For an available test time of 90 days, 69 samples are to be tested.

Result (b): Calculate the duration of the reliability test
Set the available test samples and obtain the duration of the accelerated reliability test. If 30 samples are available for testing, the required test duration is 207 days (~7 months).

Our product CoSART F1.0 can help you test such a large number of samples for such extended durations. You can find more details about CoSART F1.0 here. CoSART F1.0 stands for Compact and Scalable Accelerated Reliability Testbench for Fans 1.0.

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