Life Data Analysis
Some of the following examples use data sets in an electronic format. These files are located in the "Tutorial" directory on your CD.
Ten units are placed on a test stand. The following failures were recorded
Of the remaining 5 units, two were removed from testing without failing after 300,000 cycles, and three were removed from testing after 600,000 cycles without failing.
A. Compute the lower 80% confidence limit for reliability at 200,000 cycles.
B. Compute the lower 80% confidence limit for the time to fail at 99% reliability.
One million units were introduced into the field 6 months ago. The number of failures per month are shown below.
What is the expected reliability of the population after 1 year in service?
Given the data in the file "Demo2.dat",
A. Does the product represented in the data meet a requirement of 99% reliability with 80% confidence at time = 40?
B. At what time does the product meet the requirement of 99% reliability with 80% confidence?
A new product is required to demonstrate 99% reliability at 1.5 million cycles with 80% confidence. Given a Weibull shape parameter of 2.8, how long must 8 units be tested to demonstrate the required reliability assuming no failures?
Nine samples were tested for 3 million cycles without failure, and 1 sample survived 2.84 million cycles before failing. Given a Weibull shape parameter of 3.8, what is the lower 95% confidence limit for reliability at 2 million cycles? What is the lower 95% confidence limit for the time to fail when the reliability is 99%?