To illustrate the principles behind accelerated testing, consider the simple example we used previous involving a paper clip. The objective is to determine the mean number of cycles-to-failure of the paper clip.

Assume that the use cycle is a 45 bend.

The acceleration stress is determined to be the angle to which the paper clip is bent. In this case, assume that the two accelerated bend stresses are 90 and 180.

For the 90 bend, test the paper clip using the following procedure. Use a similar procedure for the 180 test.

Note that the paper clips used in this example are the same paper clips used when we did the experiment looking at the reliability distributions of a use cycle of a 45 bend. Different paper clips will yield different results - please be sure to see your professor for the correct paperclips. Additionally, and so that no other stresses are imposed, take caution to assure that the rate at which the paper clips are cycled remains the same across the experiment.

Paper Clip Test

• Open the Paper Clip.
  • With one hand, hold the clip by the longer, outer loop.
  • With the thumb and forefinger of the other hand, grasp the smaller, inner loop.
  • Pull the smaller, inner loop out and down 90 so that a right angle is formed as shown.
• Close the Paper Clip.
  • With one hand, continue to hold the clip by the longer, outer loop.
  • With the thumb and forefinger of the other hand, grasp the smaller, inner loop.
  • Push the smaller inner loop up and in 90 so that the smaller loop is returned to the original upright position in line with the larger, outer loop as shown.
• This completes one cycle.
• Repeat steps 1 and 2 until the paper clip breaks. Count and record the cycles-to-failure for each clip.
• Repeat the test for 180

Enter the data into Minitab and perform an accelerated life test in order to predict the MTTF at use cycle of a 45 bend. (use 50th percentile to estimate MTTF). The objective of the accelerated test was to quickly estimate the mean life of the paper clip at the 45 bend. Has this objective been achieved based on your results from Assignment #1. If it did, please discuss in a short paragraph how the principles of accelerated testing helped achieve this and how accelerated testing can be helpful for reliability evaluations. If it did not, please discuss why you think this might have happened.

• Your results and discussion should be included in a brief report. Include the graphs and tables necessary to discuss your experiment. Be sure to include the probability plot for the fitted model and discuss whether the distribution, transformation, and the assumption of equal shape (Weibull or exponential) or scale parameter (other distributions) at each level of the accelerating variable is appropriate