Accelerated Life Testing for Product Lifetime Extrapolation

Cher Min Tan (Chang Gung University, Taiwan)

**Product lifetime** is a critical attribute of any technical product, as it directly influences the perceived value and long-term cost-effectiveness of the product. Meeting high product reliability standards often necessitates extensive testing to accurately predict the product's lifetime, a process that can be time-consuming. Consequently, accelerated life testing (ALT) is widely adopted to shorten the testing period. However, to ensure the reliability and accuracy of the lifetime prediction, a suitable extrapolation method must be selected based on the acceleration model. Unfortunately, identifying the most appropriate acceleration model for different failure mechanisms is a complex task, and conventional models commonly used in industry may not always be suitable. This tutorial will cover various acceleration models, discussing their applications and selection criteria for different types of failure mechanisms.

While acceleration models are primarily used to determine the acceleration factor, it is essential to use this factor effectively to perform accurate extrapolation. Traditionally, extrapolation is performed using a single reliability index, such as Mean Time to Failure (MTTF). However, a more comprehensive approach involves extrapolating the entire reliability function, a process known as two-dimensional extrapolation. This tutorial will provide an in-depth explanation of how to perform this two-dimensional extrapolation to ensure a more accurate and meaningful lifetime prediction.

For products requiring exceptionally high reliability, even accelerated life testing may not suffice due to the extended timeframes involved. In such cases, accelerated degradation testing (ADT) is increasingly employed. However, a common pitfall in ADT is the use of simple curve fitting methods to estimate failure times, which can lead to significant errors in lifetime prediction. This tutorial will present an example of proper extrapolation techniques in accelerated degradation testing to demonstrate best practices for accurate lifetime estimation.