Accelerated Life Test (ALT) Definition
Accelerated life testing is the process of running various tests on a product that exaggerate the loads that would normally be put on it. The goal to see which parameters of the product (stress, strain, temperatures, voltage, vibration rate, etc) when tested could cause failure.
A Little More on What is Accelerated Life Test (ALT)
Typically, researchers will analyze the life span of a device under normal conditions. This data is then used to quantify the product life cycle and make generalized predictions on all of the devices based off of a small sample. Accelerated life testing will allow data to be collected faster than normal methods, using accelerated load conditions instead of normal loads. ReliaSoft ALTA software provides a good set of tools to conduct an accelerated life test analysis.
Accelerated tests can be qualitative or quantitative. Qualitative tests (HALT, HAST, torsion test) are used to figure out failures that engineers can improve through product design. Quantitative tests (QALT) are what generate the data for life span data. This method essentially relies on the probability density function to estimate product life span under normal conditions of use. It is good to note that the best application of QALT is on devices that do not operate continuously for long times.
As mentioned before, there are many parameters that can be tested on each product. For example, if an analyst was to test temperatures and knew the product would normally operate at 290K, then an accelerated test would use 310K, 320K, and 330K. By testing the extremes, the analyst can figure out which probability distribution parameter to use to construct a PDF.
References for Accelerated Life Test
Academic Research for Accelerated Life Test
Optimum simple step-stress accelerated life tests with censoring, Bai, D. S., Kim, M. S., & Lee, S. H. (1989). IEEE transactions on reliability, 38(5), 528-532.
Optimal simple step stress accelerated life test design for reliability prediction, Fard, N., & Li, C. (2009). Journal of statistical planning and inference, 139(5), 1799-1808.
Accelerated life testing (ALT) in microelectronics and photonics: its role, attributes, challenges, pitfalls, and interaction with qualification tests, Suhir, E. (2002). Journal of Electronic Packaging, 124(3), 281-291.
Planning of step-stress accelerated degradation test, Tang, L. C., Yang, G. Y., & Xie, M. (2004). In Reliability and Maintainability, 2004 Annual Symposium-RAMS (pp. 287-292). IEEE.
Accelerated life test planning with independent Weibull competing risks with known shape parameter, Pascual, F. (2007). IEEE Transactions on Reliability, 56(1), 85-93.
Reliability improvement of InGaN LED backlight module by accelerated life test (ALT) and screen policy of potential leakage LED, Jeong, J. S., Jung, J. K., & Park, S. D. (2008). Microelectronics Reliability, 48(8-9), 1216-1220.
Accelerated life test planning with independent lognormal competing risks, Pascual, F. (2010). Journal of Statistical Planning and Inference, 140(4), 1089-1100.
Pitfalls of accelerated testing, Meeker, W. Q., & Escobar, L. A. (1998). IEEE Transactions on Reliability, 47(2), 114-118.
Accelerated degradation tests: modeling and analysis, Meeker, W. Q., Escobar, L. A., & Lu, C. J. (1998). Technometrics, 40(2), 89-99.
Accelerated life test plans for predicting warranty cost, Yang, G. (2010). IEEE Transactions on Reliability, 59(4), 628-634.