Lifetesting

Lifetesting, in reliability engineering, is the process of evaluating the expected lifetime and reliability of a product or component by observing its performance over time under conditions that simulate or accelerate real-world use. The goal is to estimate time-to-failure, degradation patterns, and overall longevity, to support warranty planning, maintenance schedules, and design improvements.

Accelerated life testing (ALT) is the common method, applying stresses such as higher temperature, humidity, voltage, or cyclic loads to speed aging. Other approaches include highly accelerated life testing (HALT) and highly accelerated stress screening (HASS), which seek to reveal weak points quickly. Data from lifetests are analyzed with survival analysis and reliability models (for example Weibull, lognormal, or accelerated failure time models) to estimate life distributions and extrapolate to normal-use conditions. Tests account for censoring when a unit does not fail during the observation window.

Planning emphasizes a well-defined life goal, adequate sample size, appropriate stress levels, and robust failure criteria. Care is taken to ensure that accelerated conditions do not change the fundamental failure mechanisms. Ongoing failure analysis, root-cause investigation, and sometimes acceleration factor studies accompany the testing.

Applications span consumer electronics, automotive parts, aerospace components, and medical devices. Outcomes include mean time to failure (MTTF) or failure rate over time, reliability at target lifetimes, and confidence bounds. Results inform design changes, component selection, quality control, and warranty risk assessment, though extrapolation from accelerated tests to normal use carries uncertainties and requires careful validation.