Calibrated Accelerated Life Testing (CALT) First Load Determination Using Systematic Step Stress Concept

Calibrated Accelerated Life Testing (CALT) is a sequential and quantitative method to Accelerated Life Testing (ALT). Its design aims to optimize test efficiency by minimizing both test duration and sample size while estimating product life. In the CALT context, the focus is on testing specimen under three or more distinct stresses or loads to estimate the life span/BX life, which is a crucial parameter in reliability estimation. Determining the first load in CALT typically involves exploratory testing on a limited number of specimens and relies heavily on engineering judgments such as analyzing Finite Element Analysis (FEA) outcomes, referencing test data from comparable designs and materials, and considering stiffness results etc. This often leads to challenges in accurately identifying the first load/stress. To address this issue, we propose a systematic step-stress test approach instead of exploratory testing. This approach aims to efficiently identify the first load in CALT. The step stress concept is a key part of this approach, where the product is exposed to increasing levels of stress or loads until failure is observed. This approach streamlines the determination of the first load, providing a more systematic and validated methodology. The validation process leverages existing fatigue test data from a specific program, thereby adding a robust layer of credibility to the findings. This research contributes to the field reliability engineering by offering a practical and efficient method for first load determination in CALT, thereby enhancing the test execution process.