Re:Test, Inc. Develops an Automated Block Cycle Program
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The cornerstone of durability testing
Introduction
Block Cycles accelerate evaluation by condensing load histories into simplified, repeatable sequences. Using sine waves of varying amplitudes, means, and frequencies, applied through minimal channels, they reproduce the entire fatigue life of a component in a fraction of the time. This method provides rapid feedback on fatigue viability and product quality, reducing the need for lengthy real time testing. Traditionally, however, developing these programs has been a slow, manual, and expertise-heavy task. Engineers often spend weeks refining cycles to balance accuracy with efficiency. Re:Test, Inc. has transformed this process with a proprietary algorithm that fully automates block cycle creation. At the push of a button, complex load histories are distilled into accurate, efficient test protocols. The result is faster development, higher fidelity, and consistent, repeatable durability tests that teams can trust to guide critical decisions.
Conventional Development Process
To date, Block Cycle Programs are created through an iterative engineering process: Loads data are converted to stress at critical locations. Then, multi-axiality is evaluated to determine if stresses can be reduced to single, dual or multiple vectors. The stress history is Rainflow counted, processed through a damage model, and visualized with Level Crossing. Next, engineers manually select and sequence cycles to minimize test duration while reproducing actual damage without over-stressing the component. Lastly, for multi-axis tests, channels are adjusted to ensure combined stresses reproduce real-world behavior. This process can take significant time, and a full vehicle program can take months.
Challenges with Current Methods
A key limitation of the traditional approach is that it does not adequately differentiate between Low Cycle Fatigue (LCF) and High Cycle Fatigue (HCF) events.
HCF events—such as those from rough road surfaces—occur frequently, contribute linear strain, and can be compressed without losing accuracy.
LCF events—like potholes or curb strikes—are infrequent but cause nonlinear, highly damaging plastic deformation, requiring precise representation. In reality, LCF cycles may occur within rough road events, and HCF cycles may appear during abusive events. Proper classification must be performed cycle by cycle to ensure both types of damage are captured accurately.
Re:Test’s Automated Solution
Re:Test has developed a proprietary algorithm that resolves these challenges. The algorithm classifies every cycle individually as LCF or HCF. It preserves LCF cycles due to their high damage impact while not adding significant test time. Then compresses HCF cycles efficiently, reflecting their linear damage contribution. Lastly, it will construct an optimized block cycle program that reproduces accumulated damage accurately while significantly reducing test time. This automated process eliminates much of the manual iteration, delivering consistent and repeatable results, and does not necessarily require expensive strain-life material data.
Integration and Knowledge Transfer
The automated process integrates seamlessly with existing durability workflows, using instrumented proving ground data or Multi-Body Dynamics (MBD) load measurements. We also use Finite Element Analysis (FEA), and multi-axial fatigue analysis to evaluate Test vs In-Vehicle differences. Re:Test provides training programs so your engineers can understand and apply the method independently, in the context of CAE and physical validation for a complete durability approach.
The Re:Test Advantage
With 45 years of experience and partnerships with over 160 OEMs and suppliers, Re:Test delivers not just faster block program development, but a proven methodology for embedding durability into every stage of product development. Re:Test – Automating block cycle development with accuracy, efficiency, and confidence.
Click here for more information: https://re-test.com/BCP
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