Applications of a Fatigue Damage Sum (Electronic Copy)

Shock and Vibration Severity

Applications of a Fatigue Damage Sum (∑FDS)

By Steve Smithson, BSME, MBA — Smithson & Associates, Inc.

An incentive for engineers and test professionals seeking to quantify real-world vibration severity beyond traditional frequency-domain shortcomings.



(Electronic Version)

For decades, shock and vibration practitioners have relied on FFT, PSD, and gRMS to describe test environments—tools that fall short when data are non-Gaussian, non-stationary, or multi-axis.

Steve Smithson’s Applications of a Fatigue Damage Sum (∑FDS) introduces a decisive step forward: a time-domain metric that correlates directly with cumulative fatigue damage and perceived severity.

Built on the foundations of the Smallwood Ramp-Invariant Recursive Digital Filter (RIRDF) and guided by Irvine’s Admonition against false precision, this 110-page reference connects test profile parameters to end-use environment damage with clarity and practical rigor.

What You’ll Learn

• How to move from frequency-domain snapshots to deterministic, damage-based severity metrics
• Implementation of ∑FDS for HALT, HASS, ESS, and RS/ED shaker processes
• Methods for compressing test durations without sacrificing correlation to real-life conditions
• Using a Q-Map to model damping and resonance more realistically across bandwidths
• Real-world case studies from commercial, automotive, aerospace, and defense industries
• Statistical applications of ∑FDS for reliability and confidence estimates

Whom It’s For

• Shock and vibration engineers
• Reliability and test lab managers
• OEMs and system integrators in commercial, aerospace, automotive, and defense industries
• Researchers and consultants seeking actionable fatigue metrics

Why It Matters

The ∑FDS framework bridges the gap between traditional modeling and applied reliability testing.

It empowers engineers to quantify causes of failure—cumulative damage over time, not just snapshot spectral energy.

Includes: glossary, references, and key papers by the author and others

Format: Secure PDF (110 pages)

Purchase includes 12 months of free errata and updates

“A collection of approaches to quantifying the severity of shock and vibration in end-use environments and test requirements.”

What to Expect When You Order the Electronic version

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