Damage accumulates on all products because of vibration. The damage from vibration stresses on a product eventually results in catastrophic failures. Understanding and quantifying the “damage” characteristics of an environment or a combination of environments allow an engineer to avoid catastrophic failures. The fatigue damage spectrum is used to analyze time history files, evaluate qualification test standards as compared to actual end use environments, and define new vibration tests representative of the actual use of a product. This presentation addresses the methodology used to analyze, compare and combine field environments as well as generate the appropriate test profile based on the real-world vibration exposure a product will experience.