手法を比較

	レインフロー計数法	二次信頼性解析法 (SORM)
分野	信頼性工学	信頼性工学
系統	Process / pipeline	Process / pipeline
提唱年	1974	1979
提唱者	Tatsuo Endo	Bernd Fiessler
種類	Cycle counting algorithm	Reliability analysis method
原典	Goodman, J. (1899). Mechanics Applied to Engineering. Longman, Green and Co.	Fiessler, B., Neumann, H. J., & Rackwitz, R. (1979). Quadratic limit states in structural reliability. Journal of the Engineering Mechanics Division, 105(4), 661-676.
別名	Rainflow cycle counting, RFC	SORM, Second-order approximation
関連	4	4
概要	Rainflow counting is a fatigue cycle counting method that converts a complex stress history into individual cycles for damage assessment. Developed by Tatsuo Endo and colleagues in 1974, it provides the most physically realistic representation of fatigue damage when combined with Miner's linear cumulative damage hypothesis. The algorithm has become the industry standard in reliability engineering and vibration analysis.	The Second-Order Reliability Method (SORM) is an extension of FORM that improves failure probability estimates by accounting for the curvature of the limit-state surface at the design point. Introduced by Fiessler, Neumann, and Rackwitz in 1979, SORM provides more accurate approximations for nonlinear failure surfaces while remaining computationally efficient. It has become the standard refinement when FORM accuracy is insufficient.