Reliability block diagram (RBD) visually represents how component reliabilities combine — connecting blocks in series, parallel, or k-out-of-n configurations to compute system-level availability from component failure rates.

What Is RBD?

• Definition: Graphical model of system reliability structure.
• Components: Blocks represent components with known failure rates.
• Connections: Series, parallel, k-out-of-n configurations.
• Purpose: Calculate system reliability from component reliabilities.

Configuration Types: Series (all must work), parallel (redundancy, any can work), k-out-of-n (k of n must work), complex (combinations).

Series System: R_system = R₁ × R₂ × ... × Rn (weakest link).

Parallel System: R_system = 1 - (1-R₁) × (1-R₂) × ... × (1-Rn) (redundancy improves reliability).

Applications: System design, reliability prediction, bottleneck identification, redundancy analysis, availability calculations.

Benefits: Highlight reliability bottlenecks, model redundancy effects, support design trade-offs, enable what-if analysis.

RBDs are reliability schematics — converting component-level data into system-level availability predictions for design optimization.