reliability block diagram

**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.