Nacre Composite Truss (2D): Brick-and-Mortar Load Model

Nacre (mother-of-pearl) gets its toughness not from being a strong mineral — aragonite alone is brittle — but from geometry: thin hard platelets stacked with a soft organic "mortar" between them that deflects an advancing crack sideways along each interface instead of letting it run straight through the material. This 2D companion draws that same zigzag brick-and-mortar chain from the side: a rolling load sags the nearest platelets proportional to load and inversely to mortar toughness, and every mortar link between platelets is colour-coded live from green (low stress) through yellow to red as it approaches its own failure limit, so you can watch exactly where a real composite would start to crack first as the load rolls across the span.