How do you design for roof crush resistance in rollover accidents?

Roof crush design focuses on maintaining occupant survival space during rollover. Key elements include: Strong A, B, C pillars (often hot-stamped steel), continuous load paths from pillars through roof rail to opposite pillars, roof bows for lateral stiffness, reinforced header and backlight openings, and connection stiffness to floor structure. FMVSS 216 requires withstanding 3x vehicle weight. Design uses CAE quasi-static analysis validated with physical testing. Balancing roof strength with weight, visibility (pillar thickness), and manufacturing is critical. Roof-mounted components like panoramic sunroofs add complexity.