Nested Underrun Protector Structure for Buckling Resistance

The patent employs a nested structure where an inner member is positioned within an outer member, creating a multi-layered protective system. The inner member includes a bottom wall and side walls, while the outer member encompasses an inner space that receives the inner member. This nesting arrangement enhances load-bearing strength through layered protection while efficiently utilizing space, avoiding the need for excessively thick single-layer structures.

The underrun protector is divided into distinct functional segments: the inner member with its bottom wall and side walls, the outer member with its inner space, and connection members joining them. This segmentation allows each component to be optimized for specific structural roles, distributing collision forces across multiple elements rather than requiring one monolithic high-strength structure.

The patent applies local quality by concentrating structural reinforcement where buckling is most likely to occur. The inner member's side walls are positioned to provide localized support against inward buckling of the outer member during collision. The connection members are strategically placed to join critical sections, providing targeted reinforcement without uniformly thickening the entire structure.

The underrun protector utilizes a composite structure combining inner and outer members made of different materials or with different structural properties. This allows optimization of each layer for specific functions - the outer member provides initial collision resistance while the inner member prevents buckling - achieving superior buckling resistance without the weight penalty of a single uniformly thick structure.