Bioinspired Mechanical Structures for Load Bearing and Energy Absorption: Cross-Scale Design and Fabrication Strategies.

Biological systems achieve efficient load bearing and energy absorption through coordinated material organization, structural geometry, and deformation mechanisms across multiple length scales. Translating these principles into engineering structures requires a framework that connects biological mechanisms with mechanical functions and manufacturable architectures. This review examines bioinspired mechanical structures from the coupled perspectives of cross-scale design and fabrication. The design discussion is organized into four routes according to their primary mechanical roles. Internal material architectures and macroscopic structural arrangements are discussed in relation to load transfer, stress redistribution, and structural stability. Multilayer configurations and lattice-filled architectures are analyzed with emphasis on progressive deformation, failure regulation, and energy absorption. The review then compares biomineralization, self-assembly, freeze casting, and additive manufacturing in terms of accessible length scales, material compatibility, geometric freedom, and structural fidelity. Particular attention is given to the interactions among material distribution, load paths, deformation modes, and manufacturing defects. Current challenges include quantitative extraction of biological design principles, cross-scale integration, discrepancies between designed and as-built structures, and limited validation under realistic loading conditions. Future research should combine data-driven inverse design, multimaterial fabrication, in situ characterization, and defect-informed modeling. This review provides a function-oriented framework for developing lightweight bioinspired structures with reliable load-bearing and energy absorption performance.