Extremal structures with embedded prefailure indicators.

Preemptive identification of potential failure under loading of engineering structures is a critical challenge. Our study presents an innovative approach to design built-in prefailure indicators within multiscale structural designs with optimized load carrying capabilities utilizing the design freedom of topology optimization. The indicators are engineered to visibly signal load conditions approaching the global critical buckling load at predefined locations. By showing noncritical local buckling when activated, the indicators provide early warning without compromising the overall structural integrity of the design. This proactive safety feature enhances structural reliability. The method is particularly beneficial for offshore wind turbines, where many sensors are located below sea level and are inaccessible for maintenance. By allowing the placement of indicators in accessible predetermined locations, our method can reduce the number of required sensors and improve structural health monitoring. Additionally, the potential use of memory overload indicators exploiting plasticity offers a reliable means of detecting overloads during offline periods. Experimental testing of 3D-printed designs confirms a strong correlation between measurements and numerical simulations, demonstrating the feasibility of creating structures that can signal the need for load reduction or maintenance at predetermined locations. This research contributes to the design of safer structures by introducing built-in early-warning failure systems.