Pressure-Actuated Cellular Structures for Adaptive Wingtips

Aviation has a substantial environmental impact, necessitating a shift towards more sustainability. High-aspect-ratio (HAR) wings increase the efficiency of future transport aircraft by significantly reducing induced drag and, consequently, fuel consumption. However, the extended wingspan of HAR wings is accompanied by challenges, including ground operations, structural loads, and aircraft control. Folding wingtips (FWTs) address these challenges by incorporating a hinge at the outboard wing section, enabling the wingtip to fold during ground operations or specific flight scenarios. Wingtip actuators that allow active adjustment of the wingtip's cant angle and hinge stiffness can expand the potential operating modes of FWTs beyond the current state-of-the-art. Possible operating modes include extended load alleviation, mission adaptability, advanced flight control, and active flutter suppression. While most research on FWTs focuses on flight dynamics and aeroelasticity, little attention has been given to the structural design of wingtip actuators. This book introduces an actuator concept that transforms FWTs into multifunctional wingtip devices, referred to as actuated adaptive wingtips. The concept of actuated adaptive wingtips is based on a compliant morphing structure that adapts its mechanical properties by varying the fluid pressure in structure-integrated chambers.

Introduction. - In-Flight Folding Wingtips. - Morphing Structures with Fluidic Actuation. - Actuated Adaptive Wingtips on Transport Aircraft. - Test Methods for Flexure Hinges. - Production-Induced Characteristics ofWoven Flexure Hinges. - Conclusions and Outlook.