A Multiaxial Fracture of Ecoflex Skin with Different Shore Hardness for Morphing Wing Application

Abstract

The use of elastomer-based skins in morphing wings has become increasingly popular due to their remarkable stretchability and mechanical properties. However, the possibility of the skin fracturing during multiaxial stretching remains a significant design challenge. The propagation of cracks originating from flaws or notches in the skin can lead to the specimen breaking into two parts. This paper presents an experimental study aimed at comprehensively evaluating crack propagation direction, stretchability, and fracture toughness of silicone-based elastomeric skin (Ecoflex) for morphing wing applications, using varying Shore hardness values (10, 30, and 50). The findings show that the lower Shore hardness value of 10 exhibits a unique Sideways crack propagation characteristic, which is ideal for morphing skins due to its high stretchability, low actuation load, and high fracture toughness. The study also reveals that the Ecoflex 10 is suitable for use in span morphing, with a fracture toughness of approximately 1.1 kJ/m2 for all thicknesses at a slower strain rate of 0.4 mm/min. Overall, this work highlights the superior properties of Ecoflex 10 and its potential use as a morphing skin material, offering a groundbreaking solution to the challenges faced in this field.

Modeling Elastomer Compression: Exploring Ten Constitutive Equations

“…The experimental part of the research concerned the material tests necessary to determine the constants in the constitutive equations and the verifying compression test. In order to determine the material constants via four variants, the following tests were carried out: uniaxial tensile test, biaxial tensile test and plane strain tensile test [13,22,23]. The material tests and the conditions for their implementation are described below.…”

Low-Cycle Fatigue Behavior and the Combined Cyclic Hardening Material Model of Plate-Shaped Zn-22Al Alloy for Seismic Dampers

“…The details of the material test specimens are succinctly presented in Table 1. As research by Hong et al, Ahmad and Ajaj, and Saini et al indicated, the loading frequency had a remarkable effect on fatigue performance [30][31][32], and the chosen loading frequency adequately covered the strain rate of energy dissipation materials inside seismic damping devices during earthquake actions. For monotonic tests, specimens were firmly secured using wedge jaws on a universal material testing machine equipped with a long-stroke extensometer.…”

Aerodynamic Analysis of Variable Camber-Morphing Airfoils with Substantial Camber Deflections

“…Observing the smooth and gentle way birds of pray sail through the air using their wing-morphing abilities has inspired researchers of all times to create visionary aerodynamic concepts [2][3][4]. The dynamic development of intelligent shape-changing materials in the 21st Century empowered the scientific world to excavate these concepts and adjust them to the economic needs of the current era of aviation [5][6][7].…”