High-Performance T-Joint Using Asymmetric Laminate Design and Atypical Deltoid Structure
One of the difficulties in composite structural application is joining components. T-joint is one of the important elements in aircraft structures that transfers load between vertical and horizontal panels. T-joint is composed of two L-shaped parts, skin laminate, and deltoid region. T-joint often fails at low load in deltoid and corner regions because of its low through-thickness properties and process-induced defects. In previous work, Burns et al. proposed novel ply design approaches to increase the strength of T-joint. Trask et al. investigated the influence of process-induced defects in deltoid region on the failure of composite T-joint. In this current study, we proposed T-joint designs using atypical stacking sequence to simultaneously enhance strength and shape-stability. We evaluated the effectiveness of the design using a three-dimensional shape measurement system. It was revealed that high shape-stability could be achieved using asymmetric laminate design. Moreover, we proposed new deltoid structures to improve the strength of T-joint. We conducted tensile tests of several T-joint specimens while measuring cross-sectional strain distribution using digital image correlation (DIC). The specimens using atypical deltoid structure showed higher strength and larger maximum displacement compared to the conventional ones, confirming the effectiveness of the proposed design.
Author: Shinsaku Hisada, Kazunori Takagaki, Shu Minakuchi, and Nobuo Takeda
Conference: SAMPE Seattle 2017