High-performance bio-inspired composite T-joints

Abstract

This paper introduces a novel bio-inspired design strategy based on the optimised topology of bird bone's joint to improve the strength-to-weight ratio and damage tolerance of composite T-joints. Better structuring the constituents' materials near the sharp bends results in redistribution of stress over a larger area and reduces the stress concentration. This is done by an integrally formed support structure that is spaced apart from the main body of the Tjoint in the vicinity of the bend using a Polyvinyl Chloride (PVC) foam. The support structure acts as a buttress across the bend and improves the performance of the T-joint. The T-joints are fabricated using wet l ay up process, from 2/2 twill TC35-carbon fibre fabric/SR5550 epoxy resin, and are subjected to quasi-static and fatigue bending, and quasi-static tensile pull-out tests. The quasi-static results reveal that the bio-inspired T-joint design has huge improvements compared to a conventional T-joint in the elastic stiffness (over 60%), peak load (over 40%) and absorbed mechanical energy (over 130%). There is only 3% weight increase in the bio-inspired T-joint compared to the conventional one. The fatigue results show a significant improvement for the bio-inspired design proving the efficiency of the novel bio-inspired design for both quasi-static and cyclic loadings.

Methods to increase the mechanical performance of composite adhesive joints: An overview with focus on joints with natural fibre composite adherends

“…117 Several researchers were inspired by bones and trees to improve the interfacial bonding of adhesive joints. [118][119][120][121] For example, recently Wagih et al 121 proposed a bioinspired adhesive joint with improved interlaminar fracture toughness by generating sacrificial cracks inside the adhesive layer with specific topology that activates nonlocal dissipation damage mechanisms through the development of bridging ligaments. However, more research has to be done to simplify the manufacturing process in order to apply this method to real-life composite bonded structures.…”

Investigating the Effect of Interface Morphology in Adhesively Bonded Composite Wavy-Lap Joints

“…Surface treatment was also used to modify the bond quality by improving the micro-topography of the adherend surfaces [15,16]. Changing the joint geometry (e.g., adherend scarfing or tapering, adhesive fillets or foam spacers) was also used for improving bond properties [17][18][19]. For instance, bonded wavy-lap joints show a higher strength than a flat-lap joint [20][21][22].…”

In-Plane Shear Strength of Single-Lap Co-Cured Joints of Self-Reinforced Polyethylene Composites

“…Structures formed by the assembly of two or more parts are commonly used to overcome the impracticality of manufacturing large structures in a single piece due to processing and cost limitations [ 45 ]. The resulting joints are responsible for ensuring effective load transfer between parts, thus maintaining the integrity of the linked components [ 46 ]. For composites, there are two main joining methods: mechanical fastening (which infers undesired and prejudicial stress concentration spots and an overall weight increase caused by additional fasteners [ 47 ]) and adhesive bonding (which provides load transfer with more uniform distribution over larger areas) [ 48 ].…”