Elastic Fibre Prestressing Mechanics within a Polymeric Matrix Composite

Abstract

The elastic fibre prestressing (EFP) technique has been developed to balance the thermal residual stress generated during curing of a polymeric composite. The continuous fibre reinforcements are prestressed and then impregnated into a polymeric matrix, where the prestress load is only removed after the resin is fully cured in order to produce an elastically prestressed polymeric matrix composite (EPPMC). Although the EFP is active in improving the static mechanical performance of a composite, its mechanics on dynamic mechanical performance and viscoelasticity of a composite is still limited. Here, we established a theoretical model in order to decouple the EFP principle, aiming to better analyse the underlying mechanics. A bespoke fibre prestressing rig was then developed to apply tension on a unidirectional carbon-fibre-reinforced epoxy prepreg to produce EPPMC samples with various EFP levels. The effects of EFP were then investigated by carrying out both static and dynamic mechanical testing, as well as the viscoelastic creep performance. It was found that there is an optimal level of EFP in order to maximise the prestress benefits, whilst the EFP is detrimental to the fibre/matrix interface. The EFP mechanisms are then proposed based on these observations to reveal the in-plane stress evolutions within a polymeric composite.

Finite Element Analysis of Residual Stress Distribution Patterns of Prestressed Composites Considering Interphases

“…Combined with the increase in the longitudinal shear stress, it can be deduced that a large prestress level would result in the interphase debonding according to the widely used failure criteria of the interphase [ 37 ]. The debonding of the interphase is believed to be responsible for the decrease in the strength values after applying a large prestress value [ 38 ].…”

Biomimetic Venus Flytrap Structures Using Smart Composites: A Review

“…For the piezoelectric actuation-based OSB structure, in-plane stress is altered by using piezoelectric strips which are responsive to temperature changes and controlled through voltage [43], see Figure 2b. The continuous fiber prestressing techniques employ elastic (see Figure 2c) or viscoelastic (see Figure 2d) recovery within a composite structure, which would introduce compressive stresses and interact with the intrinsic thermal residual stress in order to induce out-of-plane deflections [53,54]. As for ESB structure, a composite tape-spring structure explores the positive Gaussian curvature effects, see Figure 2e, the governing factors of its bistability depend on the material constitutive behavior, initial geometric proportions, as well as the geometrically non-linear structural behavior [55].…”

“…posite structure, which would introduce compressive stresses and interact with the intrin-sic thermal residual stress in order to induce out-of-plane deflections [53,54]. As for ESB structure, a composite tape-spring structure explores the positive Gaussian curvature effects, see Figure 2e, the governing factors of its bistability depend on the material constitutive behavior, initial geometric proportions, as well as the geometrically non-linear structural behavior [55].…”

Preparation and Interfacial Properties of Hydroxyl-Containing Polyimide Fibers

“…Epoxy resin with excellent mechanical properties and heat resistance is an ideal resin matrix for manufacturing FRPs with high mechanical strength. Additionally, the 3D cross-linking network structure of the epoxy molecular chain will produce a large number of active -OH groups during the curing process [ 26 , 27 , 28 ]. Based on these reasons, in order to improve the interfacial adhesion of PI fiber-reinforced epoxy composites, the 4,4′-diamino-(1,1′-biphenyl)-3,3′-diol (HAB) diamine monomer containing bis-OH group was selected as the fourth monomer to introduce the BPDA/ p -PDA/BIA polyimide molecular chains in this work, which has been shown to significantly improve the cathode–electrolyte interface stability of lithium-ion batteries due to its rich chemical active sites for the polymer chains [ 29 ], and then, five kinds of PI fibers with different diamine ratios were manufactured through typical wet spinning technology.…”