Viscoelastic fibre prestressing (VFP) is a promising technique to counterbalance the potential thermal residual stress within a polymeric composite, offering superior mechanical benefits for structural engineering applications. It has been demonstrated that the time required for a desirable creep strain can be significantly reduced by implementing higher creep stress, while its long-term stability is still unknown. Here, we developed the prestress equivalence principle and investigated the durability of viscoelastic fibre prestressing within a composite in order to further enrich the prestress mechanisms. The effectiveness of the prestress equivalence principle was refined through Charpy impact testing of prestressed samples with various pre-strain levels. The durability was investigated by subjecting samples to both natural aging (up to 0.5 years) and accelerated aging (by using the time-temperature superposition principle). It is found that the prestress equivalence principle offers flexibility for viscoelastically prestressed polymeric matrix composite (VPPMC) technology; the impact benefits offered by VFP are still active after being accelerated aged to an equivalent of 20,000 years at 20 °C, inferring long-term reliability of VFP-generated fibre recovery within a polymeric composite. These findings demonstrated that both materials and energy consumption could be conserved for advanced composites. Therefore, they promote further steps of VPPMC technology toward potential industrial applications, especially for impact protection.
Composite tape-springs (CTS) structure has been applied to spatial developable structures due to its bistability. There is growing interest in smart driving of the CTS-based structures because of the limitations on the working environment. Here, we propose a detailed analysis of the smart driving of the CTS structure. This is achieved by using smart materials to develop a bilayered CTS intelligent structure: the smart material forms the active layer to generate stress/strain to drive the structure; the CTS layer acts as a passive layer where its intrinsic bistability, designability further enriches the diversity of intelligent morphing structures. A theoretical analytical model is developed to anticipate the bistability; the stability criteria are then determined to guide the intelligent morphing design. These will facilitate the future smart driving design of aerospace deployable structures.
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