Geometric Accuracy and Energy Absorption Characteristics of 3D Printed Continuous Ramie Fiber Reinforced Thin-Walled Composite Structures

The application of continuous natural fibers as reinforcement in composite thin-walled structures offers a feasible approach to achieve light weight and high strength while remaining environmentally friendly.In addition,additive manufacturing technology provides a favorable process foundation for its realization.In this study,the printability and energy absorption properties of 3D printed continuous fiber reinforced thin-walled structures with different configurations were investigated.The results suggested that a low printing speed and a proper layer thickness would mitigate the printing defects within the structures.The printing geometry accuracy of the structures could be further improved by rounding the sharp corners with appropriate radii.This study successfully fabricated structures with vari-ous configurations characterized by high geometric accuracy through printing parameters optimization and path smoothing.Moreover,the compressive property and energy absorption characteristics of the structures under quasi-static axial compression were evaluated and compared.It was found that all studied thin-walled structures exhibited progressive folding deformation patterns during compression.In particular,energy absorption process was achieved through the combined damage modes of plastic deformation,fiber pullout and delamination.Furthermore,the com-parison results showed that the hexagonal structure exhibited the best energy absorption performance.The study revealed the structure-mechanical property relationship of 3D printed continuous fiber reinforced composite thin-walled structures through the analysis of multiscale failure characteristics and load response,which is valuable for broadening their applications.

3D/4D Printed Functional Continuous Fiber-reinforced Polymer Composites:Progress and Perspectives

In recent years,innovations in 3D/4D printing techniques for continuous fiber-reinforced polymer composites(CFRPCs)have opened new perspectives for the integrated design and manufacture of composites with customized functions.This paper reviews the current state of 3D/4D printed functional composites,including the materi-als,shape memory/changing effects,self-monitoring/healing behaviors,and challenges surrounding additive-manufactured functional composites.Specifically,continuous fibers and matrices that provide functional roles are classified and discussed in detail.4D printed shape memory and changing CFRPCs can retain their original shapes from a designed shape upon exposure to different external stimuli,including heat,electricity,humidity,and multi-stimuli activation.Furthermore,self-monitoring of structural health is achieved through the piezore-sistive features of reinforced fibers in 3D printed CFRPCs.Finally,this review concludes with an outlook on the future research opportunities for 3D/4D printed functional CFRPCs.