Search

A novel integrated manufacturing process based on continuous fibre reinforced thermoplastic composites 3D printing of continuous fibre reinforced composite lightweight structures (CFRCLSs) was proposed. Cross lap and panel-core lap design strategies were proposed to fabricate the CFRCLSs with a complex shape. The fracture modes during compression loading were analysed. Correlations between the process parameters, structure parameters, density, fibre content, and final performance of the printed specimens were discussed. The fibre content of the printed CFRCLSs were controlled by changing the process parameters. With a fibre content of 11.5% vol, a compression strength of 17.17 MPa was obtained for the 3D printed CFRCLSs. A heterogeneous lightweight sandwich structure specimen was fabricated to demonstrate process feasibility. This new and improved process has great potential for fabricating CFRCLSs with complex shapes, high mechanical properties, and multifunctional benefits. [ABSTRACT FROM AUTHOR]

In this paper, a multidisciplinary framework to design and produce a topological structure with inhomogeneous distributions of fiber orientation and content for 3D printed continuous fiber reinforced polymer composites (CFRPCs) was proposed to maximize load and fiber utilization efficiency. The combination of optimization design and 3D printing for composites with curvilinear fiber was achieved that the fiber orientation and content were progressively designed in the two-stage procedure. The fiber orientation and topological structure were concurrently optimized firstly. Then, the fiber content was designed through finite element analysis (FEA) and realized by changing continuous fiber path with a hierarchical structure design method. Based on this, the topological beam has been additively manufactured and experimentally investigated, showing 38.55% and 25.40% in stiffness and peak load enhancement compared with the original CFRPCs design, while 264.39% and 165.84% increments compared with pure polymer design. The proposed approach has widened design freedom of CFRPCs 3D printing, possessing potential application to solve engineering problem in aerospace, automotive and other fields. [ABSTRACT FROM AUTHOR]

Over the last few years, three-dimensional printing(3DP) technology has evolved to incorporate composite materials. However, using material extrusion (ME) technology, it is still difficult to improve the stiffness with stable elongation and energy absorption of continuous fiber reinforced composites at the same time. This study aimed to 3D print hybrid threads by merging several types of continuous Kevlar and Carbon fibers. Which were created using material extrusion 3D printing to accomplish cooperative ductility and brittleness augmentation. To analyze the mechanical performance and reveal the failure and deformation mechanisms, tension tests, three-point bending tests, and drop hammer impact tests were performed. The proposed hybrids have substantially greater flexural modulus, flexural strength, tension modulus, and tension strengths with absorbed energies than standard single type fiber composites. Crack resistance during impact test of hybrid composites was enhanced by over 91% compared to carbon fiber non-hybrid composites. SEM images of hybrid specimens provided an insight of the failure mechanisms, resulting in stable hybrid composites. Positive hybrid effect further demonstrates its great energy absorption capacity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Modeling and 3D printing of variable stiffness composites with curved fibers. • Limitations of 3D printing are taken into account in the modeling. • 3D printing of the variable stiffness composites without gaps and overlaps. • 3D printing by the control of positioning a nozzle and the adaptive feed of plastic. • Comparison of numerical and experimental strain fields of the VSCs via FEM and DIC. In this paper, biomimetic continuous fiber reinforced composite structures were modeled and printed on the basis of variable distributions of fiber orientation and the fiber volume fraction, which are similar to the wood structure in the vicinity of a knot. The variable distributions of curved fibers in the variable stiffness composites (VSCs) without gaps and overlaps were realized during the 3D printing process by the control of positioning a nozzle and the adaptive feed of plastic. To demonstrate efficiency of the modeling method and the 3D printing process, a VSC plate with a hole under tensile loading was designed, printed and tested. The results of tensile tests showed that the main failure of the composite plates occurs far from the hole. Furthermore, numerical and experimental strain fields obtained by the finite element method and digital image correlation, respectively, are similar. The efficiency in fiber savings for the composite plates was improved by the change in reinforcement from unidirectional fibers to curved fibers adapted to heterogeneous stress fields. [ABSTRACT FROM AUTHOR]

3D printing provides a new technical means for the preparation of functionally controlled continuous fiber reinforced composites (CFRCs) with variable fiber content. The constitutive model of 3D printed CFRCs with different fiber contents are the basis for establishing mechanical analysis models and design methods of functionally regulated CFRCs based on 3D printing. In this paper, stiffness and strength properties of 3D printed CFRCs with different fiber contents were systematically studied, and the mapping relationship between material properties and fiber content was obtained. The failure processes of 3D printed CFRCs under different loads were studied by microstructural morphology and interfacial performance analysis, revealing the formation mechanisms of the material properties. The constitutive model and finite element analysis method of 3D printed CFRCs were established by using the material properties of 3D printed CFRCs with different fiber contents. The mechanical analysis mode was used to predict and analyze the performance of functionally graded CFRCs with variable fiber content. The results show that the mechanical analysis mode can be used for the optimization design and mechanical analysis of functionally controlled CFRCs. [ABSTRACT FROM AUTHOR]

A shape-performance synergistic design and additive manufacturing strategy was developed for the transfemoral prosthetic sockets (TPS) to fulfill the demands of customized geometry and long-term load bearing. The 3D printing path of the continuous fiber reinforced polymer composites (CFRPC) was generated by reversing the milling path of subtractive manufacturing. The mechanical properties of the 3D printed CFRPC samples were investigated as a foundation, and the customized fiber trajectories were designed based on the analyzed stress pattern of the TPS in daily gait. The CFRPC TPS with weight of 28 % less than those made by pure resin had a safety factor larger than 3 and passed the fatigue testing of 3 million cycles. The design and additive manufacturing strategy developed in this study was also applicable for other parts with freeform surfaces. • Fiber trajectory was designed based on the stress analyses of prosthetic socket. • Multi-DOF system enabled 3D printing of thin-walled freeform surface with CFRPC. • Self-adjusting printing speed and feeding rate improved surface quality of CFRPC. • Shape-performance synergistic strategy can apply to other freeform surface parts. [ABSTRACT FROM AUTHOR]