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Continuous fiber-reinforced composite truss structures have broad application prospects in aerospace engineering owing to their high structural bearing efficiency and multifunctional applications. This paper presents the design and fabrication of multilayer truss structures with controlled mechanical properties based on continuous fiber-reinforced thermoplastic composite 3D printing. Continuous fiber composite pyramid trusses fabricated by 3D printing have high specific stiffness and strength, with maximum equivalent compression modulus and strength of 401.91 MPa and 30.26 MPa, respectively. Moreover, the relative density of a truss structure can be as low as 1.45%. Additionally, structural units can be extended in any direction to form a multilayer truss structure. Structural performance can be controlled by designing the parameters of each layer. This study offers a novel approach for designing a multifunctional multilayer truss structure, a structure with low-density needs and unique load-bearing effects. [ABSTRACT FROM AUTHOR]

Poly-ether-ether-ketone (PEEK) is a high-performance, temperature-resistant semicrystalline polymer which is frequently used as a replacement for metals in a wide variety of high-performance end-use application. Thermal processing conditions during manufacturing process for PEEK can implement a significant impact on its crystallinity and mechanical properties directly and indirectly. In this paper, we have used a temperature-control 3D printing system to prepare all the PEEK samples for calculating crystallinity and performing tension tests, in order to investigate the relationship between various thermal processing conditions (the ambient temperature, the nozzle temperature and heat treatment methods) in FDM process and crystallinity and mechanical properties (tensile strength, elastic modulus and breaking elongation) of pure PEEK material. All experiment results show temperature-control 3D printing method has tremendous potential to design, control and realize different degrees of crystallinity and mechanical properties for different PEEK parts, even in different regions of the same PEEK part. [ABSTRACT FROM AUTHOR]

Particle size gradation is regarded as an effective method for overcoming the contradicting requirements in three-dimensional printing (3DP). In present work, particle size gradation was optimized to obtain both acceptable flowability of the powder material and high-strength 3D-printed glass-ceramic products. The effect of gradation on the printing process, sintering process and performance of the 3D-printed glass-ceramic products was investigated comprehensively. The glass-ceramic powders with three size ranges were mixed in certain proportions and applied to print parts. The result showed parts printed with powder mixed by 60 wt% 45–100 µm and 40 wt% 0–25 µm particles had satisfactory density of 1.60 g/cm 3 and bending strength of 13.8 MPa. The flowability decreased with an increasing proportion of fine particles. Part density was determined by the powder bulk density in the powder bed as well as the shrinkage during sintering while strength of part was found to be dependent on the sintering degree. [ABSTRACT FROM AUTHOR]

Abstract: The effects of laser sintering parameters (laser power, scan speed and hatching space) and post sintering process (heating rate, sintering temperature and holding time) on the physical and mechanical properties of porcelain components have been investigated. The study has been carried out using the Taguchi''s method for the experimental design. In the laser sintering process, lower laser energy density and higher hatching space will increase the final mechanical properties of the porcelain components. A stress relief principle has been put forward to explain the different influence of the factors. The appropriate laser sintering parameters are attained in this paper: laser power 50W; scan speed 85mm/s; and hatching space 0.6mm. Sintering temperature has been determined to be the most important factor in the post sintering process. Appropriate sintering temperature for the laser sintered porcelain bodies is in the range of 1425–1475°C regarding the mechanical properties of the porcelain components. The maximum bending strength, 34.0±4.9MPa, is reached. [Copyright &y& Elsevier]

To fully exploit the preponderance of three-dimensional (3D)-printed, continuous, fiber-reinforced, thermoplastic composites (CFRTPCs) and self-reinforced composites (which exhibit excellent interfacial affinity and are fully recyclable), an approach in which continuous fiber self-reinforced composites (CFSRCs) can be fabricated by 3D printing is proposed. The influence of 3D-printing temperature on the mechanical performance of 3D-printed CFSRCs based on homogeneous, continuous, ultra-high-molecular-weight polyethylene (UHMWPE) fibers and high-density polyethylene (HDPE) filament, utilized as a reinforcing phase and matrix, respectively, was studied. Experimental results showed a qualitative relationship between the printing temperature and the mechanical properties. The ultimate tensile strength, as well as Young's modulus, were 300.2 MPa and 8.2 GPa, respectively. Furthermore, transcrystallization that occurred in the process of 3D printing resulted in an interface between fibers and the matrix. Finally, the recyclability of 3D-printed CFSRCs has also been demonstrated in this research for potential applications of green composites. [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]