Search

With the increasing application of additive manufacturing (AM) in the industry, more attention has been paid to the performance of the additively manufactured part. How to maximize the structural efficiency of a part to achieve the desired performance has become the focus and challenge of design for additive manufacturing (DFAM). To give full play to the complex-geometry, multi-material, multi-scale, and multi-function manufacturing capabilities of AM, new approaches in DFAM have to be explored. The relationship between stress and growth in biology indicates that naturally evolved perfect structures are all optimal responses to their applied force. This work discusses a novel method to DFAM at the macroscale, mesoscale and microscale from a force-flow perspective, aiming to achieve an organic integration of force-flow based design with AM-driven manufacturing. Firstly, the characteristics of force-flow and its embodiment in nature and engineering are analyzed. Then, an overview of topology optimization, lattice/cellular structure design and infill pattern design are respectively provided in the combination of force-flow and AM. Finally, the future development directions of DFAM based on force-flow are proposed according to the limitations of current research. [Display omitted] • A multi-scale design method for additive manufacturing is discussed from a force-flow perspective. • The visualization forms, characteristics and the application of force-flow are elucidated. • Force-flow based topology optimization, mesoscopic structure design and infill pattern design are respectively reviewed. • Future research directions are indicated to make AM and force flow highly compatible. [ABSTRACT FROM AUTHOR]

Currently, the unique 5D 4 energy level of terbium (Tb3+) can contribute to narrow-band green light emission, which has high application prospects. However, due to its poor thermal stability at high temperatures, how to enhance the antithermal-quenching properties of Tb-doped phosphors has become a research difficulty in the field of solid-state lighting and temperature sensing. In this contribution, the antithermal-quenching green-emitting of terbium was achieved by Nb/Ta substitution to form GdNb 1-x Ta x O 4 :Tb3+ phosphors with various components. Photoluminescence analyses reveal an increasing trend in both the optical band gap and the intervalence charge transfer (IVCT) energy level positions with substitution. Variable-temperature spectrums observed that the phosphors under different compositions presented a large discrepancy in thermal quenching performance. It is elucidated that the elevated position of the IVCT energy level (IVCT-EL) predominantly influences thermal quenching, bolstering its role as a compensatory luminescence channel of 5D 3 →5D 4 far more than functioning as a quenching luminescence channel for Tb3+5D 3 /5D 4. Delving into the perspective of IVCT-EL positioning unveils the intrinsic mechanism through which IVCT-EL positions modulate the thermal quenching properties of phosphors with varying compositions due to the substitution of Ta for Nb. This insight facilitates the realization of enhanced thermal quenching resistance in phosphors. Furthermore, the antithermal-quenching property of Tb3+ in single-phase phosphors can be effectively modulated by excitation at different wavelengths. This tuning scheme not only advances the exploration of terbium-doped antithermal-quenching phosphors but also provides a novel strategy and reference for designing green-emitting phosphors in the fields of lighting and sensing. [Display omitted] [ABSTRACT FROM AUTHOR]

• Designed dual-activators in double perovskite according to site-beneficial occupation principle. • Perovskite La 3 Li 3 W 2 O 12 matrix contains abundant sites that suitable the doping of Mn4+ and Lanthanide. • Taking advantage of diverse thermal quenching between Mn4+ and Eu3+ ions for optical thermometry. Currently, Eu3+ or Mn4+ activated red-emitting fluorescent materials are widely used for solid-state lighting and optical temperature sensing. Here, we have chosen an abundant double perovskite structure that provides not only a trivalent Eu3+ lattice but also a tetravalent Mn4+ lattice and guarantees simultaneous emission. A family of rare earth (Eu3+) and transition metal (Mn4+) co-doped La 3 Li 3 W 2 O 12 (LLWO) red-emitting phosphors were obtained by designing a site-occupation strategy. By changing the concentration of Eu3+, the coordination environment of the activator is adjusted to finally achieve the adjustable emission of the phosphor from orange to red. In addition, when the doping concentration of Eu3+ is greater than 0.05, the symmetry of the doping sites in the perovskite structure decreases leading to the luminescence performance of red color and the enhancement of luminescence intensity. Finally, optical thermometry based on fluorescence intensity ratio shows that the developed phosphor has high sensitivity. [Display omitted] [ABSTRACT FROM AUTHOR]

Replacing solid structures with lattice structure is a way enabled by additive manufacturing (AM) to realize part lightweight design. Conventional design optimization method based on homogeneous periodic lattice structure cannot achieve the optimal structure without taking the stress magnitude and orientation into account. A design optimization method of heterogeneous conformal lattice structure coupling constraints and anisotropy of AM based on principal stress lines (PSL) is proposed. (1) The PSL is calculated based on finite element analysis to visualize the path of load transfer. (2) The load-adapted lattice structure is generated guided by the PSL. (3) In order to further optimize lattice structure, the lattice structure optimization model is established by coupling anisotropy and constraints of AM based on the fused deposition modeling (FDM) experiment. Taking a cantilever beam as a case, the maximum force-to-weight ratio and the stiffness-to-weight ratio of the optimized heterogeneous conformal lattice structure are increased by 11.8% and 41.8% respectively compared with homogeneous conformal lattice structure, which verified the feasibility of the proposed method. Unlabelled Image • A design optimization method of lattice structure coupling constraints and anisotropy of AM was proposed. • The superiority of the lattice structure based on principal stress lines was verified by finite element analysis. • The anisotropy model was established based on FDM specimens with different diameters and deposition orientations. • The strength and stiffness of the optimized cantilever beam with heterogeneous conformal lattice structure were improved. [ABSTRACT FROM AUTHOR]