Design Of Lattice Research Articles

Crashworthiness and optimization design of additive manufacturing double gradient lattice enhanced thin-walled tubes under dynamic impact loading

It is of paramount importance to ensure the protection of both infrastructure and personnel in scenarios characterized by a high strain rate dynamic impact. In order to develop lighter weight and higher crashworthiness energy-absorbing structures, this paper incorporates the bionic design of lattice reinforced thin-walled tube structures in the form of double gradient, as a means of achieving the aforementioned objectives. Material mechanical properties and the designed structures at high strain rate were researched using Split Hopkinson Pressure Bar (SHPB) experiment. The effects of gradient form and gradient parameters on the deformation pattern and crashworthiness of lattice enhanced thin-walled tubes are researched by means of the validated finite element model and the experimentally fitted Johnson-Cook material model. The results indicate that the specific energy absorption of the double gradient lattice enhanced thin-walled tube (T3L3) is increased by 36.19 % and the peak crush force is reduced by 21.19 % compared to the lattice enhanced thin-walled tube without gradient. Finally, the multi-objective optimization analysis of the T3L3 with the objective of achieving the maximum SEA and minimum PCF is carried out by Response Surface Methodology (RSM) and Non-dominated Sorting Genetic Algorithm-II (NSGA-II) to find the Pareto optimal solution set. Double-gradient bionic structure offers a new idea for designing energy-absorbing structures under high-speed impact conditions.

Design and parametrization of TPMS lattice using computational and experimental approach

Triply periodic minimal surface (TPMS) based lattices are extensively explored as a scaffold design for bone regeneration. TPMS maintains zero mean curvature at each point and offers a large surface area comparable to a trabecular bone. The best four TPMS minimal surfaces (IWP. Neovius, primitive, and F-RD) were selected, designed, and fabricated using acrylonitrile butadiene styrene (ABS) resin through the stereolithography (SLA) technique. The results indicate that small changes in unit cell dimensions do not significantly alter the structure topology, which ensures stress distribution within the lattice remains relatively uniform across different unit cell sizes when the porosity level is constant. The optimal unit cell size (2 to 5 mm) and porosity (70 to 80%) significantly affect the compressive strength and surface area to volume (SA/V) ratio due to a unique arrangement of the internal architecture of each TPMS unit cell. The lattice structure (formed by stacking unit cell) of unit cell size 2.11 mm with 70% porosity exhibited a maximum compressive strength of 39.8 MPa in IWP, followed by Neovius, primitive, and F-RD-based lattice structures. Moreover, the lattice showed more stability under compression force, minimized stress concentration compared to a unit cell, and exhibited distinct deformation patterns at different strain levels during compression.

Manufacturing trials of PFCs with low thermal conductivity features for limiters

In future demonstration fusion power plants, plasma facing components will face high steady state and ultra-high transient heat loads from the plasma. Introducing low thermal conductivity features to the component can reduce the peak temperatures seen by the coolant pipe during transient loads, but at the trade-off of a loss of steady-state performance. Producing low-conductivity tungsten by additive methods has been investigated elsewhere, so this trial investigates production through subtractive means i.e., conventional milling. This method preserves the original temperature limits and majority of the microstructure and is much higher Technology Readiness Level (TRL) so requires less development to reach series manufacture. In this trial, diamond drilling produced holes in monoblocks down to 0.6 mm and ligaments down to 0.7 mm, showing that this method is capable of producing small features in a controlled way. With the geometric design of lattice used in this trial, these samples achieved thermal conductivity reductions of 15% to 40%. One monoblock assembly was tested up to 1100 °C for 500 cycles in the Heating by Induction to Verify Extremes (HIVE) High Heat Flux test rig and showed no signs of ligament cracking or thermal degradation. Electromagnetic modelling has been validated against the experimental results, so future designs can be accurately modelled ahead of testing in HIVE.

Inverse design of a pyrochlore lattice of DNA origami through model-driven experiments.

Sophisticated statistical mechanics approaches and human intuition have demonstrated the possibility of self-assembling complex lattices or finite-size constructs. However, attempts so far have mostly only been successful in silico and often fail in experiment because of unpredicted traps associated with kinetic slowing down (gelation, glass transition) and competing ordered structures. Theoretical predictions also face the difficulty of encoding the desired interparticle interaction potential with the experimentally available nano- and micrometer-sized particles. To overcome these issues, we combine SAT assembly (a patchy-particle interaction design algorithm based on constrained optimization) with coarse-grained simulations of DNA nanotechnology to experimentally realize trap-free self-assembly pathways. We use this approach to assemble a pyrochlore three-dimensional lattice, coveted for its promise in the construction of optical metamaterials, and characterize it with small-angle x-ray scattering and scanning electron microscopy visualization.

Deep learning-based inverse design of lattice metamaterials for tuning bandgap

In this paper, deep learning neural networks is used to predict the band structure of metamaterial lattices, and proactive inverse design is employed in bandgap modulation. A parametric design of the metamaterial lattice is proposed to achieve a rich design space. The corresponding band structure data is calculated by finite element method (FEM) to construct the data set. We successfully bypass complex theoretical or numerical methods to establish the mapping relationship between the lattice geometry parameters of metamaterials and the band structure data by constructing and training fully connected neural networks and convolutional neural networks (CNN). By combining the trained neural network model into an inverse design method of bandgap tuning, the geometric parameters of the metamaterial lattice can be obtained directly by inputting the target band structure. Finally, three object band structures are designed and verified by finite element simulation and experiment, which verifies the effectiveness of the inverse design method. This design approach can be extended to design other metamaterial properties.

Predictive modeling of lattice structure design for 316L stainless steel using machine learning in the L-PBF process

Lattice structures in additive manufacturing of 316L stainless steel have gained increasing attention due to their well-suited mechanical properties and lightweight characteristics. Infill structures such as honeycomb, lattice, and gyroid have shown promise in achieving desirable mechanical properties for various applications. However, the design process of these structures is complex and time-consuming. In this study, we propose a machine learning-based approach to optimize the design of honeycomb, lattice, and gyroid infill structures in 316L stainless steel fabricated using laser powder bed fusion (L-PBF) technology under different loading conditions. A dataset of simulated lattice structures with varying geometries, wall thickness, distance, and angle using a computational model that simulates the mechanical behavior of infill structures under different loading conditions was generated. The dataset was then used to train a machine learning model to predict the mechanical properties of infill structures based on their design parameters. Using the trained machine learning model, we then performed a design exploration to identify the optimal infill structure geometry for a given set of mechanical requirements and loading conditions. Finally, we fabricated the optimized infill structures using L-PBF technology and conducted a series of mechanical tests to validate their performance under different loading conditions. Overall, our study demonstrates the potential of machine learning-based approaches for efficient and effective designing of honeycomb, lattice, and gyroid infill structures in 316L stainless steel fabricated using L-PBF technology under different loading conditions. Furthermore, this approach can be used for dynamic loading studies of infill structures.

Synergetic control mechanism for enhancing energy-absorption of 3D-printed lattice structures

It is difficult for controlling the failure mechanisms to improve the mechanical properties of lattice structures in a specified way. To this end, inspired by biological tissue/alloy microstructure, a novel synergetic control mechanism with gradient- and Orowan-strengthening is proposed to enhance energy-absorption (EA) of lattice. Gradient, Orowan and Grad-Oro lattices with different Reinforcement Phase (RP) spacing are designed and manufactured by 3D-printing with little defect. By experiments, simulations and theoretical analysis, compressive behaviors and failure modes of designed lattices are studied to explore the effects of synergetic control mechanism on mechanical properties. Results show that a 31.0%∼35.1% higher SEA than Matrix lattice is identified for Grad-Oro lattices which also surpass Orowan or Gradient lattices. Then, the transitional failure mechanisms of lattices are revealed to explain the improvement. It is illustrated that Zigzag shear-path induced by the Gradient-Orowan synergism can dissipate more energy than any single mechanism (bypassing shear-path or progressive collapse). It is finally found that closer RP spacing brings about stronger interactions between RP boundaries to affect failure modes like the grain boundary strengthening. This novel concept and structural design method greatly contribute to controllable mechanical design of lattice.

Bismuth layer-structured Bi4Ti3O12-CaBi4Ti4O15 intergrowth ferroelectric films for high-performance dielectric energy storage on Si substrate

Bismuth layer-structured ferroelectrics (BLSFs) have shown a great design capability for electrical energy storage, due to a highly anisotropic lattice and dielectric property. In this work, we add another notch to their qualifications as high energy density dielectrics, by demonstrating an ultrahigh recyclable energy density (Wrec ∼ 151.1 J/cm3 @ 4 MV/cm) and a good energy efficiency (η ∼ 72.0%) in Bi4Ti3O12-CaBi4Ti4O15 intergrowth ferroelectric films integrated on Si. This performance was achieved by the combination of a high spontaneous polarization (Ps) of the intergrown superlattice, and a polycrystalline nanograin microstructure. The high Ps is obtained through design of a special lattice, which determines the up limit of the energy density. On the other hand, the nanograin structure corresponds to a reduce remnant polarization, an intermediate dielectric constant and a delayed polarization saturation, all are ideal features for achieving a high recyclable energy density and energy efficiency. Such a structure is the consequence of a limited grain growth under the effect of a buffer layer. Lastly, a remarkable fatigue-resistance and an excellent charge-retaining ability were exhibited by these lead-free BLSF films. We expect this work will pave the way for designing high performance bismuth layer-structured ferroelectric films targeted for dielectric energy storage applications.

Structural Transformable Coulomb Lattice of n-Type Semiconductors for Guest Sorption

In recent years, highly designable organic porous materials have attracted considerable attention in the development of new types of molecular adsorption-desorption materials. The adsorption-desorption process also changes the electronic structure via the existence of guest molecules. Therefore, it is possible to change the physical property during the guest adsorption-desorption cycle using an appropriate chemical design of the host crystal lattice. As the development of n-type organic semiconductors has been limited, we focused on designing an n-type organic semiconductor material to control the host crystal lattice, electronic dimensionality, chemical stability, and high electron mobility using an ionic naphthalenediimide (NDI) derivative. Low symmetrical dianionic bis(benzene-m-sulfonate)-naphthalenediimide (m-BSNDI2-) forms various types of single-crystal (M+)2(m-BSNDI2-)·n(guest) with a combination of M+ = Na+, K+, Rb+, and guest = H2O, CH3OH. Four crystals of (K+)2(m-BSNDI2-)·n(H2O), (K+)2(m-BSNDI2-)·n(CH3OH), α-(K+)2(m-BSNDI2-), and β-(K+)2(m-BSNDI2-) were transformable using the guest adsorption-desorption cycle. Two kinds of single-crystal (K+)2(m-BSNDI2-)·n(CH3OH) with n = 0 and 2.0 showed a single-crystal to single-crystal (SCSC) transformation through CH3OH desorption. On the contrary, five kinds of single crystals with n = 0, 3.0, 3.3, 4.75, and 5.5 were identified in the single-crystal X-ray structural analyses of (K+)2(m-BSNDI2-)·n(H2O). Systematic change of the ionic radii in (M+)2(m-BSNDI2-) modified the crystal lattice flexibility for the guest adsorption-desorption cycles.

Enhanced valley topological defect-edge states in all-dielectric photonic crystal

The valley topological edge states (VTESs) have become a new research hotspot in topological photonics because of its flexibility and diversity. The major challenge for them comes from the limit bandwidth, the weak energy of localized field and the weak ability of direction-locked. In this paper, through the design of a triangular lattice with a compound unit cell, it is demonstrated that with the coupling of the VTESs and the defect states, some new hybrid VTESs called valley topological defect-edge states (VTDESs) occur and their performance can be greatly enhanced. Through enlarging the interval between the two lattices with opposite valley topological phases, the VTDESs absorb both the topological properties of the pure VTESs, and the properties of intense field and wide bandwidth of the defect states. The VTDESs have larger bandwidth, more intense transmission energy and the ideal ability of direction-locked. The robust transmission property against the structure obstacle has been demonstrated for the VTDESs.

Study on the energy dissipation mechanism of the pyramidal lattice sandwich panel subjected to underwater explosion

The energy dissipation mechanism of a pyramidal lattice sandwich panel subjected to underwater explosion (UNDEX) is studied. Firstly, a three-layer pyramidal lattice sandwich panel with a dimension of 500 mm × 500 mm × 120 mm was fabricated by welding. The deformation mode of the pyramidal lattice sandwich panel subjected to UNDEX is revealed through an experiment. Furthermore, the deformation process of the front and back plates, interlayer sheets, and pyramidal lattices is demonstrated by simulation. The energy absorbed by every component is attained according to simulation results. Finally, the theoretical solution of the dynamic response of the experiment model in the stage of fluid-solid coupling, lattice collapse, and whole deformation is presented. Simulation and theoretical results are consistent with experimental results. Theoretical analysis shows that the advantage of the pyramidal lattice sandwich panel in the resistance to UNDEX is that the fluid-structure coupling effect could be controlled by strength design of the pyramidal lattice. The impulse transmitted to the experiment model could be considerably attenuated to 54.97% of the incident impulse, which is more efficient than the reported literature. This research could support the protection of ship structures subjected to UNDEX.

Modeling and Design of Periodic Polygonal Lattices Constructed from Microstructures with Varying Curvatures

Lattice structures can exhibit unusual mechanical properties by appropriate design and arrangement of the microstructures, and have already found applications in areas such as tissue engineering, stretchable electronics, and soft robotics. However, the designed microstructures generally follow simple geometric patterns with constant curvatures and theoretical models are developed for each geometry particularly. It lacks a universal method to model and design the periodic lattice constructed from microstructures with varying curvatures. In this paper, we develop a universal approach to design polygonal lattices with a wide range of microstructures with varying curvatures using instant curvature and parametric functions. A finite deformation model is proposed for the microstructures and the corresponding lattices, which considers the wavy or curled microstructure, hierarchical geometry, and large deformation. Experiments and finite-element simulations are conducted to validate the theoretical model. All of Young's modulus, stretchability, and Poisson's ratio can be inversely designed using the developed theoretical model. Results show that the stretchability of the highly stretchable lattice can be further increased by more than 4 times using densely curled microstructure. The signs of Poisson's ratio can also change with the axial strain by rationally designing the microstructures. By combining curve fitting and curvature and parametric functions, the mechanical behaviors of lattices constructed by bioinspired microstructures can also be predicted. The lattice structures are then demonstrated to reinforce a hydrogel with modulus increased by around 2 orders and act as a biomimetic soft-strain sensor. This work could aid the design of a hierarchical lattice and have potential applications in tissue engineering, stretchable electronics, and soft robotics.

Multielectrode registration of episodic discharges generated by weakly electric fishes

Purpose of this study introduces a multielectrode array (MEA) registration system in order to generate electric field images of the episodic discharges generated by weakly electric fish. A multielectrode registration system has several important features: the design of the multielectrode lattice, the amplifier circuit, the choice of reference points for differential measurements, the recovery of the absolute values of the electric field potentials, and the application of principal components analysis. Methods. There are several advantages of our MEA registration as compared with the traditional twoelectrode registration: (a) the signal-to-noise ratio is significantly increased, (b) it is possible to construct the spatial distribution of the electric field for a single electric discharge, (c) the signals’ sources can be easily separated and identified, and (d) quantitative data on the electrical potential distribution can be obtained throughout the entire experimental tank. Results. The results illustrate an example of applied MEA registration. Electric discharges were recorded from a weakly electric catfish, Clarias gariepinus, using an array of 8 x 8 electrodes at a sampling rate of 20 kHz. Data show oscillograms and two-dimensional plots of the spatial distribution of the electrical field.

Crushing analysis and optimization for bio-inspired hierarchical 3D cellular structure

Three-dimensional (3D) cellular structures have been widely used in many aspects, e.g., protective equipment, aerospace, vehicles and so on, due to its lightweight and excellent energy absorption characteristics. Triply periodic minimal surface (TPMS) has more uniform energy absorption and mechanical properties than foam due to its structural characteristics. Therefore, a novel 3D hierarchical structure based on TPMS inspired by natural hierarchical biological structure is proposed in this study. Then, the numerical simulation is carried out using the nonlinear finite element code through LS-DYNA to study the crushing behavior of the hierarchical 3D cellular structure. And, the accuracy of finite element model is validated by quasi-static compression experiments on hierarchical structures manufactured by 3D printing. According to the numerical simulation results, the bio-inspired hierarchical 3D lattice is found to have excellent energy absorption characteristics than the non-hierarchical 3D lattice. In addition, the energy absorption characteristics of hierarchical structure is found to be affected by the design parameters of density and constant C. In order to obtain the optimal design of the bio-inspired hierarchical 3D lattice, Kriging (KRG) surrogate models and non-dominated sorting genetic algorithm II (NSGA-II) are jointly used to optimize the hierarchical 3D cellular structure. Moreover, the approximate expression of the specific energy absorption (SEA) of the hierarchical 3D cellular structure is obtained by fitting Gibson and Ashby empirical formula for prediction. Based on our study, the novel hierarchical 3D cellular structure has extremely excellent energy absorption characteristics and has very good application prospect in impact engineering.

Compression behavior of strut-reinforced hierarchical lattice—Experiment and simulation

The reinforcement design of lightweight lattice is a hot spot to seek for higher mechanical performance. In this study, the strut-reinforced concept is proposed from the perspective of space filling. The specimens with 4 × 4 × 4 cells were fabricated through Selective Laser Melting (SLM) technique with the metallic 316L stainless steel. The mechanical response and deformation mechanism were investigated by means of quasi-static compression test and numerical simulation. Superior performance was obtained in strut-reinforced hierarchical lattices compared with conventional one, in terms of total energy absorption, specific energy absorption, mean force and deformation process. The filled effect, ribbed effect and interaction effect of specific parts generated by the hierarchical configuration were proved to enhance the compression behavior. The influence of geometry variations on mechanical response was determined and the function of struts becomes more dominant as the diameter increases. In addition, the reinforcement mechanism was revealed via comparing the different deformation characteristics. Afterwards, the bearing capacity of the reinforced lattice subjected to oblique loading was compared with conventional lattice.

X -band linac design

In order to explore physics in the EUV to soft x-ray region, we have designed a machine which is capable of accelerating a $\ensuremath{\sim}250\text{ }\text{ }\mathrm{pC}$ electron bunch to an energy of $\ensuremath{\sim}1\text{ }\text{ }\mathrm{GeV}$. The front end of the CLARA (Compact Linear Accelerator for Research and Applications) system at Daresbury Labs will be used as an S-band injector of $\ensuremath{\sim}180\text{ }\text{ }\mathrm{MeV}/\mathrm{c}$, sub-ps FWHM, $\ensuremath{\sim}250\text{ }\text{ }\mathrm{pC}$ electron bunches into the XARA (X-Band Accelerator for Research and Application) system. A rf feasibility study has been carried out for a structure operating in the $2\ensuremath{\pi}/3$ mode at a frequency of 11.9942 GHz which is fed by a SLED klyston setup. The average cell of this structure has an iris radius of $⟨a⟩=3.2\text{ }\text{ }\mathrm{mm}$ and a shunt impedance of $⟨{R}_{s}⟩=106.55\text{ }\text{ }\mathrm{M}\mathrm{\ensuremath{\Omega}}/\mathrm{m}$. A high target gradient of $80\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ for a single-bunch operation of the linac is necessary due to spatial constraints at Daresbury Labs. We have also implemented Gaussian detuning of the linac in order to future-proof the project for potential multibunch operation of the machine. After combining the rf study with an analysis of the uncoupled long-range wakefield and the short-range transverse wakefields, the optimal structure parameters are outlined as a compromise between the shunt impedance, electrical breakdown rate and wakefields in the structure. As novel designs will be tested using this free-electron laser (FEL) an increased beam charge may be useful. Therefore a beam dynamics study via the particle tracking code elegant has been performed to assess how the beam quality evolves while traveling through the XARA rf structures for different bunch charges and beam offsets. These simulations reveal how the bunch is disturbed for varying bunch charges and offsets and give an initial indication of how sensitive the beam parameters (beam centroid position, emittance, RMS beam size, etc.) are to the wakefields generated in XARA. An analytical formulation of the beam motion as it travels through the XARA linac has been utilized to calculate the emittance growth. This allows for comparison between analytical and numerical simulation of the beam dynamics to give confidence in the results. The beam dynamics study shows that for a bunch charge of ${Q}_{b}=250\text{ }\text{ }\mathrm{pC}$ and a beam offset of ${C}_{x}={\ensuremath{\sigma}}_{z}/2=0.253\text{ }\text{ }\mathrm{mm}$, the normalized emittance growth at the end of the XARA linac is $\mathrm{\ensuremath{\Delta}}{\ensuremath{\epsilon}}_{Nx}/{\ensuremath{\epsilon}}_{Nx}\ensuremath{\sim}270%$. This may be mitigated by the design of a magnetic lattice which would include kickers to recenter the beam on the electrical axis of the structure, reducing the effect of the wakefields on the bunch. Currently it is probable that a maximum bunch charge of $\ensuremath{\sim}250\text{ }\text{ }\mathrm{pC}$ will be utilized for this machine; however a future design of a magnetic focusing lattice may allow higher charges to be viable and will reduce the emittance growth.

In-plane wave propagation analysis for waveguide design of hexagonal lattice with Koch snowflake

In this study, the band structure and directional characteristics of the hexagonal lattice with Koch snowflake are investigated. The finite element method and Bloch theorem are used to analyze the wave propagation in hexagonal lattice with Koch snowflake for different fractal orders. The effects of the geometric parameters on band structures are discussed in detail. The group velocities at given frequencies are calculated for analyzing the directional characteristics of the wave propagation. The dynamic responses of the periodic lattice are investigated via numerical simulation to confirm the directional features. The vibration experiments are conducted to verify the existence of band gap and vibration suppression performances of the structures, which are used to design the waveguide in the lattices. The results demonstrate that the hexagonal lattice with Koch snowflake for different fractal orders can tune the elastic wave behaviors in a specific way. As the fractal order increases, multiple band gaps appear and the band structure has self-similarity in the low-frequency range. The directional characteristics of wave propagation in the hexagonal lattice with Koch snowflake can be used to further expand the vibration attenuation range. The results also show the potential importance and feasibility of using the hexagonal lattice with Koch snowflake for vibration isolation and control using the hexagonal lattice with Koch snowflake.

Analysis and design of symmetric lattice based wideband 2-bit digital phase shifter

Analysis and design of symmetric lattice based wideband 2-bit digital phase shifter

Design of the HEPS booster lattice

The high energy photon source (HEPS) is a diffraction-limited storage ring light source being built in China. Along with the deeper studies of booster and the evolution of the lattice design and injection scheme of the storage ring, four versions of the booster lattices have been proposed from the project proposal stage. Unlike the design of the storage ring, in the booster design, more effort was made to realize stable and reliable operation rather than advanced performance. A FODO structure lattice and the “high-energy accumulation” scheme was adopted in the HEPS booster design. To find the ultimate performance of the lattice, a multi-objective genetic algorithm (MOGA) and particle swarm optimization (PSO) were used to optimize the emittance and the dynamic aperture. In the latest booster lattice design, the emittance was reduced to 16.3 nm rad. At the same time, the single-bunch charge limit was increased by minimizing the average vertical beta function and reducing the chromaticity. Through multi iterations with the hardware system, the current lattice was basically frozen and can be used as a basis for related physics studies, hardware and engineering design of the booster. In the future, more detailed physical studies will be performed based on this lattice.

The transfer line design for the HEPS project

The high energy photon source (HEPS), a 6-GeV synchrotron radiation facility with ultralow emittance, is under construction in China. Three transfer lines are designed for HEPS. One low-energy transfer line is used to deliver the 500 MeV beam provided by the linac to the booster. Two high-energy transfer lines are used to connect the booster and the storage ring to realize beam accumulation in the booster at 6 GeV. The design of the transfer lines is closely related to the layout and optics design of the storage ring, booster and linac. Based on the physics design of the storage ring, booster and linac, the design of the transfer lines has been adjusted. In this paper, the considerations and design of the latest lattice of transfer lines are described. The design satisfies the requirements of the high efficiency transmission and injection.