Mode shape-informed design of lightweight metal lattice structures produced by laser powder bed fusion for enhanced dynamic properties

Microstructure and geometry effects on the compressive behavior of LPBF-manufactured inconel 718 honeycomb structures

The use of additive manufacturing technology for the lightweight design of complex lattice structures is becoming increasingly popular, but research on lattice structure design and strength evaluation still relies on the visual comparison of stress distributions and lacks quantitative assessment data. Given this perspective, this study explored the effects of structural parameters (relative density, cell size, and sample size) on the compressive strength of diamond lattice structures prepared by Stereolithography (SLA) and revealed the underlying mechanisms through stress distribution simulations and the calculation of characteristic stress distribution parameters (structural efficiency and stress concentration coefficient). The results showed that a greater relative density can increase structural efficiency, but it hardly affects the stress concentration coefficient, and smaller cell sizes and larger sample sizes increase the stress concentration coefficient without affecting the structural efficiency. Lattice structures with a greater relative density, higher structural efficiency, and a larger stress concentration coefficient exhibit higher compressive strength according to the lattice strength formula, which indicates that lattice strength is determined by the product of structural efficiency, stress concentration coefficient, relative density, and material strength. The relevant conclusions could guide the analysis of lattice stress distribution and the design of lattice structures.

Dimensionless process development for lattice structure design in laser powder bed fusion

This paper presents the design, analysis and experimental verification of strut-based lattice structures to enhance the mechanical vibration isolation properties of a machine frame, whilst also conserving its structural integrity. In addition, design parameters that correlate lattices, with fixed volume and similar material, to natural frequency and structural integrity are also presented. To achieve high efficiency of vibration isolation and to conserve the structural integrity, a trade-off needs to be made between the frame’s natural frequency and its compressive strength. The total area moment of inertia and the mass (at fixed volume and with similar material) are proposed design parameters to compare and select the lattice structures; these parameters are computationally efficient and straight-forward to compute, as opposed to the use of finite element modelling to estimate both natural frequency and compressive strength. However, to validate the design parameters, finite element modelling has been used to determine the theoretical static and dynamic mechanical properties of the lattice structures. The lattices have been fabricated by laser powder bed fusion and experimentally tested to compare their static and dynamic properties to the theoretical model. Correlations between the proposed design parameters, and the natural frequency and strength of the lattices are presented.

As a kind of novel multifunctional structure with three-dimensional pores characterized by low relative density, lattice structures can attain a lightweight design while maintaining high specific mechanical properties in three-dimensional solid structures. Focusing on the challenge of finding the optimal design of lattice structures in the design object, a design and modeling method of non-uniform three-dimensional lattice structures is proposed while ensuring the selective laser sintering manufacturability. Optimization for cell type, cell size, and strut size distribution of lattices is specified with the mechanical properties analyzed and the material model calculated beforehand. The manufacturing constraints are analyzed and expressed in topology optimization and the optimal distribution of topology optimization results is mapped to the strut size distribution of lattice cells. The rapid and automatic computer-aided design modeling of optimized structures is realized by the parametric definition and assembling of lattice components. Finally, the non-uniform structures are successfully manufactured by selective laser sintering and it is shown by means of finite element analysis and experiments that the proposed design approach can improve the mechanical performance compared to the uniform lattice structure under the same weight reduction. And for the design object in this study, body-centered structure with cell size [Formula: see text]mm is chosen as the optimal cell type and cell size under the given selective laser sintering manufacturing constraints.

16 - Lattice structures made by laser powder bed fusion

Lightweight design of lattice structure of boron steel prepared by selective laser melting

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.

Laser powder bed fusion of node-reinforced hybrid lattice structure inspired by crystal microstructure: Structural feature sensitivity and mechanical performance

This scientific research deals with lattice structures manufactured with laser powder bed fusion. Laser powder bed fusion is part of additive manufacturing. The so called layered construction is an increasingly used innovative manufacturing process that can be used to realize new design possibilities. Lightweight structures or bionic structures play a key role here. The focus of this work is on periodic lattice structures. In addition to saving resources and reducing the weight of components, lattice structures have particularly pronounced mechanical properties. However, little is known about their thermo- and fluid-dynamic properties. This work describes the first influencing factors of lattice structures ina thermo- and fluid-dynamic context using a case study. The aim of this paper is to evaluate important design and simulation criteria of lattice structures. Different lattice structures are considered, whose strut geometry is varied. The case study is carried out using a heat exchanger. While classical heat exchangers have lamellar structures, the substitution of these by lattice structures is evaluated. Thiswork represents a first consideration of the most important parameters and gives an overview of the most important core points.

Aluminium alloy lattice structures are prospective candidates for high-value engineering applications due to their excellent comprehensive properties. Selective laser melting (SLM), a promising additive manufacturing (AM) process, enables the fabrication of metallic periodic lattices with complex and controllable internal design. In this paper, finite element (FE) analysis with the Johnson–Cook model was employed to investigate the compressive plastic deformation and the fracture mechanisms of AlSi10Mg Gyroid lattice structures (GLSs). The simulated accuracy was then validated by the compression test of GLS samples with various volume fractions fabricated via SLM. The results revealed that FE simulations were in conformity with the experimental testing with most prediction errors less than 25% and could be utilised to estimate and characterise the mechanical properties for AlSi10Mg GLSs. Finally, the discussion about the energy absorption of GLSs during the elastic and yield stage demonstrated that the FE data were comparable with the experimental results, and the rise in volume fraction contributed to the increase of energy absorption capability from 1.33 J/mm3 to 9.61 J/mm3 and improved the ability to resist the decline of absorption efficiency. This study provides a deeper understanding and guidance based on FE analysis for the optimal design and AM of Al alloy lattice structures.

Layer‐by‐layer additive manufacturing (AM) by means of laser‐powder bed fusion (L‐PBF) offers many prospects regarding the design of lattice structures used, for example, in gas turbines. However, defects such as bulk porosity, surface roughness, and re‐entrant features are exacerbated in nonvertical structures, such as tilted struts. The characterization and quantification of these kinds of defects are essential for the correct estimation of fracture and fatigue properties. Herein, cylindrical struts fabricated by L‐PBF are investigated by means of X‐ray computed tomography (XCT), with the aim of casting light on the dependence of the three kinds of defects (bulk porosity, surface roughness, and re‐entrant features) on the build angle. Innovative analysis methods are proposed to correlate shape and position of pores, to determine the angular‐resolved surface roughness, and to quantify the amount of re‐entrant surface features, q. A meshing of the XCT surface enables the correlation of q with the classical surface roughness P a. This analysis leads to the conclusion that there is a linear correlation between q and P a. However, it is conjectured that there must be a threshold of surface roughness, below which no re‐entrant features can be build.

Additive manufactured Triply Periodical Minimal Surface lattice structures with modulated hybrid topology

To make lattice structures have both load-bearing and energy absorption characteristics to protect the safety of personnel and equipment in the collision, this paper proposes a multi-objective topology optimisation method for the design of lattice structures with negative Poisson's ratio. The energy absorption and load-bearing characteristics of the lattice structure are characterised by negative Poisson's ratio and stiffness, respectively. A topology optimisation model is established to maximise the stiffness and negative Poisson's ratio of the lattice structure. The design optimisation of microscopic material is conducted by the energy homogenisation method. A modified optimality criteria method is employed to update design variables. The energy absorption and load-bearing characteristics of the optimised structure are tested and analysed by finite element simulation and compression experiment, respectively. The results show that the optimised lattice structure has both energy absorption and load-bearing characteristics. In general, the proposed method can provide a feasible reference for the topology optimisation design of anti-collision structures.

To make lattice structures have both load-bearing and energy absorption characteristics to protect the safety of personnel and equipment in the collision, this paper proposes a multi-objective topology optimisation method for the design of lattice structures with negative Poisson's ratio. The energy absorption and load-bearing characteristics of the lattice structure are characterised by negative Poisson's ratio and stiffness, respectively. A topology optimisation model is established to maximise the stiffness and negative Poisson's ratio of the lattice structure. The design optimisation of microscopic material is conducted by the energy homogenisation method. A modified optimality criteria method is employed to update design variables. The energy absorption and load-bearing characteristics of the optimised structure are tested and analysed by finite element simulation and compression experiment, respectively. The results show that the optimised lattice structure has both energy absorption and load-bearing characteristics. In general, the proposed method can provide a feasible reference for the topology optimisation design of anti-collision structures.