Experimental Investigation and Simulation of 3d-Printed Lattice Structures

Heiml, Eva; Kalteis, Anna; Major, Zoltán

doi:10.14311/app.2019.25.0052

Cited by 7 publications

(2 citation statements)

References 5 publications

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“…In the quasi-static and simple impact tests on the non-graded cases, a peak was observed at the beginning of the contact in Figure 7 and Figure 9 ; this behavior was similar to that reported by Heiml et al [ 63 ]. This peak could be attributed to the numeric inelastic buckling that the structure had to overcome in order to collapse [ 80 ], and this was intensified during the impact testing due to the reduced time in which this effect had to take place.…”

Section: Resultssupporting

confidence: 87%

“…For instance, the Mooney–Rivlin material model is appropriate to simulate natural rubber of up to a 100% tensile strain [ 56 ], while the Ogden 3rd-order material model better fits carbon black-reinforced rubber with tensile data of up to ε = 6.0, while the Yeoh material model works properly for natural rubber reinforced by carbon-black [ 57 , 58 ]. Particularly for TPU, Ogden, Yeoh, and Mooney–Rivlin material models can be fitted properly if diverse experimental data are within reach [ 59 , 60 , 61 ], but if only uniaxial tensile data are available, the Ogden model provides better results than the other two [ 59 , 62 , 63 ]. Therefore, in this work, the quasi-static average stress–strain curve was fitted to an Ogden 3rd-order material model by using HYPERFIT ® 2.181, which was used as the model input.…”

Section: Methodsmentioning

confidence: 99%

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Low Impact Velocity Modeling of 3D Printed Spatially Graded Elastomeric Lattices

et al. 2022

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Additive manufacturing technologies have facilitated the construction of intricate geometries, which otherwise would be an extenuating task to accomplish by using traditional processes. Particularly, this work addresses the manufacturing, testing, and modeling of thermoplastic polyurethane (TPU) lattices. Here, a discussion of different unit cells found in the literature is presented, along with the based materials used by other authors and the tests performed in diverse studies, from which a necessity to improve the dynamic modeling of polymeric lattices was identified. This research focused on the experimental and numerical analysis of elastomeric lattices under quasi-static and dynamic compressive loads, using a Kelvin unit cell to design and build non-graded and spatially side-graded lattices. The base material behavior was fitted to an Ogden 3rd-order hyperelastic material model and used as input for the numerical work through finite element analysis (FEA). The quasi-static and impact loading FEA results from the lattices showed a good agreement with the experimental data, and by using the validated simulation methodology, additional special cases were simulated and compared. Finally, the information extracted from FEA allowed for a comparison of the performance of the lattice configurations considered herein.

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Section: Resultssupporting

confidence: 87%

Section: Methodsmentioning

confidence: 99%

Low Impact Velocity Modeling of 3D Printed Spatially Graded Elastomeric Lattices

et al. 2022

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Simulation of Lattice Structures with Johnson–Cook Material and Damage Model

Cronau,

Engstler

2024

Advanced Structured Materials

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Mechanical Characterisation and Simulation of the Tensile Behaviour of Polymeric Additively Manufactured Lattice Structures

Bruson,

Galati,

Calignano

et al. 2023

Exp Mech

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Background The mechanical properties of lattice structures have been primarily investigated using uniaxial compression loads. Particularly for polymers, tensile properties are rarely considered because of the difficulties of defining a suitable specimen design in which the fracture occurs within the gauge length. Objective This work proposes a novel formulation to obtain a specimen for the tensile test with a gradation of the lattice density at the interface with the bulk portion, which realises a uniform stress distribution. The aim is to combine a localisation of the fracture in the gauge length with a specimen geometry accomplishing the EN ISO 527 standard and analyse the correlation between the mechanical performance and the defects induced by the process on such thin structures. Methods The formulation is experimentally and numerically (FEM) tested by designed specimens with different cell topology, cell size, strut diameter, and number of cells in the sample thickness. Also, results from uniaxial compression tests are used to validate the tensile properties. The specimens are manufactured in different orientations in the building volume by laser powder bed fusion with Polyamide 12. The effects of the pores morphology, distribution, and inherent anisotropy are investigated using X-ray computed tomography analysis. This data is also used to tune a numerical model. Results The numerical analysis showed a uniform stress distribution; experimentally, the fracture is localised inside the gauge length in respect of the ISO standard. Remarkably, among the different strut-based architectures, the elongation at break is, in the best case, 50% of the corresponding bulk material, while the tensile strengths are comparable. Vertical printed specimens exhibited a slight decrease in tensile strength, and the elongation at break was lower than 50% compared to the counterparts built along the horizontal orientation. Modifying the numerical model according to process-related dimensional deviations between the actual and the nominal structures significantly improved the numerical results. The remaining deviation highlighted the incorrectness of modelling the lattice material from the bulk properties. Conclusion Density gradation is a reliable approach for describing the tensile behaviour of polymeric lattice structures. However, the lower amount of porosity and the different shape in the lattice led to a different material mechanical performance with respect to the corresponding bulk counterpart. Therefore, for polymeric lattice structures, the relationship between process-design-material appears crucial for correctly representing the structure behaviour.

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Experimental Investigation and Simulation of 3d-Printed Lattice Structures

Cited by 7 publications

References 5 publications

Low Impact Velocity Modeling of 3D Printed Spatially Graded Elastomeric Lattices

Low Impact Velocity Modeling of 3D Printed Spatially Graded Elastomeric Lattices

Simulation of Lattice Structures with Johnson–Cook Material and Damage Model

Mechanical Characterisation and Simulation of the Tensile Behaviour of Polymeric Additively Manufactured Lattice Structures

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