Multi-scale Optimisation for Additive Manufacturing of fatigue resistant shock-absorbing MetaMaterials

Project Information

MOAMMM

Grant agreement ID: 862015

DOI

10.3030/862015

Project closed

EC signature date 30 August 2019

Start date 1 January 2020

End date 30 September 2024

Funded under

• EXCELLENT SCIENCE - Future and Emerging Technologies (FET)

Total cost

€ 3 516 831,25

EU contribution

€ 3 516 831,25

Coordinated by

UNIVERSITE DE LIEGE
Belgium

Periodic Reporting for period 3 - MOAMMM (Multi-scale Optimisation for Additive Manufacturing of fatigue resistant shock-absorbing MetaMaterials)

Reporting period: 2022-07-01 to 2024-09-30

Summary of the context and overall objectives of the project

The emergence of meta-materials has opened a new paradigm in designing engineering parts in which the full structural parts can be optimized together with the meta-material they are locally composed of. Moreover, additional morphing at local and global scales may support their adaptation to variable loading conditions and shifted user needs. As polymeric materials can fulfill simultaneously structural mechanical and functional requirements, the combination of this design paradigm with additive manufacturing can support and generate novel applications.

However, many left challenges can only be addressed by considering experimental and numerical multi-scale methods. Nevertheless, current existing approaches are limited in several aspects because on the one hand of the difficulty in representing the microstructure and characterizing micro-scale constituent materials, and on the other hand in the computational cost inherent to these approaches.

The overall objective of this project is to develop a data-driven methodology relying on a structural properties-micro-structure linkage and able to design optimized devices based on meta-materials and printable using additive manufacturing.

3D-printing of polymers has recently found a lot of interest and growth, a significant portion of which concerns real applications in products. Results of this project will support significantly drivers of this growth such as low investment cost, geometrical freedom, integration and individualization, on a new level: this project is an opportunity to explore new concepts of architecture from an innovative design methodology that would enable it to offer unique products, both in terms of efficiency and comfort in different areas. The proposed microstructures can achieve light-weight designs and customized properties; and the simulation approach will guarantee the required robustness of process and a repeatable high product quality.

As a proof of concept, the methodology will be applied to design metamaterial-based structures:
i) Athletic shoe soles, relying on reversible deformation of the metamaterials that absorb energy during deformation and return it without change in shape, in which emphasis is put on fatigue performance;
ii) Bicycle helmets, relying on energy dissipation, possibly by irreversible deformations, in which emphasis is put on minimizing weight and cost whilst maximizing energy dissipation.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The MOAMMM project has contributed toward the following achievements:
i) Using different scale factors to evaluate the minimum cell size in a stochastic manner, helped to adjust machine parameters in order to optimize the AM processes for printing filigree lattice structures and to develop design guidelines for the SLS process. New material were also introduced in the SLS process.
ii) A comprehensive multi-scale experimental methodology has been developed in order to characterize (at different scales) the constitutive behavior of lattice meta-materials based structures
iii) A computational homogenisation framework for lattice materials has been developed and different non-linear material models have been implemented including plasticity, visco-elasticity and visco-plasticity.
iv) Machine-learning tools have been applied to construct surrogate models of the elasto-plastic micro-structure responses at both the meso-scale but also at the local scale (after developing an order-reduction methodology for high-dimensional outputs).
vi) Bayesian Optimization has been developed in order to optimize lattice meta-materials based structures with an application toward impact absorbers and shoe-soles.
vii) The developed methodologies have been integrated in order to develop a framework able to optimize a user-tailored device: from the 3D user scan to the testing via the optimization of the lattice meta-materials based structures.

Concerning the dissemination activities:
i) 18 peer-reviewed papers have been published in major journals and have attracted (by the end of the project) more than 430 citations, with a h-index of 10.
ii) We have been invited to deliver a semi-plenary lecture in a major conference (UNCECOMP 2023)
iii) Results have been presented at 22 conferences and two summer-schools
iv) Open data obtained in the course of the project have been downloaded more than 475 times (by the end of the project)
v) Lattice structures especially helmet and saddle have been eye catchers on many events including Formnext, Fakuma, Moulding expo, Medtec, Motek, Coachulting Forum, MOAMMM lead user workshop, 30th cirp anniversary and further events including press coverage
vi) Strategically cirp will support companies in development and introduction of new products. cirp will not introduce products to B2C market directly.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

From the technological point of view, if the project succeeds, the basis of a new technology will be established in which a high-performance device can be designed and fabricated in a fully personalised way. This new paradigm paves the way to the design of customized sport equipment, more efficient prostheses for a particular person or again lighter shock absorbers. An area which shows significant growth rates within 3D-printing is the realm of prosthesis, orthosis and body enhancement solutions. A proper simulation of the 3D-printed parts applied in those applications is a decisive factor to prevent unforeseen breakage and thus accidents or injury. Socially, this would have a strong impact in public health because it would allow a more efficient process for the personalized fabrication of some prostheses, decreasing their cost and making them affordable for the public health systems.

From the scientific point of view, the main outcome is the development of a PSP linkage for printed-metamaterial, in which additional innovations are expected:
i) New and more efficient optimization and stochastic multi-scale methods relying on surrogate models is still a challenge. The use of surrogate models in multi-scale methods has seen a growing interest to which the MOAMMM project has contributed in the case of irreversible material behaviors.
ii) A rigorous UQ methodology applied to printed metamaterials, with a view to quality control. Indeed, tomographic images of printed cells and experimental tests conducted at different length scales show that the strut material content and response significantly differs from that of the initial geometry, inducing variations in the cell responses.
iii) Accurate additive manufacturing process model and optimized process for polymers, with a particular emphasis on the cell-size reduction. Manufacturing process model will allow predicting estimating bulk material properties and in turns optimizing the process.
iv) New simulation tools to estimate the mechanical response of a lattice metamaterial cell have been developed.
v) A comprehensive material testing was carried out at different scales and under multiaxial loading conditions (axial/torsional) to characterize the selective laser sintered polymeric materials (SLS PA12 and TPU) used and to determine proper material model parameters for the simulations performed in this project. These simulations were (partly) verified by instrumented component tests at service temperatures

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