Analysis of micro-architected polymer materials fabricated using 3D printing

Andrei Costantinescu (LMS, CNRS, Ecole Polytechnique)

Thursday 10th January, 2019 14:00-15:00 Maths 311B


3D-printing is an innovative technique to manufacture three-dimensional objects with complex shape. Processed materials are metals, ceramics or polymers depending on the working principle of the printer. During the point- or layer-wise printing the material experiences a transition from a liquid to a solid and a temperature change accompanied by changes in the thermomechanical and caloric material behavior. The process leads to gradients in the material properties and to residual stresses which influence the mechanical behavior and the shape of the structure in desired or undesired manners. Since the processed materials are inelastic these effects depend on time and temperature and the parameters of the printing and post-treatment process. Due to the lack of understanding, missing constitutive models and simulation tools, such problems are usually faced by costly trial-and-error methods.

The presentation will focus on two aspects of the design of multilayer materials. Oner the one hand side we shall present how residual stresses [1] and incompatible strains can harness self-folding and self-buckling in additive manufacturing [2,3] and on the other hand side we shall make a short overview of topological shape optimization for multi-layer materials [4,5]. The presentation will highlight a series of open problems in the domain.


[1] Ballard, P., and A. Constantinescu. "On the inversion of subsurface residual stresses from surface stress measurements." Journal of the Mechanics and Physics of Solids 42.11 (1994): 1767-1787.

[2] Bauhofer, A. A., Krödel, S., Rys, J., Bilal, O. R., Constantinescu, A., & Daraio, C. (2017). Harnessing Photochemical Shrinkage in Direct Laser Writing for Shape Morphing of Polymer Sheets. Advanced Materials, 29(42).

[3] Krödel, S., Li, L., Constantinescu, A., & Daraio, C. (2017). Stress relaxation in polymeric microlattice materials. Materials & Design, 130, 433-441.

[4] Nika, G. and Constantinescu, A. Structrural Design of multi-layer materials using inverse homogenization and a level set method

[5] Agnelli, Filippo, Andrei Constantinescu, and Grigor Nika. "Optimal design of auxetic, additively manufactured, polymeric structures." arXiv preprint arXiv:1809.02467 (2018).

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