Session: 03-03-02: Processing and Design of Materials and Components for Additive Manufacturing

Paper Number: 77317

Start Time: Wednesday, 05:40 PM

77317 - Light Weight High Energy Absorption Composite by Additive Manufacturing 

 

Lightweight structures are a need in many industries such as construction, packaging,  aeronautics and automotive. Light weighting using sandwich core/skin combinations are widely used. Two options are typically considered: a honeycomb core or a chemical foam. The honeycomb core lends itself to ease of manufacturing using corrugated rolls. Reactive or physically foamed systems such as polyurethane and polyetherimide are another option. The emergence of 3d printing or additive manufacturing has led to innovation in shapes that are alternatives to the honeycomb. We combine the two approaches in our research and make a composite sandwich core where polyurethane foam is infused into the additively manufactured cellular lattices and analyze the improvements in the over all strength and increase in the light weighting capability of the entire structure.

 

A tetrahedral lattice structure using a base lattice of 10 mm lattice length is used.  A 4x4x4 grid of just the lattice and foam infused lattice structure. , This leads to 9 nodes and 20 struts frame. The lattice is fabricated using  fused deposition method or commonly known as FDM with PLA(Polylactic Acid) as the filament. PLA is chosen as it has low warping effect, thus giving more accurate samples. The polyurethane foam is made by mixing two-part chemicals, provided by US composites, which results in an exothermic reaction which causes the liquid to foam-up.

 

To have a direct comparison between the two sample types, the sample size is made sure to be kept same, which is 40x40x40mm. Three samples of each type are subjected to compression load.  Density of the lattice was extracted from the CAD model in Autodesk Inventor professional 2020. The maximum stress and total energy absorbed are calculated from the load displacement data acquired from the compression test. Specific stress and Specific energy absorbed was calculated by dividing the values by the density ratio of each sample type to estimate the impact of the both strength and strength to weight ratio.

 

 The additively manufactured lattice structure failed by the buckling of the vertical struts under the load. As the lattice is infused with the polyurethane foam, the foam acts as the matrix into which the lattice is suspended. The interaction between the lattice and the foam causes the buckling process of the struts of the lattice to be impeded. The results showed a 69.23 percent improvement in strength, 5.6 percent improvement in modulus and 51.14 percent in specific strength and a massive 118 percent bump in energy absorption This causes the creation of a very high energy absorption composite.

 

 

Presenting Author: Mahan Ghosh University of North Texas

Authors:

Mahan Ghosh University of North Texas
Nandika D'souza College of Engineering, University of North Texas