Composites (and 3D printing)

In this assignment we decided to explore the benefits of composites associated with 3D printing by analyzing the improvement in tensile strength of a hollow probe of ABS filaments (printed in a makerbot replicator 2X) filled with clear silicone sealing. In this case the filaments of ABS printed on the makerbot create the fibers of the composite while the silicone acts as the matrix.

 

 

The probes were taken to a universal testing machine that allowed us to examine the tensile strengh of the material by pulling the probe until braking point and recording the load applied.

 

 

 

The way the probes were printed led to interesting behaviors during the test. The filaments on the edges tend to stay together and separate from the top and bottom faces fairly quickly. 

 

 

 

 

 

3 probes were made and notice that in all cases the ABS failed first on the top and bottom faces that on the sides and the clear silicone is still expanding until the breaking point for it is reached.

 

 

To compare the performance 3 solid probes were printed and put to the test. These probes behaved different; the sides did not separate from the body because of the pattern used to print the part was constant all along. However, the probe broke quickly without much deformation.

 

 

The maximum load supported by the probes was registered as follow:

Composite Probes
#1: 0.70004 kN
#2: 0.70232 kN
#3: 0.65122 kN
Average: 0.68452 kN

Solid Probes
#1: 0.72271 kN
#2: 0.70877 kN
#3: 0.74304 kN
Average: 0.72484 kN

showing a similar performance for both cases, with a slight advantage from the solid probes. More elongation was observed in the composite probes due to the side walls separating from the top and bottom faces, straightening and finally breaking, while the solid probes simply broke after certain elongation. This is representative of the observations where the solid probes had better structure while the composites separated easily by faces. Looking further into the structure of the composite probes one finds how only a few filaments were really surrounded by the clear silicone and those provided a true composite behavior.

 

 

Two conclusions can be extracted from this experiment. First, in order to create composites with 3D printed filaments one needs to print an internal structure that would allow for filling it up with the matrix while providing enough fibers to allow for good interaction between fibers and matrix. Second, 3D printing may be an alternative for creating molds that can be filled with resins and later peel off the printed case since the walls and faces are fairly uniform and separate cleanly from the clear silicone.