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Use of Mycelium Core to Form a Sustainable Composite Beam for the 2015 SAMPE Bridge Competition

Ryan C. Granger (’15), Mechanical Engineering Advisor: Ronald B. Bucinell, Ph.D., P.E.

Summary The Society for the Advancement of Materials and Process Engineering (SAMPE) holds an annual competition that allows students to design, build, and test a miniature structural bridge using composite materials. In previous years, Union College has sent two students to these competitions (Rob Wagner in 2013 and Michael Allan in 2014). This years competition will be held in Baltimore, MD on May 20, 2015. The beam will be entered in the natural fiber I-beam category intended for a 3,000 lbf load. The beam will consist of a skeletal mycelium core, wrapped in a natural fiber FlaxPreg material. The use of skeletal mycelium reduces the overall weight of the beam while the FlaxPreg provides the structural strength of the beam. The FlaxPreg is cured using an autoclave at 230°F for two hours while being vacuumed bagged. The goal of this years beam was research the benefits thickening the webbing of the beam and create an adjustable support that support the flanges of the beam during the manufacturing process. [1]

Introduction

Design

Manufacturing

Testing

Refernces

Acknowledgements

1 - LINEO. FLAXPREG , 2012. LINEO. http://media.wix.com/ugd/b41c93_5bc52b45954a358a6d6e4199cac74f38.pdf?dn=2013-TDS- FlaxPreg.pdf (accessed October 6, 2014). 2 - Forbes Aird. Fiberglass & Other Composite Materials, First Edition ed.; Penguin Group: New York, New York, USA, 2006. 3 - Allan, M. Construction of a Sustainable Composite Beam for the 2014 SAMPE Bridge Competition; Senior Project; Union College: Schenectady, 2014. 4 - YouTube, G. SOLIDWORKS Simulation - Shell Elements for Frames Tutorial, 2011. Youtube.com. https://www.youtube.com/watch?v=VAoaF7KaL_Q (accessed October 27, 2014). 5 - Corp, M. SolidWorks Simulation Composite Materials 101, 2013. YouTube. . https://www.youtube.com/watch?v=G4dV7DlwwOI (accessed October 27, 2014).

OPTIONAL LOGO HERE

A composite material is a material that is made up from two or more other substances which give properties, in combination, that are not available from any of the ingredients alone [2]. Common composites that have been used for years include concrete and laminated glass. Recently, the use for composites made from fiber materials, called fiber reinforced plastic (FRP), has increased in the automotive and aerospace industries as well as in sporting goods due to the lightweight and structural properties of the material. This project was split into three processes: Research, manufacturing, and testing. Research was gathered through solidworks simulations to determine whether of not thickening the web of the beam increased its structural properties. Next, the manufacturing process was modified from previous years’ in order to assure a straight beam was made. Finally, the beam was tested using a 20,000 lb load cell, located in the Mechanics Lab in Butterfield, to determine the structural properties of the manufactured beam.

The beam for competition will have a skeletal mycelium fungus as its core, but for implementation purposes, the first few beams were manufactured with a balsa wooden core to become familiar with the manufacturing process. The orientation of the FlaxPreg material was the same that was used in last years competition. On the top and bottom of the flanges, five plies of FlaxPreg laminate was applied in the orientation of 45°/0°/90°/0°/45°. For the webbing of the beam, three layers of the FlaxPreg laminate was applied in the orientation of 45°/-45°/45° [3]. The orientation of the FlaxPreg laminates can be seen in figure 1.

Figure 1 – A cross-sectional view of the beam showing the orientation of the FlaxPreg Laminates

Previous beam designs have seen a common failure in the webbing of the beam due to the shear stresses. It was believed that thickening the webbing of the beam will reduce the stress in the web when the load is applied to the beam. In order to test this hypothesis, Solidworks simulations and optimization was performed in order to determine a core thickness for the web and flanges of the beam. Composite modeling was performed in Solidworks using a method called CAD conditioning [4][5]. A beam with a non-dimensional thickness was created and the thicknesses and orientations of each FlaxPreg laminate was applied using the composites options in Solidworks, Which can be seen in figure 2. The thicknesses of the flanges were set as a variable thickness from 1/8” to 3/8” in increments of 1/8”. Similarly, the thickness of the web was set to a variable thickness from 1/8” to 3/8” in increments of 1/16”. Next Solidworks optimization was performed in order to which web thickness is ideal for the beam. Table 1 shows the results from the Solidworks optimization. Solidworks optimizations has proved the hypothesis that increasing the core thickness of the web reduces the shear stress in the beam. A core thickness of 3/8” was decided for the web of the beam and a core thickness of 1/4” was decided for the flanges of the beam.

Component name Units Scenario

1 Scenario

2 Scenario

3 Scenario

4 Scenario

5 Scenario

6 Scenario

7 Scenario

8

Flange Thickness in 0.125 0.25 0.375 0.125 0.25 0.375 0.125 0.25

Web Thickness in 0.125 0.125 0.125 0.1875 0.1875 0.1875 0.25 0.25

Shear in Web ksi 254.33 174.39 132.55 212.74 153.08 116.98 185.03 137.42

Component name Units Scenario

9 Scenario

10 Scenario

11 Scenario

12 Scenario

13 Scenario

14 Scenario

15

Flange Thickness in 0.375 0.125 0.25 0.375 0.125 0.25 0.375

Web Thickness in 0.25 0.3125 0.3125 0.3125 0.375 0.375 0.375

Shear in Web ksi 107.39 164.72 125.23 99.562 149.02 115.37 93.002

Table 1 – Results for the beam optimization using Solidworks Design Study feature

Figure 2 – The Composite Options window during the optimization process.

The first few beams were manufactured using a balsa wooden core instead of a skeletal mycelium core in order to become familiar with the manufacturing process. Balsa wood was cut to size and glued using Elmer’s wood glue and 90-degree corner clamps. Epoxy fillets were applied to the joints were the flanges contact the web in order to reduce the stress concentrations at those locations. The FlaxPreg laminates were laid up on the beam in their orientations. Next the vacuum bagging process began to assure the beam had even pressure while the beam is curing in the autoclave.

Future Work

Once the beam is vacuumed bagged, the flange supports was wedged between the flanges to reduce the risk of the beam warping while it cures. Figure 3 shows the beam vacuum bagged and the supports wedged between the flanges. Once the beam has reached vacuum, the beam is placed into the autoclave, where the FlaxPreg material cures for two hours at 230°F. The first beam tha was manufactured did not use the flange supports. The second beam did use the flange supports and resulted in a much straighter beam. Figure 4 shows the two manufactured beams.

Figure 3 – The adjustability of the flange supports (left) and the flange supports wedged in between the flanges.

Figure 4 – The first beam manufactured without the adjustable flange supports (left) and the second manufactured beam using the flange supports (right).

The second manufactured beam was tested using a 20,000 lb compression Load Sell located in the Mechanics Lab in Butterfield. A testing apparatus similar to the one in the SAMPE Bridge Competition was used to test the beam. The apparatus was designed by Michael Allan (‘14). The beam was tested at 0.2 inches per minute until failure. The beam saw failure in the middle of the web core at just 566 lbf. Figure 5 below shows the testing apparatus used and how the beam failed.

Figure 5 – The testing apparatus used to test the beam (left) and failure in the core of the beam at 566 lbf (right).

Failure in the core of the beam is believed to be due to the high stress concentration areas where the beam is supported. A core made out of the skeletal mycelium fungus and a hard wood will used for the beam during competition. A hard wood will be used at the locations where the beam is supported to reduce the amount of stress. The final beam will be taken to Baltimore, MD on May 20, 2015 to compete in the 2015 SAMPE Bridge Competition.

•  Professor Ronald B. Bucinell •  Michael Allan (‘14) •  Rob Wagner (‘13) •  Rhonda Becker •  Paul Tomkins