Advisors: Dr. Jitendra Tate and Shane Arabie
1
Why Hemp? Hemp was chosen as a reinforcement material because of its high strength compared to other natural fibers. A local shop in town called The Hemp Store sold a woven fabric that was used for the roadway, trusses, and cross-members. The original design was to include coconut coir but was later changed. Why Nomex? If Nomex was not supplied in the kit, buying some would not have been an option due to its extremely high price. However, the honeycomb sandwich structure using two flat panels of hemp as the skins make for an extremely strong and lightweight roadway. Benefits of Natural Fiber Composites With increasing environmental awareness in a society striving toward a “greener” future, it is easy to see the pragmatic use for such materials. Natural fibers can be relatively inexpensive, have low densities, be easily recycled, give off just as much carbon dioxide when burned as they absorb while growing, and most importantly, can be grown from the earth. Being organic, natural fiber does have some limitations that make it take a back seat to other man-made fibers such as glass, carbon, and boron. Limitations of Natural Fiber Composites Natural fiber, compared to other matrix materials, is less durable, contains a lower strength, and is not available in a variety of different weaves. Manufacturing This bridge was built with simple hand lay-up and vacuum bagging. All of the panels, trusses, and cross-members were created and later assembled. The flat panels and piece of honeycomb Nomex were bonded together with 3M 460 DP epoxy to make a sandwich structure. Bio-Bridge Built with Hemp and Nomex Erik Larson Ingram School of Engineering Texas State University – San Marcos Advisors: Dr. Jitendra Tate and Shane Arabie Testing: Tension, Compression, and Bend Mechanical and Physical Properties of Natural Fibers Hemp Fabric Nomex More about Hemp and Nomex Hemp has a very good balance of tensile strength and tensile modulus which makes it a great natural fiber for construction of a load bearing structures. Also, hemp has a relatively high specific strength which gives it lighter and stronger characteristics. Honeycomb Nomex, which is actually made from Kevlar paper, is usually dipped in a phenolic resin to produce a honeycomb core with high strength and very good fire resistance. The Future of Natural Fiber Composites As written in the May/June 2008 edition of the SAMPE Journal, natural fibers are rapidly emerging in composites applications where glass fibers (predominantly E-glass) have been traditionally used. With many consumer products stressing environmental impact, the use of natural fibers should grow tremendously in the near future. Stress vs Strain: Hemp/Epoxy Composites 0.00 10.00 20.00 30.00 40.00 50.00 60.00 0.000 0.002 0.004 0.006 0.008 0.010 0.012 Strain, mm/mm Stress, MPa UTS = 52.33 Mpa (7.59 ksi) Failure strain = 0.0096 mm/mm or, 0.96% Modulus = 6.735 Gpa or, 0.98 Msi Vf, fiber volume fraction 0.6 52.33 6.735 UTS (MPa), Ultimate E (Gpa), Tensile Modulus Special thanks to: Hexcel Dr. Hans Kual (Huntsman Advanced Materials) The Hemp Store Density Tensile Strength Tensile M odulus Range of (gm/cm²) (ksi) (msi) Elongation (%) Flax 1.50 75 - 215 4 2.7 - 3.2 Hemp 1.47 100 10 2.0 - 4.0 Kenaf 1.45 135 7.7 1.60 Jute 1.30 55 - 110 3.8 1.5 - 1.8 Ramie 1.50 60 - 135 8.9 - 18.6 3.6 - 3.8 Sisal 1.50 75 - 90 1.4 - 3.2 2.0 - 2.5 Coir 1.20 85 0.6 - 0.9 ~30 Cotton 1.55 60 0.8 - 1.8 3.0 - 10.0 E-Glass 2.56 290 - 350 10 3.00 S-Glass 2.57 665 12.5 2.80 Aramid(Commercial) 1.44 435 - 455 9.0 - 10.0 3.3 - 3.7 Carbon (PAN Std. Mod.) 1.67 580 33 - 35 1.4 - 1.8 Fiber Ref # SAMPE Journal, Volume 44, No. 3, May/June 2008, pp 64 This bridge won 3 rd prize at SAMPE (Society for Advancement of Materials and Process Engineering) Lightweight Bridge Building Contest at Annual Conference, Long Beach on May 20, 08.
Transcript of Advisors: Dr. Jitendra Tate and Shane Arabie
Why Hemp?
Hemp was chosen as a reinforcementmaterial because of its high strengthcompared to other natural fibers. A localshop in town called The Hemp Store sold awoven fabric that was used for the roadway,trusses, and cross-members. The originaldesign was to include coconut coir but waslater changed.
Why Nomex?
If Nomex was not supplied in the kit, buyingsome would not have been an option due toits extremely high price. However, thehoneycomb sandwich structure using two flatpanels of hemp as the skins make for anextremely strong and lightweight roadway.
Benefits of Natural Fiber Composites
With increasing environmental awareness in asociety striving toward a “greener” future, itis easy to see the pragmatic use for suchmaterials. Natural fibers can be relativelyinexpensive, have low densities, be easilyrecycled, give off just as much carbon dioxidewhen burned as they absorb while growing,and most importantly, can be grown from theearth. Being organic, natural fiber does havesome limitations that make it take a backseat to other man-made fibers such as glass,carbon, and boron.
Limitations of Natural Fiber Composites
Natural fiber, compared to other matrixmaterials, is less durable, contains a lowerstrength, and is not available in a variety ofdifferent weaves.
Manufacturing
This bridge was built with simple hand lay-up and vacuum bagging. All of the panels, trusses, and cross-members were created and later assembled.
The flat panels and piece of honeycomb Nomex were bonded together with 3M 460 DP epoxy to make a sandwich structure.
Bio-Bridge Built with Hemp and NomexErik Larson Ingram School of Engineering Texas State University – San Marcos
Advisors: Dr. Jitendra Tate and Shane Arabie
Testing: Tension, Compression,
and Bend
Mechanical and Physical
Properties of Natural Fibers
Hemp Fabric Nomex
More about Hemp and Nomex
Hemp has a very good balance of tensilestrength and tensile modulus which makes ita great natural fiber for construction of a loadbearing structures. Also, hemp has arelatively high specific strength which gives itlighter and stronger characteristics.
Honeycomb Nomex, which is actually madefrom Kevlar paper, is usually dipped in aphenolic resin to produce a honeycomb corewith high strength and very good fireresistance.
The Future of Natural Fiber Composites
As written in the May/June 2008 edition ofthe SAMPE Journal, natural fibers are rapidlyemerging in composites applications whereglass fibers (predominantly E-glass) havebeen traditionally used. With manyconsumer products stressing environmentalimpact, the use of natural fibers should growtremendously in the near future.
Stress vs Strain:
Hemp/Epoxy
Composites
0.00
10.00
20.00
30.00
40.00
50.00
60.00
0.000 0.002 0.004 0.006 0.008 0.010 0.012
Strain, mm/mm
Str
ess, M
Pa
UTS = 52.33 Mpa (7.59 ksi)
Failure strain = 0.0096 mm/mm or, 0.96%
Modulus = 6.735 Gpa or, 0.98 Msi
Vf, fiber
volume
fraction
0.6
52.33
6.735
UTS
(MPa),
Ultimate
E (Gpa),
Tensile
Modulus
Special thanks to:Hexcel
Dr. Hans Kual
(Huntsman Advanced
Materials)
The Hemp Store
Density Tensile Strength Tensile M odulus Range of
(gm/cm²) (ksi) (msi) Elongation (%)
Flax 1.50 75 - 215 4 2.7 - 3.2
Hemp 1.47 100 10 2.0 - 4.0
Kenaf 1.45 135 7.7 1.60
Jute 1.30 55 - 110 3.8 1.5 - 1.8
Ramie 1.50 60 - 135 8.9 - 18.6 3.6 - 3.8
Sisal 1.50 75 - 90 1.4 - 3.2 2.0 - 2.5
Coir 1.20 85 0.6 - 0.9 ~30
Cotton 1.55 60 0.8 - 1.8 3.0 - 10.0
E-Glass 2.56 290 - 350 10 3.00
S-Glass 2.57 665 12.5 2.80
Aramid(Commercial) 1.44 435 - 455 9.0 - 10.0 3.3 - 3.7
Carbon (PAN Std. Mod.) 1.67 580 33 - 35 1.4 - 1.8
Fiber
Ref # SAMPE Journal, Volume 44, No. 3, May/June 2008, pp 64
This bridge won 3rd prize at SAMPE (Society for Advancement of Materials and Process Engineering) Lightweight Bridge Building Contest at Annual Conference, Long Beach on May 20, 08.
