Honors Theses

Date of Award

Spring 5-7-2022

Document Type

Undergraduate Thesis

Department

Mechanical Engineering

First Advisor

Damian Stoddard

Second Advisor

Tejas Pandya

Third Advisor

Arunachalam Rajendran

Relational Format

Dissertation/Thesis

Abstract

The introduction of hemp fibers into a polylactide (PLA) matrix creates a hemp fiber-reinforced composite with 10% hemp fibers and 90% PLA. Natural fibers are becoming a popular alternative to synthetic fibers since they are environmentally friendly, and hemp-fibers are becoming used more often as the demand for natural fibers increased. A Split-Hopkinson Pressure Bar was used to test this composite against a control group using elastic wave propagation theory. Strain gauges were mounted on the incident and transmission bars of the SHPB to measure the propagation of the wave that caused the strain in the sample, which were used to calculate the values desired. Each material was tested under three different pressures of the gas chamber in the SHPB to yield a range of strain-rates: 30, 40, and 50 psi. The ultimate compressive strength, damage initiation energy, and damage propagation energies were analyzed to conclude whether the hemp fibers had an impact on the performance on the PLA matrix. The range of strain-rates in the control group and hemp composite group was 1807-2800 /s and 2112-2925 /s, respectively, and the ultimate compressive strengths were 112.5-128.8 MPa and 72.8-110.8 MPa, respectively. Subsequently, the total specific energy of the control group and hemp composite group ranged from 24.3-35.4 kJ/kg and 19.84-25.2 kJ/kg, respectively. These results showed that the introduction of hemp fibers into the PLA matrix caused the compressive strength and specific energy to decrease significantly. The conclusion was that the hemp fiber-reinforced PLA composite showed lower compressive strength and specific energy under high strain-rates than PLA with no fibers added.

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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