Wave Propagation and Damage Characterization in Natural Fiber Hemp and LLDPE Composite
Research in incorporating natural fibers in composites has been in progress for a few decades where the various mechanical, electrical and acoustic properties of such composites were explored. Natural fiber composites (NFCs) have few benefits over the traditional glass or carbon fiber composites such as light weight, low manufacturing cost and requiring less energy for production. NFC is also bio-degradable and recyclable. The primary objectives of this research are to explore the static and dynamic properties of the hemp and linear low density polyethylene (LLDPE) and determine impact absorbing capability using the above mentioned properties. LLDPE is surface-treated with maleic anhydride grafted polyethylene (MA-g-PE) and sodium hydroxide (NaOH). A melt-mixing process is employed where LLDPE is compounded with the hemp fibers in 10%, 20% and 30% vol. fraction. Tensile and flexural properties are measured. The material is characterized by propagating Lamb waves generated using a dropped dead weight. Time-frequency information is extracted from a thin disc-like specimen using the Gabor Wavelet Transform (GWT) so as to characterize the material. Detection of defect is also established using the generated waves and GWT. Using Gabor wavelet coefficients, the dispersion and attenuation of the specimen are determined in different material directions. Comparison of attenuation of the waveforms is observed at different locations providing the knowledge of materials homogeneity, the materials behavior due to an impact and its impact absorbing character.
Natural fiber composite, Wave Propagation, Hemp
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