Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 150466

150466 - Experimental Investigation of the Fracture Behavior of Cellulose Nanopaper Under Quasi-Static and Dynamic Loading. 

In this study, the fracture characteristics of Cellulose Nanopaper (CNP), celebrated for its exceptional mechanical properties, were investigated. CNP, recognized for its renewability and biodegradability, is characterized by a wide range of applications, rendering it a subject of significant interest. The focus of this research was directed towards the exploration of CNP's fracture behavior, particularly its high stress intensity factor and remarkable resistance to crack growth.

Tension tests were conducted to evaluate CNP's elastic properties, ultimate stress, and strain at failure. The 2D Digital Image Correlation (DIC) method was employed to measure and analyze the full-field deformations during these tests, revealing significant thickness effects in these fibrous sheets. An elastic modulus of approximately 10 GPa and an ultimate stress of over 100 MPa with a strain at failure exceeding 6% were measured at the high end. Microscopy on CNP samples was used to understand the observed differences.

Quasi-static fracture tests on single-edge notched tension specimens were performed to quantify the critical stress intensity factors and assess the crack growth resistance. A crack initiation toughness of approximately 10 MPa(m)^1/2 with increasing stress intensity factor values during the stable crack growth regime was observed. Subsequently, dynamic crack growth studies in CNP were conducted at elevated rates to contrast the effect of strain rate on crack growth behavior by employing ultra-high-speed photography and DIC. A long-rod impactor was used to indirectly load an edge-cracked CNP specimen glued to an edge-notched PMMA support structure to achieve rapid loading. The full-field optical data analysis revealed rapid crack growth reaching approximately 600 m/sec in these fibrous films.

The crack initiation and growth behaviors are currently being analyzed to assess the strain rate effects. Preliminary results suggest a drop in the crack initiation toughness at the higher strain rate, indicating a rate-dependent crack initiation and growth behavior. Through the analysis of these fracture characteristics and their correlation with CNP's processing parameters, a contribution was made to the advancement of science and engineering. This knowledge not only resulted in an enhanced understanding of CNP's behavior under varying loading conditions but also laid the foundation for the optimization of its mechanical performance, durability, and resistance to fracture.

The implications of this study extend to diverse industries, including packaging, textiles, and bio-based materials, where CNP's exceptional fracture properties could foster innovative applications and the development of improved materials.The contribution of this work toward advancing science and engineering is significant. By thoroughly investigating the fracture characteristics of CNP, this study provides a deeper understanding of its mechanical behavior under different loading conditions. This knowledge enables the optimization of CNP's mechanical performance, durability, and resistance to fracture, paving the way for the development of more efficient and sustainable materials. The insights gained from this research could inspire further studies and technological advancements, promoting the broader adoption of CNP in various high-performance applications.

Presenting Author: Azeez Adebayo Auburn University

Presenting Author Biography: Mr. Adebayo is a doctoral student of Dr. Hareesh Tippur at Auburn University, AL.

Authors:

Azeez Adebayo Auburn University
Hareesh Tippur Auburn University