Session: 01-02-01: Adaptive and Multifunctional Structures

Paper Number: 137320

137320 - Auxetic Carbon Fiber Composite Laminates: A Tradeoff Between Impact Resistance and Tensile Properties 

Carbon fiber reinforced polymer (CFRP) matrix composites are widely known to be highly tailorable. For instance, different laminate-level mechanical properties for CFRP composites can be achieved by varying the individual carbon fiber laminar arrangements, among one of them is the Poisson’s ratio. Negative Poisson's ratio (NPR) can be produced in CFRP composites at the laminate level, making them auxetic laminates. Materials with NPRs have been shown to improve the indentation and impact resistances, when compared to equivalent materials with positive Poisson's ratio (PPRs). Auxetic CFRP composite laminates were also shown to have varying degrees of enhancement in these resistances when compared to their non-auxetic counterparts. However, producing NPRs could potentially compromise other properties, such as tensile properties, which has not been reported. 

In this presentation, I will first present our results on the enhacement of low velocity impact resistances in CFRP composites that are designed with auxetic layups. Both auxetic laminates with in-plane NPR and those with through-thickness NPR are investigated. Then, I will discuss the compromise in tensile properties in auxetic CFRP composites with both experimental and FEA simulation results. Specifically, to understand the role of NPR in the tensile failure of the auxetic CFRP composites, the predictions of the failure strains from FEA and classical classical lamination theory (CLT) were compared with the experimental data. Moreover, the predicted strain field was compared with the strain field obtained using digital image correlation in the experimental tests. Such comparisons allow us to investigate whether the NPR plays a role in locally changing the strain field and hence making the conventional CLT and failure criteria (e.g., maximum strain failure criterion) invalid.

The results are expected to provide guidance in exploiting NPR for designing multifunctional composite structures, specifically for impact critical applications.

Presenting Author: Wenhua Lin Syracuse University

Presenting Author Biography: Wenhua Lin is currently a 5th year PhD student in the Department of Mechanical and Aerospace Engineering at Syracuse University. He received his B.S. in Aerospace Engineering at Mississippi State University in 2019. He is a recipient of Mississippi Space Grant Consortium Summer Graduate Research Stipend in August 2020. Wenhua’s research focuses on the mechanics of carbon fiber reinforced composites subjected to various testing conditions, such as simulated lightning strike and low velocity hail impacts. His on-going research studies the mechanical response and failure mechanisms of auxetic carbon fiber reinforced composites under various mechanical loadings such as tension, uniaxial compressive buckling, indentation and impact, as well as the mechanics of the proposed auxetic pyrolytic carbon composites.