Measurements of Mode I Interlaminar Properties of Carbon Fiber Reinforced Polymers Using Digital Image Correlation

Merzkirch, Matthias; Ahure Powell, Louise; Foecke, Tim

doi:10.4028/www.scientific.net/KEM.742.652

Title: Measurements of Mode I Interlaminar Properties of Carbon Fiber Reinforced Polymers Using Digital Image Correlation

Journal Article · Mon Jul 03 00:00:00 EDT 2017 · Key Engineering Materials (Online)

DOI:https://doi.org/10.4028/www.scientific.net/KEM.742.652· OSTI ID:1504730

Merzkirch, Matthias ^[1]; Ahure Powell, Louise ^[2]; Foecke, Tim ^[2]

National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). Center for Automotive Lightweighting (NCAL)
National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). Center for Automotive Lightweighting (NCAL); Univ. of Maryland, College Park, MD (United States). Dept. of Materials Science and Engineering

Numerical models based on cohesive zones are usually used to model and simulate the mechanical behavior of laminated carbon fiber reinforced polymers (CFRP) in automotive and aerospace applications and require different interlaminar properties. This work focuses on determining the interlaminar fracture toughness (G_IC) under Mode I loading of a double cantilever beam (DCB) specimen of unidirectional CFRP, serving as prototypical material. The novelty of this investigation is the improvement of the testing methodology by introducing digital image correlation (DIC) as an extensometer and this tool allows for crack growth measurement, phenomenological visualization and quantification of various material responses to Mode I loading. Multiple methodologies from different international standards and other common techniques are compared for the determination of the evolution of G_IC as crack resistance curves (R-curves). The primarily metrological sources of uncertainty, in contrast to material specific related uncertainties, are discussed through a simple sensitivity analysis. Additionally, the current work offers a detailed insight into the constraints and assumptions to allow exploration of different methods for the determination of material properties using the DIC measured data. The main aim is an improvement of the measurement technique and an increase in the reliability of measured data during static testing, in advance of future rate dependent testing for crashworthiness simulations.

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