Title: Influence of Sample Preparation, Fiber Orientation and Deformation Mode on Dyname Mechanical Response of a Carbon-Fiber-Reinforced Composite

Authors: Alexander Klutz, Alexander Troiss, and Gunther Arnold

DOI: 10.33599/nasampe/c.19.0650

Abstract: Dynamic mechanical analysis (DMA) is an established method for studying the influence of fiber orientation and fiber-matrix interactions in polymeric composites. It is well known that fiber orientation, relative to load can affect modulus and damping properties of polymeric composites. However, there are still experimental challenges in the determination of these properties. The influence of deformation mode, fiber orientation and specimen preparation can have significant impact on DMA results. In the present contribution we investigate how the number of prepreg-plies used to prepare the specimen and the fiber orientation influences the apparent dynamic-mechanical response of an unidirectional (UD) carbon laminate.

The polymeric matrix of the investigated composite consists of a modified epoxy resin, optimized for fast curing times. Three types of samples were prepared, comprising prepregs with 2, 4 and 8 plies, respectively. Two sets of specimens were manufactured to investigate the influence of the fiber direction, featuring unidirectional fiber direction as well as a ±45° ply stack, respectively. Highly orthotropic mechanical properties are observed. The ±45° specimen exhibits a 3 times higher storage modulus in torsion, while the specimen cut in the 0° direction is 7 times stiffer in bending. In terms of magnitude of damping, i.e. the values of tan(δ), no strong dependence on the deformation mode is observed. Analyzing the impact of the deformation mode for specimens with different numbers of plies, the results show that in both deformation modes both the loss modulus tan(δ) as well as the storage modulus E’ in the entropy-elastic range increase with increasing number of plies. The fiber-matrix coupling in fiber-reinforced composites is influenced by the viscoelastic Poisson’s ratio of the polymeric matrix material. A possible way to determine this parameter as a function of time and frequency using rotational and linear actuators in a single instrument will be discussed.

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Conference: CAMX 2019

Publication Date: 2019/09/23

SKU: TP19-0650

Pages: 8

Price: $16.00