Analytical model for prediction of the damping loss factor of composite materials

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Abstract
Numerous approaches have been undertaken to determine the damping of composites. These approaches can be grouped into micromechanical, macromechanical, and structural approaches. This paper describes a macromechanical approach that has been experimentally validated using various S‐2 glass/3501‐6 laminates. Our approach is an extension of the elastic‐viscoelastic approach, which accounts for the frequency dependence of the loss factor. The experimentally determined material loss factor for the glass/epoxy determined in a previous investigation is used as input to the model. The material complex moduli are then determined and used as input to the model. The loss factor of a quasi‐isotropic configuration is analytically determined in the frequency range of the experimental data. The loss factors for these beams are then experimentally determined using a cantilever beam configuration set into vibration with an impulse excitation. The loss factor at various frequencies are determined using the half power band width technique. The analytical values are within 15% of the experimental values in the frequency range of test. In addition, a parametric study is given on the effect of fiber orientation on loss factor. The analytically determined loss factor using the proposed model shows that inconsistencies documented in the literature on the fiber orientation at which a maximum in loss factor occurs can be resolved by incorporating the frequency dependence of the composite loss factor.