An experimental and theoretical study of creep of a graphite/epoxy woven composite

Abstract

The creep behavior of woven fiber polymer composites has been investigated through both an experimental study and analytical modeling. In the modeling, the matrix is assumed to be a 4‐parameter model (a Maxwell‐Voigt combination) and the fibers to be elastic. The fiber undulation model developed by Ishikawa and Chou for elastic behavior of woven fiber composites has been extended to the viscoelastic system by the correspondence principle. This considers the longitudinal and transverse fibers separately. The weave geometry and dimensions are accounted for, thus bringing the model closer to the actual composite. While this model has been used previously to predict the composites elastic behavior, this is the first time it is considered as a viscoelastic solid, which helps determine its time dependent behavior. The resultant model takes into account the different parameters associated with the weave (the density of the fibers in the weave, the radius of the fibers and the profile of the fill and warp fibers), volume concentration of the fiber and matrix in the composite, and the elastic moduli of the fill and warp fibers and the viscoelastic properties of the polymer matrix. We have conducted creep tests on graphite fiber/epoxy composites to evaluate our model. Experiments have been conducted from room temperature (22°C) to 200°F (93°C). The results from experiments have been analyzed and an inverse simulation has been performed to obtain the unknown parameters of the matrix and fibers in the composite. The model is then used to predict the creep behavior of the woven fiber composite under other loading conditions and temperature levels, showing satisfactory agreement with the data.

A New Approach for Modeling Piezoresistive Force Sensors Based on Semiconductive Polymer Composites

“…A single Maxwell or a single Kelvin-Voigt element cannot represent the transient and instantaneous response of polymers accurately. Hence, using a combination of the two elements is recommended [28][29][30][31]. The strain in a creep test of semi-conductive polymer composites, such as Linqstat which is used when fabricating a force sensor, tends towards a constant value after a longer period of time.…”

Micromechanical modeling of deployment and shape recovery of thin-walled viscoelastic composite space structures

“…7,8 Viscoelastic moduli have also been obtained numerically through direct finite element analysis 9 assuming a uniform distribution of fibers. For woven composites, Govindarajan et al 10 and Shrotriya and Sottos 11 proposed analytical models based on simplified weave geometries, but the flexural deformation of the fiber tows was not accounted for and was believed to be the source of significant discrepancy between predicted and measured viscoelastic responses. Predictions were improved when two-dimensional 11 and three-dimensional 12 finite element based methods were utilized to incorporate the influence of weave geometry, but still did not match the experimental results.…”

Multi-Scale Modelling of Long-Term Mechanical Behaviour in Polymer Composite Laminates with Woven Fibre Architecture

“…Pasricha et al 18,19 Govindrajan et al 23 showed that the approximation of the composite as a combination of fibre undulation and the 4-parameter model (Maxwell-Voigt combination) could be successfully used to predict the time-dependent behaviour of woven-fibre polymer composites. The matrix was modelled using the 4-parameter model and fibres were assumed to be elastic in the composite model.…”