# A Model to Study the Creep Behavior of Carbon Fiber/Epoxy Resin Composites Under Temperature
## 2 Literature Review
Researchers have shown a broad acceptance of [PERSON]'s [12] paradigm for studying viscoelastic behavior. Its application made it possible for the field to advance significantly. In order to account for the discrepancies with the Schapery model that researchers have noted throughout time, this model was enhanced in [13]. [PERSON]'s method for nonlinear viscoelastic characterization enables effective test modeling, as demonstrated by the authors of a recent work [14]. The findings demonstrate that when the temperature rises, the range of strains in which linear viscoelasticity can be assumed shifts to lower values. That is true for neat resin. A useful analytical tool for researching creep failure in composites is the use of micromechanical models. Using a global fracture algorithm for the homogenized material, the creep deformation of the matrix is examined in [15]. The tests are conducted at various temperatures and loads. The temperature parameter has a significant impact on a composite material's creep behavior. The creep behavior is significantly different at temperatures around the resin's melting point if room temperature under typical circumstances is used as a reference. Several articles have described this behavior. In engineering applications, the behavior of composites at high temperatures is a crucial subject. In [16], an analytical model for examining this factor is provided. The thermomechanical creep behavior under an initial stress at higher temperatures is simulated in [17; 18]. It is interesting to see how closely the carbon fiber-reinforced composite and the polymer behave. Epoxy resin as a matrix can be used to create a wider variety of composites thanks to these kinds of applications. Epoxy resin's extensive use has also prompted the creation of theoretical research models and the execution of a large number of laboratory tests to ascertain its characteristics in many application cases [19; 20; 21; 22; 23]. Only uniaxial stresses are taken into consideration when using the constitutive equations. Based on simplified models, numerical simulations of the behavior demonstrate a satisfactory degree of agreement between the predicted and experimentally achieved results. Recent research on composite carbon nanotubes and epoxy resin has been presented in [24; 25]. The vast majority of the field's research pays little attention to developing theoretical models that explain how these materials behave at various temperatures and how creep occurs. In the last years, it has been noted that surface modification of carbon nanotubes (CNTs) affects their mechanical and electrical conductivities as well as their dispersion within epoxy resin. A recent study [26] examines how CNTs' mechanical and electrical conductivities are subsequently improved. Additionally, the creep behavior of thermosetting composites made of carbon fiber (CF) and epoxy resin was examined under various stress conditions, fiber orientations, temperatures, and humidity levels. Using Abaqus FEM 2022 software, adhesive thickness's effect on the creep behavior of a single lap adhesive joint is presented in [27]. Two-layer and two-dimensional models are taken into consideration. The adherent layers are composed of carbon steel plates that are subject to tensile pressures, and the adhesive layer is composed of reinforced epoxy resin containing 0.5% carbon fiber. Many researchers have successfully employed [PERSON]'s nonlinear formulation for viscoelastic materials at room temperature. There is not much research in the literature that applies the aforementioned method to viscoelastic materials at high temperatures. In [17], the nonlinear viscoelastic creep response of neat and carbon fiber-reinforced PEEK and epoxy resin at varying temperatures is investigated using [PERSON]'s constitutive equation. The laminates [90(4)](s) and [+/\(-\)45(4)](s) (for notation, see [14]) were examined as reinforced materials.