Due to the complexity of composite material, numerical methods are generally utilized in their analysis and design. Commercial finite element (FE) codes, such as ANSYS and ABAQUS, allow the implementation of user subroutines in the program, which provides the advantage of using high meshing and solving technologies besides the improvement of materials and/or elements models. Nonlinearities arise for many engineering problems, for example, the progressive damage of a composite element that contains sources of stress concentration or damage localization such as holes, bolts, and/or flaws causes nonlinear material behavior. In order to simulate this nonlinear behavior, especially in 3D, an accurate material constitutive model is required. Therefore, the objective of this paper was to simulate the 3D progressive damage model of composite materials by using simple numerical models. In this paper, ANSYS user subroutine (USERMAT) was used to simulate the progressive damage behavior of a composite plate containing holes using simple models. Three different material models were used: ply discount model (PDM), simple progressive damage model (SPDM) by adding an empirical progressive damage criteria to the PDM, and continuum damage mechanics model (CDMM). Good agreements were observed between SPDM, CDMM, and published experimental results. Furthermore, CDMM showed the least dependence on mesh size. Three different damage evolution laws, linear, quadratic, and degradation laws, were adjusted and tested. It was found that there was no significant difference in the predicted failure load between these selected laws.

The fiber-reinforced polymeric (FRP) composite can be joined by adhesive bonding or mechanically fastening the composite element. Carbon fiber-reinforced polymers (CFRP) and glass fiber-reinforced polymers (GFRP) are the most common types of polymers. Mechanically fastened or bolted joints do not need treatments, and the surface temperature and other environmental effects such as humidity do not affect its strength. In this research, the previous research that describes the behavior of the composite bolted joint (CBJ) is presented and summarized including the modes of failure of the CBJ, and the experimental works that explain the bearing failure (BF) of the CBJ. In addition, the effects of bolt clamping force (BCF) and techniques that are used to simulate the progressive failure and damage in composite materials and finite element simulation works are surveyed.

It is known that weathering action has a significant impact on polymer interlayer materials, and previous studies have evaluated certain aspects of weathering such as temperature, humidity, and UV radiation. In this paper, the environmental effect on the mechanical properties of the virgin and cured/processed polymer interlayer materials will be studied. Three polymer interlayer materials were focused, i.e., Polyvinyl butyral (PVB), Ethylene-vinyl acetate (EVA), and Ionomer (SG), due to their industrial interest. Testing setups were designed to apply the environmental effects and perform mechanical testing on the polymeric materials. Four environmental effects were studied, including water submersion (E1), constant high temperature (E2), cyclic temperature with low relative humidity (E3), cyclic temperature, and relative humidity (E4). After the exposure of these materials to these environmental effects, the samples were prepared and mechanically tested. Uniaxial tests were performed under static and high strain rates (around 45⁻¹). It was found that under dynamic load, the properties of EVA such as the strength, maximum strain, and the toughness were not significantly affected by the environmental effects. SG5000 properties were significantly affected.

A sustainable environment can be achieved by strengthening the existing building to avoid new construction and by replacing the construction materials with long-lasting sustainable materials such as a fiber-reinforced polymer (FRP). Using post-tensioned (PT) FRP systems has proven to be an effective technique in strengthening the structure and decreasing cracks and deformability. In this study, a 3-D finite element model was built to investigate the flexural behavior of composite beams strengthened with external PT FRP tendons. Limited research studied the use of FRP tendons to enhance the structural behavior of composite beams. This paper represents a comprehensive study of the effect of several parameters that control the design of the FRP tendons. Parameters such as PT level, tendon material, tendon length, degree of shear connection (DOSC), and tendon profile shape were considered under loading. The 3-D model’s correctness is validated using published experimental data. It was observed that of all FRP materials, carbon FRP is the best type for upgrading the beam strength, and it was recommended to use a 30 to 40% PT level. In addition, applying external PT over the full length of the beam increases the ultimate load capacity significantly. However, due to the difficulty of construction, it was recommended to use 90% of the beam span length since the difference in beam capacity does not exceed 5%. Finally, adding PT tendons with a trapezoidal and parabola profile to composite beams significantly increases the yield load and the beam capacity.