NUMERICAL FAILURE ANALYSIS OF SANDWICH COMPOSITE T-JOINTS WITH SEPARATED AND INTEGRATED CLEAT

• Main Author: Pratama Wijaya, Johanes
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67196
• Institution: Institut Teknologi Bandung

In aviation, sandwich composites are often found in T-joints, where one of the strengthening methods involves cleats. Several numerical and experimental studies have been carried out regarding the effect of the use of cleats on the improvement and failures that occur in structures. Numerically, T-joint modeling can be simulated in 3D and 2D models. This research simulates two constitutive models for T-joint simulation under quasi-static tensile load using the commercial finite element application, Abaqus/Standard (v6.17-1). First, material properties were calibrated and then implemented in T-joint simulation with two types of T-joints with different configurations of cleat types, the separated cleat, and the integrated cleat T-joint models. The separated cleat T-joint was modeled in 3D, while the integrated T-joint cleat was modeled in 2D with the assumption of plane stress. An additional simulation, a parametric study, was conducted to determine the effect of certain parameter properties on the 2D integrated cleat T-joint structure. Based on the calibration results, the core material was modeled with isotropic plasticity and calibrated damage parameter value. While the calibrated cohesive results in proper cohesive strength for both models. The 3D separated cleat T-joint model was in very good agreement with the experimental results regarding damage modes and location. While the simulation results from the 2D model are accurate enough to predict the mode and location of failure but are still overestimated with a failure load error of 6.2%. The 3D separated cleat and the 2D integrated cleat T-joint model failed in the form of fiber/fiber delamination between the cleats and the horizontal panel. However, in the integrated cleats, the failure is initiated from fiber/filler delamination and ends with failure in the vertical core panel. Furthermore, the results of parametric studies in the 2D integrated cleat T-joint model show that the effect of changes in core stiffness parameter values and adhesive strength is not linear to the failure load.