Numerical Simulation for the Pressure Distribution of the Compaction Roller in in-situ consolidation processes

Automated tape or fiber placement (ATP/AFP) with in-situ consolidation has been identified as a promising manufacturing technique for thermoplastic (TP) composites, which are highly in-demand in the aerospace industry for future aircraft structural applications. This manufacturing technique is attractive since it has the potential to eliminate the energy and time consuming autoclave consolidation. However, low quality is one of the biggest challenges in the application of in-situ consolidation. It seems that pressure contribution to the bond quality has received less attention than thermal one. Therefore, this work is initiated to simulate the pressure distribution between the compaction roller and the mandrel. The objective in this work is to predict the pressure distribution in the contact area between the rubber-covered roller and the mandrel in room temperature by finite element methods (FEM). Rubber material is characterized by mechanical testing and then modeled as hyperelastic material. 3rdd-order Ogden material model is found to well describe the strain- stress behavior of rubber material. The material constants are then implemented in FE models as an input. The pressure distribution is predicted by FE modes and the influence of compaction force, rubber thickness, pre-stretching force on the pressure distribution are discussed, followed by an optimization between compaction force and rubber thickness. Experiments are conducted to validate the FE models regarding the three influencing factors, that are: (a). compaction force, (b). with/without pre-stretching and (c). various rubber thickness. Rubber deformation can be captured by the digital image correlation (DIC) Pressure distribution is obtained from the Prescale pressure measurement film produced by Fujifilm®, which are the films that show different color densities under different pressures. Experimental results of strain and pressure distribution are compared with FEM results, followed by discussions and conclusions. It can be concluded that pre-stretching force should be used to avoid rubber-roller separation and prevent rubber from moving out to the sides. Both of the compaction force and rubber thickness affects the maximum pressure and contact length linearly. A trade- off between compaction force and rubber thickness can be made based on the force limit of the equipment and pressure requirements.