Development and verification of a cure-dependent visco-thermo-elastic simulation model for predicting the process-induced surface waviness of continuous fiber reinforced thermosets

Abstract

Process-induced surface waviness effects represent a major concern for series production of high-quality lightweight structures based on fiber reinforced plastics (FRP). This paper suggests a method for the numerical prediction of these effects by using the example of processing glass fiber reinforced plastics (GFRP) in a resin transfer molding (RTM) process. The influence of reaction kinetics, chemical shrinkage and cure-dependent viscoelastic properties of the resin are taken into account. Furthermore, the dependence of surface quality on curing cycle, consolidation pressure, textile architecture and thickness of neat resin layer (NRL) at the part surface are investigated. The work is based on published material data and a visco-thermo-elastic simulation approach which has been previously presented and validated. All numerical results are compared to the surfaces of FRP plates that were manufactured with the corresponding parameter variations. Based on a literature survey, different surface waviness values have been identified for comparison of experimental and numerical results. Satisfactory agreement between experiments and simulations is found. Furthermore, it is shown that the analyzed NRL thickness has no relevant influence on the surface waviness while the curing temperature significantly affects the surface waviness. The role of relaxation-induced change of the surface waviness is highlighted by performing long-term measurements and corresponding time-dependent simulations. It is concluded that relaxation plays a decisive role in the appropriate selection of the subsequent surface finishing process. The suggested simulation approach provides a basis for optimization strategies to improve surface quality and reduce post-processing effort.

The Three-Dimensional Printing of Composites: A Review of the Finite Element/Finite Volume Modelling of the Process

“…Due to this, the roughness before any post-processing treatment is of great concern, especially in the case of thermoset matrix composites manufactured via AM, due to amorphous polymerization. The roughness simulation for continuous GF and bisphenol photosensitive (Lorenz et al, 2022) [113]. The model was developed in TexGen software 3.13.1, with experimental material properties.…”

“…polymerization. The roughness simulation for continuous GF and bisphenol photosensitive (Lorenz et al 2022) [113] The model was developed in TexGen software, with experimental material properties. The model was developed for two directions, with mean profiles and extremum values, as shown in Figure 56 .…”

Influence of tool pin profiles on waviness and natural frequency during friction stir welding of Al-Li alloys plates

“…Lorenz et al [17] suggested a method for the numerical prediction of surface waviness effects on glass fiber reinforced plastics (GFRP) in a resin transfer molding (RTM) process. They revealed that simulations and experiments agreed satisfactorily and observed surface waviness significantly influenced by the curing temperature rather than the analyzed neat resin layer thickness.…”