Understanding the compaction behavior of uncured thermoset prepreg: Experimental investigation and theoretical analyses

The deformation behavior of uncured thermoset prepreg during hot compaction process was investigated by dividing the whole compaction process into an initial compression stage and the subsequent creep stage. At the compression stage, there existed a strain‐softening phenomenon in the temperature range of 50–90°C, indicating different deformation behavior that is mainly determined by the viscosity of prepreg. Following an appraisal of advantages and limitations of existing compaction models, a combination model consisted of a modified power‐law model including the influence of temperature and the generalized Kelvin‐Voigt model was proposed to describe the deformation behavior of prepreg during compression and creep stage, respectively. Finally, a discussion on the compaction mechanism was conducted to offer some insights into the deformation process.Highlights Strain‐softening phenomenon occurred during the compaction of uncured prepreg. Proposed combination model captures the deformation of uncured prepreg well. The percolation mechanism dominates prepreg deformation during compaction. The squeeze flow mechanism causes limited thickness reduction of prepreg.