A numerical approach to characterize the compression and relaxation behavior of uncured prepreg laminates in the process of hot press-forming

Abstract

In the pre-forming process of uncured prepreg laminates with hot press, the compaction stress is an important parameter that affects the performance and quality of the final product. Therefore, it is necessary to explore the compaction response of the prepreg during manufacturing processes. In this study, the compression and relaxation viscoelastic behaviors of uncured prepreg laminates were investigated in different temperatures, displacements, velocities, and thicknesses. The results show that the power law model and the fractional viscoelastic model could accurately describe the compression and relaxation behaviors, respectively. The theoretical fitting curves match very well with experimental data at each condition and the R-squared value is greater than 0.95. The effect mechanism of compression and relaxation viscoelastic behaviors is analyzed and the obtained results could provide a reference for the process of hot press-forming and numerical simulation.

Characterizing the stress relaxation behavior of unidirectional prepreg through a parallel fractional-order viscoelastic model

“…Notable preforming methods include hot-stamp forming and hot diaphragm forming, wherein prepregs are initially shaped under external pressure and subsequently cured in the autoclave. In contrast to hot diaphragm forming, hot-stamp molding is more suitable for the preforming process of complex structures due to its higher applied pressure and the capability to control pressure in different zones [8].…”

Determination of lubricating behavior of resin during the sliding process of unidirectional prepreg

“…In response to these limitations, automated molding methods such as hot press-forming have been introduced into the manufacturing process. During this process, prepreg sheets are fabricated through automated layup technologies, subsequently formed to designated shapes under applied pressure [1]. However, some defects like wrinkling and fiber misalignments may be produced in this molding process, which can lead to reductions in the mechanical properties of the final product [2,3].…”