Out-of-Plane Buckling of Fiber-Reinforced Thermoplastic Sheets Under Homogeneous Biaxial Conditions

Abstract

The mechanical behavior of fiber-reinforced composite thermoplastic sheets during forming processes is modelled as a viscous fluid with inextensibility and incompressibility constraints. Techniques of linear stability analysis are used to study the growth or decay of initial imperfections in plane sheets reinforced by two families of fibers subjected to biaxial strains. This theory delimits situations when buckles can be expected to form during forming operations.

Bending characterisation of a molten unidirectional carbon fibre reinforced thermoplastic composite using a Dynamic Mechanical Analysis system

“…The occurence of out-of-plane wrinkles is complex and has been studied by several researchers. For a given material, experimental studies reported that, amongst other factors, stress conditions induced by manufacturing boundary conditions, forming speeds, original blank dimensions and strain gradients play a role in their development [9,[25][26][27][28]. Considering simulation, Boisse et al also showed that the appearance of out-of-plane wrinkles is a global phenomenon which depends on boundary conditions and all types of strains and stiffness [14].…”

“…Defects such as fibre re-orientations and wrinkles (both in-plane and out-of-plane) are typically sought since they alter the mechanical performances of the final components [23]. Besides, out-of-plane wrinkles, also referred to as out-of-plane buckles, also affect the shape of the component [24,25]. The occurence of out-of-plane wrinkles is complex and has been studied by several researchers.…”

Composite preforming defects: a review and a classification

“…This angle is the rotation that the fabric is subjected to, comparing to its initial direction. In the same period, Christie et al [34] has attributed the out-ofplane deformation to the effect of the compression (negative tension). When this compression occurs in a certain location of the fiber alignment, the fabric buckles in an out-of-plane deformation.…”

Mechanisms of Origin and Classification of Out-of-Plane Fiber Waviness in Composite Materials—A Review

“…Wrinkling may occur by buckling of the tows along the circumference of the hemisphere if the compressive force exceeds the critical buckling force. Several experimental studies [34][35][36][37][38][39] have reported that, amongst other factors, stress conditions induced by manufacturing boundary conditions, deforming rates, original blank dimensions and strain gradients play a role in their development. Boisse et al [26] have also shown that the formation of out-of-plane wrinkles is a global phenomenon dependent on process conditions (e.g., blank-holder pressure, and all types of strains and rigidities of the composite material).…”