Abstract
SummaryComposite manufacturing processes usually proceed from preimpregnated preforms that are consolidated by simultaneously applying heat and pressure, so as to ensure a perfect contact compulsory for making molecular diffusion possible. However, in practice, the contact is rarely perfect. This results in a rough interface where air could remain entrapped, thus affecting the effective thermal conductivity. Moreover, the interfacial melted polymer is squeezed flowing in the rough gap created by the fibers located on the prepreg surfaces. Because of the typical dimensions of a composite prepreg, with thickness orders of magnitude smaller than its other in‐plane dimensions, and its surface roughness having a characteristic size orders of magnitude smaller than the prepreg thickness, high‐fidelity numerical simulations for elucidating the impact of surface and interface roughness remain today, despite the impressive advances in computational availabilities, unattainable. This work aims at elucidating roughness impact on heat conduction and the effective viscosity of the interfacial polymer squeeze flow by using an advanced numerical strategy able to reach resolutions never attained until now, a sort of numerical microscope able to attain the scale of the smallest geometrical detail.
Highlights
Many composite forming processes for elaborating structural parts are based on the consolidation of preimpregnated preforms in form of sheets or tapes that are put in contact, heated, and compressed to ensure its bonding.the welding of two thermoplastic layers requires specific physical conditions: an almost perfect contact, called intimate contact, and a temperature that has to be high enough during a time large enough to ensure the diffusion of macromolecules across the interface enabling the bonding, while limiting as such as possible thermal-induced material degradation.The efficient numerical simulation of automated tape placement, including all the just referred mechanisms, was addressed by the authors in Reference 1, where the use of advanced numerical techniques was emphasized
The welding of two thermoplastic layers requires specific physical conditions: an almost perfect contact, called intimate contact, and a temperature that has to be high enough during a time large enough to ensure the diffusion of macromolecules across the interface enabling the bonding, while limiting as such as possible thermal-induced material degradation
Interfacial thermal properties of two rough surfaces in contact are of major relevance for evaluating the process performances and manufactured part properties
Summary
Many composite forming processes for elaborating structural parts are based on the consolidation of preimpregnated preforms in form of sheets or tapes that are put in contact, heated, and compressed to ensure its bonding.the welding of two thermoplastic layers requires specific physical conditions: an almost perfect contact, called intimate contact, and a temperature that has to be high enough during a time large enough to ensure the diffusion of macromolecules across the interface enabling the bonding, while limiting as such as possible thermal-induced material degradation.The efficient numerical simulation of automated tape placement, including all the just referred mechanisms, was addressed by the authors in Reference 1 (the interested reader can refer to the references therein concerning the process modeling), where the use of advanced numerical techniques (revisited and discussed later) was emphasized. Many composite forming processes for elaborating structural parts are based on the consolidation of preimpregnated preforms in form of sheets or tapes that are put in contact, heated, and compressed to ensure its bonding. The welding of two thermoplastic layers requires specific physical conditions: an almost perfect contact, called intimate contact, and a temperature that has to be high enough during a time large enough to ensure the diffusion of macromolecules across the interface enabling the bonding, while limiting as such as possible thermal-induced material degradation. Consolidation implies putting plies in contact while supplying heat and pressure. The former promotes molecular diffusion at the plies interface and both (heat and pressure) facilitate the intimate contact by squeezing surface asperities. On the other hand, evaluating the interfacial polymer flow in the rough interface gap allows evaluating the asperities squeeze inducing intimate contact
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