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Process parameters and tool effects on interlaminar bonding during laser-assisted automated tape placement
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Date
2025-12
Abstract
Laser-assisted automated tape placement (LATP) has gained interest as a manufacturing method for thermoplastic composites as it can enable faster and more efficient processing of composite structures. However, when manufacturing at high placement rates, laminates are found to have lower interlaminar bond strength and higher void content than laminates manufactured by traditional composite manufacturing methods, such as with autoclaves. This issue is primarily due to the short periods a deposited layer is subject to high temperatures and pressure, with associated high cooling rates, which limit the time for interlaminar bonding to occur. As such, this work investigates: the processing parameters that affect interlaminar bonding; methods for enhancing interlaminar bond strength and energy efficient methods for reducing laminate cooling.
A parametric study helped compare the interlaminar bond strength, as measured by short beam strength, of carbon fibre-reinforced polyether ether ketone (CF/PEEK) materials based on placement rate and temperature. Results show that the interlaminar bond strength is a function of both incoming tape quality and the placement rate, with reductions in interlaminar bond strength at high placement rates. The reduction in interlaminar bond strength with increasing placement rate is due to insufficient temperature for adequate bonding to occur. As such, it was determined that reducing the rate of cooling of the substrate during manufacturing is necessary.
The laser pass frequency was investigated as a means of altering the laminate’s thermal history during manufacturing and slowing the cooling rate in the substrate. Increasing the laser pass frequency caused the substrate temperature to remain near the glass transition temperature of the matrix, producing effects similar to those of a heated tool. As a result of the higher laser pass frequency, which raises the substrate temperature, there was enhanced void compaction, and consequently, an increase in short beam strength.
Finally, the effect of the tool's thermal diffusivity and emissivity on the mechanical properties of the laminate was investigated as a means of altering the laminate's thermal history. By changing the tool material from steel to epoxy, there is increased heat retention within the laminate, which reduces matrix viscosity and facilitates interlaminar bonding. It was found that the short beam strength increases by 8% when manufacturing on a tool with low thermal diffusivity due to improved void compaction and a higher degree of crystallinity. However, the tool emissivity has a less significant effect on the mechanical properties of the laminate.
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Peer-reviewed
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University of Limerick
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Tobin_2025_Process.pdf
Adobe PDF, 7.61 MB
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Sustainable Development Goals
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Attribution-NonCommercial-ShareAlike 4.0 International