Thermoset prepreg compaction process in end to end simulation strategy
Topic(s) : Manufacturing
Co-authors :
Daniel PASTORINO JUNQUERO (SPAIN), Juan Manuel GONZÁLEZ-CANTERO (SPAIN), Sjoerd VAN DER VEEN , Domenico FURFARIAbstract :
The use of composite materials in the aerospace industry has experienced a significant increase in the last decades. The reason behind it is clear, the higher specific properties of composite materials compared to metals allow the engineers to produce lightweight structures, which in the end results in reduced operational costs and lower CO2 emissions.
Manufacturing of long-fiber composites usually involves high development costs, since a single component may require several design loops to reach the desired product, e. g. by correcting spring-in issues, and avoiding non-conformities (dry spots, undulations, fiber misalignment, etc.), or just to de-risk process modifications (material, lay-up, or geometry). The simulation of manufacturing processes becomes an extraordinary instrument to reduce development lead time and cost, and at the same time increasing the versatility of the process itself.
A complete manufacturing process simulation may have to cover multiple composite manufacturing process steps, for example from the deposition of the fiber to the assembly of different components, considering intermediate steps such as forming/draping, injection/infusion, compaction/porosity, curing distortion analysis, and demoulding/trimming, among others. Fields and state variables output by one simulation serve as input for the next.
In this article one of these simulation steps will be investigated deeper: compaction and porosity. The compaction phase comprises the part of the autoclave cycle before the gel point is reached, so the cross-linked network has not started to form inside the thermoset resin, and thus it behaves as a viscous fluid.
For the current generation of materials and structures, we know how to make quality parts. To investigate disruptive concepts using high-fidelity simulations, these simulations must be able to predict:
(1) Resin flow from high to low pressure areas, which causes thickness and fiber volume ratio variations.
(2) Ply slippage, caused by the viscous interface between plies, which leads to relative displacements between adjacent plies of the stacking.
(3) Resin bleed through the edges, which affects the resin flow behaviour.
(4) Porosity coming from trapped air, or from dissolved and absorbed water in the prepreg.
The outputs from these simulations provide important data to analyze the feasibility of the process, anticipate potential manufacturing improvements and solutions, facilitate the decision-making process, and in general, increase the quality of the final product.
Manufacturing of long-fiber composites usually involves high development costs, since a single component may require several design loops to reach the desired product, e. g. by correcting spring-in issues, and avoiding non-conformities (dry spots, undulations, fiber misalignment, etc.), or just to de-risk process modifications (material, lay-up, or geometry). The simulation of manufacturing processes becomes an extraordinary instrument to reduce development lead time and cost, and at the same time increasing the versatility of the process itself.
A complete manufacturing process simulation may have to cover multiple composite manufacturing process steps, for example from the deposition of the fiber to the assembly of different components, considering intermediate steps such as forming/draping, injection/infusion, compaction/porosity, curing distortion analysis, and demoulding/trimming, among others. Fields and state variables output by one simulation serve as input for the next.
In this article one of these simulation steps will be investigated deeper: compaction and porosity. The compaction phase comprises the part of the autoclave cycle before the gel point is reached, so the cross-linked network has not started to form inside the thermoset resin, and thus it behaves as a viscous fluid.
For the current generation of materials and structures, we know how to make quality parts. To investigate disruptive concepts using high-fidelity simulations, these simulations must be able to predict:
(1) Resin flow from high to low pressure areas, which causes thickness and fiber volume ratio variations.
(2) Ply slippage, caused by the viscous interface between plies, which leads to relative displacements between adjacent plies of the stacking.
(3) Resin bleed through the edges, which affects the resin flow behaviour.
(4) Porosity coming from trapped air, or from dissolved and absorbed water in the prepreg.
The outputs from these simulations provide important data to analyze the feasibility of the process, anticipate potential manufacturing improvements and solutions, facilitate the decision-making process, and in general, increase the quality of the final product.