Nanomaterial-Enabled Out-of-Autoclave and Out-of-Oven Manufacturing of Fiber Reinforced Polymer Composites
Fiber reinforced polymer composite materials have been a staple of the aerospace industry, integral to creating lightweight flight vehicles due to their high specific material properties. These materials often come in a prepreg form, where microfibers are pre-impregnated with a polymer matrix to for...
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| Other Authors: | |
| Format: | Thesis |
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Massachusetts Institute of Technology
2023
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| Online Access: | https://hdl.handle.net/1721.1/152800 |
| _version_ | 1811095907223994368 |
|---|---|
| author | Serrano, Steven |
| author2 | Wardle, Brian L. |
| author_facet | Wardle, Brian L. Serrano, Steven |
| author_sort | Serrano, Steven |
| collection | MIT |
| description | Fiber reinforced polymer composite materials have been a staple of the aerospace industry, integral to creating lightweight flight vehicles due to their high specific material properties. These materials often come in a prepreg form, where microfibers are pre-impregnated with a polymer matrix to form lamina that are stacked to form a composite laminate. These aerospace-grade composite structures generally require an autoclave cure, which uses both temperature and pressure to cure the thermoset polymer (or consolidate the thermoplastic polymer) in the prepreg and remove voids throughout the laminate. In this thesis, curing of autoclave-grade thermosetting prepregs using vacuum-bag only (VBO) processes are investigated and further developed through the employment of nanomaterials, both within the laminate itself and externally as a conductive heating mechanism. A preliminary void reduction study was conducted on the effects of placing different nanoporous networks (NPNs) in the interlaminar regions of a VBO manufactured quasi-isotropic laminate using autoclavegrade glass fiber reinforced polymer (GFRP) unidirectional prepreg. It was shown that vertically aligned carbon nanotubes (VA-CNTs), electrospun polymer nanofiber (EPN) veils, and polyimide (PI) aerogel thin films may each successfully evacuate voids via capillary-pressure enhanced polymer flow, as the laminate was void-free. A subsequent study placing PI aerogel NPN in each interlaminar region was shown to successfully create a void-free GFRP laminate on a hot plate using VBO manufacturing. Autoclave woven CFRP prepreg laminates were also manufactured using the same VBO with NPN technique, with PI aerogel in each interlaminar region. Laminates were shown to have minimal void content (< 0.03 vol%) using an advantageously thinner aerogel film than previous work. A previously studied out-of-oven (OoO) curing process using a carbon nanotube (CNT) thin film heating element was modeled using ANSYS Composite Cure Simulation (ACCS) to predict the temperature and degree of cure (DoC) of CFRP laminates using cure kinetics equations and the finite element method. The Limited-memory Broyden-Fletcher-Goldfarb-Shanno with Bound constraints (L-BFGS-B) algorithm was implemented to optimize the cure cycle with respect to time and DoC constraints. Two optimized cure cycles were revealed via the optimization scheme, showing significant (60% to 65%) reductions in manufacturing time. A third accelerated-cure cycle did not use the optimization scheme, but rather utilized an empirical estimation of resin rheology, time history of temperature, and DoC to obtain a cure cycle that had comparable resin flow to that of the manufacturer recommended cure cycle (MRCC) per a defined flow metric. Laminates utilizing the three accelerated cures, the MRCC cure, and a cure with an extended first hold were all modeled in ANSYS and manufactured with a CNT heater OoO set-up and an EPN NPN. The model was found to overestimate the DoC of the manufactured 152 mm x 152 mm x 2 mm (16 ply) laminates by ∼5% on average. The accelerated-cure laminates were shown to have a relatively high void content, indicating that additional considerations are necessary to successfully accelerate the VBO CFRP cure cycle. However, the laminate cured with an extended first hold, as well as the MRCC laminate, were found to have minimal void content (0.02 vol% and 0.08 vol%, respectively). Furthermore, the accelerated-cure laminate with a second hold of 200°C for 36.5 minutes was found to yield a nominal DoC (90.5%) and a comparable glass transition temperature (𝑇 subscript 𝑔) to that of the MRCC cured laminate. Together, the results found in this work show that nanomaterials (i.e. NPNs and CNT heating elements) enable the VBO manufacturing of several types of autoclave prepregs and improve manufacturing throughput via cure cycle modifications that can allow significant acceleration of the overall cure cycle. |
| first_indexed | 2024-09-23T16:33:25Z |
| format | Thesis |
| id | mit-1721.1/152800 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T16:33:25Z |
| publishDate | 2023 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/1528002023-11-03T03:04:00Z Nanomaterial-Enabled Out-of-Autoclave and Out-of-Oven Manufacturing of Fiber Reinforced Polymer Composites Serrano, Steven Wardle, Brian L. Massachusetts Institute of Technology. Department of Aeronautics and Astronautics Fiber reinforced polymer composite materials have been a staple of the aerospace industry, integral to creating lightweight flight vehicles due to their high specific material properties. These materials often come in a prepreg form, where microfibers are pre-impregnated with a polymer matrix to form lamina that are stacked to form a composite laminate. These aerospace-grade composite structures generally require an autoclave cure, which uses both temperature and pressure to cure the thermoset polymer (or consolidate the thermoplastic polymer) in the prepreg and remove voids throughout the laminate. In this thesis, curing of autoclave-grade thermosetting prepregs using vacuum-bag only (VBO) processes are investigated and further developed through the employment of nanomaterials, both within the laminate itself and externally as a conductive heating mechanism. A preliminary void reduction study was conducted on the effects of placing different nanoporous networks (NPNs) in the interlaminar regions of a VBO manufactured quasi-isotropic laminate using autoclavegrade glass fiber reinforced polymer (GFRP) unidirectional prepreg. It was shown that vertically aligned carbon nanotubes (VA-CNTs), electrospun polymer nanofiber (EPN) veils, and polyimide (PI) aerogel thin films may each successfully evacuate voids via capillary-pressure enhanced polymer flow, as the laminate was void-free. A subsequent study placing PI aerogel NPN in each interlaminar region was shown to successfully create a void-free GFRP laminate on a hot plate using VBO manufacturing. Autoclave woven CFRP prepreg laminates were also manufactured using the same VBO with NPN technique, with PI aerogel in each interlaminar region. Laminates were shown to have minimal void content (< 0.03 vol%) using an advantageously thinner aerogel film than previous work. A previously studied out-of-oven (OoO) curing process using a carbon nanotube (CNT) thin film heating element was modeled using ANSYS Composite Cure Simulation (ACCS) to predict the temperature and degree of cure (DoC) of CFRP laminates using cure kinetics equations and the finite element method. The Limited-memory Broyden-Fletcher-Goldfarb-Shanno with Bound constraints (L-BFGS-B) algorithm was implemented to optimize the cure cycle with respect to time and DoC constraints. Two optimized cure cycles were revealed via the optimization scheme, showing significant (60% to 65%) reductions in manufacturing time. A third accelerated-cure cycle did not use the optimization scheme, but rather utilized an empirical estimation of resin rheology, time history of temperature, and DoC to obtain a cure cycle that had comparable resin flow to that of the manufacturer recommended cure cycle (MRCC) per a defined flow metric. Laminates utilizing the three accelerated cures, the MRCC cure, and a cure with an extended first hold were all modeled in ANSYS and manufactured with a CNT heater OoO set-up and an EPN NPN. The model was found to overestimate the DoC of the manufactured 152 mm x 152 mm x 2 mm (16 ply) laminates by ∼5% on average. The accelerated-cure laminates were shown to have a relatively high void content, indicating that additional considerations are necessary to successfully accelerate the VBO CFRP cure cycle. However, the laminate cured with an extended first hold, as well as the MRCC laminate, were found to have minimal void content (0.02 vol% and 0.08 vol%, respectively). Furthermore, the accelerated-cure laminate with a second hold of 200°C for 36.5 minutes was found to yield a nominal DoC (90.5%) and a comparable glass transition temperature (𝑇 subscript 𝑔) to that of the MRCC cured laminate. Together, the results found in this work show that nanomaterials (i.e. NPNs and CNT heating elements) enable the VBO manufacturing of several types of autoclave prepregs and improve manufacturing throughput via cure cycle modifications that can allow significant acceleration of the overall cure cycle. S.M. 2023-11-02T20:17:23Z 2023-11-02T20:17:23Z 2023-09 2023-09-20T15:15:16.862Z Thesis https://hdl.handle.net/1721.1/152800 In Copyright - Educational Use Permitted Copyright retained by author(s) https://rightsstatements.org/page/InC-EDU/1.0/ application/pdf Massachusetts Institute of Technology |
| spellingShingle | Serrano, Steven Nanomaterial-Enabled Out-of-Autoclave and Out-of-Oven Manufacturing of Fiber Reinforced Polymer Composites |
| title | Nanomaterial-Enabled Out-of-Autoclave and Out-of-Oven Manufacturing of Fiber Reinforced Polymer Composites |
| title_full | Nanomaterial-Enabled Out-of-Autoclave and Out-of-Oven Manufacturing of Fiber Reinforced Polymer Composites |
| title_fullStr | Nanomaterial-Enabled Out-of-Autoclave and Out-of-Oven Manufacturing of Fiber Reinforced Polymer Composites |
| title_full_unstemmed | Nanomaterial-Enabled Out-of-Autoclave and Out-of-Oven Manufacturing of Fiber Reinforced Polymer Composites |
| title_short | Nanomaterial-Enabled Out-of-Autoclave and Out-of-Oven Manufacturing of Fiber Reinforced Polymer Composites |
| title_sort | nanomaterial enabled out of autoclave and out of oven manufacturing of fiber reinforced polymer composites |
| url | https://hdl.handle.net/1721.1/152800 |
| work_keys_str_mv | AT serranosteven nanomaterialenabledoutofautoclaveandoutofovenmanufacturingoffiberreinforcedpolymercomposites |