Measuring the negative pressure during processing of advanced composites
Source abstract
Abstract
Abstract Pre-impregnated sheets of advanced carbon fibers with highly viscous thermoset-based resin systems are commonly used in fabricating aerospace composite parts. As prepreg sheets are vacuum bagged and heated during processing, the resin slowly infiltrates in dry spots between fibers. Under vacuum condition, surface tension-induced capillary effects impose deep negative pressures on the liquid resin , leading to tensile stretching. A method is presented to quantify the capillary-induced negative pressure. During processing, samples are quenched to freeze the infiltration process before taking SEM images. Using image analysis and by invoking interfacial stress boundary condition, the pressure distribution is determined. Sub-micron radii of curvature at the resin interface were measured corresponding to local negative pressures up to several atmospheres and an average pressure of −10 to −50 kPa. Effects of negative pressures on the state of material and on defects such as resin phase separation are discussed.
Source: openaire · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: Fiber-reinforced polymer composites · Mechanical Behavior of Composites · Epoxy Resin Curing Processes
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (61)
Show source-provided references
1. Boyle · 1660
2. Historical notes upon surface energy and forces of short range10.1038/109375a0 ↗
3. An experiment made at Gresham-college, shewing that the seemingly spontaneous ascension of water in small tubes open at both ends is the same in vacuo as in the open Air. By Mr Fr. Hauksbee, F.R.S.10.1098/rstl.1706.0008 ↗
4. Early observations of negative pressures in liquids10.1119/1.13353 ↗
5. De Gennes · 2013
6. Thermodynamics of negative pressures in liquids10.1515/jnet.1998.23.4.351 ↗
7. Classical thermodynamics of states with negative absolute temperature or with negative absolute pressure
8. Debenedetti · 1996
9. A coherent picture of water at extreme negative pressure10.1038/nphys2475 ↗
10. Capillarity induced negative pressure of water plugs in nanochannels10.1021/nl034676e ↗
11. Plant hydraulics: the ascent of water10.1038/423923a ↗
12. Phase behavior of capillary bridges: towards nanoscale water phase diagram10.1039/b801119m ↗
13. Liquid–liquid equilibria in polymer solutions at negative pressure10.1039/a827117z ↗
14. Campbell · 2003
15. 2.3 Autoclave Processing
16. Multi-scale characterization and representation of composite materials during processing10.1098/rsta.2015.0278 ↗
17. A novel hyper-viscoelastic model for consolidation of toughened prepregs under processing conditions10.1016/j.mechmat.2016.02.019 ↗
18. A differential approach to finite element modelling of isotropic and transversely isotropic viscoelastic materials10.1016/j.mechmat.2016.02.013 ↗
19. The origins of residual stress and its evaluation in composite materials10.1016/B978-0-08-100137-0.00003-1 ↗
20. Evaluation of through-thickness permeability and the capillary effect in vacuum assisted liquid molding process10.1016/j.compscitech.2012.02.014 ↗
21. Dynamic capillary effects in liquid composite moulding with non-crimp fabrics10.1016/j.compositesa.2005.04.011 ↗
22. Capillary effects in vacuum-assisted resin transfer molding with natural fibers10.1002/pc.22290 ↗
23. Prediction of capillary pressure for resin flow between fibers10.1016/j.compscitech.2016.02.014 ↗
24. Role of fiber distribution and air evacuation time on capillary driven flow into fiber tows10.1016/j.compositesa.2016.11.016 ↗
25. An experimental study of the permeability and capillary pressure in resin-transfer moulding10.1016/S0266-3538(01)00104-X ↗
26. Modeling the impact of capillary pressure and air entrapment on fiber tow saturation during resin infusion in LCM10.1016/j.compositesa.2009.04.013 ↗
27. Analysis and characterization of relative permeability and capillary pressure for free surface flow of a viscous fluid across an array of aligned cylindrical fibers10.1006/jcis.2001.8003 ↗
28. Dynamic capillary impact on longitudinal micro-flow in vacuum assisted impregnation and the unsaturated permeability of inner fiber tows10.1016/j.compscitech.2010.06.004 ↗
29. Determination of the optimal impregnation velocity in Resin Transfer Molding by capillary rise experiments and infrared thermography10.1016/j.compscitech.2014.05.019 ↗
30. Porosity reduction using optimized flow velocity in Resin Transfer Molding10.1016/j.compositesa.2008.09.008 ↗
31. Advanced numerical simulation of liquid composite molding for process analysis and optimization10.1016/j.compositesa.2005.06.003 ↗
32. Optimization of injection flow rate to minimize micro/macro-voids formation in resin transfer molded composites10.1016/j.compscitech.2005.06.013 ↗
33. On surface energy effects in composite impregnation and consolidation10.1016/0956-7143(95)95022-Q ↗
34. Amini Niaki · 2017
35. Micro-level mechanisms of fiber waviness and wrinkling during hot drape forming of unidirectional prepreg composites10.1016/j.compositesa.2017.10.008 ↗
36. Leal · 2007
37. Bird · 2007
38. 2013
39. Sadhal · 2012
40. Existence of a superficial viscosity in the thin transition layer separating one liquid from another contiguous fluid
41. The application of the formula for surface viscosity to the surface of a slowly falling droplet in the midst of a large unlimited amount of fluid which is at rest and possesses a smaller specific gravity
42. Dynamics of a fluid interface equation of motion for Newtonian surface fluids10.1016/0009-2509(60)87003-0 ↗
43. On the two-phase Navier-Stokes equations with Boussinesq-Scriven surface fluid10.1007/s00021-008-0278-x ↗
44. The dynamic contact angle10.1016/0009-2509(80)85075-5 ↗
45. Hexcel, HexPly 8552 product data sheet; 2016. http://www.hexcel.com/user_area/content_media/raw/HexPly_8552_us_DataSheet.pdf.
46. Hexcel, HexTow AS4 product data sheet; 2016. http://www.hexcel.com/user_area/content_media/raw/AS4_HexTow_DataSheet.pdf.
47. Hexcel, Hexply 8552 Safety Data Sheet; 2010.
48. Quantitative characterization of interdiffusion at the resin-resin and resin-prepreg interphases of epoxy systems processed by model SQ-RTM10.1002/pen.24338 ↗
49. Self-assembled three-dimensional structure of epoxy/polyethersulphone/silver adhesives with electrical conductivity10.1016/j.polymer.2015.11.043 ↗
50. Van Ee · 2009
51. Shahkarami · 2009
52. Convergent Manufacturing Technologies. RAVEN simulation software, version 3.9.3; 2013. http://www.convergent.ca/products/raven-simulation-software.
53. Rasband, W.S., ImageJ, U. S. National Institutes of Health, Bethesda, Maryland, USA, https://imagej.nih.gov/ij/; 1997-2016. Version 1.51n.
54. Ridgard C. Process selection and optimization for out-of-autoclave prepreg structures. In: Conference Proceedings of the Composites and Advanced Materials Expo (CMAX), Dallas, TX; 2015.
55. ASTM Committee D-20 on Plastics. Section D20. 70.01. Standard Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement. American Society for Testing and Materials; 1991.
56. In-situ measurement of chemical shrinkage of MY750 epoxy resin by a novel gravimetric method10.1016/S0266-3538(03)00199-4 ↗
57. Surface tension of polymer liquids10.1021/j100852a025 ↗
58. Measurement of surface and interfacial tension using pendant drop tensiometry10.1016/j.jcis.2015.05.012 ↗
59. Use of the pendant drop method to measure interfacial tension between molten polymers10.1590/S1516-14391999000100005 ↗
60. Pendant_Drop: an ImageJ plugin to measure the surface tension from an image of a pendant drop10.5334/jors.97 ↗
61. Caspe · 2011