Hydrogen Gas Leak Rate Testing and Post-Testing Assessment of Microcrack Damaged Composite Laminates

Grenoble, Ray; Gates, Thomas S.

doi:10.2514/6.2006-2017

Cited by 5 publications

(6 citation statements)

References 9 publications

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“…They observed matrix microcracking and attributed it to the small part surface, but they asserted it would not be a factor in larger parts. However, microcracking can increase gas permeability, as reported by Grenoble after conducting fatigue tests on cured laminates [10].…”

Section: Introductionmentioning

confidence: 82%

Permeability of co-cured honeycomb sandwich skins: effect of gas transport during processing

Palit

Centea

Anders

et al. 2020

Advanced Manufacturing: Polymer & Composites Science

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Potential links between pressure conditions during co-cure of honeycomb sandwich panels, the extent of gas flow through facesheet and bond-line, and the level of permeability in the cured skin were evaluated. Half-sandwich structures comprised of fiber-reinforced polymer facesheets, film adhesive, and core were fabricated using a custom-built lab fixture. Autoclave, bag, and core pressures were varied to produce controlled, constant pressure differences during cure, and the resulting skins were tested for permeability using a fixture constructed to measure gas flow rate across the skins and to locate gas flow pathways. Facesheet cross-sections were analyzed to evaluate porosity. Porosity and the number of gas flow pathways were correlated to permeability, but significant gas flow was possible without high void content or with few channels, as pressure differentials led to complex variations in permeability. Overall, the study provides new insights into gas transport during composites processing and manufacturing, and the results provide guidance for modifying manufacturing processes to ensure part quality.

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Section: Introductionmentioning

confidence: 82%

Permeability of co-cured honeycomb sandwich skins: effect of gas transport during processing

Palit

Centea

Anders

et al. 2020

Advanced Manufacturing: Polymer & Composites Science

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“…Grenoble and Gates showed, in their experiment with IM7/977-2 [45/90 3 /À45/0 3 ] s laminates, higher leak rates at cryogenic temperature with increasing levels of uni-axial tensile strain than at room temperature with the same levels of strains [36]. Their results show that the thermal residual stresses at cryogenic temperature made an additional contribution to matrix cracking compared with the mechanical loading at room temperature.…”

Section: Initial and Progressive Failure Model Depending On Failure Mechanismmentioning

confidence: 94%

“…Fuel leakage, due to the transverse matrix cracks in conjunction with inter-ply delaminations resulting in an intersecting network of passages, has been an important issue for designing cryogenic fuel tank. Some researchers have studied the leakage or permeation of cryogenic fuel through composite laminates by experiment or modeling [34][35][36][37][38][39][40].…”

Section: Initial and Progressive Failure Model Depending On Failure Mechanismmentioning

confidence: 99%

“…Normally, according to X-ray or C-scan images, carbon-fiber/toughened epoxy and carbon-fiber/BMI composites have been reported to develop matrix cracks though the whole lamina width when a transverse ply strain is higher than about 0.4% [36,39,45]. Kumazawa et al showed fully developed transverse matrix cracks though the width direction and vigorous gas leakage through the matrix cracks of [0/90/0/90] s laminates under 0.45 to 0.7% of uni-axial or bi-axial mechanical strains [34,39].…”

Section: Cracking Conditions Of Each Lamina Under Different Loading Modesmentioning

confidence: 99%

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An Initial and Progressive Failure Analysis for Cryogenic Composite Fuel Tank Design

Pickle

Morgan

et al. 2007

Journal of Composite Materials

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Thermal residual stresses, internal pressure stresses, and acceleration stresses during launch were evaluated and quantified for cryogenic composite fuel tank design. Both failure initiation and progression of graphite/epoxy laminate system (IM7/977-2) [0/90/90/0/0/90] s and graphite/BMI laminate system (IM7/5250-4) [0/90/90/0/0/90] s were investigated using the non-isothermal classical laminate and plate theory (CLPT) and the maximum stress failure criterion. The thermal residual stresses in the transverse direction are the dominant stresses on each ply in the launch stage. After initial ply cracking, through-the-thickness temperature change of a laminate related to fuel leakage as well as a laminate stiffness matrix change was applied to the progressive failure analysis. The fuel leakage-based progressive analysis shows a higher number of initial ply cracking does not necessarily mean a higher chance of matrix cracking in all plies. The graphite/BMI laminate has such an advantage as transverse thermo-mechanical resistance over the graphite/epoxy laminate at an initial exposure to À253 C and 1500 kPa. In terms of complete laminate matrix cracking, however, the graphite/ epoxy laminate is more resistant to transferring stresses to other plies than the graphite/BMI laminate.KEY WORDS: cryogenic composite fuel tank, progressive failure analysis, fuel leakage, IM7/977-2 (graphite/epoxy laminate system), IM7/5250-4 (graphite/ BMI laminate system).

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“…Other experimental studies examined the effect of tensile fatigue damage on the leakage rate of hydrogen gas through a reinforced composite material at both room and cryogenic temperatures [3]. Additional studies by Bechel and Kim [4] and Bechel et al [5] investigated how the density of thermally induced cracks varied with the number of cycles, ply thickness, and ply orientation.…”

Section: Introduction Fmentioning

confidence: 99%

A Self-sealing Fiber-reinforced Composite

Moll

White

Sottos

2010

Journal of Composite Materials

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ABSTRACT:We describe a self-sealing plain weave E-glass epoxy composite with the healing components, microencapsulated dicyclopentadiene (DCPD), and paraffin wax coated Grubbs' catalyst dispersed throughout the matrix. In this work, sealing is assessed through use of a pressure cell apparatus to detect nitrogen flow through the thickness direction of a damaged composite. A controlled amount of microcracking is introduced through cyclic indentation of opposing surfaces of the sample. The resulting damage zone is proportional to the indentation load. We investigate the effect of DCPD microcapsule size and concentration on the self-sealing ability of plain weave E-glass epoxy composites. For 51 mm diameter capsules (6.5 wt%), 67% of the self-sealing composite panels fully seal with no leaking, compared to 0% of the control panels with no sealing ability. When the amount of damage is reduced, 100% of the self-sealing samples resealed. Sealing performance decreases with smaller diameter capsules (18 mm diameter) and lower capsule concentrations (2.7 wt%), indicating that there is a minimum capsule size and concentration to deliver enough healing agent to seal a given damage volume.

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Hydrogen Gas Leak Rate Testing and Post-Testing Assessment of Microcrack Damaged Composite Laminates

Cited by 5 publications

References 9 publications

Permeability of co-cured honeycomb sandwich skins: effect of gas transport during processing

Permeability of co-cured honeycomb sandwich skins: effect of gas transport during processing

An Initial and Progressive Failure Analysis for Cryogenic Composite Fuel Tank Design

A Self-sealing Fiber-reinforced Composite

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