CK
C.F.M. Kendall
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Composite casings for solid rocket motors offer significant mass savings over metallic alternatives, but their manufacture using Out-Of-Autoclave (OOA) filament winding processes remains significantly less mature than autoclave-based methods. This thesis investigates how the process parameters involved in the winding and curing operations affect the quality and hoop-direction mechanical response of OOA carbon-towpreg overwraps co-cured onto paper–phenolic liners.
The experimental campaign ran in three tranches: preliminary microscopy specimens, a broad screening tranche, and a directed low/medium/high-tension by tape/no-tape study informed by the results of the screening tranche. Split-D testing was completed for 49 coupons from Tranches 2 and 3, and optical microscopy on fifteen sections supplied the cross-sectional area, the detected void area fraction, the void-size distribution, and a descriptive interface metric.
Maximum force was treated as the primary terminal-capacity endpoint and proved comparatively stable across configurations. Nominal stress was treated only as its fixed rescaling. The stress per unit of measured cross-section varied materially because the cross-section itself varied between configurations, though no statistically significant relationship between processing and cross-sectional area could be resolved. Functional shrink tape at high tension reduced the detected optical void area fraction from approximately 12 % to 9 %, the most consistent processing signal observed in this project. It also produced a significantly improved interface appearance compared to the same configuration without tape, though it was found that this did not produce a statistically resolved improvement in ultimate force. The tape may also have slightly reduced the threshold for first damage to occur. Higher recorded tension was associated with a higher apparent system stiffness but a matching change in the intrinsic modulus of the overwrap was only suggestive. First detected force discontinuities were more sensitive to configuration than terminal force, which indicates that the onset of detectable damage responds to processing choices more strongly than the final load capacity does.
Early testing identified an issue with liner blistering. Drying a full-length phenolic liner removed 0.59 % of its initial mass, consistent with a removable volatile. However, the treatment did not prevent blistering in the directed tranche, indicating that an alternative material or a modified cure cycle may be required to avoid this defect.
The work identifies a promising process window and establishes which measurements are sensitive enough to detect manufacturing effects, but it does not establish robust statistical confidence in the observed trends. The results are therefore suitable for informing the next stage of development, but not for establishing design allowables or production readiness. The detected void area fractions of 9 % to 12 % are significantly higher than would typically be achieved with a standard autoclave processing technique, but it is expected that with the use of better manufacturing processes and equipment it may be possible to reduce the void content to acceptable levels for single-use rocket motors for unmanned systems, though not for human-rated systems or high-cycle fatigue environments. ...
The experimental campaign ran in three tranches: preliminary microscopy specimens, a broad screening tranche, and a directed low/medium/high-tension by tape/no-tape study informed by the results of the screening tranche. Split-D testing was completed for 49 coupons from Tranches 2 and 3, and optical microscopy on fifteen sections supplied the cross-sectional area, the detected void area fraction, the void-size distribution, and a descriptive interface metric.
Maximum force was treated as the primary terminal-capacity endpoint and proved comparatively stable across configurations. Nominal stress was treated only as its fixed rescaling. The stress per unit of measured cross-section varied materially because the cross-section itself varied between configurations, though no statistically significant relationship between processing and cross-sectional area could be resolved. Functional shrink tape at high tension reduced the detected optical void area fraction from approximately 12 % to 9 %, the most consistent processing signal observed in this project. It also produced a significantly improved interface appearance compared to the same configuration without tape, though it was found that this did not produce a statistically resolved improvement in ultimate force. The tape may also have slightly reduced the threshold for first damage to occur. Higher recorded tension was associated with a higher apparent system stiffness but a matching change in the intrinsic modulus of the overwrap was only suggestive. First detected force discontinuities were more sensitive to configuration than terminal force, which indicates that the onset of detectable damage responds to processing choices more strongly than the final load capacity does.
Early testing identified an issue with liner blistering. Drying a full-length phenolic liner removed 0.59 % of its initial mass, consistent with a removable volatile. However, the treatment did not prevent blistering in the directed tranche, indicating that an alternative material or a modified cure cycle may be required to avoid this defect.
The work identifies a promising process window and establishes which measurements are sensitive enough to detect manufacturing effects, but it does not establish robust statistical confidence in the observed trends. The results are therefore suitable for informing the next stage of development, but not for establishing design allowables or production readiness. The detected void area fractions of 9 % to 12 % are significantly higher than would typically be achieved with a standard autoclave processing technique, but it is expected that with the use of better manufacturing processes and equipment it may be possible to reduce the void content to acceptable levels for single-use rocket motors for unmanned systems, though not for human-rated systems or high-cycle fatigue environments. ...
Composite casings for solid rocket motors offer significant mass savings over metallic alternatives, but their manufacture using Out-Of-Autoclave (OOA) filament winding processes remains significantly less mature than autoclave-based methods. This thesis investigates how the process parameters involved in the winding and curing operations affect the quality and hoop-direction mechanical response of OOA carbon-towpreg overwraps co-cured onto paper–phenolic liners.
The experimental campaign ran in three tranches: preliminary microscopy specimens, a broad screening tranche, and a directed low/medium/high-tension by tape/no-tape study informed by the results of the screening tranche. Split-D testing was completed for 49 coupons from Tranches 2 and 3, and optical microscopy on fifteen sections supplied the cross-sectional area, the detected void area fraction, the void-size distribution, and a descriptive interface metric.
Maximum force was treated as the primary terminal-capacity endpoint and proved comparatively stable across configurations. Nominal stress was treated only as its fixed rescaling. The stress per unit of measured cross-section varied materially because the cross-section itself varied between configurations, though no statistically significant relationship between processing and cross-sectional area could be resolved. Functional shrink tape at high tension reduced the detected optical void area fraction from approximately 12 % to 9 %, the most consistent processing signal observed in this project. It also produced a significantly improved interface appearance compared to the same configuration without tape, though it was found that this did not produce a statistically resolved improvement in ultimate force. The tape may also have slightly reduced the threshold for first damage to occur. Higher recorded tension was associated with a higher apparent system stiffness but a matching change in the intrinsic modulus of the overwrap was only suggestive. First detected force discontinuities were more sensitive to configuration than terminal force, which indicates that the onset of detectable damage responds to processing choices more strongly than the final load capacity does.
Early testing identified an issue with liner blistering. Drying a full-length phenolic liner removed 0.59 % of its initial mass, consistent with a removable volatile. However, the treatment did not prevent blistering in the directed tranche, indicating that an alternative material or a modified cure cycle may be required to avoid this defect.
The work identifies a promising process window and establishes which measurements are sensitive enough to detect manufacturing effects, but it does not establish robust statistical confidence in the observed trends. The results are therefore suitable for informing the next stage of development, but not for establishing design allowables or production readiness. The detected void area fractions of 9 % to 12 % are significantly higher than would typically be achieved with a standard autoclave processing technique, but it is expected that with the use of better manufacturing processes and equipment it may be possible to reduce the void content to acceptable levels for single-use rocket motors for unmanned systems, though not for human-rated systems or high-cycle fatigue environments.
The experimental campaign ran in three tranches: preliminary microscopy specimens, a broad screening tranche, and a directed low/medium/high-tension by tape/no-tape study informed by the results of the screening tranche. Split-D testing was completed for 49 coupons from Tranches 2 and 3, and optical microscopy on fifteen sections supplied the cross-sectional area, the detected void area fraction, the void-size distribution, and a descriptive interface metric.
Maximum force was treated as the primary terminal-capacity endpoint and proved comparatively stable across configurations. Nominal stress was treated only as its fixed rescaling. The stress per unit of measured cross-section varied materially because the cross-section itself varied between configurations, though no statistically significant relationship between processing and cross-sectional area could be resolved. Functional shrink tape at high tension reduced the detected optical void area fraction from approximately 12 % to 9 %, the most consistent processing signal observed in this project. It also produced a significantly improved interface appearance compared to the same configuration without tape, though it was found that this did not produce a statistically resolved improvement in ultimate force. The tape may also have slightly reduced the threshold for first damage to occur. Higher recorded tension was associated with a higher apparent system stiffness but a matching change in the intrinsic modulus of the overwrap was only suggestive. First detected force discontinuities were more sensitive to configuration than terminal force, which indicates that the onset of detectable damage responds to processing choices more strongly than the final load capacity does.
Early testing identified an issue with liner blistering. Drying a full-length phenolic liner removed 0.59 % of its initial mass, consistent with a removable volatile. However, the treatment did not prevent blistering in the directed tranche, indicating that an alternative material or a modified cure cycle may be required to avoid this defect.
The work identifies a promising process window and establishes which measurements are sensitive enough to detect manufacturing effects, but it does not establish robust statistical confidence in the observed trends. The results are therefore suitable for informing the next stage of development, but not for establishing design allowables or production readiness. The detected void area fractions of 9 % to 12 % are significantly higher than would typically be achieved with a standard autoclave processing technique, but it is expected that with the use of better manufacturing processes and equipment it may be possible to reduce the void content to acceptable levels for single-use rocket motors for unmanned systems, though not for human-rated systems or high-cycle fatigue environments.
Bachelor thesis
(2023)
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L. Alonso Antona, S. Aurori, M. Beenders, E.G. Chen, C.F.M. Kendall, D.J.D. Norbart, T. Odijk, M.H. Rusch, L.M.N. Tabaksblat, S. Yorucu, I. Akay, A.O. Başkaya, P. Piron
The goal of project Altus is to do an in-situ investigation of Polar Mesospheric Clouds (PMCs). These clouds form around an altitude of 84 km, and only for 60 to 80 days per year, during the summer. Normally, these clouds only form in the polar regions, from around 50◦ latitude north and south. Recently, however, PMCs have been observed as low as 40◦ north. There are theories linking this change in location, and other unexpected behaviours of PMCs, to climate change. However, further research is still required to confirm these theories. As these changes are happening at a slow rate, a database of PMC measurements would be extremely beneficial to track indicator values over time. Project Altus sets out to bridge this knowledge gap by taking regular measurements of PMCs over an extended period of time.
...
The goal of project Altus is to do an in-situ investigation of Polar Mesospheric Clouds (PMCs). These clouds form around an altitude of 84 km, and only for 60 to 80 days per year, during the summer. Normally, these clouds only form in the polar regions, from around 50◦ latitude north and south. Recently, however, PMCs have been observed as low as 40◦ north. There are theories linking this change in location, and other unexpected behaviours of PMCs, to climate change. However, further research is still required to confirm these theories. As these changes are happening at a slow rate, a database of PMC measurements would be extremely beneficial to track indicator values over time. Project Altus sets out to bridge this knowledge gap by taking regular measurements of PMCs over an extended period of time.