Processing and environmental effects on composite repairs

The scarf-joint technique is one of the latest techniques used for repairing composite aircraft structures. But this technique is mostly used at depot level repairing activities since it requires autoclave and other equipments. This article focuses on scarf joint comprised of vacuum and autoclave precured and co-cured composite patches bonded to autoclave and vacuum precured parent laminates. Autoclave and vacuum cured parent laminates and scarf joints were prepared and exposed to the same temperature and moisture environment for comparison. All specimens were loaded in tension at three temperatures. Interlaminar shear strength (ILSS) tests were also carried out for the parent materials. As noted, the tensile strength and ILSS decrease when the material has been exposed to moisture and tested at elevated temperature. But, no significant difference was reported for either tensile strength or ILSS between autoclave and vacuum cured materials. The room temperature repair efficiencies are reported for single scarf repairs comprised of vacuum co-cured and precured patches. These vacuum cured repair efficiencies were found to be similar to the efficiency of the autoclave precured patch repair. This result supports the feasibility of scarf joint repairs with precured or co-cured patches under vacuum curing conditions in field level facilities. Therefore, repairs with vacuum precured or vacuum co-cured patches requiring less equipment seems to be a serious potential alternative to the composite patch repair requiring autoclave conditions which might be only available at depot level maintenance centers. © 2012 Copyright Taylor and Francis Group, LLC

A study on curing processes and environmental effects for rapid composite repair

This article focuses on scarf joint comprised of vacuum-precured, vacuum-cocured, autoclave-procured, and autoclave-cocured composite patches bonded to autoclave- and vacuum-precured parent laminates. Autoclave- and vacuum-cured parent laminates and scarf joints were prepared and exposed to the same temperature and moisture environment for comparison. All specimens were loaded in tension at three temperatures. Interlaminar shear strength (ILSS) tests were also carried out for the parent materials. As noted, the tensile strength and ILSS decrease when the material has been exposed to moisture and tested at elevated temperature. But, no significant difference was reported for either tensile strength or ILSS between autoclave- and vacuum-cured materials. The room temperature repair efficiencies are reported for single-scarf repairs comprised of vacuum-cocured and vacuum-precured patches. These vacuum-cured repair efficiencies were found to be similar to the efficiency of the autoclave-precured patch repair. This result supports the feasibility of scarf joint repairs with precured or cocured patches under vacuum curing conditions in field-level facilities. Therefore, repairs with vacuum-precured or vacuum-cocured patches requiring less equipments seem to be a serious potential alternative to the composite patch repair requiring autoclave conditions which might be only available at depot-level maintenance centers. © The Author(s) 2011

Scarf Joint Technique with Cocured and Precured Patches for Composite Repair

NRC publication: Ye

Manufacture of Composite Panels with J-Shape Stiffeners

NRC publication: Ye

Experimental and Analytical Study of J-Stiffened Composite Panels Loaded in Axial Compression

NRC publication: Ye

Design and Manufacture of Stiffened Composite Panels

NRC publication: Ye

Healthcare-associated Crimean-Congo haemorrhagic fever in Turkey, 2002–2014: a multicentre retrospective cross-sectional study

Healthcare-related transmission of Crimean-Congo haemorrhagic fever (CCHF) is a well-recognized hazard. We report a multicentre retrospective cross-sectional study undertaken in Turkey in 2014 in nine hospitals, regional reference centres for CCHF, covering the years 2002 to 2014 inclusive. Data were systematically extracted from charts of all personnel with a reported health care injury/accident related to CCHF. Blood samples were tested for CCHF IgM/IgG by enzyme-linked immunosorbent assay and/or viral nucleic acid detection by PCR after the injury. Fifty-one healthcare-related exposures were identified. Twenty-five (49%) of 51 resulted in laboratory-confirmed infection, with a 16% (4/25) overall mortality. The main route of exposure was needlestick injury in 32/51 (62.7%). A potential benefit of post-exposure prophylaxis with ribavirin was identified