Processing and Performance of Out-of-Autoclave Bismaleimide Composite Sandwich Structures


Composite sandwich structures offer several advantages over conventional structural materials such as lightweight, high bending and torsional stiffness, superior thermal insulation and excellent acoustic damping. In the aerospace industry, sandwich composites are commonly manufactured using the autoclave process which is associated with high operating cost. Out-of-Autoclave (OOA) manufacturing has been shown to be capable of producing low cost and high performance composites. Unlike the autoclave process, OOA processing avoids the issue of core-crushing due to high pressure. However, Bismaleimide (BMI) prepregs require high cure and post-cure temperatures which can lead to high internal core pressures, core-to-facesheet disbonding and voids. In the current work, OOA sandwich composite panels are manufactured using aluminum honeycomb core, BMI adhesive film and carbon/BMI prepregs. Two vacuum levels were used during OOA processing, full vacuum (100 kPa) and partial vacuum (80 kPa). Adhesive bond quality was evaluated using flatwise tensile and fracture toughness tests. Mechanical performance was evaluated using edgewise compression. It was observed that vacuum level variation during processing had no significant effect on mechanical properties of manufactured laminates. Tests are performed at room temperature and 177 °C (350 °F). All manufactured laminates exhibited room temperature flatwise tensile strengths comparable to those of aerospace grade epoxy adhesives. Sandwich mechanical properties reduced when test temperature was increased.

Meeting Name

Composites and Advanced Materials Expo 2015, CAMX 2015 (2015: Oct. 27-29, Dallas, TX)


Mechanical and Aerospace Engineering

Research Center/Lab(s)

Intelligent Systems Center

Keywords and Phrases

Aerospace industry; Carbon; Curing; Honeycomb structures; Joints (structural components); Mechanical properties; Pressure vessels; Quality control; Sandwich structures; Tensile strength; Thermal insulation; Aluminum honeycomb cores; Bismaleimide composites; Composite sandwich structure; Fracture toughness tests; High performance composites; Internal core pressure; Mechanical performance; Sandwich composite panels; Fracture toughness

International Standard Serial Number (ISSN)


Document Type

Article - Conference proceedings

Document Version


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© 2016 Society for the Advancement of Material and Process Engineering (SAMPE), All rights reserved.

Publication Date

01 May 2016

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