Bladder molding has been used to fabricate hollow composite components for more than two decades. In bladder molding, the requisite consolidation pressure is applied from the inside of the composite laminate during cure via a flexible bladder. In conventional bladder molding, the cure assembly is most often heated using an external heat source such as an oven or an autoclave. Due to the flexibility of the technique in applying pressure, the method is often the only process suitable to
fabricate composite components with complicated geometry, i.e. non-axis symmetric, and varying wall thicknesses. Despite these advantages, the technique is often overlooked because it requires the use of an oven or autoclave to cure the part, and the void contents of the components produced may not satisfy the quality needed for structural applications.
In this paper, we will introduce and discuss the important features of the recently developed Bladder Assisted Composite Manufacturing (BACM) technique. BACM eliminates the disadvantages of conventional bladder molding applications by heating the composite laminate internally during cure and controlling resin pressure and outflow. As a result, the BACM technique was found capable of producing aerospace quality composite structures with fiber volume contents as high as 67% and void contents as low as 0.2%. In addition, compared to the conventional bladder molding techniques which utilize external heating, the BACM process was observed to reduce the energy required to fabricate a composite component by over 50%. These results make the BACM technique a feasible alternative to current fabrication methods for the production of composite components of varying geometrical complexity. Moreover, with further development, the fabrication of large hollow composite structures such as aircraft wings and fuselages via BACM is promising.
