Achieving the best-performing composite part requires that the processing method and cure cycle create high-quality, low-void-content structures. If voids are present, the performance of the composite will be significantly reduced. There are multiple causes of voids in composite materials; they are generally categorized as voids that are due to volatiles (such as solvents, water) or voids that result from entrapped air. This chapter describes the analysis of various types of voids. It reviews techniques for analysis of voids at ply-drops, voids due to high fiber packing, and voids that occur in honeycomb core composites. The final section of the chapter discusses void documentation through the use of nondestructive inspection techniques and density/specific gravity measurement methods.

The honeycomb sandwich structure composite is a very efficient and complex structure widely used in the aircraft industry. Honeycomb-cored sandwich panels increase part stiffness at a lower weight than monolithic composite materials. This chapter describes the analysis of the intermingling of the film adhesive/prepreg resin system. It discusses the causes and effects of honeycomb core movement, which results in core crush. The chapter also explains the formation of a void in honeycomb composites and the failure mechanisms in honeycomb sandwich structure composites.