Z-Pin Stubble Technology Advanced Research (ZSTAR)
Abstract
Z-pins are small-diameter carbon rods that are ultrasonically inserted through composite laminates in the z-direction to provide extra resistance to crack growth and delamination. They are normally inserted through co-cured composites, but this report presents an experimental study on a new z-pin stubble manufacturing technique that is compatible with the co-bonding process. Early researchers were limited to an exposed stubble height of 0.030 inch, which would not provide all of the benefits of a full-depth co-cured z-pin reinforced joint. This report describes a study in which the stubble lengths were increased to 0.250 inch. Double cantilever beam specimens were used to characterize the effect of stubble diameter and height on the Mode I crack resistance. It was found that increasing the stubble height from 0.040 inch to 0.125 inch resulted in a significant improvement in Mode I properties. Z-pins are small diameter carbon rods that are ultrasonically inserted through composite laminates in the z-direction to provide extra resistance to crack growth and delamination. They are normally inserted through co-cured composites, but this paper presents an experimental study on a new z-pin stubble manufacturing technique that is compatible with the co-bonding process. Z-pin stubble is created by inserting pins through the thickness of an uncured laminate and trimming the pins to a certain height above the surface. After initial cure, another uncured composite part is cured on the exposed stubble. Early researchers were limited to an exposed stubble height of 0.030 inch, which would not provide all of the benefits of a full-depth co-cured z-pin reinforced joint. This paper describes a study in which the stubble lengths were increased to 0.250 inch. Double cantilever beam (DCB) specimens were used to characterize the effect of stubble diameter and height
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 2008
- Accession Number
- ADA483021
Entities
People
- Amanda K. Pommer
- Stephen B. Clay
Organizations
- Air Force Research Laboratory