COMPOSITE MATERIALS HANDBOOK VOLUME 1
|Publication Date:||1 March 2012|
PURPOSE AND SCOPE OF VOLUME 1
Volume 1 provides material characterization, test methodology, and data development guidelines adaptable to a wide variety of needs for polymeric matrix composite materials. It includes methods for obtaining data for constituent materials (i.e., fibers, matrices), combined material forms (e.g., prepreg), and cured lamina and laminates. Information is provided on the range of test types, environmental conditioning methods, and data handling techniques commonly used during composite structure development programs. Although this Volume includes guidelines for testing at some higher structural complexity levels (i.e., laminates, joints, etc.), the principal focus is material-level property characterization. Particular emphasis is given to statistical methods typically used for the determination of property values, as well as the specific requirements for data published in Volume 2 of the handbook.
It must be emphasized that this handbook differentiates between material basis values (material allowables) and design values. Material basis values, being a statistical lower-bound estimate of a property of a composite material system, are the focus of this handbook, and this Volume in particular. See Figure
Design values which directly satisfy regulatory requirements, while often rooted in material basis values, are application dependent, and must account for many additional considerations that can affect the strength and stiffness of the structure. Also, when establishing design values for a specific application there may be additional certification or procurement agency requirements that go beyond CMH-17 (for guidance see CMH-17 Volume 3, Chapter 3).
While the process of establishing structural design values for an application can begin with the data contained in Volume 2, most applications require collection of additional data, especially data from the laminate or higher structural complexity levels. Also, the ability to manufacture material equivalent to that from which the data in Volume 2 were obtained typically must be proven to the certifying or procuring agency, which usually involves limited testing and data comparison. General guidelines for such material/ process equivalence evaluation are presented in Volume 1; however, many of the details of such an evaluation remain at the discretion of the certifying or procuring agency.
Most certifying and procuring agencies prefer, and some may require, that composite material systems used in critical applications be characterized in accordance with Volume 1 testing and data analysis guidelines. When the guidelines or data requirements of CMH-17 cannot be followed, the certifying or procuring agency should be contacted to determine data requirements and other documentation which may be necessary to justify data values proposed or used during structure development.