MIL-HDBK-17-2E (VOL. 2 OF 3), DEPARTMENT OF DEFENSE HANDBOOK: COMPOSITE MATERIALS HANDBOOK - POLYMER MATRIX COMPOSITES MATERIALS PROPERTIES (23 JAN 1997)., This handbook is for guidance only. This handbook cannot be cited as a requirement. If it is, the contractor does not have to comply. This mandate is a DoD requirement only; it is not applicable to the Federal Aviation Administration (FAA) or other government agencies. The purpose of this handbook is to provide a standard source of statistically-based mechanical property data for current and emerging composite materials. Strength and strain-to-failure properties will be reported either in terms of B-values or S-values. A B-basis value is the mechanical property value above which at least 90 percent of the population is expected to fall, with a confidence of 95 percent. An S-basis value is the mechanical property value which is usually the specified minimum value of the appropriate government specification for the material. Physical, chemical, and mechanical values of the composite constituents - the fibers, matrix material, and prepreg - will be reported where applicable. Later chapters will include data summaries for the various composite systems. Individual chapters focus on particular reinforcement fibers. Statistically-based strength properties will be defined for each composite material system over a range of potential usage conditions. The intent will be to provide data at the upper and lower limits of the potential environmental conditions for a particular material, so that application issues do not govern the mechanical property characterizations. If data are also available at intermediate environmental condi- tions, they will also be used to more exactly define the relationship between the material properties and the effect of the environment on those properties. The statistically-based strength data which are avail- able are tabulated in Volume 2. These data are useful as a starting point for establishing structural design allowables when stress and strength analysis capabilities permit lamina level margin of safety checks. Depending on the application, some structural design allowables will have to be determined empirically at the laminate and composite level, since MIL-HDBK-17 does not provide these data. Additional information and properties will be added as they become available and are demonstrated to meet the guideline criteria. All data included herein are based on test specimens only. Test specimen dimensions conform with those specified for the particular test method which is used. Standard test methods are recommended where possible (ASTM standards are the primary source). The designer and all users must be responsible for any translation of the data contained herein to other coupon dimensions, temperature, humidity, and other environmental conditions not covered in this document. Problems such as scale-up effects and the influence of the test method selected on properties are also not addressed in this document. The manner in which S-basis values are used is also up to the discretion of the designer. In general, decisions concerning which properties to use for a specific application or design are the responsibility of the designer and are outside the scope of this handbook.