Managing the data in a composite materials data base, such as the data base required for MIL-HDBK-17, is a complex task. MIL-HDBK-17, “Polymer Matrix Composites,” is a fully coordinated military document currently supported by the Army, the Air Force, and the Federal Aviation Administration. The guidelines in Volume I of the handbook provide the requirements for a statistically based data base of polymer matrix composite materials properties.
The MIL-HDBK-17 data base must be capable of handling property values for fibers, matrix materials, prepregs, laminae, and simple laminates. A prepreg is a ready-to-mold or -cure material in sheet form. It may be fiber, cloth, or a mat impregnated with resin and stored for use. The properties of each of these types of materials can be further divided into chemical, physical, and mechanical categories. While the material types and property categories readily provide an outline for a data base, a number of properties must overlap the data base boundaries to adequately describe a given material.
Statistical analysis requirements for evaluating batch-to-batch variability and an interest in pooling data from various sources dictate the analysis and storage of all raw data in addition to the statistical parameters reported in MIL-HDBK-17. The capabilities for tracking these data use four types of files—raw data files, statistical parameter files, analysis files, and files that record the history of pooled data. In addition, a hard-copy record is retained for both analysis files and summary tables. The analysis files report raw data, the method of analysis as determined by batch-to-batch variability and the distribution of the data, and the resulting statistical parameters. The summary tables contain the statistical parameters in the MIL-HDBK-17 format tabulated by orientation, loading, temperature, and moisture conditions. These tabulated values can be readily transferred to a word processor for incorporation into the printed handbook.
Data-base management on personal computers was selected for several reasons. PC availability is desirable for the statistical analysis program since each company or laboratory that submits data to MIL-HDBK-17 will want access to this program. Management of the data base itself is conducted through the use of METSEL2. METSEL2 is an interactive data-base program originally designed to store metals properties and currently being revised to include composite materials. Storage and manipulation of the statistical parameters are enhanced by using this program. The in-house data base is also considered a trial run for a data base that may be distributed to the members of the coordination group and other appropriate organizations. The establishment of this permanent, accessible data base depends on factors that have not yet been resolved, such as the export control of data.