Significance and Use
5.1 The techniques described in this guide, if properly used in conjunction with a knowledge of behavior of particular material systems, will aid in the proper preparation of consolidated laminates for mechanical property testing.
5.2 The techniques described are recommended to facilitate the consistent production of satisfactory test specimens by minimizing uncontrolled processing variance during specimen fabrication.
5.3 Steps 3 through 8 of the 8-step process may not be required for particular specimen or test types. If the specimen or test does not require a given step in the process of specimen fabrication, that particular step may be skipped.
5.4 A test specimen represents a simplification of the structural part. The test specimen’s value lies in the ability of several sites to be able to test the specimen using standard techniques. Test data may not show identical properties to those obtained in a large structure, but a correlation can be made between test results and part performance. This may be due, in part, to the difficulty of creating a processing environment for test specimens that identically duplicates that of larger scale processes.
5.5 Tolerances are guidelines based on current lab practices. This guide does not attempt to give detailed instructions due to the variety of possible panels and specimens that could be made. The tolerances should be used as a starting reference from which refinements can be made.
Scope
1.1 This guide provides guidelines to facilitate the proper preparation of laminates and test specimens from fiber-reinforced organic matrix composite prepregs. The scope is limited to organic matrices and fiber reinforcement in unidirectional (tape) or orthagonal weave patterns. Other forms may require deviations from these general guidelines. Other processing techniques for test coupon preparation, for example, pultrusion, filament winding and resin-transfer molding, are not addressed.
1.2 Specimen preparation is modeled as an 8-step process that is presented in Fig. 1 and Section 8. Laminate consolidation techniques are assumed to be by press or autoclave. This practice assumes that the materials are properly handled by the test facility to meet the requirements specified by the material supplier(s) or specification, or both. Proper test specimen identification also includes designation of process equipment, process steps, and any irregularities identified during processing.
FIG. 1 8 Step Mechanical Test Data Model
NOTE 1: Material identification is mandatory. Continuous traceability of specimens is required throughout the process.
Process checks (Appendix X4) may be done at the end of each step to verify that the step was performed to give a laminate or specimen of satisfactory quality.
Steps 4 and 5 may be interchanged. For aramid fibers, step 5 routinely precedes step 4.
Steps 6, 7 and 8 may be interchanged.
1.3 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.
1.3.1 Within the text, the inch-pound units are shown in brackets.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
