Standard Test Method for Translaminar Fracture Toughness of Laminated and Pultruded Polymer Matrix Composite Materials

Importancia y uso:

5.1 The parameter K_TL determined by this test method is a measure of the resistance of a polymer matrix composite laminate to notch-tip damage and effective translaminar crack growth under opening mode loading. The result is valid only for conditions in which the damage zone at the notch tip is small compared with the notch length and the in-plane specimen dimensions. Alternately, for materials exhibiting distributed damage in a larger volume, observed force-displacement and discrete damage events are still valid structural responses for certain specific engineering applications.

5.2 This test method can serve the following purposes. In research and development, (a) K_TL data can quantitatively establish the effects of fiber and matrix variables and stacking sequence of the laminate on the translaminar fracture resistance of composite laminates; and (b) quantified distributed damage measurements can be used to validate progressive composite damage models. In structural design, K_TL data can, within the constraints of the specimen geometry and loading, be used to assess composite laminate resistance to damage growth from edge flaws and notches.

5.3 The translaminar fracture toughness, K_TL, as well as distributed damage observations, determined by this test method may be a function of the testing speed and temperature. This test method is intended for room temperature and quasi-static conditions, but it can apply to other test conditions provided that the requirements of 13.2 and 13.3 are met. Application of K_TL in the design of service components should be made with awareness that the test parameters specified by this test may differ from service conditions, possibly resulting in a different material response than that seen in service. Distributed damage observations are also limited to the material and geometry tested, but may be more generally applied to a variety of structural analysis validation applications.

5.4 Not all types of laminated polymer matrix composite materials experience the contained notch-tip damage and effective translaminar crack growth of concern in this test method. In such circumstances, the force-displacement and discrete damage observations – not K_TL – shall be used.

5.5 The reporting section requires items that tend to influence translaminar fracture toughness and discrete damage progression to be reported; these include the following: material, methods of material fabrication, accuracy of lay-up orientation, laminate stacking sequence and overall thickness, specimen geometry, specimen preparation, specimen conditioning, environment of testing, void content, volume percent reinforcement, size and method of notch preparation, specimen/fixture alignment, and speed of testing.

Subcomité:

D30.05

Volúmen:

15.03

Número ICS:

83.140.20 (Laminated sheets)