4.1 This practice provides a simple means of classifying failure modes for adhesively bonded FRP joints.

4.2 Each failure mode classification is based solely on a visual observation of the failure surface without the aid of a microscope or other means to magnify the surface.

4.3 Except for the line-drawing representations given, this practice does not contain descriptions of failure modes possible when using adhesion promoters. However, similar analogies to the failure modes described herein can be made.

4.4 This practice does not address the acceptability of any specific failure mode.

1.1 This practice covers the method of classifying, identifying, and characterizing the failure modes in adhesively bonded fiber-reinforced-plastic (FRP) joints. The FRP used in developing this practice consists of glass fibers in a thermoset-polyester-resin matrix, commonly referred to as sheet-molding compound, or SMC.

1.2 One objective of this practice is to present comprehensive definitions of possible failure modes to serve as a guide for contracts, drawings, product specifications, and product performance.

Note 1: Figures 2 through 11 referred to in the practice are contained in the ASTM adjunct, Color Photographs of Failure Modes.2

Fig. 2—Side-by Side Comparison of Failure Modes

Fig. 3—Adhesive Failure

Fig. 4—Cohesive Failure

Fig. 5—Thin-Layer Cohesive Failure

Fig. 6—Fiber-Tear Failure

Fig. 7—Light-Fiber-Tear Failure

Fig. 8—Stock-Break Failure

Fig. 9—Mixed Failure—40 % Fiber-Tear Failure, 60 % Light-Fiber-Tear Fiber

Fig. 10—Mixed Failure—32 % Adhesive Failure, 68 % Fiber-Tear Failure

Fig. 11—Mixed Failure—20 % Adhesive Failure, 60 % Light-Fiber-Tear Failure, 20 % Fiber-Tear Failure

Note 2: This practice may be used to describe the failure modes generated from testing, using procedures such as Test Methods D3163, D3164, D3165, D3807, D5041, D5868, and SAE J1525.

1.3 The values stated in SI units are to be regarded as the standard.

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.