ASTM D6671 determines interlaminar fracture toughness, Gc, of continuous fiber-reinforced composite materials at various Mode I to Mode II loading ratios using the Mixed-Mode Bending (MMB) Test. This test is most useful for composites with carbon fiber tape laminates. Susceptibility to delamination is one of the major weaknesses of advanced laminated composite structures. ASTM D6671 provides knowledge of the interlaminar fracture resistance of composites which is useful for product development and material selection.

By means of our composite testing expertise and modular product design, we will help find the testing solution that is right for you. Contact one of our application engineers today for help with creating the best budget and testing plan according to ASTM D6671.

Test Procedure

  1. Measure the width and thickness or each test specimen (rounding to the nearest 0.025 mm from the middle and 25 mm from each end)
  2. Mark the end of the delamination insert
  3. Coat the edges of each specimen ahead of the insert with a thin layer of water soluble typewriter correction fluid to help see delamination onset
  4. Set the length of the lever, c, of the MMB apparatus to get the desired mode mixture
  5. Measure the compliance of the loading system
  6. Attach and center the MMB specimen in the apparatus
  7. Apply load to the specimen
  8. After the test is completed, remove the specimen from the MMB apparatus and measure
  9. Calculate

Related Standards

  • ASTM D883 Terminology Relating to Plastics
  • ASTM D2651 Guide for Preparation of Metal Surfaces for Adhesive Bonding
  • ASTM D2734 Test Methods for Void Content of Reinforced Plastics
  • ASTM D3171 Test Methods for Constituent Content of Composite Materials
  • ASTM D3878 Terminology for Composite Materials
  • ASTM D5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite Materials
  • ASTM D5528 Test Method for Mode I Interlaminar Fracture Toughness of Unidirectional Fiber-Reinforced Polymer Matrix Composites
  • ASTM E4 Practices for Force Verification of Testing Machines
  • ASTM E6 Terminology Relating to Methods of Mechanical Testing
  • ASTM E122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot or Process
  • ASTM E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
  • ASTM E456 Terminology Relating to Quality and Statistics

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