Direct measurement of axial compressive strength of carbon fibers using multifilament method

Abstract To measuring the compressive strength of carbon fibers accurately and effectively, a specially designed fixture was applied for directly measuring axial compressive strength of carbon fibers using T800HB‐12 K multifilament. Influence of adhesive thickness and specimen length on the testing results was investigated. Adhesive of epoxy effectively transferred compressive stress from the fixture to the specimen and provided enough support of multifilament rod from bending during compressive load. Typical shear failure for multifilament rod was realized for T800HB‐12 K carbon fibers during compression testing using the purposely designed fixture at adhesive thickness of 0.101–0.110 mm and test length of 2.0–3.0 mm. Compressive strength of about 2700 MPa with variation coefficient of 8% was obtained for T800HB‐12 K carbon fibers. The fixture and method established were capable for characterizing axial compressive strength of 1–24 K carbon fibers.