AUTOMATED TESTING OF CARBON FIBRE FABRICS FOR HIGH-PERFORMANCE COMPOSITE MATERIALS

Abstract

The production of advanced composites using carbon fibre fabric preforms requires manufacturers to have information on key fabric mechanical properties that affect formability - the ability of the preform to conform to the doubly curved shape of a mould. Although test methods for these key properties - low stress tensile, shear and bending stiffnesses - exist for traditional apparel fabrics. An examination of these methods concluded that they are not suitable for woven carbon fibre fabrics which are much stiffer. New test methods are required for these fabrics, which should be automated to remove sources of human error and make them applicable to industrial testing. Two automated test machines have been developed, one for low stress tensile and shear testing, the other for measuring fabric bending properties. As woven carbon fibre fabrics are prone to unravelling when cut into rectangular specimens, the new test machines make use of circular specimens that have a much greater degree of stability. Development of the test machines has required the development of automated specimen transfer devices, grippers, and computer vision, to remove sources of operator errors. The use of circular specimens also permits tests to be carried out at a succession of angles to the warp direction on each individual sample, speeding up the testing process. The two machines have been used to carry out a series of tests on a limited range of woven carbon fibre fabrics. The results of the tensile and shear tests compare well with the results obtained from tests on circular specimens using an Instron testing machine. The results of bending tests on the new machine produce results that match theoretical considerations. These preliminary results confirm that the two new testing machines meet the aims of the research and offer the foundation for further development.

Date of Award	30 May 2024
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Prasad Potluri (Supervisor)