Automated Testing of Carbon Fibers With Zwick Robotic Testing Systems

Light, flexible, and extremely strong: Because of these properties carbon fiber finds many applications as a component in today’s composite materials.  It is increasingly used in the aerospace and automotive industry, high performance sports, and medical science.

The mechanical testing of carbon fibers has always been relatively complex and expensive, with specimen production being one of the most critical issues. Since carbon fibers are very sensitive and difficult to hold in the specimen grips of a testing machine, molded end tabs are used to prevent the specimen from breaking when it is clamped.  Zwick recently solved this problem and has developed a completely automated solution for one of their customers which ensures safe and reliable testing around the clock and no longer requires the expensive end tab process.

The machine operator manually loads a magazine with specimens, and the “Polar System” takes over the handling of each specimen for all further steps of the testing process.  The robot removes the specimen from the magazine and places it into the specially designed pneumatic grips of the testing machine.  The testing machine is an electromechanical table-top machine with a capacity of 20 kN and equipped with a multiXtens extensometer for the measurement of strain.  The multiXtens is a unique device having very high-resolution, measurement accuracy and an extremely large measurement range.  The specimen remains are also disposed of automatically at the end of each test.

As with all Zwick robotic testing systems, testXpert^® software controls all of the control parameters for the test which can either be entered directly in a remote quality management system, or automatically online.  At the end of the test, testXpert^® either prints the results in a test report, or exports to an external data base, Microsoft Office^®, or alternatively the results can be stored as an ASCII file together with all test control parameters.

In summary the system offers major cost and time benefits to laboratories testing composite materials as the specimens no longer need to be specially prepared.   The automatic system typically pays for itself within approximately two years.