INTEGRATION OF CARBON FIBER AND FIBER OPTICAL SENSORS IN CONTINUOUS FIBER-REINFORCED ADDITIVELY MANUFACTURED PARTS
Topic(s) : Material and Structural Behavior - Simulation & Testing
Co-authors :
Jan SEIFFERT (FRANCE), Dr.Klaus DRECHSLER (GERMANY)Abstract :
Continuous fiber-reinforced polymer composites are increasingly utilized in various engineering applications due to their superior mechanical properties. To further enhance their functionality, integrating sensors directly into these composites is an area of growing interest. Hereby, fibrous sensors are of superior interest, as they can be integrated without compromising the structural integrity and the mechanical properties of the part. Carbon fibers are widely used as a reinforcement material, but due to their piezoresistive behavior, they can also be used as sensors (CFS), which is also referred to as self-sensing [1]. Some carbon fibers show linear piezoresistive behavior, which is a fundamental property for CFS, as was shown by Horoschenkoff et al. [2]. In this study, we present a novel approach for integrating CFS and fiber optical sensors (FOS) into continuous fiber-reinforced parts fabricated via Fused Filament Fabrication (FFF). Furthermore, we demonstrate the sensors’ capability and accuracy of measuring strain during both tensile and three-point bending tests.
A custom-built 3D printer equipped with a tool changer was utilized to fabricate the specimens. The reinforcement fibers were printed using a printhead provided by Anisoprint 3D Printing Technology Limited Company. Anisoprint’s Composite Carbon Fiber (CCF) was used as a CFS and as the reinforcement fiber and white PETG by Material4Print was used as a matrix material for the specimens. The CFS were electrically connected and bonded to copper wires by means of a highly conductive silver paste. A polyimide-coated single mode SM1550P fiber by Thorlabs was used as a FOS.
During the tests, reference strain measurements were taken by means of a video-extensometer. The resistance measurement of the CFS was done by a 4-wire setup to eliminate potential parasitary influences of the contact surfaces. A LUNA ODiSI-A was used to measure the rayleigh-backscattering along the FOS. 15 measuring points were chosen along the specimen length to evaluate the strain.
The results demonstrate that both the CFS and FOS are well-suited for measuring strain in continuous fiber-reinforced additively manufactured parts. The data obtained from the FOS exhibited very good correlation with the reference strain measurements and furthermore allow for localized strain measurements along the fiber. The CFS presented a linear piezoresistive behavior until fiber damage occurred, which caused an exponential rise in the resistance. The three-point bending tests revealed the high accuracy of the CFS, which allowed for identification of the layer in which the CFS was integrated. Further research will focus on fatigue tests, optimizing the integration process and exploring additional sensor functionalities to broaden the scope of applications for sensor-integrated composite materials.
A custom-built 3D printer equipped with a tool changer was utilized to fabricate the specimens. The reinforcement fibers were printed using a printhead provided by Anisoprint 3D Printing Technology Limited Company. Anisoprint’s Composite Carbon Fiber (CCF) was used as a CFS and as the reinforcement fiber and white PETG by Material4Print was used as a matrix material for the specimens. The CFS were electrically connected and bonded to copper wires by means of a highly conductive silver paste. A polyimide-coated single mode SM1550P fiber by Thorlabs was used as a FOS.
During the tests, reference strain measurements were taken by means of a video-extensometer. The resistance measurement of the CFS was done by a 4-wire setup to eliminate potential parasitary influences of the contact surfaces. A LUNA ODiSI-A was used to measure the rayleigh-backscattering along the FOS. 15 measuring points were chosen along the specimen length to evaluate the strain.
The results demonstrate that both the CFS and FOS are well-suited for measuring strain in continuous fiber-reinforced additively manufactured parts. The data obtained from the FOS exhibited very good correlation with the reference strain measurements and furthermore allow for localized strain measurements along the fiber. The CFS presented a linear piezoresistive behavior until fiber damage occurred, which caused an exponential rise in the resistance. The three-point bending tests revealed the high accuracy of the CFS, which allowed for identification of the layer in which the CFS was integrated. Further research will focus on fatigue tests, optimizing the integration process and exploring additional sensor functionalities to broaden the scope of applications for sensor-integrated composite materials.