Experimental Characterization of the Fiber Angles of Multiple Curved Laminate Segments Using Prepreg-Based Carbon Fiber Reinforced Polymers as a Structure for a Non-Engaging Bellows Coupling

2019 ◽  
Vol 809 ◽  
pp. 555-562
Author(s):  
Christian Oblinger ◽  
André Baeten ◽  
Klaus Drechsler

This paper deals with the experimental characterization of the fiber angles of multiple curved laminate segments using prepreg-based carbon fiber reinforced polymers as a structure for a non-engaging bellows coupling. The main task of this generic shaft coupling is the torsionally stiff torque transmission and the compensation of axial displacement as well as the angular misalignment of metallic shafts. The multiple curved structure can be manually draped by several cut segments using epoxy-based fabric prepreg. Moreover, the intended initial fiber orientation of the laminate is ±45° with respect to the rotation axis of the structure. For the experimental determination of the local fiber angles various CFRP cut segments were defined as CFRP specimens with varying number of layers and constant width. All investigations were based on cured CFRP specimens. The measurements were performed with a robot-assisted optical surface sensor and an optical digital microscope. The influence of the manual draping process according to the z-method could be quantitatively determined by the fiber angle measurements.

2020 ◽  
Vol 54 (24) ◽  
pp. 3699-3713
Author(s):  
Tanja Marina Vetter ◽  
Johannes Bibinger ◽  
Felix Zimmer ◽  
Sebastian Eibl ◽  
Hans-Joachim Gudladt

This study investigates one-sided thermal damage of carbon fiber reinforced polymers (CFRP) by means of depth resolved infrared spectroscopy, tomography and mechanical testing. All CFRP samples are thermally irradiated at one side with a heat flux of 50 kW/m2 over various time intervals. ATR-FTIR spectroscopy along a ground incline plane through the sample allows a chemical characterization of the thermal degradation of the polymer matrix into depth. Developing delaminations are observed with a depth-resolved gray-value-analysis of microfocused computed X-ray tomographic (µCT) data. Mechanical behavior is determined by tensile, compressive, and interlaminar shear strength (ILSS) testing of specimens taken from different depths of the irradiated samples. The depth profiles show how pronounced damage phenomena like matrix degradation and the development of delaminations are after one-sided thermal loading and how they influence strength in different ways. Compressive strength and ILSS is found to be more sensitive towards thermal damage than tensile strength, as they are most influenced by formed delaminations at higher thermal loads.


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