33 Fatigue Behavior of Novel Hybrid Fastening System with Adhesive Inserts 271 Fig. 33.1 Novel bolted composite joint (hybrid-bolt): (a) schematic diagram, (b) sectional view of scaled-up channel (green) Fig. 33.2 Experimental setup After assembly, the samples that were selected for the hybrid joint were injected with SC-15 resin through the channels in the bolts so as to fill the clearance space between the threaded bolt shank and the work pieces. The injected inserts were cured by a convection oven at 60 ıC for 2 h followed by post curing at 94 ıC for 4 h. Fig. 33.1b shows a cross-section of the bolted joint, wherein the channels are exaggerated for better understanding, and the resin is filled with a ultra-violet dye marker. As it could be seen, the resin fills all intricate areas including the threads of the bolts and upon curing creates a monolithic structure. 33.4 Experimental Setup All quasi-static testing was performed using a 100 kN load cell servo-hydraulic testing machine (MTS 810), and a typical test setup is shown in Fig. 33.2. The machine is equipped with a standard load cell and an internal crosshead displacement measuring extensometer. An external laser extensometer was also used to measure the joint longitudinal displacement, as shown in Fig. 33.2. To acquire the strain gage data, a Vishay Model P3 Strain Indicator and Recorder was used. Prior to testing the bolted joints, five GFRP specimens were tested according to ASTM D3039 to characterize the material properties. In order to avoid the influence of tab and gripping pressure in the case of GFRP, the experimental setup was modified based on previous experience [9]. As specified in ASTM D3039, the GFRP specimens were subjected to monotonic tensile loading with a stroke rate of 2 mm/min. Quasi-static joint tests were performed according to ASTM STP1455-EB. In this work, five tests were carried out for each joint configuration. The average shear strength of the joint was calculated by dividing the maximum load reached in each test divided by the cross-sectional area of the bolt.
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