Examination of Pull-out Test: Response of Sandwich Panels with Different Core Materials – Part 1
In a collaborative endeavor between the Concordia Centre for Composites CONCOM and Innovative Composite Products (I-C-P), a comprehensive series of mechanical tests has been undertaken to optimize processes and characterize materials. This report presents findings from supplementary tests aimed at assessing manufactured sandwich panels and their core components.
I-C-P supplied a variety of panels and core materials, outlined in Table 1, which underwent pull-out tests, each repeated for all samples. These tests employed galvanized flanged hex head screws provided by I-C-P, featuring partial threading, a pointed tip, a total length of 1-1/2”, thread length of 1-5/16”, screw size of 5/16”, and 8 threads per inch. Notably, these tests were conducted without pre-drilling.
In the realm of test procedures, it’s noteworthy that although ASTM C900 specifies the standard method for pull-out tests on concrete walls, the study did not adhere to these details due to limited facilities. Instead, all tests were performed using a universal tensile MTS machine.
The initial set of tests involved clamping samples with two bar clamps onto the moving head, with screws machined to provide head grip. Consequently, only half of the screw length was embedded in samples during testing. Aiming to establish consistent boundary conditions, a second series of tests was executed using a stainless steel circular plate with an inner diameter of 3.125”, an outer diameter of 5.5”, and a thickness of 0.3”. A specific setup, depicted in Figure 1, facilitated maximum screw length insertion into samples. It’s pertinent to mention that approximately 8mm of screw length extended beyond the grip part, encompassing the 3⁄16 inches grip length. With the exception of the initial 100KN load cell test set, all other tests employed either a 5KN or 1KN load cell based on exhibited force-displacement behavior. The pull-out tests operated at a speed rate of 2mm/min.
A total of 18 mixed samples, combining cores and sandwich panels, were prepared for testing. The initial round of tests occurred without the specified boundary condition, securing sandwich panels to a lower bed through clamping. It’s important to highlight that this setup’s grip limitations only allowed for half of the screw length to be screwed into sandwich panels.
In the forthcoming series, we will present and analyze the results in three separate articles. Part 1 will focus on reviewing outcomes related to cores exclusively.
To read more about the pull-out test, click to open the attached PDF file.