Bending tests, panels

For the three-point bending test of the sixth plys laminate panels, the flexural strength of the PTFE / FP composite was about 2.9 times higher than that of the PTFE composite. Moreover, the flexural modulus of the PTFE / FP... 

Table III shows the flexural properties of RX-PTFE composite with an EB dose of 500 kGy and SX-PTFE composite (fluorinated-pitch 1.8 wt% additive) with an EB dose of 500 kGy. For the three-point bending test of the sixth plys laminate panels, the flexural strength of SX-PTFE composite was about 1.1 times higher than that of the RX-PTFE composite. The flexural modulus of SX-PTFE composite was about 1.3 times higher than that of RX-PTFE composite. It was found that the flexural properties of SX-PTFE were improved, compared with RX-PTFE composite.

Bend test of coated panel over a 1-in. mandrel at 0 C pass pass pass ... 

One method occasionally used evaluate the relationship of silicone release liners or other materials of very low surface energy to a pressure sensitive, is to bring a coated pressure sensitive into contact with the liner under pressure, to carry out an adhesion test. This is of little value, as the adhesive is unable to wet out and so come into intimate contact with the release liner. The adhesive must first be coated onto the liner, dried, or cooled in the case of a hot melt, and then a carrier laminated to it, as is standard practice for transfer coating. As low values of adhesion can be expected, the force required to bend the backing may dominate, and so a thin flexible backing should be used, to maintain a constant peel angle, 25 pm polyester being satisfactory. Then a standard 180° peel test can be carried out with the release liner secured to a test panel. 

Ten prototype elements were tested in four-point bending tests under static and cyclic loading to determine the load-bearing behavior and capacity. The results of three representative bending tests are depicted in Fig. 11. As calculated, all sandwich panels failed by shear rupture of the core. The load level at which the shear failure occurred was significantly influenced by the quality of the adhesive bond between the notched core and concrete facings, [5]. After the tests, the joint quality of the panels was examined by saw cuts. 

An overall view of the bending test is given in Figure 4. The panels were tested under actual conditions of support. This means that the specimen was hung at the four corners below a static frame with brackets and rods exactly as happens in practise. In fact two panels were tested for two different types of loading. 

Figure 4 Overall bending test frame supporting the panel.

Furthermore, this value is not far away from the value which could be deduced from the overall bending test, assuming each corner would take 1/4 of the total load. In fact as the panel fractured at around 35-45 kN, the maximum load capacity of the corner which could be expected would be approximately 8.75-11,25 kN. These values are lower than the values obtained in the individual tests. This can be explained by the fact that in the overall test, once one corner began to crack it induced in the component additional moments and forces which had the effect of accelerating the failure mechanism and thus reducing the ultimate load. This was not the case in the corner test because the corner was isolated , even if it was still attached to the rest of the panel. 

A finite element analysis was performed for the overall behaviour in bending under actual conditions of support of the panel and for the compression test on the central longitudinal stiffener. Shell 63 elements (4 nodes, 6 dof s per node) were used to model the panel, and Beam 4 elements (2 nodes, 6 dof s per node) were used to model the brackets at the corners. The material properties used were those computed from the theory, taking into account the orthotropic features of the panel. The load applied for the simulation of the bending test was a pressure distributed on elements corresponding to the area in contact with the spreaders during the experiments. 

T-bend flexibility test n. Simple method for determining the flexibility of coatings by bending a coated metal test strip over itself. A panel is bent and pressed flat by means of a jig to achieve a 180° bend. Subsequent folds are equivalent to bending the panel around a rod of diameter equal to the thickness of the panel. 

Years of development have led to a standardized system for objective evaluation of fabric hand (129). This, the Kawabata evaluation system (KES), consists of four basic testing machines a tensile and shear tester, a bending tester, a compression tester, and a surface tester for measuring friction and surface roughness. To complete the evaluation, fabric weight and thickness are determined. The measurements result in 16 different hand parameters or characteristic values, which have been correlated to appraisals of fabric hand by panels of experts (121). Translation formulas have also been developed based on required levels of each hand property for specific end uses (129). The properties include stiffness, smoothness, and fullness levels as well as the total hand value. In more recent years, abundant research has been documented concerning hand assessment (130—133). 

The current European standards for wood-based panels deal with evaluation of properties of end-products such as internal bond strength or bending strength. In case of plywood, the bonding quality can be evaluated by tensile shear testing according to EN 314-1 (2005) [1]. These properties are fully linked to adhesives used and process parameters. Nevertheless, no standard exists in Europe for the assessment of adhesives for wood-based panels. 

The two most common specimen types used to measure fracture toughness are (a) the three-point bend specimen shown schematically, and (b) the compact specimen shown mounted in grips with a clip gage extensometer attached. Panel (c) shows a schematic diagram of various types of load vs displacement plots describing the determination of an LEFM test (ASTM, 2013c). 

Mandrel test n. Test for determining the flexibility and adhesion of surface coatings, so named because it involves the bending of coated metal panels around mandrels. 

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