Small-Unit Durability Testing

The purpose of the small-unit test was to determine the durability of a cold-bent IGU using the industry-standard testing protocol as specified in ASTM E2188- 10 [6]. The edge-seal conditions of a full-scale, cold-bent curtain-wall panel can­not be simply converted into an equivalent degree of bending in a small test specimen. Because of the specific requirements of this testing protocol, the glass stiffness, the IGU spacer size, and PIB size could not be scaled and still maintain comparable results to a “standard" ASTM E2188-10 test. Therefore, the edge seal was strained an amount equal to that observed in the full-scale testing and validated by the finite-element model. Following this method a similar edge-seal condition was recreated between the full-scale and small-scale tests.

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FIG. 5—120 x 60 x 1 in3. (1.5 x 3.0 m2 x 25 mm). Full-scale test assembly 2 in partial test frame.

The small-scale test was broken into four sets of identically constructed specimens with varying amounts of edge-seal strain. The first set was a control and was tested without any additional edge-seal deformation. The second set had edge-seal deformations that corresponded to a “100 %” allowable amount of bend. The 100 % allowable amount of bend was determined through a combination of engineering judgment and the results of full-scale testing. The third and fourth set contained edge-seal deformations that corresponded to “50 %” and “150 %” of the allowable amount of bend. It is important to note that 50 % and 150 % are not indicative of the amount of edge-seal strain, but relate to the amount of displacement in the full-scale test. The amount of edge – seal strain in these cases was determined through a combination of the full – scale test and finite-element model.