The breakage of the small insulating-glass units in the thermal cycling is most likely caused by the way the assemblies containing the test specimens were fabricated. This was the first attempt and the epoxy-anchorage method appeared to have the best chance for success. Additional testing of small IG units to the protocol in a deflected position is the most challenging, yet the protocol is the basis for specifications of pass or fail. In hindsight, the glass in the small test units should have been increased to a 3/8-in. (9-mm) thickness in lieu of the thinner glass suggested by the specification. There was also a consideration regarding the thickness of the assembly to be able to fit into the test chamber. Finally, the epoxy that was used to displace the glass in the Z direction should have been replaced with an extremely-high-strength silicone adhesive, such as the one also presented in this symposium .
Additionally, future work needs to be done to more strongly correlate the amount of bending in a full-size panel to the exact amount of edge-seal strain in an IGU. The sample size of the full-scale test was too small (one panel; assembly 2) to properly conclude that the induced edge-seal strains are exactly equal to those used in the small-scale durability test. Also, this research has not correlated other factors to edge-seal strain, such as: glass aspect ratio, framing member section properties, glass thickness or makeup, spacer design, etc.
Future research would refine the testing methods as laid out in this project by reexamining the design of the small unit displacement apparatus to lower the induced stress on the glass and reduce the risk of thermal breakage, to procure glass with a higher resistance to thermal fracture (thicker glass or higher edge strength), to improve the method of application of “z" displacement so that it survives the weathering process, and to anticipate thermal breakage and procure more specimens to complete the testing.
Future projects that consider cold-bend IGUs should indeed have a level of understanding whether or not the bent glass will indeed hold up to the durability standards. This knowledge must come from a study of the particular variables present in such a project. As mentioned above, the effects of glass make-up, frame behavior, spacer design, silicone size, or unit typology and geometry could drastically affect durability, as well as other factors that were not examined in this study, such as glass stress, silicone stress, or aesthetic appeal.