Interaction between glass thermal breakage and interlayer combustion in laminated glass with different thicknesses of glass panels and interlayers

Laminated glass (LG) offers superior impact resistance and reduced shard fallout compared to monolithic glass, leading to high demand in modern buildings, such as structural glass façade. However, the flammable interlayer of laminated glass poses fire risks in its application. To understand LG's thermal performance and breakage behavior, a total of 36 experiments were conducted with varying glass and Ethyl Vinyl Acetate (EVA) interlayer thicknesses under a uniform incident heat flux of 40 kW/m2. Results showed that the EVA ignited from both the unshielded edges and through cracks. A positive feedback loop between glass cracking and interlayer combustion was discovered, exacerbating the progressive failure of LG. The crack initiation points of the top radiation-exposed glass panel (Pane 1) were on the radiation-exposed surface (S1), while those on the bottom glass panel (Pane 2) were on the ambient, unexposed surface (S4). All crack initiation points appear at both the glass edge and near the borderline of the exposed and shielded areas. The breakage time of Pane 1 varied from 51 to 72 s, influenced by both the glass and interlayer thicknesses. A FE model was developed for simulating heat transfer and thermal stress, achieving a maximum temperature prediction error of 14.3% and an average prediction error for Pane 1’s breakage time of 11.2%. Furthermore, simulation results showed that the position of critical tensile stress and three types of stress concentration zones were consistent with the crack initiation points and three crack path types observed in the experiments, providing confidence in the model's accuracy.