Experimental and Numerical Peeling Investigation on Aged Multi-Layer Anti-Shatter Safety Films (ASFs) for Structural Glass Retrofit

Abstract

Anti-shatter safety films (ASFs) are often used for structural glass applications. The goal is to improve the response of monolithic elements and prevent fragments from shattering. Thus, the main reason behind their use is the possibility to upgrade safety levels against the brittle failure of glass and minimize the number of possible injuries. However, the impact response of glass elements bonded with Polyethylene terephthalate (PET)-films and pressure sensitive adhesives (PSAs) still represents a research topic of open discussion. Major challenges derive from material characterization and asymmetrical variability under design loads and ageing. In particular, the measurement of interface mechanical characteristics for the adhesive layer in contact with glass is a primary parameter for the ASF choice optimization. For this reason, the present paper presents an experimental campaign aimed at calibrating some basic mechanical parameters that provide the characterization of constitutive models, such as tensile properties (yielding stress and Young modulus) for PET-film and adhesive properties for PSA (energy fracture and peel force). In doing so, both tensile tests for PET-films and peeling specimens are taken into account for a commercially available ASF, given that the peeling test protocol is one of most common methods for the definition of adhesion properties. Moreover, an extensive calibration of the Finite Element (FE) model is performed in order to conduct a parametric numerical analysis of ASF bonded glass solutions. Furthermore, a Kinloch approach typically used to determine the fracture energy of a given tape by considering a variable peel angle, is also adopted to compare the outcomes of calibration analyses and FE investigations on the tested specimens. Finally, a study of the effect of multiple aspects is also presented. The results of the experimental program and the following considerations confirm the rate dependence and ageing dependence in peel tests.

Pre- and Post-Failure Experimental Bending Analysis of Glass Elements Coated by Aged Anti-Shatter Safety Films

“…The load-displacement curves of tensile tests for PET tape showed a very similar qualitative behaviour before and after aging; as shown in Fig. 10 (b), there was no discernible difference in E values (3.3 GPa the average), giving evidence of high consistency with previous analyses on similar components (Mattei et al 2022).…”

Post-Fracture Stiffness and Residual Capacity Assessment of Film-Retrofitted Monolithic Glass Elements by Frequency Change

“…In terms of structural safety, anti-shatter films can support the post-fracture stage, as they can prevent the spread of critical shards from cracked monolithic glass components (Figure 1 and study by Figuli et al [15]). Given that these films are typically used for post-fracture hazard minimization, but are characterized by the small thickness, very limited bending stiffness, and uncertain adhesion properties, an open question is represented by the quantification of their mechanical potential in keeping glass fragments together, especially under aging or unfavorable conditions [18][19][20]. Among others, debonding and fall-out of glass shards [21,22] would in fact result in major consequences for glass section, and thus for the customers.…”

“…Following the above considerations, the present investigation focuses on the dynamic characterization of small-scale samples consisting of a fractured monolithic glass plate with fragments bonded by antishatter film. To verify the proposed experimental strategy, a commercial safety film based on polyethylene terephthalate (PET)-layers and pressure sensitive adhesives (PSAs) is taken into account, with mechanical and thermo-physical properties as in [18][19][20]. By taking an advantage of previous experimental efforts at the material characterization level [18][19][20], the primary goal of current investigation is represented by the experimental characterization of cracked glass-film composite samples in cantilever setup and subjected to the random repeated vibrations.…”

“…To verify the proposed experimental strategy, a commercial safety film based on polyethylene terephthalate (PET)-layers and pressure sensitive adhesives (PSAs) is taken into account, with mechanical and thermo-physical properties as in [18][19][20]. By taking an advantage of previous experimental efforts at the material characterization level [18][19][20], the primary goal of current investigation is represented by the experimental characterization of cracked glass-film composite samples in cantilever setup and subjected to the random repeated vibrations. Based on vibration frequency analysis, their residual post-fracture stiffness and mechanical capacity is tracked and measured.…”

Investigating Mechanical Behaviours of PDMS Films under Cyclic Loading

“…Bedon and Mattei (2021) investigated the advantages of operational modal analysis (OMA) techniques by obtaining the elastic modulus of multilayer anti-shatter safety films (ASFs) [18]. Mattei et al (2022) analysed the effects of strain rate and specimen aging on the mechanical properties of ASFs based on ASTM-D882 [19]. However, the aforementioned studies only considered monotonic loading, without considering cyclic loading, to derive the mechanical properties of the PDMS, or suggested only the difference in the mechanical characteristics through mutual comparison between specimens against experimental variables.…”