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Transparent polymer interlayer foils are widely used to increase the safety of glass applications, mainly in construction and automotive industry. In case one or more glass sheets in a laminate fracture, the remaining structural capacity (i.e. stiffness and strength) highly depends on the solicitation and mechanical properties of the interlayer. In such a post-breakage state, the interlayer is subjected to a complex combination of phenomena such as partial delamination, large strain deformation, strain hardening, rupture, etc. In part 1, an analytical model was presented to describe the mechanical behavior of glass laminates in a post-breakage state in which both glass plates are broken. In addition, a comparison of the theoretical model with experimental results is presented in part 2 below.

Transparent polymer interlayer foils are widely used to increase the safety of glass applications, mainly in construction and automotive industry. In case one or more glass sheets in a laminate fracture, the remaining structural capacity (i.e. stiffness and strength) highly depends on the solicitation and mechanical properties of the interlayer. In such a post-breakage state, the interlayer is subjected to a complex combination of phenomena such as partial delamination, large strain deformation, strain hardening, rupture, etc. In partim 1, an analytical model is presented in order to describe the mechanical behavior of glass laminates in post-breakage state for a simple configuration. In addition, the theoretical model is compared to experimental results in part 2, which is published together with part 1.

Laminated glass is a simple sandwiched structure, which, however, is widely used in automotive and architectural industries. The well-known extrinsic cohesive zone model has proved to be a powerful numerical approach for the glass-ply crack simulations in laminated glass, where the classical node-to-segment contact treatment is usually employed. However, an unphysical phenomenon, named contact force jump, may arise during crack simulations, thereby resulting in numerical instabilities or incorrect simulation results. To address this issue, we develop an improved node-to-segment contact formulation to make the contact interactions in extrinsic crack simulations more stable. The main idea is to keep the number of contact constraints constant before and after cracking. The improved contact formulation is very simple and easy to implement, which, however, is effective to address the unphysical phenomenon. Three numerical examples, including the impact crack simulations of a laminated glass beam, are performed to validate the accuracy and effectiveness of the improved contact formulation.

Laminated glass has been wildly employed in automobile windshields, modern buildings, etc. thanks to its security and durability performance. A novel 3D adaptive combined DE/FE algorithm is proposed to research its impact fracture mechanical properties if the fracture region is small relative to a specimen while the cracks are propagating at a random position. The proposed method can automatically convert the distorted finite elements into the spherical discrete elements during simulating the impact fracture of laminated glass. In this method a system is completely discretized into the finite elements at the initial moment without any discrete element existing until part of the finite elements becoming severely deformed. Subsequently each finite element, whose maximum tensile stress exceeds a user-specified conversion criterion, is converted into eight spherical discrete elements. At the same time the system is fragmented into two subdomains, the finite element (FE) and the discrete element (DE) subdomains. An extrinsic cohesive fracture model is adaptively adopted only in the DE subregion to capture the crack propagation when the normal stress between the DEs equals or exceeds the cohesive strength. The impact fracture of a glass beam is simulated by the adaptive algorithm and the discrete element method, respectively. Beside of the micro-cracks and cohesive zone, almost the same crack patterns are captured by both the numerical methods. Fortunately, the efficiency of the proposed method is much higher (10 times in this case) than that of the pure DEM. A satisfactory agreement of the simulation results certified the feasibility and effectiveness of such an adaptive algorithm. Finally, the impact fracture simulation is performed by the adaptive algorithm on a laminated glass beam which has the same size as the experimental specimens. Besides of the differences on the cracks occurrence and propagation angle, a similar agreement of the fracture patterns is observed as the experimental results. The common conclusions on the role of PVB interlayer can be obviously obtained by analyzing the simulation results, the same by analyzing the experimental ones. The proposed method is hopeful to be employed to analyze the impact fracture of an automobile windshield subjects to the head impact for the protection of pedestrians safety, the traffic accident reconstruction and the structural optimization of windshield.

Transparent polymer interlayer foils are widely used to increase the safety of glass applications, mainly in construction and automotive industry. In case one or more glass sheets in a laminate fracture, the remaining structural capacity (i.e. stiffness and strength) highly depends on the solicitation and mechanical properties of the interlayer. In such a post-breakage state, the interlayer is subjected to a complex combination of phenomena such as partial delamination, large strain deformation, strain hardening, rupture, etc. In part 1, an analytical model was presented to describe the mechanical behavior of glass laminates in a post-breakage state in which both glass plates are broken. In addition, a comparison of the theoretical model with experimental results is presented in part 2 below.

Transparent polymer interlayer foils are widely used to increase the safety of glass applications, mainly in construction and automotive industry. In case one or more glass sheets in a laminate fracture, the remaining structural capacity (i.e. stiffness and strength) highly depends on the solicitation and mechanical properties of the interlayer. In such a post-breakage state, the interlayer is subjected to a complex combination of phenomena such as partial delamination, large strain deformation, strain hardening, rupture, etc. In partim 1, an analytical model is presented in order to describe the mechanical behavior of glass laminates in post-breakage state for a simple configuration. In addition, the theoretical model is compared to experimental results in part 2, which is published together with part 1.

To investigate the mechanical behaviour of laminated glass with the elasto-viscoplastic ionomer interlayer SentryGlas® by DuPont, an experimental program was executed on full-scale glass laminates. The results of this research improved the insight in the complex mechanical behaviour of this stiff interlayer. More specifically, a clear influence of load duration and temperature could be observed for both creep and relaxation during torsion experiments. Namely, within the tested temperature range of 5 °C up to 65 °C, torsional stiffness changed with a factor 3.

To investigate the mechanical behaviour of laminated glass with the elasto-viscoplastic ionomer interlayer SentryGlas® by DuPont, an experimental program was executed on full-scale glass laminates. The results of this research improved the insight in the complex mechanical behaviour of this stiff interlayer. More specifically, a clear influence of load duration and temperature could be observed for both creep and relaxation setups during bending experiments. The stiffness reduction due to the load duration and the temperature raise was most significant for the smaller specimens — with a span of 1m — while for the largest specimen — with a span of almost 3 meter — the reduction remained less than 25% of the monolithic bending stiffness, even after a load duration of 48 hours at 65°C.

The assessment of the post-breakage performances of laminated safety glass elements used in construction needs to take into account the sensitivity to the temperature of the mechanical behaviour and properties of the product, in particular of the interlayer material. After a general problem statement, an overview is given of tests at different scales, with typical observations and results for two different interlayer materials. Through the different presented experimental scales, the mechanisms ruling the bridging behaviour in cracked laminated safety glass are explained, highlighting the difficulty of assessing the mechanical properties to be used in practical design calculations.