3D Adaptive Combined DE/FE Algorithm for Analyzing Impact Fracture of Laminated Glass

Abstract

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.