# Research on Out-of-Plane Bending Test of PVB Laminated Glass Plate with Different Number of Layers
## 4 Conclusions  
In addressing the complex mechanical behavior of PVB laminated glass, this study conducted loading tests. Observations were made of the load-displacement curve, as well as the displacement and strain distribution during loading. The study analyzed variations in stiffness and ultimate bearing capacity with respect to the number of glass layers. Additionally, the mechanical properties of PVB were examined to assess their constitutive characteristics. The findings are summarized as follows:The load-displacement curve remains approximately linear prior to damage in the LG. Displacement manifests a circular distribution within the plane, with the first principal strain value increasing towards the center of the plate. The direction of the first principal strain radiates from the center of the plate.
2. The average ultimate load capacity for three-layer, two-layer, and single-layer PVB laminated glass is 37.8 kN, 36 kN, and 24.7 kN, respectively, corresponding to a ratio of 1:0.95:0.65. The bending stiffness values for the same are 2.77 kN/mm, 1.71 kN/mm, and 1.21 kN/mm, respectively, with a ratio of 1:0.62:0.44. The ultimate bearing capacity of PVB LG increases with the number of layers; however, this increase diminishes with additional layers, leading to material waste. For economic efficiency, it is advisable to utilize LG with fewer layers in practical applications. The stiffness of LG increases nonlinearly with the addition of layers, an effect attributable to the characteristics of PVB. For engineering structures with strict deformation limits, selecting PVB LG with more layers is necessary.
3. The mechanical property testing presented in this paper reveals that the constitutive model of PVB laminate transitions from tensile deformation to fracture with a bilinear relationship to strain rate. Elastic modulus is found to be lower at reduced strain rates. Linearity is maintained when axial strain is below 0.6. Beyond an axial strain of 1.6, the elastic modulus significantly increases, the differential being more than tenfold. Considering the overall bending deformation of laminated glass plates, the maximum principal strain on the surface is two orders of magnitude less than 0.6. Therefore, this study concludes that the PVB layer involved in deformation coordination is within the low strain rate stage. For calculating the out-of-plane bending of laminated glass, it may be treated as a material with small-scale linear elasticity. The recommended elastic modulus is 1.34 MPa.  
It should be noted that these conclusions are derived from quasi-static experiments and do not apply to the mechanical response under high-speed impact loading. Furthermore, these conclusions pertain solely to PVB LG under four-sided simple support conditions, necessitating further research to ascertain their relevance to point-supported LG.  
Conceptualization, H.L.; Methodology, L.Y., H.L., N.Z. and W.S.; Validation, R.H.; Writing--original draft, L.Y.; Writing--review and editing, N.Z., W.S. and R.H.; Visualization, L.Y.; Supervision, H.L. and W.S.; Project administration, H.L. and N.Z. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China (No. 52208207), the Natural Science Basic Research Plan in Shaanxi Province of China (No. 2022)Q-475).  
The raw data supporting the conclusions of this article will be made available by the authors on request.  
The authors declare no conflicts of interest.