Keywords: laminated glass, viscoelasticity, temperature dependency, frequency dependency, simplified numerical models, iterative modal identification, polyvinyl butyral.

Commercial laminated glass is usually composed of two glass layers and an interlayer of polyvinyl butyral (PVB). The viscoelastic behaviour of the PVB layer has to be taken into account when dealing with dynamic loads. This paper shows different finite element models developed to characterize laminated glass. Results are contrasted with data from different reference test cases. First, a quasi-static test is reproduced with a two-dimensional model using a transient analysis. In addition, flexural modes of vibration in a free-free test configuration have been analysed using two-dimensional as well as three-dimensional finite element models. Apart from using transient analysis in order to simulate the dynamic behaviour of laminated glass, an iterative procedure has been employed which permits the identification of the correct value of the shear modulus of the PVB layer for each mode in an eigenvalue analysis.

The modelling of laminated glass has attracted much attention [1] as the material's popularity is further increasing due to its multiple uses. While the static behaviour is well understood and several design codes such as [2] are available, the dynamic response of laminated glass is an important research topic due to its complex nature.

Different laminated glass tests have been simulated with the finite element method in order to investigate the influence of important parameters like the time step size or duration of the numerical simulation on the values obtained for natural frequencies and damping ratios. The results obtained indicate that the number of cycles during the simulation should be significantly higher than the recommended minimum values stated in [3].

It is shown that even quasi-static tests have to be simulated by means of transient analysis as the time dependency of the PVB layer is important. It is of primary importance to account for all environmental factors which affect the material properties during the tests such as temperature variations.

The results obtained show that two-dimensional models may be used for the identification of bending modes or the simulation of the four point bending test. This is particularly interesting when using iterative procedures or performing parametric studies as computer time is crucial in these cases.

1

M.A. García Prieto, "Dimensionamiento probabilístico y análisis experimental de vidrios en rotura", Doctoral thesis, 2001.

2

ASTM E1300-09a, "Standard Practice for Determining Load Resistance of Glass in Buildings".

3

ANSYS 12.1, "Structural Analysis Guide: 5.9.1 Guidelines for Integration Time Step".

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £145 +P&P)