Windscreen

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Description

Figure 1

Figure 2

This is an example for a model in the frequency domain of the form

$\begin{array}{rcl} K_d x - \omega^2 M x & = & f \\ y & = & f^* x \end{array}$

where $f$ represents a unit point load in one unknown of the state vector. $M$ is a symmetric positive-definite matrix and $K_d = (1+i\gamma) K$ where $K$ is symmetric positive semi-definite.

The test problem is a structural model of a car windscreen. This is a 3D problem discretized with $7564$ nodes and $5400$ linear hexahedral elements (3 layers of $60 \times 30$ elements). The mesh is shown in Figure 1. The material is glass with the following properties: The Young modulus is $7\times10^{10}\mathrm{N}/\mathrm{m}^2$, the density is $2490 \mathrm{kg}/\mathrm{m}^3$, and the Poisson ratio is $0.23$. The natural damping is $10\%$, i.e. $\gamma=0.1$. The structural boundaries are free (free-free boundary conditions). The windscreen is subjected to a point force applied on a corner. The goal of the model reduction is the fast evaluation of y. Model reduction is used as a fast linear solver for a sequence of parametrized linear systems.

The discretized problem has dimension $n=22692$. The goal is to estimate $x(\omega)$ for $\omega\in[0.5,200]$. In order to generate the plots the frequency range was discretized as $\{\omega_1,\ldots,\omega_m\} = \{0.5j,j=1,\ldots,m\}$ with $m=400$.

Figure 1 and Figure 2 show the mesh of the car windscreen and frequency response function.

Origin

This benchmark is part of the Oberwolfach Benchmark Collection.

Data

Download matrices in the Matrix Market format:

• windscreen.tar.gz (21.5 MB)

The archive contains files windscreen.K, windscreen.M and windscreen.B representing $Kd$, $M$ and $f$ accordingly.