Issue with crack propagation in LS-DYNA simulation of bullet impact on laminated glass sample
Rajat Bhaisare
Dear LS-DYNA Users,
I am simulating bullet impact on laminated glass to validate my numerical results against experiments. The laminated glass configuration is 6 mm float glass + 1.52 mm EVA interlayer + 6 mm float glass. The glass is modeled using MAT_110 (Johnson–Holmquist) with material properties taken from literature, and the EVA interlayer is modeled using MAT_024 (piecewise linear plasticity), also based on literature data. The model uses Lagrangian solid elements, and the projectile is modeled as a rigid bullet impacting at 135 m/s. I have also varied the impact velocity, but the damage pattern remains similar.
The issue is that the damage remains highly localized near the impact point, forming a circular radial damage zone, with no crack propagation towards the panel edges and no clear in-plane radial cracks on either the front or back glass face. This behavior does not match my experimental observations, where long radial cracks extending towards the edges and cracking on both front and back faces are clearly visible.
To address this, I have tried adaptive FEM-to-SPH conversion and full SPH modeling for the glass. Although fragmentation and the number of cracks increase, the cracks still do not propagate towards the edges, and the overall crack pattern does not correlate well with the experimental results, even after changing the impact velocity.
I would appreciate guidance on how to achieve realistic crack propagation and crack patterns in laminated glass under bullet impact in LS-DYNA, particularly regarding damage and failure parameters in MAT_110, mesh strategy, erosion criteria, glass–EVA contact definition, or alternative modeling approaches suitable for this problem. I will attach images of the experimental specimen and the numerical results for comparison.
Thank you all for your time and support
Евгений Калентьев
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Rajat Bhaisare
The Glass and EVA is connected with using Automatic Surface to Surface tiebreak and then the bullet and LG panel with Eroding surface to surface, Keyword for this work is attached. https://doi.org/10.1177/1369433219845691 - Float Glass properties are taken from this paper
if you have any suggestions for EVA properties or material model please let me know,in the attached keyword i used PVB properties for interlayer still the cracking pattern remained same i.e no crack was propogating towards the edge and a localised failure similar to previously attached image.
Rajat Bhaisare
Евгений Калентьев
I looked at your model and noticed that some of your material model constants differ from those specified in the literature. I tried using these (as in the screenshot), and the cracks began to look more realistic. The result depends heavily on the combination of specific parameters; try changing them. To simplify the model, I left only the top glass layer. You might also want to carefully examine the contact between the glass and EVA.
