FEM crash analysis of Transparent SUV

 From conservation of momentum,

we can assume that F*dt = m*v

dt is just an arbitrary time interval but it turned out that 1 second is a good estimate for actual deformation of a car during a crash based on comparisons of videos of car crashes.

https://www.arcjournals.org/pdfs/ijmsme/v3-i1/1.pdf

The better approach should just be to check the deformation in the direction of travel and force applied in front. The back is assumed to be constrained during the FEM analysis.

The FEM was done using Calculix solver in FreeCAD running on a Mac. Unlike the Windows version, gmsh does not work so Netgen was used.

When force applied in front is 80,000 N, the x direction displacement is 0.25 m, so the energy absorved is 20,000 J. For a mass of 1000 kg, using kinertic energy equation, the velocity of travel is sq. root 40, 6.3 m/s. Maximum von Mises stress is 96 MPa located in front. We can assume that an acrylic body can crash with a speed of 5 m/s without any major damage to its body.

The grey areas are the original portions of the object which are not hidden. This original object should be hidden so only the results are visible.


With 177,000 N, the displacement and speed are also multiplied according to the proportion resulting in a speed of 50 km/h 545 mm displacement.

Von mises stress is also concentrated in front. None on the body of the car.


In a side crash, the displacement is similar. Von Mises stress is a little less. 


 


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