# Two identical elastic bars colliding (explicit contact)

Two bars 10 × 0.1 × 0.1 of 200 one-point hex8 elements each (E = 10⁴, ρ = 1, ν = 0, c = 100),
end to end and touching at x = 10 with separate nodes; the first moves at v₀ = 0.1 into the
second, at rest. A frictionless contact pair joins the two end faces (each face's nodes kept out
of the other, segment to segment). One-dimensional theory: the bars stay in contact for 2L/c =
0.2 with a force ρcAv₀/2 across the interface, then the striker stops and the struck bar leaves at
v₀ with all the kinetic energy. Linear bulk viscosity is off (it dissipates at the wave fronts).
Solved to t = 0.3.