T3D3 too soft

[victorkemp]

The ends of the element seems to be connected to constraints, other truss elements, and forces by only the corner nodes so their stiffness is lower than what you specify.

*NODE
1,0,0.0005,0
2,0,0.00025,0
3,0,0.00075,0
4,0,0.001,0
5,0,0,0
*ELEMENT,TYPE=T3D3,ELSET=Eall
1,1,3,4
2,5,2,1
*MATERIAL,NAME=Material
*ELASTIC,TYPE=ISOTROPIC
2000000000,0
*SOLID SECTION,ELSET=Eall,MATERIAL=Material
4E-08
*BOUNDARY
4,1,3,0
*STEP
*STATIC
*CLOAD
5,2,-10
*NODE FILE,GLOBAL=YES,OUTPUT=3D
U
*END STEP

The axial displacement should be
u = F L / (E A)
= -10×0.001/(2e9×4e-8)
= -0.000125
but it's more like -0.00022