3 pointing bending test of sandwich
i am trying to simulate the 3 point bending test on honeycomb type sandwich panel according to ASTM-393 norms.
i am using solid core geometry with same orthotropic properties as that of honeycomb geometry core.
i meshed sandwich with shell-solid-shell elements.
To simulate the pressure pads i made a face on upper face sheet and then applied remote force. For roller supports i drew the center lines of rollers on lower face sheet and then fixed it by remote displacement.
By the above boundary conditions i got the bending stress in the face sheet close to the analytical value(~2 %) but the deformation predicted by ansys is about 23% lesser than the analytical one. Similarly the shear stress in core is 100 times lesser than the analytical.
in this discussion, peter suggested to use the 1/4 th of the model.
1. Ansys used Solid 186 elements to mesh solid core geometry. Will the honeycomb core behavior be captured by the solid core with this mesh element.
2. What is the advantage of using 1/4th model? And how i can use it.( i modeled the face sheets in ACPs and solid core in the mechanical model).
sanswich height , d=13.1mm
core height ,c = 12.7 mm
sandwich width, b=42 mm
young modulus face sheet, E =6900 Mpa
shear modulus core, G= 18.616 Mpa
load p =400 N
Length of , sandwich = 130 mm
Deformation D= PL^3 / 48S + PL / 4U
panel bending stiffness S = E(d^2-c^2)xb/12
panel bending rigidity U = G(d+c)^2 x b/4c
D =1.6485 while deformation by ansys is 1.25 mm
Core shear stress
T = P/ (d+c)xb =0.369 Mpa
while by ansys it is 0.00373 Mpa
Face sheet bending stress
B.S = PxL / 2t(d+c)b =119 Mpa
( face sheet thickness, t=0.2 mm)