Stress

BC stresses can be applied to volumetric or flat surfaces entity, as well as to the surfaces of elements. To do this, you need to perform the following:

On the Command Bar, select Mode - Boundary Conditions.
Select Stress.
Depending on the situation, select Action - Create or Action - Modify.

If the BC is applied to the plane, it is possible to use three the stress components are normal stresses perpendicular to the plane and two tangential stresses in the plane. If the surface has a curvature, the remaining stress components will also load it.

The applied stresses are recalculated into the load according to the integral over the surface:

Thus, if, for example, we consider a platform perpendicular to the X axis, then the normal stresses σ_x on the surface will be recalculated into the normal force N, and the tangential stresses τ_xy and τ_xz - into the cutting forces Q_x and Q_y.

Example 1.

Normal stress S_x = 10⁶ Pa on the end surface. The surface area is 1 m². Stress in any the cross-sections away from the edge effect are 10⁶ Pa. Reactions in support directed along the axis of the body and equal to 10⁶ N.

Figure 1 - Normal voltages

Script

brick x 10 y 1 z 1
volume  size auto factor 5
volume 1  size auto factor 6
volume 1  size auto factor 6
mesh volume 1 
create material 1 from 'Steel'
block 1 add volume 1
block 1 material 1
block 1 element solid 
create displacement  on surface 6  dof all fix  
create stress on surface 4 
modify stress 1 xx value 1e+6
analysis type static elasticity dim3
calculation start path 'C:/Users/Desktop/results/new/stress1.pvd'

Example 2.

Tangential stresses τ_xy = 10⁶ Pa on the surface. The surface area is 1 m². Reactions in the support are directed along Y axes and are equal to 10⁶ N.

Figure 2 - Total displacement, m

Figure 3 - Tangential stresses XY, Pa

Script

brick x 10 y 1 z 1
volume 1  size auto factor 6
mesh volume 1 
undo group end
create material 1 from 'Steel'
block 1 add volume 1
block 1 material 1
block 1 element solid 
create displacement  on surface 6  dof all fix  
create stress on surface 4 
modify stress 1 xy value 1e+6
output nodalforce on energy off midresults on record3d on log on vtu on material off
analysis type static elasticity dim3
calculation start path 'C:/Users/Desktop/results/new/1133.pvd'

Positive is the stress acting in the direction of the faces of the elements. It is always oriented normal to the face.

Stress value

The voltage value is set using the option XX, YY, ZZ, XY, YZ, XZ, <value>, where the first three components determine normal stresses, and the second ones are tangential. If the user has not entered the value (<value>), then it will be taken equal to zero.

These interactive operations correspond to the commands:

[create] stress [name <name>] [<id>]

     [{add|on} {curve|edge|face|sideset|surface|tri} {[[id] {[<id>] [<id range start> to <id range finish>]}...] [all]}]

     [XX {[value] <value>|formula <formula id>|table <table id>|remove}]

     [YY {[value] <value>|formula <formula id>|table <table id>|remove}]

     [ZZ {[value] <value>|formula <formula id>|table <table id>|remove}]

     [XY {[value] <value>|formula <formula id>|table <table id>|remove}]

     [YZ {[value] <value>|formula <formula id>|table <table id>|remove}]

     [XZ {[value] <value>|formula <formula id>|table <table id>|remove}]

modify stress {[[id] {[<id>] [<id range start> to <id range finish>]}...] [<name>] [all]}

     [{add|remove} {curve|edge|face|sideset|surface|tri} {[[id] {[<id>] [<id range start> to <id range finish>]}...] [all]}]

     [name <name>]

     [XX {[value] <value>|formula <formula id>|table <table id>|remove}]

     [YY {[value] <value>|formula <formula id>|table <table id>|remove}]

     [ZZ {[value] <value>|formula <formula id>|table <table id>|remove}]

     [XY {[value] <value>|formula <formula id>|table <table id>|remove}]

     [YZ {[value] <value>|formula <formula id>|table <table id>|remove}]

     [XZ {[value] <value>|formula <formula id>|table <table id>|remove}]

     [cs {<ID>|<name>}]

     [step {[[id] {[<id>] [<id range start> to <id range finish>]}...] [all]}]