evaluatePrincipalStress
Evaluate principal stress at nodal locations
Description
pStress = evaluatePrincipalStress(structuralresults)structuralresults. For transient and frequency response
structural problems, evaluatePrincipalStress evaluates principal
stress for all time- and frequency-steps, respectively.
Examples
Solve a static structural model representing a bimetallic cable under tension, and compute octahedral shear stress.
Create and plot a geometry representing a bimetallic cable.
gm = multicylinder([0.01,0.015],0.05); pdegplot(gm,FaceLabels="on", ... CellLabels="on", ... FaceAlpha=0.5)
Create an femodel object for static structural analysis and include the geometry into the model.
model = femodel(AnalysisType="structuralStatic", ... Geometry=gm);
Specify Young's modulus and Poisson's ratio for each metal.
model.MaterialProperties(1) = ... materialProperties(YoungsModulus=110E9, ... PoissonsRatio=0.28); model.MaterialProperties(2) = ... materialProperties(YoungsModulus=210E9, ... PoissonsRatio=0.3);
Specify that faces 1 and 4 are fixed boundaries.
model.FaceBC([1 4]) = faceBC(Constraint="fixed");Specify the surface traction for faces 2 and 5.
model.FaceLoad([2 5]) = faceLoad(SurfaceTraction=[0;0;100]);
Generate a mesh and solve the problem.
model = generateMesh(model); R = solve(model);
Evaluate the principal stress at nodal locations.
pStress = evaluatePrincipalStress(R);
Use the principal stress to evaluate the first and second invariant of stress.
I1 = pStress.s1 + pStress.s2 + pStress.s3; I2 = pStress.s1.*pStress.s2 + ... pStress.s2.*pStress.s3 + ... pStress.s3.*pStress.s1; tauOct = sqrt(2*(I1.^2 -3*I2))/3; pdeplot3D(R.Mesh,ColorMapData=tauOct)
Evaluate the principal stress and octahedral shear stress in a beam under a harmonic excitation.
Create and plot a beam geometry.
gm = multicuboid(0.06,0.005,0.01);
pdegplot(gm,FaceLabels="on",FaceAlpha=0.5)
view(50,20)
Create an femodel object for transient structural analysis and include the geometry into the model.
model = femodel(AnalysisType="structuralTransient", ... Geometry=gm);
Specify Young's modulus, Poisson's ratio, and the mass density of the material.
model.MaterialProperties(1) = ... materialProperties(YoungsModulus=210E9, ... PoissonsRatio=0.3, ... MassDensity=7800);
Fix one end of the beam.
model.FaceBC(5) = faceBC(Constraint="fixed");Apply a sinusoidal displacement along the y-direction on the end opposite the fixed end of the beam.
yDisplacementFunc = ...
@(location,state) ones(size(location.y))*1E-4*sin(50*state.time);
model.FaceBC(3) = faceBC(YDisplacement=yDisplacementFunc);Generate a mesh.
model = generateMesh(model,Hmax=0.01);
Specify the zero initial displacement and velocity.
model.CellIC = cellIC(Displacement=[0;0;0],Velocity=[0;0;0]);
Solve the problem.
tlist = 0:0.002:0.2; R = solve(model,tlist);
Evaluate the principal stress in the beam.
pStress = evaluatePrincipalStress(R);
Use the principal stress to evaluate the first and second invariants.
I1 = pStress.s1 + pStress.s2 + pStress.s3; I2 = pStress.s1.*pStress.s2 + ... pStress.s2.*pStress.s3 + ... pStress.s3.*pStress.s1;
Use the stress invariants to compute the octahedral shear stress.
tauOct = sqrt(2*(I1.^2 -3*I2))/3;
Plot the results.
figure pdeplot3D(R.Mesh,ColorMapData=tauOct(:,end))
