Solution Analysis Guidelines

Simcenter STAR-CCM+ offers various field functions and tools that you can use to visualize the solution and monitor the relevant quantities. For example, you can visualize the deformed geometry and the stress and strain distribution throughout the solid structure.

For scalar displayers, Smooth Filled contours display vertex values (a single value per vertex). Filled contours display face values at surfaces (a single value per face) and element values inside an element (one value per element). In solid stress applications, the Automatic Contour Style is equivalent to Smooth Filled.

For information on smooth and non-smooth values on derived parts, see Finite Element Interpolation.

On meshes with mid-side vertices, contour plots can present some visual artifacts. To improve the rendering quality, you can select Tools > Options and activate the Triangulate Part Surfaces property. See Simcenter STAR-CCM+ Default Options.

When recording solution data in a simulation history file, add any derived part of interest to the solution history inputs, rather than creating a derived part in the recorded solution view. In general, the interpolation accuracy that is achieved during the solution run cannot be obtained from recorded history files. For more information, see Recording Transient Solution Data.

Displacement

Simcenter STAR-CCM+ computes the displacement field at element vertices. Displacements are continuous across elements.

You can visualize the displacement field in two ways:

In a scalar scene, you can visualize the displacement components i, j, k, or magnitude at any point in the structure.
In a vector scene, you can visualize the displacement vectors at the element vertices.

The Automatic and Smooth Filled contours display the computed vertex values.

You can use a vector warp to visualize the deformed and undeformed shape, together in a scalar scene.

For infinitesimal strain, the displacements are very small, but can be scaled for visualization purposes using a warp surface. In a scalar scene, you can set up a geometry displayer to visualize the undeformed geometry, and use the scalar displayer to visualize the displacement on a vector warp derived part. For the vector warp, set Vector Field to Displacement. The vector warp auto-scales the displacement field, so that the visualized displacement magnitude is about 15% of the largest diagonal of the model.

When the solid structure has prescribed rigid motion (see Prescribing Rigid Rotations and Translations), set the vector warp using relative coordinates (see Vector Warp Properties).

Stresses and Strains

Simcenter STAR-CCM+ calculates stress and strain tensors on demand when you create a scene or report that uses stress or strain field functions.

For each element, Simcenter STAR-CCM+ extrapolates stresses and strains from Gauss integration points (see Eqn. (4832)) to vertices, faces, and the element centroid. In general, stresses and strains are constant within linear elements and vary linearly within quadratic elements.

Unlike displacements, stresses and strains are not continuous across elements. For display, the Automatic and Smooth Filled contours display average vertex values. The Filled contour displays face and element centroid values, showing the discontinuities across elements.

In general, for a tensor field function, you can access the following quantities:

Scalars

Tensor components in the Laboratory or any local coordinate system.

Note	The shear components of the strain tensor are not equal to the engineering strain.

Tensor eigenvalues in signed order,

λ_{0} \geq λ_{1} \geq λ_{2}

The eigenvalues of the stress tensor are the maximum, intermediate, and minimum principal stresses (see Principal Stresses). The corresponding eigenvectors are also available as field functions.

Tensor norms: infinity, 1, 2, and Frobenius.

Tensor invariants:

$I_{0} = t r (A)$
$I_{1} = ({t r (A)}^{2} - t r (A^{2})) / 2$
$I_{2} = \det (A)$

Vectors

Tensor eigenvectors 0,1, and 2, corresponding to the eigenvalues

λ_{0}

λ_{1}

, and

λ_{2}

, respectively.

Simcenter STAR-CCM+ scales the magnitude of an eigenvector by the value of the corresponding eigenvalue.

The following stress measures are available as separate scalar field functions:

Stress Max Shear
Stress Mean
Stress Von Mises

For more information on the available field functions, refer to the physics model reference sections, under Solid Stress Reference.

Forces and Moments

You can analyze the forces acting on specified input parts, by displaying the corresponding vector field functions in a scene:

Applied Force—resultant of all surface, curve, and point loads.
Body Force—resultant of all body forces, including body loads, gravity, centrifugal forces, inertia forces, and damping forces.
Internal Force—resultant of all internal elastic forces. When the solution is converged, its value is zero at internal vertices and vertices at free boundaries. The Internal Force value is equal and opposite to the Applied Force acting on loaded surfaces, and equal and opposite to the Constraint Force acting on interfaces and constrained surfaces.
Constraint Force—resultant of all reaction forces.

All of these field functions are available at the mesh vertices. The Applied Force is also available on surfaces; the Body Force is also available at the element centroids. To visualize vertex data, set the contour style of the relevant scalar or vector displayer to either Automatic or Smooth Filled. To visualize data at face or element centroids, set the contour style to Filled. For more details, see Field Functions.

You can also use the Sum Force and Sum Moment reports to check for equilibrium of all the forces and moments acting on specified input parts. The Sum Force and Sum Moment reports are defined in Cartesian coordinate systems only. As these reports use the force field functions, which are defined at the mesh vertices, activate the Smooth Values option. The For more details, see Reports.

Local Material Coordinate Systems

In solid stress applications, you define the material properties of anisotropic and orthotropic materials with respect to a local coordinate system (see Material Properties). You can define the coordinate system independently for each solid region. Simcenter STAR-CCM+ provides material basis vector field functions that allow you to visualize the axes of the local coordinate system:

Material Basis Vector 1
Material Basis Vector 2
Material Basis Vector 3