All Terms A–Z
All important FEM and platform terms explained — from A to Z.
All key terms around FEM simulation and the Dr.Q platform, explained clearly and practically.
Use search (Ctrl+K) to quickly find a specific term.
C
CAD — Computer-Aided Design. Software for creating 3D models (SolidWorks, Fusion 360, Inventor, etc.).
Convergence — The property of a numerical solution approaching the exact solution as the mesh is refined. A converged result doesn't change significantly when you add more elements.
D
Degree of Freedom (DOF) — A possible direction of movement for a node: three translations (X, Y, Z) and three rotations = max. 6 DOF per node. Boundary conditions remove DOFs.
Density (ρ) — Mass per unit volume. Required for self-weight (gravity) loads and dynamic analyses.
E
Element — The basic building block of the FEM mesh. Common types: tetrahedra (Tet4, Tet10), hexahedra (Hex8, Hex20), triangles, quads.
Strain — Relative change in length of a material under load. Dimensionless (often expressed in % or mm/mm).
Young's modulus (E) — Stiffness of a material — the ratio of stress to strain in the elastic range. Unit: MPa or GPa.
F
FEM — Finite Element Method. A numerical method for calculating stresses, deformations, temperatures, etc. in structures by dividing them into small elements.
Fixed support — A boundary condition that locks all degrees of freedom at a surface (zero displacement and rotation in all directions).
J
Jacobian — A mesh quality measure. Negative Jacobian values indicate inverted (invalid) elements that cause solver errors.
L
Load case — A specific combination of boundary conditions and loads describing one loading scenario.
M
Mesh (FE mesh) — The subdivision of the geometry into finite elements (triangles, tetrahedra, hexahedra, etc.).
N
Node — A point in the FE mesh at which displacements and forces are calculated. Elements are connected at their nodes.
P
Poisson's ratio (ν) — Ratio of lateral strain to axial strain under uniaxial loading. Typical value: 0.3 for steel. Must be between 0 and 0.5.
Principal stress — Normal stress along a principal axis (a direction with no shear stress). The three principal stresses σ₁ ≥ σ₂ ≥ σ₃ describe the full stress state.
R
Boundary condition — A constraint on the degrees of freedom at specific locations in the model (supports, symmetry planes).
Reaction force — The force that a boundary condition exerts on the model in response to the applied loads. Sum of reaction forces = sum of applied loads (Newton's third law).
S
Singularity — A location where the mathematical stress tends to infinity — caused by sharp re-entrant corners, point loads, or point supports. A numerical artefact, not a real physical stress.
Skewness — A mesh quality metric measuring how distorted an element is from its ideal shape. Values close to 0 are good; values close to 1 indicate highly distorted elements.
Solver — The algorithm that solves the FEM equation system. Dr.Q offers linear static, nonlinear static, and modal solvers.
Stress — Force per unit area in the material. Unit: MPa (N/mm²).
V
Von Mises stress — A scalar equivalent stress for ductile materials. Combines the multi-axial stress state into a single value for yield assessment. Yield occurs when σ_VM ≥ R_p0.2.
Y
Yield strength (R_p0.2) — The stress at which a material begins to deform plastically (permanently). FEM results are typically compared against this value to assess safety.