CalculiX (official versions are on www.calculix.de, the official GitHub repository is at https://github.com/Dhondtguido/CalculiX).

Topic	Replies	Views	Activity
CalculiX User Meeting 2026 Official announcements Dear CalculiX users, We are pleased to announce the first CalculiX User Meeting, hosted by MTU Aero Engines in Munich. The meeting is aimed at professional CalculiX users and has the following objectives: Learning ab…	5	982	October 19, 2026
Welcome to Discourse Uncategorized	0	3614	July 28, 2020
DEFORMATION PLASTICITY in a FREQUENCY step: ccx stops after the eigenvalues with "negative eigenvalue of the Cauchy-Green tensor", depending on the units Analysis issues	3	55	October 24, 2026
Ccxview: results viewer for CalculiX Postprocessing/Visualization	34	686	October 24, 2026
CalculiX ccx, cgx and zstd compression Code development	5	234	October 24, 2026
Abq2ccx input converter (Abaqus to CalculiX) Tool interfaces	21	570	October 23, 2026
Engineering suite CAD, Calculix, OpenRadioss (OpenCourant) Tool interfaces	5	104	October 23, 2026
CalculiX and LIS solver Code development	16	269	October 23, 2026
Segmentation fault with ccx_2.19 dynamic modal analysis Uncategorized	15	1273	October 23, 2026
How to use surface set in radiate boundary condition Uncategorized	7	421	October 23, 2026
*ELEMENT with an unlisted TYPE starting with "D" (e.g. DASHPOT2) is read as a 3-node network element: two DASHPOT2 elements run with exit 0 and no damping Analysis issues	2	51	October 23, 2026
PERTURBATION *BUCKLE after a heated step: the base thermal strain enters the buckling load case; the factor is wrong and depends on the load size (exit 0) Analysis issues	3	33	October 23, 2026
HEAT TRANSFER, (UN)COUPLED TEMPERATURE-DISPLACEMENT, *VISCO: a blank or zero period (default 1.) prints "step size is negative" and runs with NaN time Analysis issues	2	44	October 23, 2026
Node surface on a *RIGID BODY node of plane elements, even an unused one: ccx adds a z-SPC and stops with "dependent side of a MPC and a SPC" Analysis issues	2	26	October 23, 2026
*MEMBRANE SECTION, COMPOSITE stops on every element, M3D8R and M3D6 included: "Element 1 is not a M3D8R nor a M3D6 membrane element" Analysis issues	2	23	October 23, 2026
CLOAD / DLOAD with TIME DELAY: two cards with the same AMPLITUDE and delay on one node DOF or face stop ccx with "different amplitudes in one step" Analysis issues	2	28	October 23, 2026
*KINEMATIC coupling of one DOF without ORIENTATION: the unused reference rotation stops SPOOLES with exit 255 and no message; an identity ORIENTATION solves Analysis issues	2	35	October 23, 2026
DYNAMIC: a moment (CLOAD on DOF 4-6) on a beam node stops ccx with exit 255 and no message (NaN in explicit), because the new knot's rotation starts at 0/0 Analysis issues	2	35	October 23, 2026
TIE with the same surface as slave and master: ccx loops forever printing "zero coefficient on the dependent side of an equation" (up to 2.21 an ERROR) Analysis issues	2	38	October 23, 2026
DYNAMIC step after a STATIC step: random segfault or bus error in tempload when the step creates a knot and the deck has an *AMPLITUDE Analysis issues	2	25	October 23, 2026
NO ANALYSIS step after a solved step: EL FILE S, E or ENER segfaults, and *NODE FILE U or RF writes freed memory to the .frd with exit 0 Analysis issues	2	25	October 23, 2026
Plastic, creep or user material: segfault in NO ANALYSIS, BUCKLE, COMPLEX FREQUENCY, a linear STATIC after *FREQUENCY, and modal steps with S/RF output Analysis issues	2	31	October 23, 2026
*TEMPERATURE with a step-time AMPLITUDE: at most one node is held at its end-of-step value; the others follow the amplitude again in the next step (exit 0) Analysis issues	2	24	October 23, 2026
PERTURBATION BUCKLE / FREQUENCY after a BUCKLE step, or FREQUENCY after a *MODAL DYNAMIC step, takes that step's displacements as reference state (exit 0) Analysis issues	2	32	October 23, 2026
DASHPOTA in implicit DYNAMIC ignores the velocity of an end moved by BOUNDARY (also through an *EQUATION): the free end stays at rest (exit 0) Analysis issues	2	36	October 22, 2026
C3D8R hourglass force uses the current tangent C1111: an unreached *PLASTIC card makes it 35 % stiffer, and elastoplastic C3D8R models can stop (too many cutbacks) Analysis issues	2	26	October 22, 2026
Two *KINEMATIC couplings on one REF NODE: the surfaces turn independently, and a moment on the reference node reaches only one, chosen by card order (exit 0) Analysis issues	2	36	October 22, 2026
Point mass (MASS element) on a node with no other element gets no DOFs: stays at 0 in DYNAMIC (exit 0); tied by EQUATION it stops *FREQUENCY or loses mass terms Analysis issues	2	29	October 22, 2026
DLOAD, DSLOAD, DFLUX, FILM: an element-set line after a facial-surface line of the same card is read as a surface, so its load is lost or misplaced Analysis issues	2	37	October 22, 2026
BUCKLE with fewer unknowns than ARPACK needs: "ERROR in arpackbu: info=-3", but ccx goes on, writes a buckling factor of 0 and exits 0 Analysis issues	2	29	October 22, 2026

CalculiX User Meeting 2026

Dear CalculiX users, We are pleased to announce the first CalculiX User Meeting, hosted by MTU Aero Engines in Munich. The meeting is aimed at professional CalculiX users and has the following objectives: Learning ab…