New Features in PERMAS Version 21
The new Version 21 of PERMAS and VisPER is available from July 2026.
The most important new PERMAS features:
- A new binary model format based on the HDF file format reduces file size and accelerates model import.
- Contact analysis introduces automatic surface splitting at large kinks substantially reducing modeling effort and improving efficiency and robustness.
- The new automatic search of contact partners automatically introduces the necessary surfaces and the corresponding contact definitions in the model.
- A completely new stabilized contact algorithm with great improvements in terms of stability and performance was developed for normal contact.
- A new default solver and more robust convergence criteria improve the performance and stability of nonlinear material analysis.
- Vibration analysis now also calculates Eigenpairs with negative Eigenvalues to deal with instabilities after a nonlinear material analysis.
- A new criterion for distinguishing between global and local mode shapes supports the automatic classification of vibrations.
- MAC factors can now also be computed for complex modes and for a single DOF to improve comparability with experimental measurements.
- It is now possible to reconstruct a matrix model from (measured) eigenmodes to be used internally or for export to e.g. MBS codes.
- The MLDR solver was adapted to deal with many additional static mode shapes (addmodes), especially contact addmodes.
- Dynamic contact and friction is now available in most dynamic analyses.
- Completely new time integration methods in timehistory analyses are available to improve stability and the treatment of nonlinear forces.
- The definition of loads for a transient response analysis now supports a variety of new features including automatic translation of PSD signals to the time domain and filter options.
- The handling of frequency-dependent material has been extended to rubber-like and absorbant materials.
- Rigid body modes can now be excluded from the modal basis used for modal transformation which is particularly beneficial for subsequent analyses, e.g. fatigue analysis.
- Extensions and improvements of the direct random response analysis greatly improve performance and are useful e.g. with the new frequency-dependent materials.
- Enhancements of the Harmonic Balance Method improve computational efficiency and provide additional insight into the dynamic behavior of the computed solutions.
- The new direct fluid-structure coupled timehistory enables fully-copuled analysis for high frequency tasks, e.g. underwater acoustic for ships, noise-generation from brake squeal and many more.
- New features in PERMAS-OPT include fully integrated optimization based on fatiguie-analysis results and a complete revision of the bead optimization method.
- PERMAS-TOPO can now consider load patterns which are defined by a result combination rule and stresses at the integration points instead of the element-averaged stresses.
- Direct matrix input now supports both symmetric and non-symmetric matrices, mass and damping matrices.
Binary Model data
The PERMAS binary model format reducies the storage requirements to about half of those of the Medina binary (.bif) format. A single HDF file can store both model data and analysis results. PERMAS and VisPER provide full read and write support for the PERMAS binary model format, enabling seamless data exchange between preprocessing, analysis, and postprocessing.
Automatic Contact Surface Splitting
Instead of smoothing contact normals across large kinks, they are treated as shared edges with separate normals on each side.
For the shown example only one surface per wheel is required. In earlier PERMAS versions, a total of 168 surfaces had to be defined manually, corresponding to four surfaces per tooth for 21 teeth on each wheel.
Automatic Search of Contact Partners
The new contact definition $CONTACT AUTO automatically will find potential contact partners, introducing the necessary surfaces and the corresponding contact definitions in the model.
This feature dramatically speeds up contact modeling, makes the use of contact analyses more accessible, and significantly increases overall modeling efficiency and reliability due to:
- one contact definition leads to many contacts, i.e. less effort is necessary to define contacts,
- the automatic handling of contact normals, kinks and already defined MPCs leads to faster and more reliable contact modeling,
- no manually modeling of surfaces is necessary,
- for contact definitions with shells, the normal vector of the shell elements is automatically corrected if it does not match to the contact definition.
New Stabilized Contact Algorithm
The contact for normal contact was extended to frictional contact problems.
A completely new innovative and extremly robust algorithm with high performance was developed. Still accurate Coulomb friction law is solved.
Runtime reduction of up to a factor of 3.7 are observed for the new alorithm.
New Solver for Nonlinear Material Analysis
Eigenpairs with negative Eigenvalues
The new parameter SIGN was added to the vibration analysis to also calculate eigenpairs with negative eigenvalues. Negative eigenvalues may occur if the vibration analysis is run on a deformed system after a NLMATERIAL computation. It may happen that the system is unstable, i.e. the stiffness matrix is not positive definite any longer. The corresponding eigenmodes then are related to the instability and can be interpreted e.g. as buckling modes.Distinguishing between Global and Local Mode Shapes
A new criterion for distinguishing between global and local mode shapes has been introduced. The evaluation method for the globality can be selected and the limit factor for the calculation can be individually specified. The classification results are provided in a dedicated table in the RES file, indicating whether each mode shape is identified as global or local.MAC Factors for Complex Modes
- MAC factors can also be computed for complex modes. Measurement data only delivers complex mode shapes.
- MAC factors can now be computed for a single DOF. Often, measurements are limited to single translational DOFs, for example when using uni-axial accelerometers. Also the global UCI switch MACDOFS was extended to single DOFs.
Reconstruct a Matrix Model from (Measured) Eigenmodes
- Generate Matrix model from measured eigenmodes & frequencies (including rigid body modes).
- Matrix model contains external and modal DOFs.
- Matrix model can be used for computations in PERMAS or for export to e.g. MBS codes.
Many Additional Static Mode Shapes
The MLDR solver for vibration anlysis was adapted to deal with many additional static mode shapes, especially contact addmodes. If a model with many contact definitions is simulated, the orthonormalization of thousands of contact addmodes will be very fast with the MLDR solver. The MLDR solver is not only a big performance advantage for many elastic mode shapes, but also for many additional static mode shapes.Dynamic contact and friction
- DIRECT TIMEhistory
- DIRECT FSCoupled TIMEhistory
- MODAL TIMEhistory
- MODAL FSCoupled TIMEhistory
- DIRECT HARMonic BALance
- MODAL HARMonic BALance
- MODAL FSCoupled HARMonic BALance
New Time Integration in Timehistory Analyses
Completely new time integration methods are now available in PERMAS in direct timehistory analyses:- The option SOLV = TWOSTEP is using the Bathe time integration method and offers high numerical dissipation and is well suited for nonlinear problems. In the nonlinear case, the method is also fully implicit and enables the use of bigger timesteps.
- The option SOLV = SEMIIMPLICIT additionally treats nonlinear forces explicitly. The integration is only stable when the timestep is sufficiently small. This condition is automatically checked for MODAL TIMEhistory and normal contact.
Extended Loads for Timehistory Analysis
The definition of loads for a transient response analysis has been greatly extended and is now supporting a variety of new features:- Prescribed velocities or accelerations may now be assigned.
- It is now possible to define a power spectral density (PSD) signal which will be automatically converted to the time domain.
- A bandpass filter may be used to remove unwanted frequency content or drift from velocity or acceleration signals.
Frequency-dependent Material
The options for frequency-dependent material have been greatly extended, including the elastic properties for rubber-like material as well as compressibility and density for absorber materials in a fluid-structure coupled analysis.The frequency-dependent materials are available for modal and direct analyses.
Excluding Rigid Body Modes from the Modal Basis
A new option controls the modal basis used for modal transformation. When selected, only elastic and additional eigenmodes are included in the modal transformation, while rigid body modes are excluded from the modal space. This helps to prevent unwanted drift caused by unintended excitation from the excluded modes. In addition, no modal stresses are generated for rigid body modes, which is particularly beneficial for subsequent analyses, e.g. fatigue analysis.Extended Random Response Analysis
The following new features and extension were done for Random Response analysis:- A completely new analysis, DIRECT RANDOM is now available. This analysis enables direct calculation of random response without generation of a modal basis. This is useful e.g. with the new frequency-dependent material properties.
- The definition of a stochastic loads was revised and extended with new features:
- If both power spectral densities and cross spectral densities are defined, the disk space usage is significantly reduced.
- It now supports the option to directly assign a prescribed velocity or acceleration.
Extended Harmonic Balance Method
The Harmonic Balance Method (HBM) is a steady-state method for solving nonlinear differential equations which is used in nonlinear frequency response. The following enhancements have been developed for this method:- A new stability criterion identifies stable and unstable solutions by evaluating the complex eigenvalues of the
Hill matrix, providing additional insight into the dynamic behavior of the computed periodic solutions.
The stability calculation is supported for direct and modal as well as fluid-structure coupled HBM analyses.
Two different methods are available to calculate the stability:
- Imaginary value based sorting criteria,
- Koopman-Hill projection method.
- HBM now supports a reduced harmonic ansatz allowing even harmonics to be excluded from the solution ansatz, which is a valid assumption for systems with point-symmetric nonlinearities. By reducing the number of harmonic components, computational efficiency can be significantly improved. In addition, this feature enhances of HBM analyses for problems involving rigid body modes.
- In modal HBM analyses a new option is available converting the structural damping to an equivalent viscous damping. This is needed for stability calculation.
Changes and Enhancements in PERMAS FS
- A completely new analysis type DIRECT FSCoupled TIMEhistory is now available. This enables direct fully-copuled fluid-structure acoustic time analysis for high frequency problems. This could be underwater acoustics for ships, noise-generation from brake squeal and many other applications.
- A completely new analysis type DIRECT FSCoupled RANDOM is now available. This enables direct fully-coupled fluid-structure acoustic analysis for random loads. A special feature of this analysis is, that the user may specify an arbitrary hermitian spectral density matrix.
- The direct fluid frequency analysis now supports an assembly situation.
Changes and Enhancements in PERMAS-OPT
- A major new feature is damage-driven optimization based on results from a PERMAS fatigue analysis. Damage may be defined either as an optimization objective or as a constraint, both locally and globally. The complete workflow is fully integrated into PERMAS, providing an efficient and user-friendly process that eliminates the need for data transfer between different software tools.
- A second major new feature is a complete revision of the bead optimization method, with the following objectives:
- The new bead optimization method provides results that require significantly less design interpretation and accurately realize the geometric bead properties specified by the user.
- A GUI for setting up the bead optimization model, guiding the user through the input data required for the new optimization method, has been developed in VisPER.
- An option for transforming the bead optimization results into a new model for further processing (e.g., reanalysis) has been implemented in VisPER.
- Optimization can now consider load patterns which are defined by a result combination rule.
Changes and Enhancements in PERMAS-TOPO
- Optimization can now consider load patterns which are defined by a result combination rule. Currently, the combined load cases must belong to the same situation.
- For global stress-based topology optimization, a new option is available that considers stresses at the integration points instead of the element-averaged stresses in the global aggregation function. Using integration-point stresses leads to more realistic topology optimization results. The optimized design typically exhibits lower actual maximum stress values and reduced localized stress concentrations compared to approaches based on element-averaged stresses.