Up till 2011 we provided CONTACT for free and tried to obtain voluntary support from the user community. This did not work well enough to finance the further development on the longer term. Therefore we introduced a premium version, on the basis of a license checking mechanism.
The two versions of CONTACT are both comprised in the same code. (You may download the free version first and have a look around.) The premium version contains all basic functionality plus several extended features, marked blue in the user guide. Currently these are:
- The ability to compute falling friction effects at higher creep velocities.
- A model for an interfacial layer (e.g. contaminants), that reduces the initial slope of the creep force characteristic.
- Fast and detailed calculation of the normal contact problem.
- The use of viscoelastic materials.
- Support with and advise on the use of the software (fair use policy).