A new type of loading platen minimizing frictional restraint at the specimen boundary

초록

Side restraint generated along the specimen/loading platen interface is a one of key issue determining the accuracy of the multiaxial test results. In this study a steel piston type loading platen supported by rollers has been developed and the occurrence of side restraint for a new type of loading platen and typical unlubricated steel platen is investigated. The rollers installed at the end of each steel piston are purposed to rotate allowing the free translation of steel piston with the deformation of the specimens. The measured translation of several pistons clearly shows the no side restraint generated from the new type of loading platen. However, the unlubricated steel platen shows variable coefficients of friction with confinement and sliding distance.