A New Three Loading Axes Machine for Static and Fatigue Tests

摘要

A new machine has been designed and manufactured at the Department of Design and Industrial Management of the University of Naples Federico Ⅱ. It is able to test very large panels, like the full scale aeronautical ones. Hydraulic cylinders along three different axes, two orthogonal between them for traction and one diagonal for shear, assure loads application . The loading introduction system is based on eight grips for each specimen's edge; each grip links up the test panel with four pins. This localized loading system allows independent deformations along different directions on the skin plane. The same set of grips applies both normal and shear loads; a balancing system assures that the normal load is uniformly distributed on the edge. The shear load is applied by wire ropes wrapped around pulleys shrunk on the grips. The maximum normal load is 600 kN, while the maximum shear load is 1000 kN. They can be applied simultaneously and independently (different loading versus time laws). Tests are in load control and it's possible to apply both static and dynamic loads. The boundary conditions are 'simply supported edges' constraints, i.e. the in-plane displacements are allowable, while the out-of-plane displacement of the panel edges is constrained by means of a rolling bearing system.