One recent project we completed was a long-term fatigue test rig which was specifically designed as a self-reacting structure, where fully welded movable A-frames were attached to a fully welded floor frame.
All components mounted onto the floor frame were adjustable to enable the test rig to be future proof, as other test articles of various lengths and sections may be required in the future. It was produced using S355 Structural Steel beams, columns and plate, chosen for their strength and ease of fabrication.
Where possible, standard off the shelf industrial components were used, and integrated into the design to form large assemblies that can constrain the degrees of freedom specified by our client. The central hinge fittings were designed to withstand side-loading and prevent rollover of the beam during compression loading of the cycle whilst still allowing vertical displacement and rotation.
The outer fittings needed to be substantial, to allow for the applied moments and vertical forces with additional expected side loading. We designed them to rotate for allowance of displacement. Both inner and outer fittings benefited from elastomeric bearings which not only restrained the beam, but had allowable slippage built in to the specification of the rubber to allow free movement of the beam laterally when the loads were applied by the actuator.
This allowed the beam to be held securely but to not deform as if it were fully constrained, this is important as if permanently restrained it would change the desired load path, and give false readings for the test.