Experimental part
The effectiveness and reliability of the stretcher-frame Leonardo are guaranteed by the numerous trials conducted during the design phase for the development of the various elements that compose it: the program has provided an experimental test on the canvas: on the individual structural elements of the frame, on the pushing elements (the jacks), and on portions of the assembled frame, in order to provide useful elements for the proper sizing of the parts, to define the forces applied for the tensioning and to check the resistance of the paintings once installed on the frame.
The canvas used for the tests are those commonly used for the relining paintings operations (in order to improve the resistance): the specimens, measuring 45x30 cm, were subjected to different tensile tests to assess their tensile and deformation strength, and were exposed in a climatic chamber for the measurement of the changes related to changes in thermo-humidity.
Later the various components of the frame were tested: the box-section profile used for rigid internal structure, the joint crosses, the open-section profiles used for the perimeters of the frame (on which the canvas is fixed) and the fixing system. Of all these elements have been evaluated the tensile strength, the bending resistance in different directions, and other mechanical properties. Particular attention was paid to evidence on the pushing elements, consisting of opposite springs placed through a threaded pivot, to know exactly the value of force placed based on the type of spring to be used in relation to the size of the canvas and the number of elements thrust provided.
Finally the tests were performed on the assembled system to assess the overall behaviour of the frame in place, both in the forces acting on the frame itself, and in the forces transferred to the canvas.
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Experimental part
