Adjustable hard and brittle material surface stress loading device

The invention provides an adjustable hard and brittle material surface stress loading device. The adjustable hard and brittle material surface stress loading device comprises an outer supporting seat, a fastening pressing plate, a lifting platform, an optical platform, two supports and two inner supporting rods. The adjustable hard and brittle material surface stress loading device is simple in structure and easy to machine and manufacture, the stress state of the surface of a test piece can be changed only by adjusting the height of the lifting table, the stress value can be continuously changed, the adjusting range is flexible, and one clamp can be suitable for various materials at the same time; stress loading is carried out in a four-point bending mode, the defect that hard and brittle materials such as silicon wafers are not prone to tension and compression deformation and thermal deformation is overcome, a uniform and consistent stress layer is generated in the middle section of the test piece, and meas