Abstract: The fracture behavior of brittle materials under biaxial plane stress, especially theinfluence of the stress parallel to the crack plane on critical fracture parameters, was investigated by means of thermomechanical method. Biaxial and uniaxial tension tests were performed with thin glass and zirconia disk specimens. The aims of this study is to clarify the fracture dependenceof brittle material in plane stress state and their difference between biaxial and uniaxial tension,baized on experimental and analyt...