Mechanical testing biaxial tensile test

Another apparatus for general biaxial extension testing, illustrated in Fig. 8, was built at our laboratory27). A square sheet of rubber, 11.5 cm long and 1 mm thick, is clamped at the edges by several pieces of movable chucks and stretched biaxially by means of the two bars that can be displaced separately bade and forth by a servo-meachnism. Tensile forces acting on the sheet in the stretching directions are transmitted to the bars and measured by two transducers mounted at the ends of each bar. After many modifications and improvements on the mechanical and electric parts,... 

The most commonly measured mechanical properties for films are tensile strength, tear strength, and impact resistance. The first two are generally measured in both the machine and transverse directions (MD and TD). The last one is a biaxial test, examining MD and TD simultaneously. 

---