DESIGN AND DEVELOPMENT OF A FIXTURE TO STUDY BIAXIAL BEHAVIOR OF MATERIALS IN TENSION

Abstract

Numerous components during forming operations or in general use, like pressure vessels, structures and sheet metal parts may undergo biaxial state of stress and the tensile properties obtained from the uniaxial tests do not exhibit the true plastic behavior of sheet materials. So, it is important to predict this biaxial behavior of engineering materials before used in actual applications but Biaxial or Multiaxial experimental data is quite limited. Consequently, strength and applications of materials needs extensive testing and necessitates the development of reliable testing methods. The present work deals with the design of a light weight fixture which is used to characterize the material in biaxial tension. This fixture has been designed for a 50kN universal testing machine. The fixture is an innovative design with optimum size and its weight is optimized by employing high strength steels. Due consideration has been given to factor of safety to avoid the fixture from being fatigued. The fixture distributes equal stress in both directions; however, the ratio of stress in the direction cannot be changed. Only equal stress in each direction can be carried out. Simulations have been carried out on Ansys® Workbench 15.0 and Abaqus® software environments. The computational results obtained are used to evaluate the performance of the fixture and to analyze stress and strain distributions on cruciform shaped specimen for better understanding of the effects of miniaturization. The simulation work is validated by conducting the uniaxial testing on UTM. Then validated material model is used for biaxial testing simulation of the cruciform specimen.