Research Of Effect Of Temperature On The Buckling-Resistance Of Thin Steel Sheet

Thin sheet and mould will be heated in the process of cold forming due to the friction and deformation, and the temperature could be up to 100 degrees Celsius after a period of time's rapid continuous stamping of U-shape parts. To be precise, it can no longer be called “cold forming” in this condition. The variation of properties and thickness of thin sheet because of the rise of temperature can greatly influence its buckling-resistance, and the surface quality of stamping parts will be influenced as a consequence. Therefore it is of great significance to research the buckling-resistance of thin sheet when temperature rises from room temperature to more than 100 degrees Celsius.Deep drawing steel is becoming widely used in automobile production because of its superior ductility; the wrinkle problem in the process of deep draw steel stamping, however, is drawing more and more attention. In this paper, taking the wrinkle height as the assessment indicator and choosing the deep drawing steel DC04 as the material for test, Yoshida Buckling Tests at room temperature, 75 degrees Celsius and 150 degrees Celsius were performed to investigate the consequence of temperature variation on the sheet's buckling-resistance.To perform the finite element simulations of YBT at different temperatures, the properties of thin sheet at room temperature, 75 degrees Celsius and 150 degrees Celsius are acquired through uniaxial tensile experiments and it's found that the elasticity modulus, yield stress and tangent modulus decrease when temperature rises.The finite element simulations of YBT at different temperatures were performed based on LS-DYNA, and a good agreement of force-displacement curves of YBT and the simulations was found. The comparison of results of YBT and the finite element simulations indicates that thin sheet's buckling-resistance is susceptible to the change of temperature and it goes through the change processes of rise and fall when temperature rises from room temperature to 150?.Four material parameters including elasticity modulus, yield stress, tangent modulus and thickness were selected to study their sensitivity on buckling-resistance by uniform experiment design method. And the sensitivity analysis of these four parameters was carried out from two aspects-one single parameter floating and multi-parameters interaction. Results show the yield stress have the most significant impact on wrinkling resistance, following with tangent modulus, elasticity modulus and thickness.