Study On Theory And Simulation Of Tensile Failure Of Multi-gauge High Strength Steel Laser Tailor-welded Blanks

The technique of laser tailor-welded blank is an important development direction of automobile lightweight. The property difference of base metals as well as weld's existence changed the plasticity forming mobile rule of traditional sole plate, which caused multi-gauge laser tailor -welded blank displays particular characteristic. Laser tailor-welded blanks face new challenge. As an effective tool of process analysis and process designing of tailor-welded blanks, the establishing of forming limit curve has an important status in tailor-welded blanks' practical application. Forming limit curve is not only used directly to instruct the production technique, moreover widely applied as the stretch failure criterion in the numerical simulation domain of sheet metal forming, which is the key technique to improve the manufacture precision and agileness of tailor-welded blanks. It has a vital academic significance and engineering significance to put together the theoretical establishment method of forming limit curve and the numerical simulation domain of sheet metal forming, base on which this article launch the research of stretch failure of multi-gauge high strength steel (B170P1) laser tailor-welded blankFirstly, the brief outline of the sheet plastic deformation's elementary theory and finite element analysis method of the plate forming process are discussed. Then the distortion characteristic and stretch failure rule of multi-gauge tailor-welded blanks are analyzed to establish a new theoretical model, a method to get the material parameter of welded zone of tailor-welded blank and the algorithm is proposed to obtain the forming limit curve (FLC) of 0.7mm/1.0mm combined laser tailor-welded blanks of B170P1 steel. Later, the finite element model of stretch forming tool and multi-gauge laser tailor-welded blanks are established in the software of Dynaform to simulate the process of laser tailor-welded blanks, whose FLC is also introduced as a failure criterion in Dynaform. At last, stretch forming test of 0.7mm/1.0mm combined laser tailor-welded blanks of B170P1 steel is carried on to validate the simulation result and the FLC obtained from theoretical calculation.The theoretical model to analyze the stretch failure of multi-gauge laser tailor-welded blanks and the method of combining theory and simulation to study the stretch failure of multi-gauge laser tailor-welded blanks, which has proposed in this article, able to provide reference to study stretch failure of kinds of multi-gauge tailor-welded blanks. The formability of tailor-welded blanks can be speculated conveniently and the researching-application cycle is shortened with the combination of theoretical analyzing method and finite element analysis technique.