Research On Snapping With Tearing Mechanism On Light Metal Of End-of-life Vehicles

With the rapid develop of our social economy and the increasing of people’s living standard, automobiles and household appliances has gradually become popular consumer products, also the number of scrap is increasing. In the near future, how to adopt high efficiency, low consumption, no pollution recycling method to reuse the scrapped automobiles and household appliances is one of the major problems we are facing on.Currently, the most effective way to treat end-of-life vehicles and household appliances is crack of whole vehicles, and light metals are one of the main components of the vehicles. In order to further study the harmer crusher mechanism of light metals, the pendulum impact crushing test is done. In the course of cracking, the main patterns are tearing and snapping-with-tearing (SWT). But the study found that SWT boundary condition was easier to set up and the separate chunks of debris was beneficial to reduce comprehensive energy consumption during the breakage process, so SWT was more conducive to recycle metal crush.Based on the random number of scrap metal materials from different parts of the car as tear test research object, while because of its metal material mechanics performance parameters unknown, therefore, the single tensile tests have multiple conducted on metal materials which are randomly selected. Then the stress-strain relationship is simplified to bilinear model and basic performance parameters of material were obtained. These results lay the foundation for the analysis investigation of subsequent SWT fracture process.In order to further study the harmer crusher mechanism of light metals, the SWT test research of rectangular light metal with quadrilateral prefabricated hole is conducted using MTS810material testing machine and homemade tool; Known from the analysis of a large number of broken results it shows that high speed load of rectangular cross section SWT tools-rectangular prefabricated hole specimen produce good crushing effect under the same condition, the process can be divided into the instability of the crack, rapidly expanding and path deflection. Before the instability of the crack, with SWT stress increasing, the sheet contacted with SWT tools first appear sag deformation, the interface micro crack of straight edge belongs to prefabricated hole appears instability of the crack at the most concentrated stress, and also appears trend of mode Ⅲ fracture along the direction of z, and there is singularity in crack tip strain field at the same time. However, in the process of rapid expansion, the singularity is weaker than the previous period which is also named the critical that crack need to overcome from crack to expanding. The SWT stress can provide the surface energy and the elastic-plastic deformation of the specimens for crack expanding at the same time, and mode Ⅲ fracture continue rapid expanding promoted by it. When the modulus of local and overall bending section increases to a certain value, the direction of crack propagation will deflect. During the process, mode Ⅰ-Ⅱ fracture plays a leading role, and its dehiscence and crack angle influence each other, and finally the direction of crack propagation will deflect and not stop expanding until large light metal debris are tearing down from its parent.The paper based on ANSYS/LS-DYNA simulates the process of SWT test with three different parameters that are speed of SWT load, shape of cross section, and specimen shape of prefabricated hole, and gets the its impact on recycling metal materials crushing, and confirmed the rule that it appears whole bend in transverse and longitudinal direction and local bending deformation during process of crushing. These phenomenon and rules lays a theoretical basis for further study of metal recycling and development of equipment.