Ðề: Johnson Cook Material law là gì?
Hôm nay làm state of the arts tình cờ thấy cuốn này, chuyên về FEM cho metal cutting.
http://rd.springer.com/book/10.1007/978-1-4471-4330-7
Về các phần mềm, bạn tham khảo đoạn sau trong sách, rất pertinent ! Tổng quan hết tất cả phần mềm trên thị trường, điểm mạnh yếu mỗi phần mềm.
Regarding machining, FEM codes that have been used for the simulation of machining include: Abaqus [43, 79, 125], FORGE 2 [32], N
[107], DEFORM 2D/3D [18, 49, 62, 126], I-FORM 2 [78], MSC.Marc [41], LS-DYNA [127] and AvantEdge [19, 78, 122, 123, 128, 129]. Some of these programs are general purpose software, i.e. MSC.Marc and ABAQUS, or specific purpose programs for machining or other uses. LS-DYNA is a program used mainly in crashworthiness analysis and forming problems, DEFORM 2D is a program for forming processes, which has a machining module to accommodate turning, milling, boring and drilling operations and AdvantEdge is a FEM program that is only used to simulate machining. It can simulate orthogonal and oblique cutting, 3D modeling of turning, milling, drilling, boring and taping, and 2D modeling of micromachining among others. AdvantEdge is a Lagrangian, explicit, dynamic code which can perform coupled thermo-mechanical transient analysis. The program applies adaptive meshing and continuous re-meshing automatically. The drawback of this software is that some parameters are fixed and the user cannot intervene, e.g. friction coefficient is constant in the tool-chip interface.
Bil, Kılıç and Tekkaya have compared models from three different commercial software, namely, MSC.Marc, DEFORM 2D and AdvantEdge [130]. In all three cases an orthogonal plane strain model is constructed but some features of the models are quite different, e.g. MSC.Marc and DEFORM 2D are implicit codes while AdvantEdge is explicit, chip separation in MSC.Marc and AdvantEdge is through re-meshing and in DEFORM 2D a damage criterion and element deletion are applied. Other differences pertain to friction model, element types and material model. The results of the models are compared to experimental results and not a good agreement in all the parameters was found. Firstly, the material data are not obtained for high strain rates such as those encountered in machining but are extrapolated and need to be improved. Friction modeling needs to be tuned in order to provide more reliable results; although cutting forces are in good agreement with experimental ones, thrust forces are more accurately predicted with larger friction parameters. The plain Coulomb friction model, used in AdvantEdge, is not adequate for providing good approximations of the forces. However, it is argued that a more reliable chip separation criterion needs to be proposed. The authors state that, although chip formation by re-meshing provides better results, it is based on the misconception of crack generation in the material near the tool tip. The technique resembles crack generation because of the way the new mesh is formed after re-meshing.
Cũng vậy, behavior laws không chỉ có johnson-cook mà nhiều laws khác có thể sử dụng.