Sheet-bulk metal forming

Simulation of titanium cup drawing in QForm. Elastic strain fieldSheet-bulk metal forming means technological processes in which plastic deformation zone size is comparable to the sheet thickness. For example, processes such as forming operation, small-radius bending, and ironing of small-sized parts. These processes have a local deformation zone with a significant for simulation changing of the stress-strain state through sheet thickness. Such deformation zone should be simulated using solid finite elements because of using 3D-shell elements would result in a significant precision loss or make impossible to run the solver for performing the simulation.

Conventional sheet metal forming of small parts we also refer to sheet-bulk metal forming. The simulation of large area parts in the QForm software, such as body parts, is inefficient because of the too large number of finite elements and excessive computation time. However, there are no limitations on the size and complexity of axisymmetric parts due to high-parallelization of simulation process and special algorithms for solving of 2D problems implemented in the QForm software.

Advantages

  • Estimating the deformation distribution through sheet thickness
  • Determination the shape of struck or molded geometric elements of the part
  • Determination of the accumulated stresses value caused by local shape changing in zones of low-radius tool to assess their impact on the further performance of the part.
  • Exact solving of forming problems

Simulation of cup deep drawing by ribbed punch in QForm. Plastic strain fieldComparison of real experiment with simulation results in QForm. Maximum values of Bai & Wierzbicki fracture criterion indicate crack appearing

Special QForm features that help simulate sheet-bulk metal forming

  • The elastic-plastic material model for accurate simulation of cold deformation and forecast of spring back
  • Forecasting of destruction by known criteria, such as Cockroft-Latham, Kolmogorov, Verzhbitskiy, etc.
  • Simulation of pre-tension compound tooling sets
  • Simulation of a spring-loaded tool with multiple moving forming elements

Pull test simulation in QForm. Effective stress fieldDeep drawing simulation in QForm. Plastic strain field

Example

A good example of sheet-bulk metal forming simulation is the barrel drawing technology presented in the animation below.
A comparison of two forming technologies with a smooth and finned punch has presented in this example. It has shown clearly that workpiece is destroyed during the forming operation while using a smooth punch. Implementation of the punch with a surface microrelief ensures a higher drawing ratio due to increasing of contact interaction on the lateral surface.

*M. Mrklein, D. Grobel, M. Loffler, T. Schneider and P. Hildenbrand. Sheet-bulk metal forming – forming of functional components from sheet metals / Proceedings of ICNFT 2015, August, 6 – 9, Glasgow, UK / MATEC Web of Conferences 21 01001 (2015).- p.1-12