Stainless steel bipolar plates for proton exchange membrane fuel cells: Materials, flow channel design and forming processes

Towards mass applications: A review on the challenges and developments in metallic bipolar plates for PEMFC

Micromanufacturing technologies of compact heat exchangers for hypersonic precooled airbreathing propulsion: A review

A basic ductile fracture testing program is carried out on specimens extracted from TRIP780 steel sheets including tensile specimens with a central hole and circular notches. In addition, equi-biaxial punch tests are performed. The surface strain fields are measured using two- and three-dimensional digital image correlation. Due to the localization of plastic deformation during the testing of the tensile specimens, finite element simulations are performed of each test to obtain the stress and strain histories at the material point where fracture initiates. Error estimates are made based on the differences between the predicted and measured local strains. The results from the testing of tensile specimens with a central hole as well as from punch tests show that equivalent strains of more than 0.8 can be achieved at approximately constant stress triaxialities to fracture of about 0.3 and 0.66, respectively. The error analysis demonstrates that both the equivalent plastic strain and the stress triaxiality are very sensitive to uncertainties in the experimental measurements and the numerical model assumptions. The results from computations with very fine solid element meshes agree well with the experiments when the strain hardening is identified from experiments up to very large strains.

Hybrid experimental–numerical analysis of basic ductile fracture experiments for sheet metals

A comprehensive comparison of state-of-the-art manufacturing methods for fuel cell bipolar plates including anticipated future industry trends

Applying a new constitutive model to analyse the springback behaviour of titanium in bending and roll forming

Micro-roll forming of stainless steel bipolar plates for fuel cells

Micro roll forming is a new processing technology to produce bipolar plates for Proton Exchange Membrane Fuel Cells (PEMFC) from thin stainless steel foil. To gain a better understanding of the deformation of the material in this process, numerical studies are necessary before experimental implementation. In general, solid elements with several layers through the material thickness are required to analyse material thinning in processes where the deformation mode is that of bending combined with tension, but this results in high computational costs. This pure solid element approach is especially time-consuming when analysing roll forming processes which generally involves feeding a long strip through a number of successive roll stands. In an attempt to develop a more efficient modelling approach without sacrificing accuracy, two solutions are numerically analysed with ABAQUS/Explicit in this paper. In the first, a small patch of solid elements over the strip width and in the centre of the "pre-cut" sheet is coupled with shell elements while in the second approach pure shell elements are used to discretize the full sheet. In the first approach, the shell element enables accounting for the effect of material being held in the roll stands on material flow while solid elements can be applied to analyse material thinning in a small discrete area of the sheet. Experimental micro roll forming trials are performed to prove that the coupling of solid and shell elements can give acceptable model accuracy while using shell elements alone is shown to result in major deviations between numerical and experimental results.

http://dro.deakin.edu.au/eserv/DU:30102969/rolfe-deformationinmicro-2017.pdf

Peng Zhang

Papers

Applying a new constitutive model to analyse the springback behaviour of titanium in bending and roll forming

Micro-roll forming of stainless steel bipolar plates for fuel cells

Deformation in micro roll forming of bipolar plate

Improving the shear test to determine shear fracture limits for thin stainless steel sheet by shape optimisation

Plastic instability and fracture of ultra-thin stainless-steel sheet