Research of Sets of Solid Oxide Fuel Cells in Packed Version

The stressed state of fuel cells in a package is considered. It was found that for αi=1.2×10−5k−1, the rational geometric characteristic for a planar SOFC in a batch design is γi=6×10−2. It is concluded that if the relative thickness of the edge element of the SOFC stack is of planar design γi>6×10−2, then the resulting deformation complication will be characterized by the loss of stability of the structure. Otherwise, i. e. at γi<6×10−2, stacked SOFC elements can lose stability until plasticity appears in their materials. Consequently, only at γi=6×10−2, the use of the potentials of structures can be achieved both in terms of the stability of its elements and the strength of their materials.

An adaptive edge element method and its convergence for an electromagnetic constrained optimal control problem

In this work, an adaptive edge element method is developed for an H(curl)-elliptic constrained optimal control problem. We use the lowest-order Nedelec’s edge elements of first family and the piecewise (element-wise) constant functions to approximate the state and the control, respectively, and propose a new adaptive algorithm with error estimators involving both residual-type error estimators and lower-order data oscillations. By using a local regular decomposition for H(curl)-functions and the standard bubble function techniques, we derive the a posteriori error estimates for the proposed error estimators. Then we exploit the convergence properties of the orthogonal L^2- projections and the mesh-size functions to demonstrate that the sequences of the discrete states and controls generated by the adaptive algorithm converge strongly to the exact solutions of the state and control in the energy norm and L^2 -norm, respectively, by first achieving the strong convergence towards the solution to a limiting control problem. Three-dimensional numerical experiments are also presented to confirm our theoretical results and the quasi-optimality of the adaptive edge element method.

Force Model of Freeform Surface Multi-axis Machining With Fillet End Mill Based on Analytical Contact Analysis

In the multi-axis machining of freeform surface, compared with ball end mill, the fillet end mill has higher machining efficiency under the same residual height and has been widely used. As the most important physical quantity in machining process, milling force has always been the focus of research. In this paper, the geometry contact between fillet end mill and freeform surface is analyzed by analytical method, and then the milling force prediction model of multi-axis machining is established. Based on differential discretization, the cutter location of multi-axis machining of freeform surface is approximate to multi-axis machining of oblique plane, which simplifies the research object. The inclination angle is defined to describe the relationship among cutter axis, feed and workpiece in cutter coordinate system. The space range of the cutting edge element participating in material cutting is constructed by the swept surface of previous tool path, the to-be machined surface and the feed direction surface, and the in cut cutting edge is determined by judging the cutting edge element one by one. Considering cutter run-out, the element cutting forces on the cylindrical and fillet surfaces of the fillet end mill are derived, and all the element forces within in cut cutting edge are summed by vector to obtain the overall milling force of fillet end mill. Simulation results show that, compared with the solid method, this contact analysis method between cutter and workpiece can take both efficiency and accuracy into account. In the machining experiment, the measured force and predicted force along tool path are consistent in trend and amplitude, which verifies the effectiveness of the milling force prediction model.

An adaptive edge element approximation of a quasilinear H(curl)-elliptic problem

An adaptive edge element method is designed to approximate a quasilinear [Formula: see text]-elliptic problem in magnetism, based on a residual-type a posteriori error estimator and general marking strategies. The error estimator is shown to be both reliable and efficient, and its resulting sequence of adaptively generated solutions converges strongly to the exact solution of the original quasilinear system. Numerical experiments are provided to verify the validity of the theoretical results.