Research and application of variable-thickness thin-layer element method

A variable-thickness thin-layer element (VTE) method is proposed to address the challenges in parameter determination and the limited computational accuracy of the conventional thin-layer element (TE) method. Underpinned by the fundamental assumption of a Gaussian random distribution for rough surfaces, a numerical characterization model of a 3D rough surface was first established to investigate microscopic contact behaviors. Based on the simulation data of the elastoplastic deformation of micro-convex bodies, a method for determining the equivalent elastic modulus of the TE was developed. Subsequently, the contact stress distribution across the casing flange was obtained via finite element analysis. By integrating the TE theory with the non-uniform contact stress distributions, the VTE model was established and experimentally validated. The results demonstrate that the VTE model significantly enhances simulation fidelity compared to the TE model. Specifically, the maximum error in modal frequency prediction compared to experimental measurements was reduced from 6.14% to 3.66%, while the average error decreased from 2.85% to 1.14%. The VTE method offers a high-fidelity modeling approach for characterizing the contact stiffness of complex joint structures, such as aero-engine casing flanges.