Two-Step Calibration Method for Inverse Finite Element with Small Sample Features

Abstract

When the inverse finite element method (inverse FEM) is used to reconstruct the deformation field of a multi-element structure with strain measurements, strain measurement errors can lower the reconstruction accuracy of the deformation field. Furthermore, the calibration ability of a self-structuring fuzzy network (SSFN) is weak when few strain samples are used to train the SSFN. To solve this problem, a novel two-step calibration method for improving the reconstruction accuracy of the inverse FEM method is proposed in this paper. Initially, the errors derived from measured displacements and reconstructed displacements are distributed to the degrees of freedom (DOFs) of nodes. Then, the DOFs of nodes are used as knots, in order to produce non-uniform rational B-spline (NURBS) curves, such that the sample size employed to train the SSFN can be enriched. Next, the SSFN model is used to determine the relationship between the measured strain and the DOFs of the end nodes. A loading deformation experiment using a three-element structure demonstrates that the proposed algorithm can significantly improve the accuracy of reconstruction displacement.

A New Processing Method for the Nonlinear Signals Produced by Electromagnetic Flowmeters in Conditions of Pipe Partial Filling

“…When the induced EMF output by the electromagnetic flowmeter sensor is E j ðj ¼ 1; 2; Á Á Á ; nÞ and the corresponding fluid flow rate is q j ðj ¼ 1; 2; Á Á Á ; nÞ, q ¼ f ðEÞ can be described by the following B-spline curve fitting equation [21][22][23]…”

“…B-spline curve fitting [19][20][21][22][23] is an approach that performs a nonlinear fit of data based on a limited selection of these data. As the B-spline curve method is a simple calculation procedure with fast calculation speed and geometric invariance, it is widely used in engineering practice, such as for the geometric definition of various industrial products and nonlinear curve reconstruction.…”

“…Gao et al [20] proposed a double B-Spline curve fitting and synchronization-integrated federate scheduling method for a Five-Axis linear-segment tool path, and simulation showed that this method can generate a smooth tool path and constrain the fitting error. Xu et al [21] rebuilt the strain field of multiple elements by using the B-spline curve and inverse finite element methods to prove that the proposed algorithm can significantly improve the accuracy of reconstruction displacement. Jiang et al [22] reconstructed the under-sampling flow velocity distribution of partially filled pipes using the B-spline curve method, showing that this method effectively reduces the number of measurement data.…”