Material Identification of Heterogeneous Isogeometric Bernoulli–Euler Beams With Pretensioning

ABSTRACT This study employs the Finite Element Model Updating (FEMU) method for identification of material parameters and pretensioning forces in heterogeneous planar Bernoulli–Euler beams, which are analyzed using isogeometric analysis. The unknown material fields are discretized with a separate mesh based on Lagrange interpolation, referred to as the material mesh. The nodal values of the material mesh and the pretensioning force become discrete unknowns of the inverse problem. The FEMU objective function is formulated as a least‐square error, consisting of the differences between experimental and finite element displacements obtained from quasi‐static nonlinear calculations. To solve this problem, the Trust Region Interior Reflective algorithm is used. In addition, analytical derivatives are provided to accelerate the computations. The proposed approach is verified by the example of identifying Young's modulus distribution and pretensioning based on artificially generated experimental data. Results show that the material parameter identification is sensitive to noise. However, with sufficient experimental data, the influence of noise can be significantly reduced. The pretensioning force can be robustly reconstructed even for high noise levels.