We congratulate Daobo Zhang on his PhD

5 May 2026

Daobo Zhang, a research associate at our institute, successfully defended his PhD thesis on May 5, 2026. We congratulate him most sincerely!

The title of his PhD thesis:

"Variationally Consistent Approaches for Numerical Modeling of Membrane Wrinkling"

Prof. Dr.-Ing. Josef Kiendl (University of the Bundeswehr Munich), Prof. Dr.-Ing. Ralf Müller (TU Darmstadt) and Prof. Dr.-Ing. Roland Wüchner (TU Munich) acted as reviewers for this PhD thesis.

This PhD thesis proposes a novel, variationally consistent model for membrane wrinkling, designed to analyze the mechanical behavior of wrinkled thin membranes. The elastic strain energy density is decomposed into tensile and compressive components through a spectral decomposition of the strain tensor. Subsequently, the tensile and compressive components of both the stress and material tensors are derived from their respective strain energies using a variationally consistent approach. By exclusively considering the positive component of the strain energy within the variational formulation, a membrane model with vanishing compressive stiffness is obtained. Furthermore, by additionally incorporating the negative strain energy—multiplied by a very small factor—a residual compressive stiffness is introduced; this enhances numerical stability and enables the capture of states of membrane slackness. Comparisons with analytical, numerical, and experimental examples from the literature on membrane wrinkling problems demonstrate the high performance and suitability of the proposed approach, which is also compatible with commercial finite element software.