As part of the research colloquium for students, doctoral and habiliation candidates, we cordially invite you to attend on Tuesday, 04.11.2025 at 16:30 in room 3516 (Mönchebergstr. 7). Dr.-Ing. Jonas Boungard will present the current status of his research at the Institute of Structural Analysis in his lecture entitled "Finding Indicators for the Influence of Constraints Induced by Kinematic Assumptions Using the Example of the Euler-Bernoulli and Timoshenko Hypothesis". We look forward to seeing you there!

Abstract

Beam models rely on kinematic assumptions that restrict the possible deformations and describe the structural behaviour using a reduced set of parameters, i.e.\ the kinematics of the reference axis. A well-known example is the Euler–Bernoulli hypothesis, which comes with the following three assumptions on the deformation of the cross-section: it remains plane, perpendicular to the beam’s reference axis and of same dimensions over the course of the deformation.

While these assumptions allow for a drastic reduction in computational complexity, they also act as kinematic constraints. A beam model inherently satisfies these constraints, but when its results are compared to a more detailed continuum model without constraints, deviations can be observed. In many cases, these deviations remain within acceptable limits, and beam models provide an accurate and efficient representation of the structural behaviour. Yet, there are scenarios where the standard kinematic assumptions are ill suited, leading to significant errors.

Although this phenomenon is well known, no method has been developed to generally quantify the influence of the kinematic assumptions on the local and global structural behaviour. Such a method is of great interest because it allows the adequate selection of kinematic assumptions and the corresponding beam theory for each part of the structure. As a basis for the method, indicators for the influence of constraints induced by kinematic assumptions are required.

The main objective of this talk is to explicitly quantify the influence of constraints induced by kinematic assumptions and finding indicators to characterize this influence. For this, the study focuses on the kinematic assumptions of the Euler-Bernoulli as well as Timoshenko hypothesis as a proof of concept.