Large displacements and the stiffness of a flexible shell
The design of static thin shell structures can be carried out using analytical and numerical approaches. Recently, thin shells have been studied for their flexibility, which can be beneficial for adaptive systems. However flexible systems involve large displacements and precise kinematics. The analysis of flexible shell systems is challenging due to the nonlinearities induced by these large displacements. This study addresses the nonlinear behaviour and stress-stiffening effects caused by large displacements in a 0.80 m-long carbon fibre reinforced plastic shell consisting of two monolithically connected lobes. The structural behaviour of this system is investigated both numerically and experimentally. Following the analysis
framework, the non-linear effects of the large displacements on the shell stiffness are numerically determined using eigenvalue analysis and the displacement response to external loading on deformed shell configurations. The numerical displacement results are compared with results obtained in the experimental study. In conclusion, our study shows that the stiffness of the shell system under study increases 113% during deformation. More precisely, we establish that this change in stiffness is governed by the presence of tensile stresses in the shell surface due to deployment rather than by the change of the system’s geometry.
A project-based approach to learning of structural surfaces
In the last two decades, a renewed interest has arisen, both from the structural engineering and architectural field, to exploit the elegance and structural efficiency of structural surfaces. This paper discusses a project based course aimed at graduate architecture and civil engineering students to i) develop an in-depth understanding of the basics of surface structures, ii)
cultivate relevant numerical and physical form finding proficiency, iii) communicate complex technical issues with peers and iv) problem scope, brainstorm and generate design alternatives for force-modeled systems. Because of the nature of the course and workshop objectives, the evaluation of the effectiveness is qualitative rather than quantitative. Therefore, the findings
are supported by students’ reactions captured in their course evaluations as well as their chosen careers paths after graduation. Since there is rarely room for the introduction of new courses in an established academic curricula, this paper also shows how the course can be adapted to project-based workshops which can vary in length from half of a day to three days. In conclusion, this paper is of interest to educators in structural engineering and architecture because it contributes to methods for effectively teaching structural surface structures.