Rib‐reinforced Shell Structure

Abstract

Figure 1: We present a computational framework to generate ribs to enhance the structural strength and stiffness of a shell (a). Our ribreinforced shell structure (c) costs the same amount of material as a pure shell without any ribs (a), while achieving much better mechanical performance. And (b) and (d) are coloring visualizations of the magnitude of von Mises stress of (a) and (c), respectively, under the same load and boundary conditions. Warmer color represents higher stress and red encodes stress exceeding the yield strength 42 MPa. The maximum stress in (b) is 109.84 MPa, which far exceeds 42 MPa, while the maximum stress in (d) is below 40 MPa with the contribution from ribs. The maximum stress of the shell is about 3 times of the stress of the rib-reinforced shell structure, indicating the latter achieves much higher strength than the former. We also fabricated the two structures by 3D printing and made a stiffness comparison as shown in Figure 19 which indicates much higher stiffness of the rib-reinforced shell structure. AbstractShell structures are extensively used in engineering due to their efficient load-carrying capacity relative to material volume. However, large-span shells require additional supporting structures to strengthen fragile regions. The problem of designing optimal stiffeners is therefore becoming a major challenge for shell applications. To address it, we propose a computational framework to design and optimize rib layout on arbitrary shell to improve the overall structural stiffness and mechanical performance. The essential of our method is to place ribs along the principal stress lines which reflect paths of material continuity and indicates trajectories of internal forces. Given a surface and user-specified external loads, we perform a Finite Element Analysis. Using the resulting principal stress field, we generate a quad-mesh whose edges align with this cross field. Then we extract an initial rib network from the quad-mesh. After simplifying rib network by removing ribs with little contribution, we perform a rib flow optimization which allows ribs to swing on surface to further adjust rib distribution. Finally, we optimize rib cross-section to maximally reduce material usage while achieving certain structural stiffness requirements. We demonstrate that our rib-reinforced shell structures achieve good static performances. And experimental results by 3D printed objects show the effectiveness of our method.

Design and Optimization of Conforming Lattice Structures

“…This principle has been applied to 2D planes (e.g. [17]) and curved surfaces [18], [19], [20]. The appealing 2D results are achieved by tracing stress directions or based on a ground structure approach [21], [22].…”

Minimizing Material Consumption of 3D Printing with Stress-Guided Optimization

“…The material consumption of honeycomb-like 3D models is reduced via a hollowing optimization algorithm in [17]. Stiffened objects were first investigated in [18]. A method to produce optimized structures for any input surface with any load configurations was researched in [22].…”

3D printing: a critical review of current development and future prospects

“…Li W. et al (2017) proposed the rib reinforcement as a way to enhance the shell structures (Li et al , 2017) as shown in Figure 18 (Figure 19). The technology was proposed for AM so that the reinforcements do not require additional material because it is extracted from the thickness of the shell.…”