Search

The snap fit is a commonly used jointing/connection mechanism because it is simple and reusable, and its easy installation and difficult removal are the result of the coordinated interaction between friction, geometric shape, and elasticity. This paper presents a detailed study on the assembly/disassembly forces of thin-walled torus snap-fit through finite element simulation, experimental testing, and data fitting of approximate analytical solutions. The research reveals that the non-zero Gaussian curvature of the torus has a significant impact on the mechanical performance of the torus snap fit. The findings in this study are of great significance for future design of high-performance structural connections. • Studied the segmental torus snap fit assembly/disassembly mechanics for the first time. • Carried out FEM analysis on assembly/disassembly process. • Conducted experiments on assembly/disassembly process. • Proposed approximate analytical assembly/disassembly force. [ABSTRACT FROM AUTHOR]

Spatial thin film structures exhibit high sensitivity to shear deformation, often exhibiting wrinkling phenomena under minimal shear loads. In this study, we used a combined experimental and theoretical approach to investigate the wrinkling and post-buckling behaviors of thin films subjected to shear forces. Initially, we designed and fabricated a high-precision experimental apparatus, which, in conjunction with the MTS Exceed 40 series universal testing machine, was a versatile experimental platform for evaluating the responses of thin films to shear. Subsequently, we extended the classical Föppl–von Kármán nonlinear plate model to capture the large deformation behaviors of thin films under shear. This development led to the formulation of governing equations that describe the shear-induced deformation of the films. We introduced two boundary conditions to characterize these deformations: one in which the non-loaded edge was free (unconstrained), and another in which the non-loaded edge was constrained (analogous to a frame constraining a painting). To solve the governing equations, we treated the incremental shear displacement angle of the thin film as a small parameter and devised a numerical method grounded in perturbation theory. We further formulated an implicit difference method of arbitrary order accuracy to enhance the precision and stability of the numerical solution. Our experimental and theoretical analyses revealed a comprehensive buckling pathway for thin films under shear, characterized by an initial wrinkling configuration (Config. 1), followed by a transition to a secondary wrinkling state (Config. 2), and culminating in a wrinkling splitting pattern (Config. 3). We also determined that by increasing the pre-stretching of thin films, their resistance to wrinkling along the entire buckling pathway could be significantly enhanced. • Proposed a perturbation method to solve the buckling problems of thin film. • Developed an implicit difference method with an arbitrary order accuracy. • Designed and manufactured a high-precision experimental fixture equipment. • Discovered a complete buckling path of thin film under shearing. [ABSTRACT FROM AUTHOR]

Temporary structures necessitate lightweight, easy transportation, and rapid deployment. However, conventional metal temporary bridges are often constrained by weight and scale, while inflatable structures rely on the maintenance of internal over-pressure for stability. To address this issue, a bistable folding beam that can be unfolded through pneumatic actuation is created by integrating origami with inflatable structures. Utilizing planar laser cutting techniques, a novel folding beam is manufactured, followed by three-point bending tests to analyze its bending performance. The evaluation includes considering factors such as internal air pressure, support conditions, folding/unfolding cycles, and geometric parameters. The findings reveal that the beam's foldable nature compromises its structural strength. Nevertheless, enhanced bending performance can be achieved through measures such as increased support end constraints, the addition of upper section plates, and adjustments to the angles of the basic units. • Conducted bending experiments on the folding beam derived from origami structures. • Proposed a method for manufacturing folding beams using plastic sheets and cardboard. • Assessed how factors such as internal air pressure affect structural strength. • Revealed the mechanisms responsible for changes in folding beam stiffness. [ABSTRACT FROM AUTHOR]

Triaxial weaving can form two-dimensional structures into three-dimensional structures using initially straight and flat ribbons. However, most of the 3D structures fabricated with conventional weaving methods using straight ribbons have some topological defects. To obtain smoother 3D surface structures, Baek proposed a novel weaving method using naturally curved (in-plane) ribbons to fabricate three-dimensional curved structures. We believe that an ellipsoidal weave with smooth geometric properties must have new mechanical properties. To this end, the buckling behavior of an ellipsoidal weave with naturally in-plane curved ribbons is investigated with a test and dimensional analysis in this research. The results of the calculations and experiments show that the failure modes of an ellipsoidal weave under vertical loading are divided into the inward deformation of the ribbon, overall wave buckling, and "blister" buckling along the strong radius. The aspect ratios, ribbon width, and thickness have a great effect on the buckling behavior of ellipsoidal weaves. The high load capacity and strong stability of ellipsoidal weaves with thicker or wider ribbons are exhibited. Moreover, the geometric size limit of the curved ribbons of an ellipsoidal weave is obtained with experiments. In addition, in this research, the buckling load equation and initial stiffness equation for an ellipsoidal weave are proposed using the method of testing and theoretical analysis. Our study can provide a theoretical basis for the stable design of an ellipsoidal weave structure. • Studied the buckling behavior of ellipsoidal grid-shells by experimental. • The failure mode of ellipsoidal weave with naturally curved ribbons are investigated. • Width and thickness of ribbons on the buckling behavior of the ellipsoidal weaves. • The buckling load equation and initial stiffness of ellipsoidal weaves are carried out. [ABSTRACT FROM AUTHOR]

The diagonal-enhanced square grid configuration inspired by glass sponge has great potential in mechanics, with geometries serving as honeycomb cores for sandwich panels, which can improve the structure's energy absorption capabilities. Modeling the hexagonal honeycomb core (HHC) sandwich panels, a finite element numerical model for low-speed impact of sandwich panels with high accuracy is proposed, and low-speed impact response of bio-inspired diagonal-enhanced square honeycomb core (BSHC) sandwich panels is studied. The impact response of BSHC sandwich panels, Hexagonal honeycomb core (HHC) sandwich panels and ordinary square honeycomb core (OSHC) sandwich panels were studied with the same relative densities and the same face-sheets. BSHC can lead to significantly enhanced the peak loads and stiffness of the sandwich panels. BSHC sandwich panels not only have excellent energy absorption performance, but also outperform HHC sandwich panels in terms of resistance to impact deformation. BSHC can transfer dynamic loads from the front face-sheet to the back face-sheet efficiently without stress concentration in the core itself. A theoretical analysis of the energy absorption capacity of the BSHCs and HHC were performed to illustrate the energy absorption mechanism. In addition, the peak load and contact energy of BSHC sandwich panels and HHC sandwich panels were theoretically predicted under low-speed impact. • The BSHC lead to significant peak load and higher stiffness of sandwich panels, increasing impact resistance. • The BSHC sandwich panels have excellent energy absorption performance. • The BSHC can effectively reduce the stress and deformation of sandwich panels. [ABSTRACT FROM AUTHOR]

The cuttlebone structure is a complex porous bionic structure with an asymmetric S-shaped wall structure connecting laminar septa. Studies have shown that the cuttlebone structure has a low weight, high strength, and excellent energy absorption capability. To establish bio-inspired structures with superior biological functions, researchers have proposed the sinusoidally corrugated cuttlebone-like array structure (SCS). In this study, referring to Euler's theory combined with the Gaussian curvature, the effects of the thickness t , height H , amplitude A , and period P of the SCS under compressive shearing were analyzed. Through finite element calculations and parameter sensitivity analysis, the optimized Su4-Sl2 SCS was obtained. Based on the optimization results, a structure named the elliptical corrugated cuttlebone-like array structure (ECS) was designed. Various ECSs were prepared via three-dimensional (3D) printing, and the compression and shear deformation characteristics of the ECSs were analyzed through experiments and simulations. The results showed that the bearing capacities of the new ECSs were improved compared with those of SCSs; moreover, Eu60-El90, Eu60-El60, and Eu60-El60 ECSs had the best compressive and shear capacities. From the perspective of the stress, the peak compression, peak shear stress in the y-direction, and peak shear stress in the x-direction were increased by 14.2%, 32.8%, and 14.9%, respectively. From the perspective of the energy, the compressive strain energy, shear strain energy in the y-direction, and shear strain energy in the x-direction were increased by 22.8%, 33.0%, and 78.1%, respectively. [ABSTRACT FROM AUTHOR]

The Gol'denveizer problem of a torus can be simply described as follows: the inner and outer equator of the torus shell is loaded by the vertical opposite balanced forces. Gol'denveizer proposed that the membrane theory of shells does not yield a valid solution to this problem. Following this, Audoly and Pomeau used a membrane theory of a toroidal shell and nonlinear boundary-layer to study the linear Gol'denveizer problem and gave a simple solution relating resultant force F and vertical displacement. Sun used the bending theory of shells to solve the linear Gol'denveizer problem, and demonstrated that the solution by Audoly and Pomeau for the linear Gol'denveizer problem is extremely accurate. However, to the best of our knowledge, no one has examined the nonlinear Gol'denveizer problem. In this study, the finite element method is used to observe the nonlinear mechanical property and buckling of the Gol'denveizer problem of a circular and elliptic torus. Investigations reveal that the radius ratios a / R and a / b have great influences on the deformation and force of a circular torus and elliptical torus, respectively, and that the negative Gaussian part of a torus has a stronger bearing than the positive Gaussian part. Additionally, when the vertical force is large enough, shear buckling may occur in the circular and elliptic tori. We propose the buckling failure modes of circular and elliptical torus. As a / b increases, the collapse load of an elliptic torus of the Gol'denveizer problem is enhanced gradually. • Studied the nonlinear Gol'denveizer problem of torus shells by using FEM. • Identified the negative Gaussian part of circular torus has a stronger bearing. • Force and displacement of circular tori are not equal to zero at crown line. • Studied the buckling behaviors of Gol'denveizer's problem of half-circular tori. • Found a new buckling phenomenon that called a "skirt" shape. [ABSTRACT FROM AUTHOR]

Computation of rotation tensor is essential in the analysis of deformable bodies. This paper proposes an explicit expression for rotation tensor R of deformation gradient F , and successfully establishes an intrinsic relation between the exponential mapping Q = exp A and the deformation F. As an application, Truesdell's simple shear deformation is revisited. For easy use of our formulation, we provide a Maple code for a general 2D problem. [ABSTRACT FROM AUTHOR]