Influence of reinforcing ribs on the deformed state of ellipsoidal shells under distributed load

This paper presents the problem about non-stationary oscillations of reinforced ellipsoidal shells, taking into account the discrete location of the ribs. Problem bases on a geometrically nonlinear variant of the Tymoshenko theory for shells and rods. A numerical method for solving problems of this class has been developed and substantiated. This article focuses on the location of the reinforcing ribs. On the basis of the developed numerical method the deformed state of discretely supported ellipsoidal shells for internal, external and internal-external placement of ribs is investigated. Boundary conditions for rigidly clamped edges of the shell were studied.

The Role of Expanded Polystyrene and Geocell in Enhancing the Behavior of Buried HDPE Pipes under Trench Loading Using Numerical Analyses

In recent years, much research has focused on the use of various materials for relieving and strengthening soil, e.g., steel reinforcing ribs, geosynthetics, geocell, waste tires, and expanded polystyrene (EPS). EPS is being used increasingly in geo-infrastructure, being a super-light material, to replace part of the soil and decrease the ground pressure on buried structures. This paper presents experimental and numerical analyses of the effectiveness of expanded polystyrene and geocell reinforcement for ameliorating the behavior of unpressurized buried pipes exposed to surface loading. A 3-D finite element method (FEM) model of soil, geofoam, geocell, and piping was generated in ABAQUS, and the model was verified by experimental analyses conducted at a laboratory. The results show that reinforcing the soil cover with geocell and geofoam has a substantial impact, decreasing the maximum surface settlement by around 29% and maximum pipe crown displacement by up to 39.5%. In addition, the EPS block density can reduce the maximum pipe crown displacement substantially.

Modal Analysis and Optimization of Typical Parts of 2K-V Reducer

As a new type of high-precision gear transmission mechanism, the transmission accuracy of the 2K-V reducer will be greatly affected by vibration. With the RV110E reducer as the research object, a three-dimensional model of the needle wheel is established. Using the finite element analysis software, the natural frequency and mode shape of the needle wheel are calculated, when it’s under the output condition, then compared with the calculated gear meshing frequency. It is found when the needle wheel is used as an output, the vibration frequency is within the gear meshing frequency range, which is easy to cause resonance, thereby affects the transmission precision of the whole machine. The part of the outer shell of the needle wheel and the oil seal of the skeleton is the weakest and prone to deformation. By adding 6 reinforcing ribs between the needle wheel flange and the outer casing, increasing the flange outer diameter at the same time, the natural frequency can be increased, the deformation concentrated region can be transferred to the outer casing and the reinforcing rib. The connected parts avoid resonance and increase the service life of the needle wheel.

Elastic Response of Acoustic Coating on Fluid-Loaded Rib-Stiffened Cylindrical Shells

Reinforced cylindrical shells are used in numerous industries; common examples include undersea vehicles, aircraft, and industrial piping. Current models typically incorporate approximation theories to determine shell behavior, which are limited by both thickness and frequency. In addition, many applications feature coatings on the shell interior or exterior that normally have thicknesses which must also be considered. To increase the fidelity of such systems, this work develops an analytic model of an elastic cylindrical shell featuring periodically spaced ring stiffeners with a coating applied to the outer surface. There is an external fluid environment. Beginning with the equations of elasticity for a solid, spatial-domain displacement field solutions are developed incorporating unknown wave propagation coefficients. These fields are used to determine stresses at the boundaries of the shell and coating, which are then coupled with stresses from the stiffeners and fluid. The stress boundary conditions contain double-index infinite summations, which are decoupled, truncated, and recombined into a global matrix equation. The solution to this global equation results in the displacement responses of the system as well as the exterior scattered pressure field. An incident acoustic wave excitation is considered. Thin-shell reference models are used for validation, and the predicted system response to an example simulation is examined. It is shown that the reinforcing ribs and coating add significant complexity to the overall cylindrical shell model; however, the proposed approach enables the study of structural and acoustic responses of the coupled system.

STABILITY PERFORMANCE OF INFLATABLE TUBE IMITATING CLANIS BILINEATA LARVA UNDER AXIAL PRESSURE

The body wall structure of Clanis bilineata larva exhibits strong stability. This characteristic prompted the development of a new inflatable tube to improve the stability under axial pressure. The C. bilineata larva was chosen to observe the connection between its body wall and nearby muscle tissues, as well as the distribution of these tissues, by using the tissue section technique. Using this method, an inflatable tube with reinforcing ribs was designed. Simulation using the finite element method and experimentation were employed to compare and analyze the stability of the inflatable tube with and without reinforcing ribs under different axial pressure levels. Results indicate that the ultimate load of both inflatable tubes increases linearly with increasing pressure. The difference between the slopes of the two lines is small. Under different axial pressure levels, the ultimate load of the inflatable tube with reinforcing ribs is about 1.34[Formula: see text]N higher than that without reinforcing ribs; the ultimate compression power increased by 31% to 68% compared with that without ribs. The simulation results are slightly larger than the experimental results, but the ultimate load value in the simulation exhibits the same trend as that in the experiment. Finally, the limit load and ultimate compression power are used as evaluation criteria to quantitatively analyze the stability performance of an inflatable tube with reinforcing ribs under axial pressure.

Optimal Design of Panel Reinforcements With Ribs Made of Plates

The stiffness of plate structures can be significantly improved by adding reinforcing ribs. In this paper, we are concerned with the stiffening of panels using ribs made of constant-thickness plates. These ribs are common in, for example, the reinforcement of ship hulls, aircraft wings, pressure vessels, and storage tanks. Here, we present a method for optimally designing the locations and dimensions of rectangular ribs to reinforce a panel. The work presented here is an extension to our previous work to design structures made solely of discrete plate elements. The most important feature of our method is that the explicit geometry representation provides a direct translation to a computer-aided design (CAD) model, thereby producing reinforcement designs that conform to available plate cutting and joining processes. The main contributions of this paper are the introduction of two important design and manufacturing constraints for the optimal rib layout problem. One is a constraint on the minimum separation between any two ribs to guarantee adequate weld gun access. The other is a constraint that guarantees that ribs do not interfere with holes in the panel. These holes may be needed to, for example, route components or provide access, such as a manhole. We present numerical examples of our method under different types of loadings to demonstrate its applicability.