Generation of filament winding patterns for elbows with various cross-sections

As a connecting component of tubes, the elbow is indispensable to pipe-fitting in composite products. Previous studies have addressed methods for generating winding paths based on parametric equations on the elbow. However, these methods are unsuitable for elbows whose surfaces are difficult to describe using mathematical expressions. In this study, a geometric method was proposed for generating winding patterns for various elbow types. With this method, the mandrel surface is first converted into uniform and high-quality quadrilateral elements; an algorithm is then provided for calculating the minimum winding angle for bridging-free. Next, an angle for non-bridging was defined as the design-winding angle to generate the uniform and slippage-free basic winding paths on the quadrilateral elements in non-geodesic directions. Finally, after a series of uniform points were calculated on the selected vertical edge according to the elbow type, the pattern paths were generated with the uniform points and basic paths. The proposed method is advantageously not limited to the elbow’s shape.

Design and Analysis of a Laminated Composite Tube

Piping is an important material for fluid transportation in modern industry, and well-structured piping can reduce losses due to maintenance and replacement downtime. Therefore it is necessary to design and analyze the pipes in order to optimize their structure. This paper focuses on composite laminated pipes. In this design case, the structural analysis of this pipe will be carried out by applying the laminate theory, and the structural analysis model will be established by using Mathcad software. The stress and strain of each laminate will be calculated by entering the winding angle and the corresponding equations in this software. The final optimal winding Angle can be determined by verifying the winding angles that can be maintained under maximum stress failure criteria using Mathcad contours and detailed tables of winding and torsion angles.

A Study on a Slotless Brushless DC Motor with Toroidal Winding

In this study we developed a brushless DC (BLDC) slotless motor with toroidal winding. The proposed toroidal winding is a method of winding a coil around a ring-type stator yoke in the circumferential direction. As there is no need for a slot or tooth structure, it can be designed with a slotless motor structure that is advantageous for vibration and noise. The basic principle of operation and motor characteristics of a slotless motor with toroidal winding were explained using an analytical method and finite element analysis (FEA). Further, the air gap flux density, winding factor, and back electromotive force (EMF) for changes in the winding angle and number of coil turns were calculated using the analytical method and compared with the FEA results. Finally, the resistance, back EMF, cogging torque, and performance of the prototype were measured and compared with the FEA results. The results show that the air gap flux density and winding factor were approximately the same with an error of <2%, while the back EMF had an error of ~10% from the analysis result. Thus, the proposed slotless motor provides a basic design for conveniently manufacturing brushless DC (BLDC) slotless motors with toroidal windings.

MULTI-OBJECTIVE OPTIMIZATION OF SNAKE ROBOT IN SERPENTINE LOCOMOTION

This paper presents multi-objective optimization for a snake robot with serpentine locomotion. Genetic algorithm (GA) is used to achieve two objectives: minimizing the total travelling time and minimizing the total energy consumption. The effect of initial values of winding angle and acceleration on energy consumption and average speed is depicted. The simulation results show a periodic pattern of the joint torques when the robot maintains a serpenoid curve during travel. Moreover, a Pareto-optimal front was generated for optimal solutions of both of the objectives, while the weighted sum method was used for selecting the best solution. Finally, the simulation results were verified experimentally on an eight-link snake robot considering the limitations of the servomotors used in the experiment. The experimental results with the winding angle of 30° was found as the optimum winding angle that can achieve both objectives of minimizing the energy consumption and the travelling time. ABSTRAK: Kajian ini berkenaan pelbagai-objektif optimum bagi robot ular dengan gerakan serpentin. Algoritma genetik (GA) diguna bagi mencapai dua objektif ini iaitu mengurangkan jumlah masa gerakan dan guna tenaga. Gambaran kesan awal nilai sudut belitan dan pecutan pada guna tenaga dan purata kelajuan dihasilkan. Dapatan simulasi menunjukkan corak berkala tork sendi yang tetap terhasil semasa robot ini berkeadaan lengkung serpenoid ketika bergerak. Tambahan, Pareto-optimal berdepan terhasil bagi solusi optimum pada kedua-dua objektif, sementara kaedah berat campuran digunakan bagi menentukan solusi terbaik. Akhirnya, dapatan simulasi disahkan secara eksperimen pada robot ular lapan-bahagian dengan menimbangkan kekurangan servomotor yang digunakan dalam eksperimen. Dapatan eksperimen menunjukkan sudut belitan 30° adalah sudut belitan optimum bagi kedua-dua objektif iaitu mengurangkan tenaga dan masa gerakan.

Stability of filament-wound hyperbolic flexible pipes under internal pressure based on non-geodesic winding

Filament-wound flexible pipes are widely used to transport fluid in pipeline systems, proved extremely useful in marine engineering. The hyperbolic flexible pipes have good vibration suppression performance, but they are easily deformed under internal pressure. This paper focuses on the stability of hyperbolic flexible pipes based on the composite Reissner shell theory and the transfer-matrix method. The nonlinear stretch of the reinforced filament and the fiber bridge effect are considered in the model. The calculation results show that a large winding angle reduces the deformation and the meridional stress. The available initial winding angle is limited by the geometry and the slippage coefficient of flexible pipe. The reinforced filament of high tensile modulus will reduce the deformation of the pipe. Compared with the geodesic winding trajectory, non-geodesic winding trajectories improves the stability of the pipe. The theoretical result is verified by the finite element analysis. The investigation method and results present in this paper will guide the design and optimization of more novel flexible pipes in the future.

Effects of Thickness and Winding Angle of Reinforcement Laminates on Burst Pressure Capacity of Thermoplastic Composite Pipes

The cross section of thermoplastic composite pipes (TCPs) consists of three layers: an inner liner, reinforcement laminates, and an outer jacket; the three layers are fully bonded together to form a solid-walled structure. In this study, the mechanical behaviors of TCPs under internal pressures were investigated using analytical and finite element analysis (FEA) methods. The analytical method that is based on the three-dimensional (3D) anisotropy elastic theory takes into account the nonuniform distribution of stresses and strains through the wall thickness of the pipe. FEA models were setup using the software abaqus to predict the stress distribution of a TCP. The 3D Tsai-Wu failure criterion was used to predict the maximum burst pressure of TCPs. Effects of winding angles and the number of reinforcement plies on the burst pressure of TCPs were studied. Results derived from the analytical method and the FEA method verified each other, which show that the burst pressure of a TCP increases asymptotically as the number of reinforcement plies increases. The optimal winding angle associated with the maximum burst pressure is not a constant value, instead, it varies as the thickness of the laminate layer increases. This study provides useful tools and guidance for the design and analysis of TCPs, while further validation experiments are still needed.