Papers by Keyword: Twist

Abstract: Single point incremental forming (SPIF) is a choice of interest in many manufacturing industries due to its wide range of applications. Materials such as copper, aluminum, steel, and many others formed various complex shapes through this process. However, the forming process could sometimes result in process defects, which could strongly influence the formed parts' geometric accuracy. The twist defect is one of them, which incrementally twists the forming sheet with a small angle at each forming step. In this paper, twist phenomena in the SPIF process have been investigated both numerically and experimentally. In the experiment, Aluminum Alloy (AA5052) was used to form a truncated pyramid shape, and a room temperature tensile test has been conducted to achieve the material's tensile properties. Then, the material property used in the simulation study of the SPIF using LS-DYNA software, where twist defect, stresses, strain, and thickness distribution are studied. The results from simulation and experiment show significant similarity against the expected results and this conveys that the proposed FE model of the SPIF process can be used to investigate the presence of twist, distributions of stress and strain, and thinning locations in the formed part.

Abstract: In this paper, a novel continuum robot for search and rescue is presented. A detailed formulation of fundamentally new kinematic model is then introduced. Kinematic analysis adopt product of exponentials formula, compare with conventional D-H method, this method is concise and simplicity. Finally, the forward kinematic simulation is completed by Matlab software.

Abstract: This study examines the twist design of chenille yarns from theoretical consideration. Four kind of chenille yarns were selected for practice validation. The results indicate that there was little deviation between the twist under theoretical approach and the actual tested values; linear density of centre yarn and pile yarn, pile yarn density have significant effects on the twist design of chenille yarns.

Abstract: During the cold rolling forming of non-symmetric Z-section steel, the twist will appear because two sides of the blank suffering bending moments of the same direction. In this paper, simplified FE model was used to simulate the closing process of the rolls. The contact forces of the rollers on blank, and the stress and strain of the blank was obtained by FE analysis, and relations between section torque and the position angle θ as studied and the result that when θ=10⁰ the torque is minimum was discovered. The further detailed calculations showed that angle θ was only correlative with the geometry of the product section and didn’t change with the altering of material properties.

Abstract: In this paper the dynamics of updating designs of rotors with variable parameters developed during last fifteen years at the Georgian Technical University are presented. All the positive and negative appearances of each design have been analyzed and advantages of the last design based on the principles of ropes and hydro-system have been validated.

Abstract: From the angle of saving material, the author make the related computing, as well as compare and analysis to the biggest torsion shearing stress of the hollow or solid circle cross section shaft. Simultaneously it is elaborated, when the most torsion shearing stress of the hollow circular cross-section axis is smaller than the solid circular cross-section axis, the rule of economizing material and the change of the appearance size. Elaborate further, the related reasonable sizes are given, in order to have the prior adoptions during the design or transform. For example, the ratio of the hollow circle cross section shaft external diameter and inner diameter is two in the engineering, and the economical material is in 15%-inside 25% ranges.

Abstract: In order to explore the filtration performance of woven filter cloth to provide a design basis for filter cloth, the relationship of water permeability of filter cloth and fabric structural parameters is analyzed and studied by measuring the mass of water through the filter cloth within a specified time. The results show that water permeability rate of filter cloth decreases with the increase of fabric tightness, and the two assume the exponential function relationship. The relationship between yarn twist and water permeability rate assumes the linear positive correlation. The increase of yarn twist makes water permeability rate of filter cloth increase. The effect of textile weave on water permeability of filter cloth is that the water permeability rate of plain weave is the smallest and that of twill weave is the biggest.

Abstract: A new three-dimensional (3D) nonlinear guidance law is proposed and developed for bank-to-turn (BTT) with motion coupling. First of all, the 3D guidance model is established. In detail, the line-of-sight (LOS) rate model is established with the vector description method, and the kinematics model is divided into three terms of pitching, swerving and coupling, then by using the twist-based method, the LOS direction changing model is built for designing the guidance law with terminal angular constraints. Secondly, the 3D guidance laws are designed with Lyapunov theory, corresponding to no terminal constraints and terminal constraints, respectively. And finally, the simulation results show that the proposed guidance law can effectively satisfy the guidance precision requirements of BTT missile.

Abstract: The nerve system has the upmost role in coordinating the actions of an animal. It is, therefore, important to repair the damaged nerve to restore its functions. In this study, we braided poly(lactic acid) ply yarn into a tubular structure using a 16-spindle braiding machine, aiming at making a nerve conduit. The results showed that the poly(lactic acid) braid obtains the maximum tensile stress when the ratio of take-up gear and braid gear is 60/50. The extensibility of the produced braid makes it a suitable conduit for nerve regeneration.

Abstract: Yarns with high performance are more and more widely used in geotextiles. In this paper, the author researched the effect of twist on the tensile behaviors of high performance yarns. Due to the superior tensile strength of these yarns, the tensile tests can’t be operated on the normal textile yarns testing machine and all yarns were tested on the fabric strength tester. The results reveal that the tensile strength of yarns will firstly increase, and then decrease with the increasing twist. The simple analyses were also proposed to demonstrate this phenomenon.