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Article
Publication date: 4 October 2011

Mohammad Ghane, Iman Azimpour and Seyed A. Hosseini Ravandi

The purpose of this paper is to establish a simple and practical elastica model for the deflection of weft (warp) in a plain wave fabric.

Abstract

Purpose

The purpose of this paper is to establish a simple and practical elastica model for the deflection of weft (warp) in a plain wave fabric.

Design/methodology/approach

The weft yarn is considered as an elastic beam fixed supported at the ends and deflected in the middle by a vertical load. An analytical model, based on the elastic theory and small deflection case is adopted to study the factors affecting the deflection of the yarn. To investigate the model, yarns with different rigidities are used. A total of five different yarn counts are produced in the same ring spinning system and then used as weft yarn in a plain weave fabric. All other parameters of the yarns and the fabrics are kept identical. Fresh fabrics are analyzed and the maximum deflection of the weft is measured using the microscope. The actual curves of the deflected weft are then compared with the theoretical curves.

Findings

The experimental curves show to agree well with the theoretical model. The results also show that as yarn linear density decreases, the deflection increases.

Originality/value

The paper shows that while the large deformation “elastica” theory is typically used for woven fabric modeling, the small deflection theory can be useful for rapid computation.

Details

International Journal of Clothing Science and Technology, vol. 23 no. 5
Type: Research Article
ISSN: 0955-6222

Keywords

Article
Publication date: 2 November 2018

Jinwu Xiang, Kai Liu, Daochun Li, Chunxiao Cheng and Enlai Sha

The purpose of this paper is to investigate the unsteady aerodynamic characteristics in the deflection process of a morphing wing with flexible trailing edge, which is…

415

Abstract

Purpose

The purpose of this paper is to investigate the unsteady aerodynamic characteristics in the deflection process of a morphing wing with flexible trailing edge, which is based on time-accurate solutions. The dynamic effect of deflection process on the aerodynamics of morphing wing was studied.

Design/methodology/approach

The computational fluid dynamic method and dynamic mesh combined with user-defined functions were used to simulate the continuous morphing of the flexible trailing edge. The steady aerodynamic characteristics of the morphing deflection and the conventional deflection were studied first. Then, the unsteady aerodynamic characteristics of the morphing wing were investigated as the trailing edge deflects at different rates.

Findings

The numerical results show that the transient lift coefficient in the deflection process is higher than that of the static case one in large angle of attack. The larger the deflection frequency is, the higher the transient lift coefficient will become. However, the situations are contrary in a small angle of attack. The periodic morphing of the trailing edge with small amplitude and high frequency can increase the lift coefficient after the stall angle.

Practical implications

The investigation can afford accurate aerodynamic information for the design of aircraft with the morphing wing technology, which has significant advantages in aerodynamic efficiency and control performance.

Originality/value

The dynamic effects of the deflection process of the morphing trailing edge on aerodynamics were studied. Furthermore, time-accurate solutions can fully explore the unsteady aerodynamics and pressure distribution of the morphing wing.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 1
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 14 September 2010

Bian Tian, Yulong Zhao and Zhuangde Jiang

The purpose of this paper is to investigate the disadvantages of traditional sensors and establish a new structure for pressure measurement.

1248

Abstract

Purpose

The purpose of this paper is to investigate the disadvantages of traditional sensors and establish a new structure for pressure measurement.

Design/methodology/approach

A kind of novel piezoresistive micro‐pressure sensor with a cross‐beam membrane (CBM) structure is designed based on the silicon substrate. Through analyzing the stress distribution of the new structure by finite element method, the model of structure is established and compared with traditional structures. The fabrication is operated on silicon wafer, which applies the technology of anisotropy chemical etching and inductively coupled plasma.

Findings

Compared to the traditional C‐ and E‐type structures, this new CBM structure has the advantages of low nonlinearity and high sensitivities by the cross‐beam on the membrane, which cause the stress is more concentrated in sensitive area and the deflections that relate to the linearity are decreased.

Originality/value

The paper provides the first empirical reports on the new piezoresistive structure for the pressure measurement by fabricating a cross‐beam on the membrane and resolving the conflict of nonlinearity and sensitivity of the piezoresistive sensors.

Details

Sensor Review, vol. 30 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 1 October 2006

Nathan B. Crane, J. Wilkes, E. Sachs and Samuel M. Allen

Solid freeform fabrication processes such as three‐dimensional printing (3DP) and selective laser sintering (SLS) produce porous parts. Metal parts produced by these…

1549

Abstract

Purpose

Solid freeform fabrication processes such as three‐dimensional printing (3DP) and selective laser sintering (SLS) produce porous parts. Metal parts produced by these processes must be densified by sintering or infiltration to achieve maximum material performance. New steel infiltration methods can produce parts of standard alloy compositions with properties comparable to wrought materials. However, the infiltration process introduces dimensional errors due to both shrinkage and creep — particularly at the high temperatures required for steel infiltration. Aims to develop post‐processing method to reduce creep and shrinkage of porous metal skeletons.

Design/methodology/approach

The proposed process treats porous metal parts with a nanoparticle suspension that strengthens the bonds between particles to reduce creep and sintering shrinkage during infiltration. The process is tested by comparing the deflection and shrinkage of treated and untreated cantilevers heated to infiltration temperatures. The method is demonstrated with an iron nanoparticles suspension applied to parts made of 410 SS powder.

Findings

This process reduced creep by up to 95 percent and shrinkage by 50 percent. The best results were obtained using multiple applications of the nanoparticles dried under a magnetic field. Carbon deposited with the iron is shown to provide substantial benefit, but the iron is critical to establish strong bonds at low temperatures for minimal creep.

Research limitations/implications

This work shows that dimensional stability of porous metal skeletons during infiltration processes can be significantly improved by treatment with nanoparticles. The increased dimensional stability afforded by this technique can combine the excellent properties of homogenous infiltration with substantially improved part accuracy and open up new applications for this manufacturing technology.

Originality/value

The work shows how solid freeform fabrication processes can be improved.

Details

Rapid Prototyping Journal, vol. 12 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 April 1955

E.H. Mansfield and P.W. Kleeman

This report presents a simplified large‐deflexion theory for thin flat plates subjected to normal loading. The theory is applicable to plates in which the loading is…

Abstract

This report presents a simplified large‐deflexion theory for thin flat plates subjected to normal loading. The theory is applicable to plates in which the loading is resisted primarily by the flexural rigidity of the plate. The middle surface of the plate is assumed to be inextensional so that the mode of deformation is a developable surface. There is good agreement with experiment.

Details

Aircraft Engineering and Aerospace Technology, vol. 27 no. 4
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 5 February 2018

Fangwei Xie, Erming Ding, Rui Xuan, Xinxing Zhang, Yixian Feng and Jie Zhu

The purpose of this paper is to study the influence rules of geometric parameters on deformation of valve slices.

Abstract

Purpose

The purpose of this paper is to study the influence rules of geometric parameters on deformation of valve slices.

Design/methodology/approach

Based on the theory of flexural deformation of elastic thin slice, differential functions of deformation for both single and multi-slices are given and derived in detail. Furthermore, the effects of geometric dimensions on deformation are analyzed particularly by using Matlab/simulink.

Findings

The results indicated that the deformation decreases with the increment of fixed ring radius ra, slice thickness h, and its number n. Meanwhile, the deformation increases with a rise of slice radius rb, throttle position rk, the radius ratio λ1 and thickness ratio λ2 of slices.

Originality/value

This research can provide some theoretical supports for the parametric and optimal design of adjustable damping shock absorber.

Details

International Journal of Structural Integrity, vol. 9 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

Open Access
Article
Publication date: 14 August 2017

Venkatesh Kodur and Mohannad Z. Naser

This purpose of this paper is to quantify the effect of local instability arising from high shear loading on response of steel girders subjected to fire conditions.

1294

Abstract

Purpose

This purpose of this paper is to quantify the effect of local instability arising from high shear loading on response of steel girders subjected to fire conditions.

Design/methodology/approach

A three-dimensional nonlinear finite element model able to evaluate behavior of fire-exposed steel girders is developed. This model, is capable of predicting fire response of steel girders taking into consideration flexural, shear and deflection limit states.

Findings

Results obtained from numerical studies show that shear capacity can degrade at a higher pace than flexural capacity under certain loading scenarios, and hence, failure can result from shear effects prior to attaining failure in flexural mode.

Originality/value

The developed model is unique and provides valuable insight (and information) to the fire response of typical hot-rolled steel girder subjected to high shear loading.

Details

PSU Research Review, vol. 1 no. 2
Type: Research Article
ISSN: 2399-1747

Keywords

Article
Publication date: 20 March 2017

Yong Zhao, Jue Yu, Hao Wang, Genliang Chen and Xinmin Lai

This paper aims to propose an electromagnetic prismatic joint with variable stiffness. The joint can absorb the sudden shocks and improve the natural dynamics of robotics…

Abstract

Purpose

This paper aims to propose an electromagnetic prismatic joint with variable stiffness. The joint can absorb the sudden shocks and improve the natural dynamics of robotics. The ability of regulating the output stiffness can also be used for force control in industrial applications.

Design/methodology/approach

Unlike some existing designs of variable stiffness joints (VSJs) in which the stiffness regulation is implemented using the stiffness adjustment motor and mechanisms, the main structure of the electromagnetic VSJ is a permanent magnet (PM) arranged inside coaxial cylinder coils. The adjustment of input current can cause the change of magnetic force between the PM and the cylinder coils, and thus leads to the variation of output stiffness.

Findings

According to the theoretical model, the output stiffness of the electromagnetic VSJ is linearly proportional to the input current. The experiments further indicate that the current-controlled stiffness can make the stiffness variation response of this VSJ more rapid for practical applications. Due to the large damping introduced by the copper-based self-lubrication bearings, the VSJ shows good properties in motion positioning and trajectory tracking.

Originality/value

In summary, the electromagnetic VSJ is compact in size and light in weight. It is possible to realize the online adaptability to work conditions with dynamic load by using this VSJ.

Details

Industrial Robot: An International Journal, vol. 44 no. 2
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 1 July 1939

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National…

Abstract

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National Advisory Committee for Aeronautics and publications of other similar research bodies as issued

Details

Aircraft Engineering and Aerospace Technology, vol. 11 no. 7
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 7 October 2014

V. Kobelev

The purpose of this paper is to derive the exact analytical expressions for torsion and bending creep of rods with the Norton-Bailey, Garofalo and…

Abstract

Purpose

The purpose of this paper is to derive the exact analytical expressions for torsion and bending creep of rods with the Norton-Bailey, Garofalo and Naumenko-Altenbach-Gorash constitutive models. These simple constitutive models, for example, the time- and strain-hardening constitutive equations, were based on adaptations for time-varying stress of equally simple models for the secondary creep stage from constant load/stress uniaxial tests where minimum creep rate is constant. The analytical solution is studied for Norton-Bailey and Garofalo laws in uniaxial states of stress.

Design/methodology/approach

The creep component of strain rate is defined by material-specific creep law. In this paper the authors adopt, following the common procedure Betten, an isotropic stress function. The paper derives the expressions for strain rate for uniaxial and shear stress states for the definite representations of stress function. First, in this paper the authors investigate the creep for the total deformation that remains constant in time.

Findings

The exact analytical expressions giving the torque and bending moment as a function of the time were derived.

Research limitations/implications

The material isotropy and homogeneity preimposed. The secondary creep phase is considered.

Practical implications

The results of creep simulation are applied to practically important problem of engineering, namely for simulation of creep and relaxation of helical and disk springs.

Originality/value

The new, closed form solutions with commonly accepted creep models allow a deeper understanding of such a constitutive model's effect on stress and deformation and the implications for high temperature design. The application of the original solutions allows accurate analytic description of creep and relaxation of practically important problems in mechanical engineering. Following the procedure the paper establishes closed form solutions for creep and relaxation in helical, leaf and disk springs.

Details

Multidiscipline Modeling in Materials and Structures, vol. 10 no. 3
Type: Research Article
ISSN: 1573-6105

Keywords

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