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Article
Publication date: 7 August 2017

Xue Yang, Li Yu and Xiao-Shun Zhao

The purpose of this paper is to find optimal reef parameters to minimize the maximum instantaneous opening load for a reefed parachute with geometry and environmental…

Abstract

Purpose

The purpose of this paper is to find optimal reef parameters to minimize the maximum instantaneous opening load for a reefed parachute with geometry and environmental parameters given in the model.

Design/methodology/approach

The dynamic model Drop Test Vehicle Simulation (DTVSim) is used to model the inflation and descent of the reefed parachute system. It is solved by the fourth-order Runge–Kutta method, and the opening load values are thereby obtained. A parallel genetic algorithm (GA) code is developed to optimize the reefed parachute. A penalty scheme is used to have the maximum dynamic pressure restricted within a certain range.

Findings

The simulation results from DTVSim fit well with experimental data from drop tests, showing that the simulator has high accuracy. The one-stage and two-stage reefed parachute systems are optimized by GA and their maximum opening loads are decreased by 43 and 25 per cent, respectively. With the optimal reef parameters, two of the peaks in the opening load curve are almost equal. The velocity, loiter time and flight path angle of the parachute system all change, but these changes have no negative effect on the parachute’s operational performance.

Originality/value

An optimization method for reefed parachute design is proposed for the first time. This methodology can be used in the preliminary design phase for a reefed parachute system and significantly improve design efficiency.

Details

Engineering Computations, vol. 34 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 16 July 2021

Fatimah De’nan, Nor Salwani Hashim, Xing Yong Sua and Pui Yee Lock

Due to economic development, tapered members are commonly applied in steel frames, namely, industrial halls, warehouses, exhibition centres, etc. In the design of…

Abstract

Purpose

Due to economic development, tapered members are commonly applied in steel frames, namely, industrial halls, warehouses, exhibition centres, etc. In the design of cantilever steel beam structures in cities building design, tapering is introduced at the web profile to achieve utmost economy and suit the bending moment distributions. The cross-sectional shape of the beam is varied linearly to the moment gradient to achieve the target of higher efficiency with lower cost.

Design/methodology/approach

The shear deformation pattern and efficiency of the tapered steel section with perforation were investigated using finite element analysis. In addition, I-beam with web opening is studied numerically via LUSAS software for different parameters of tapering ratio, perforation shape and perforation size and perforation layout.

Findings

The highest contributing parameters for the highest shear buckling capacity and efficiency of the section were due to the small opening size and tapering ratio. Whilst the variation of perforation layout and spacing give a major effect on the shear strength and efficiency of the tapered steel section with perforation. Besides that, the highest efficiency model is found when the section is designed with 0.4 D diamond perforation in Layout 3 under a tapering ratio of 0.3. The critical shear buckling load and efficiency is reduced 14.39% and 13.91%, respectively, when perforations are added onto the tapered steel sections.

Originality/value

The tapered steel section with perforation has lower critical shear buckling load and efficiency compared to the tapered section without perforation but obtains a higher critical shear buckling load and efficiency compared to the uniform section without perforation.

Details

World Journal of Engineering, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 17 July 2009

Hamidreza Arabshahi and Vahid Lotfi

The purpose of this paper is to obtain an insight into the effects of sliding and/or joint opening at the contraction, perimeter and concrete lift joints on the nonlinear…

Abstract

Purpose

The purpose of this paper is to obtain an insight into the effects of sliding and/or joint opening at the contraction, perimeter and concrete lift joints on the nonlinear seismic response of arch dams.

Design/methodology/approach

The seismic behavior of a typical thin double curvature arch dam is studied by a nonlinear finite element program developed by the authors. Joints are modeled with the use of zero thickness interface elements. Various constitutive relationships are implemented to account for sliding and opening along the joints. Effects of joint sliding parameters and foundation rock flexibility are also considered in the analyses.

Findings

The findings provide information about dynamic stress distribution through the dam body and stability of the dam as a whole and also the local stability of the most critical concrete blocks in the dam body.

Practical implications

Useful information for designing new arch dams or seismic evaluation of constructed dams.

Originality/value

This paper takes into account the stability of concrete blocks in the dam body as well as stability of the structure as a whole. Except for contraction joints, perimeter and concrete lift joints are also modeled. Practical as well as detailed models of sliding are provided for the analyses. The paper offers practical help to design and dam engineers.

Details

Engineering Computations, vol. 26 no. 5
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 29 March 2011

Yong Tian and Tian Li

The purpose of this paper is to develop a novel type of full‐size flight control iron bird based on a passive electronic hydraulic servo loading system.

Abstract

Purpose

The purpose of this paper is to develop a novel type of full‐size flight control iron bird based on a passive electronic hydraulic servo loading system.

Design/methodology/approach

On the basis of mathematical modeling of passive loading system math model, the detailed design process of the flight control iron bird is presented. Subsequently, the system digital simulation and physical verification are also given.

Findings

Experimental results show that the proposed approach can reduce the redundant forces and improve the system dynamic and force‐tracking accuracy.

Practical implications

This newly‐developed flight control iron bird system has been successfully applied in the flight control system design of some fighters.

Originality/value

The proposed approach for flight control iron bird is new and significant for the design of fighter flight control systems.

Details

International Journal of Intelligent Computing and Cybernetics, vol. 4 no. 1
Type: Research Article
ISSN: 1756-378X

Keywords

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Article
Publication date: 1 June 1959

THE opening months of the last war were conducted in a very leisurely fashion because the expected disasters had not befallen us. Not until our armies were rescued from…

Abstract

THE opening months of the last war were conducted in a very leisurely fashion because the expected disasters had not befallen us. Not until our armies were rescued from the beaches of Dunkirk did the stark realities of the situation percolate into the public mind. Once the facts were understood the whole country was galvanised into activity.

Details

Work Study, vol. 8 no. 6
Type: Research Article
ISSN: 0043-8022

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Article
Publication date: 6 February 2017

Sayed Behzad Talaeitaba, Hamed Esmaeili and Mohammad Ebrahim Torki

Steel shear walls have recently received exclusive remark. Respective of most building code requirements, design of shear wall vertical boundary elements (VBEs) and local…

Abstract

Purpose

Steel shear walls have recently received exclusive remark. Respective of most building code requirements, design of shear wall vertical boundary elements (VBEs) and local boundary elements (LBEs) against web yielding triggers exaggerated stiffness. The extent of stiffness reduction effects in boundary elements thus calls for more exhaustive investigation. The paper aims to discuss these issues.

Design/methodology/approach

To this end, FEM-based push-over curves demonstrating base shear vs roof displacement, and von Mises plastic strains were scrutinized in half-scale and full-size models. Analyses were in perfect conformity with experimental data.

Findings

With reference to the AISC requirement, up to 35 percent decrease in the VBE moments of inertia could be imparted in higher levels without the ultimate load capacity nor displacement to failure being reduced. Also considered was open shear walls with reduced or minimum-design LBEs, the latter being used in continuous or abridged form. LBEs could be used with a moment of inertia 80 percent smaller than required if only used in a continuous form. The effect due to opening geometry was negligible on loading capacity but distinguished on the post-yielding buckling-induced softening.

Practical implications

Light-weight design of low- to medium-level steel structures against earthquake loads.

Originality/value

With respect to continuous walls, the results are more comprehensive than those existing in the literature in that they combine the effects due to scale and orientation (horizontal or vertical) of boundary elements. The results for open shear walls are not only comprehensive but also original in a sense that they account for the influences induced by the opening type (door or window), orientation (horizontal or vertical), and design (full-length or abridged) of boundary elements, in reduced form, on the lateral stiffness of the frame.

Details

International Journal of Structural Integrity, vol. 8 no. 1
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 2 March 2021

Md. Jewel Rana, Md. Rakibul Hasan and Md. Habibur Rahman Sobuz

Application of appropriate shading device strategies in buildings can reduce direct solar heat gain through windows as well as optimize cooling and artificial lighting load

Abstract

Purpose

Application of appropriate shading device strategies in buildings can reduce direct solar heat gain through windows as well as optimize cooling and artificial lighting load. This study investigates the impact of common shading devices such as overhangs, fins, horizontal blinds, vertical blinds and drapes on energy consumption of an office building and suggests energy efficient shading device strategies in the contexts of unique Bangladeshi subtropical monsoon climate.

Design/methodology/approach

This research was performed through the energy simulation perspective of a prototype office building using a validated building energy simulation tool eQUEST. Around 100 simulation patterns were created considering various types of shading devices and building orientations. The simulation results were analysed comprehensively to find out energy-efficient shading device strategies.

Findings

Optimum overhang and fin height is equal to half of the window height in the context of the subtropical climate of Bangladesh. South and West are the most vulnerable orientations, and application of shading devices on these two orientations shows the highest reduction of cooling load and the lowest increment of lighting load. An existing building was able to save approximately 7.05% annual energy consumption by applying the shading device strategies that were suggested by this study.

Originality/value

The shading device strategies of this study can be incorporated into the Bangladesh National Building Code (BNBC) as new energy-efficient building design strategies because the BNBC does not have any codes or regulations regarding energy-efficient shading device. It can also be used as energy-efficient shading device strategies to other Southeast Asian countries with similar climatic contexts of Bangladesh.

Details

Smart and Sustainable Built Environment, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2046-6099

Keywords

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Article
Publication date: 1 August 1965

The Origins of the Argosy and its Progressive Development from the AW.66 through to the Hawker Siddeley Series 222 Argosy including a Description of the Various Freight…

Abstract

The Origins of the Argosy and its Progressive Development from the AW.66 through to the Hawker Siddeley Series 222 Argosy including a Description of the Various Freight Handling Systems Devised for Use with the Aircraft and Concluding with a Review of Operational Experience. ALTHOUGH it was some years later that the name Argosy was given to the aircraft, the project began in 1955 when Sir W. G. Armstrong‐Whitworth Aircraft were invited to tender for a Medium Transport Aircraft to meet OR.323. This requirement called for an aircraft capable of carrying a payload of 10,000 lb. over a stage length of 1,500 nautical miles, with operation from 2,000 yds. runways at I.S.A.C.+30 deg. C. It had a freight hold over 42 ft. long, 9 ft. wide and 8 ft. high with a built‐in ramp/door at the rear for loading and supplies dropping. Inward opening paratroop doors were fitted on each side of the rear fuselage and there was an outward opening freight‐cum‐passenger door on the port side of the front fuselage. In this proposal the company considered various approaches for the tail configuration, a twin‐tail boom layout, a single tail boom layout and a twin‐tail boom layout with the booms projecting from the rear of the fuselage. This last layout was the one selected for submission as it gave more freedom for the loading ramp and a stiff tail support. Fig. 1 shows a model of the aircraft, powered with two Napier Eland engines and known as the AW.66.

Details

Aircraft Engineering and Aerospace Technology, vol. 37 no. 8
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 14 November 2008

Virgínia Maria Rosito d'Avila, Daiane de Sena Brisotto and Eduardo Bittencourt

The purpose of this paper is to describe the development of an embedded crack finite element (FE) model for reinforced concrete (RC) structures, including a bond‐slip…

Abstract

Purpose

The purpose of this paper is to describe the development of an embedded crack finite element (FE) model for reinforced concrete (RC) structures, including a bond‐slip methodology to take into consideration the steel contribution in the rupture process, capable of capturing the global behavior of the structure as well as details of cracking phenomenon.

Design/methodology/approach

The reinforcement contribution is added in the equilibrium at element level in an embedded crack FE model, based on displacement localization lines inside the elements.

Findings

The model is able to determine the steel stress in the crack besides the volumetric average steel stress. It is shown that the steel stress in the crack can be considerable greater than the average value. Other important aspect detected is the contribution of the concrete softening in the steel stress in the crack and in the overall behavior. The number, the distribution and the opening of cracks can be estimated too.

Practical implications

The yield of the steel in the cracking process can be detected more precisely by this methodology, allowing a better design and understanding of RC structures. In addition, the knowledge of crack openings is an important information to predict corrosion and other degradation phenomena of the reinforcement bars.

Originality/value

The bond‐slip procedure is linked with the embedded crack model in an original way: sliding gives the crack width. Moreover, the inclusion of steel forces in the crack equilibrium balance was not a usual procedure and permits an understanding of reinforcement effect in both levels (macro and micro) studied in this work.

Details

Engineering Computations, vol. 25 no. 8
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 4 February 2014

Yuan Kang, Ding-Wen Yang, Sheng-Yan Hu, Yu-Hong Hung, De-Xing Peng and Shih-Kang Chen

This paper is the third part of a serial studies for constant and variable compensations of the closed-type hydrostatic thrust bearings which has face-to-face recesses…

Abstract

Purpose

This paper is the third part of a serial studies for constant and variable compensations of the closed-type hydrostatic thrust bearings which has face-to-face recesses couple. The static stiffness of closed-type hydrostatic thrust bearings can then be obtained from the differentiation of recess pressure with respect to worktable displacement. The paper aims to discuss these issues.

Design/methodology/approach

In this paper, the double-action restrictors of cylindrical-spool-type and tapered-spool-type are taken into consideration for variable compensation of hydrostatic bearings.

Findings

The static stiffness in thrust direction of hydrostatic bearing is determined by the flow continuity equations that are formulated by film flow and compensation flow for each recess, respectively. The type selection and parameter determination of the double-action spool-type restrictors can be obtained from finding results of this study for maximum stiffness in design of hydrostatic bearings.

Originality/value

This study reveals that the appropriate range of recess pressure ratio and design parameters of restrictors for the maximum stiffness can be obtained, the avoidance of negative stiffness is also provided.

Details

Industrial Lubrication and Tribology, vol. 66 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

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