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Article
Publication date: 1 March 1941

R. Isermann and E. Beck

In the spring of 1937, take‐off tests down slopes of various gradients were carried out by the Flug‐technisch Institut. The gradients reached up to 35 deg. The…

Abstract

In the spring of 1937, take‐off tests down slopes of various gradients were carried out by the Flug‐technisch Institut. The gradients reached up to 35 deg. The experimental results are compared with calculation. The efficiency of this method of take‐off, together with its advantages and disadvantages, is investigated.

Details

Aircraft Engineering and Aerospace Technology, vol. 13 no. 3
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 26 March 2019

M.V.A. Raju Bahubalendruni, Anil Gulivindala, Manish Kumar, Bibhuti Bhusan Biswal and Lakshumu Naidu Annepu

The purpose of this paper is to develop an efficient hybrid method that can collectively address assembly sequence generation (ASG) and exploded view generation (EVG…

Abstract

Purpose

The purpose of this paper is to develop an efficient hybrid method that can collectively address assembly sequence generation (ASG) and exploded view generation (EVG) problem effectively. ASG is an act of finding feasible collision free movement of components of a mechanical product in accordance with the assembly design. Although the execution of ASG is complex and time-consuming in calculation, it is highly essential for efficient manufacturing process. Because of numerous limitations of the ASG algorithms, a definite method is still unavailable in the computer-aided design (CAD) software, and therefore the explosion of the product is not found to be in accordance with any feasible disassembly sequence (disassembly sequence is reverse progression of assembly sequence). The existing EVG algorithms in the CAD software result in visualization of the entire constituent parts of the product over single screen without taking into consideration the feasible order of assembly operations; thus, it becomes necessary to formulate an algorithm which effectively solves ASG and EVG problem in conjugation. This requirement has also been documented as standard in the “General Information Concerning Patents: 1.84 Standards for drawings” in the United States Patent and Trademark office (2005) which states that the exploded view created for any product should show the relationship or order of assembly of various parts that are permissible.

Design/methodology/approach

In this paper, a unique ASG method has been proposed and is further extended for EVG. The ASG follows a deterministic approach to avoid redundant data collection and calculation. The proposed method is effectively applied on products which require such feasible paths of disassembly other than canonical directions.

Findings

The method is capable of organizing the assembly operations as linear or parallel progression of assembly such that the assembly task is completed in minimum number of stages. This result is further taken for EVG and is found to be proven effective.

Originality/value

Assembly sequence planning (ASP) is performed most of the times considering the geometric feasibility along canonical axes without considering parallel possibility of assembly operations. In this paper, the proposed method is robust to address this issue. Exploded view generation considering feasible ASP is also one of the novel approaches illustrated in this paper.

Article
Publication date: 28 August 2007

M. Rezaiee‐Pajand and Cyrus Nasirai

This paper aims to provide a more rapid stress updating algorithm for von‐Mises plasticity with mixed‐hardening and to compare it with the previous works.

Abstract

Purpose

This paper aims to provide a more rapid stress updating algorithm for von‐Mises plasticity with mixed‐hardening and to compare it with the previous works.

Design/methodology/approach

An augmented stress vector is defined. This can convert the original nonlinear differential equation system to a quasi‐linear one. Then the dynamical system can be solved with an exponential map approach in a semi‐implicit manner.

Findings

The presented stress updating algorithm gives very accurate results and it has a quadratic convergence rate.

Research limitations/implications

Von‐Mises plasticity in a small strain regime is considered. Furthermore, the material is supposed to have linear hardening.

Practical implications

Stress updating is the heart of a nonlinear finite element analysis due to the large consumption of computation time. The efficiency and accuracy of the calculations of nonlinear finite element analysis are strongly influenced by the efficiency and accuracy of stress updating schemes.

Originality/value

The paper offers a new stress updating strategy based on exponential maps. This may be used as a routine in a nonlinear finite element analysis software to enhance its performance.

Details

Engineering Computations, vol. 24 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 27 September 2011

Qiang Liu and Chengen Wang

The purpose of this paper is to develop a new rectilinear branch pipe‐routing algorithm for automatic generation of rectilinear branch pipe routes in constrained spaces of…

Abstract

Purpose

The purpose of this paper is to develop a new rectilinear branch pipe‐routing algorithm for automatic generation of rectilinear branch pipe routes in constrained spaces of aero‐engines.

Design/methodology/approach

Rectilinear branch pipe routing that connects multiple terminals in a constrained space with obstacles can be formulated as a rectilinear Steiner minimum tree with obstacles (RSMTO) problem while meeting certain engineering rules, which has been proved to be an NP‐hard and discrete problem. This paper presents a discrete particle swarm optimization (PSO) algorithm for rectilinear branch pipe routing (DPSO‐RBPRA) problems, which adopts an attraction operator and an energy function to plan the shortest collision‐free connecting networks in a discrete graph space. Moreover, this paper integrates several existing techniques to evaluate particles for the RSMTO problem in discrete Manhattan spaces. Further, the DPSO‐RBPRA is extended to surface cases to adapt to requirements of routing pipes on the surfaces of aero‐engines.

Findings

Pipe routing numeral computations show that, DPSO‐RBPRA finds satisfactory connecting networks while considering several engineering rules, which demonstrates the effectiveness of the proposed method.

Originality/value

This paper applies the Steiner tree theory and develops a DPSO algorithm to plan the aero‐engine rectilinear branch pipe‐routing layouts.

Article
Publication date: 18 August 2021

Nadim S. Hmeidat, Bailey Brown, Xiu Jia, Natasha Vermaak and Brett Compton

Mechanical anisotropy associated with material extrusion additive manufacturing (AM) complicates the design of complex structures. This study aims to focus on…

Abstract

Purpose

Mechanical anisotropy associated with material extrusion additive manufacturing (AM) complicates the design of complex structures. This study aims to focus on investigating the effects of design choices offered by material extrusion AM – namely, the choice of infill pattern – on the structural performance and optimality of a given optimized topology. Elucidation of these effects provides evidence that using design tools that incorporate anisotropic behavior is necessary for designing truly optimal structures for manufacturing via AM.

Design/methodology/approach

A benchmark topology optimization (TO) problem was solved for compliance minimization of a thick beam in three-point bending and the resulting geometry was printed using fused filament fabrication. The optimized geometry was printed using a variety of infill patterns and the strength, stiffness and failure behavior were analyzed and compared. The bending tests were accompanied by corresponding elastic finite element analyzes (FEA) in ABAQUS. The FEA used the material properties obtained during tensile and shear testing to define orthotropic composite plies and simulate individual printed layers in the physical specimens.

Findings

Experiments showed that stiffness varied by as much as 22% and failure load varied by as much as 426% between structures printed with different infill patterns. The observed failure modes were also highly dependent on infill patterns with failure propagating along with printed interfaces for all infill patterns that were consistent between layers. Elastic FEA using orthotropic composite plies was found to accurately predict the stiffness of printed structures, but a simple maximum stress failure criterion was not sufficient to predict strength. Despite this, FE stress contours proved beneficial in identifying the locations of failure in printed structures.

Originality/value

This study quantifies the effects of infill patterns in printed structures using a classic TO geometry. The results presented to establish a benchmark that can be used to guide the development of emerging manufacturing-oriented TO protocols that incorporate directionally-dependent, process-specific material properties.

Details

Rapid Prototyping Journal, vol. 27 no. 8
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 7 August 2021

Tagir Z. Muslimov and Rustem A. Munasypov

This paper aims to propose a multi-agent approach to adaptive control of fixed-wing unmanned aerial vehicles (UAVs) tracking a moving ground target. The approach implies…

Abstract

Purpose

This paper aims to propose a multi-agent approach to adaptive control of fixed-wing unmanned aerial vehicles (UAVs) tracking a moving ground target. The approach implies that the UAVs in a single group must maintain preset phase shift angles while rotating around the target so as to evaluate the target’s movement more accurately. Thus, the controls should ensure that the UAV swarm follows a moving circular path whose center is the target while also attaining and maintaining a circular formation of a specific geometric shape; and the formation control system is capable of self-tuning because the UAV dynamics is uncertain.

Design/methodology/approach

This paper considers two interaction architectures: an open-chain where each UAV only interacts with its neighbors; and a cooperative leader, where the leading UAV is involved in attaining the formation. The cooperative controllers are self-tuned by fuzzy model reference adaptive control (MRAC).

Findings

Using open-chain decentralized architecture allows to have an unlimited number of aircraft in a formation, which is in line with the swarm behavior concept. The approach was tested for efficiency and performance in various scenarios using complete nonlinear flying-wing UAV models equipped with configured standard autopilot models.

Research limitations/implications

Assume the target follows a rectilinear trajectory at a constant speed. The speed is supposed to be known in advance. Another assumption is that the weather is windless.

Originality/value

In contrast to known studies, this one uses Lyapunov guidance vector fields that are direction- and magnitude-nonuniform. The overall cooperative controller structure is based on a decentralized and centralized consensus.

Details

Aircraft Engineering and Aerospace Technology, vol. 93 no. 7
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 1 November 1996

Félix Darve

Liquefaction phenomenon and its catastrophic nature can be analysed as a particular material behaviour of granular media under certain loading paths. Proposes a definition…

Abstract

Liquefaction phenomenon and its catastrophic nature can be analysed as a particular material behaviour of granular media under certain loading paths. Proposes a definition of liquefaction and its modelling by constitutive relations. Discusses this modelling in relation to the questions of stability and uniqueness. Considers the signs of three scalar quantities: the work of second order, the determinant of the symmetric part of the tangent constitutive tensor and the determinant of the tensor itself. Concludes that the liquefaction path is situated inside a potentially unstable domain and that in some cases this path reaches some states of loss of uniqueness, which are essentially bifurcation points.

Details

Engineering Computations, vol. 13 no. 7
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 December 1957

G.V.E. Thompson

Data on the behaviour of materials at high temperatures are needed to improve current designs for missile skins, rocket motors, gas turbines and nuclear applications, but…

Abstract

Data on the behaviour of materials at high temperatures are needed to improve current designs for missile skins, rocket motors, gas turbines and nuclear applications, but it is only within the last few years that new research tools have been developed to enable materials to bs studied under such conditions in the laboratory. This paper reviews the available techniques, with emphasis placed on the range 2,000–5,000 deg. K.: furnaces (electric resistance, induction, arc, solar), high‐intensity electric arcs, flames, combustion of molten metals, shock tubes, ultra‐high‐frequency are discharges, plasma jets, thermonuclear reactions.

Details

Aircraft Engineering and Aerospace Technology, vol. 29 no. 12
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 27 September 2011

Mohammad Rezaiee‐Pajand, Cyrus Nasirai and Mehrzad Sharifian

The purpose of this paper is to present a new effective integration method for cyclic plasticity models.

Abstract

Purpose

The purpose of this paper is to present a new effective integration method for cyclic plasticity models.

Design/methodology/approach

By defining an integrating factor and an augmented stress vector, the system of differential equations of the constitutive model is converted into a nonlinear dynamical system, which could be solved by an exponential map algorithm.

Findings

The numerical tests show the robustness and high efficiency of the proposed integration scheme.

Research limitations/implications

The von‐Mises yield criterion in the regime of small deformation is assumed. In addition, the model obeys a general nonlinear kinematic hardening and an exponential isotropic hardening.

Practical implications

Integrating the constitutive equations in order to update the material state is one of the most important steps in a nonlinear finite element analysis. The accuracy of the integration method could directly influence the result of the elastoplastic analyses.

Originality/value

The paper deals with integrating the constitutive equations in a nonlinear finite element analysis. This subject could be interesting for the academy as well as industry. The proposed exponential‐based integration method is more efficient than the classical strategies.

Article
Publication date: 9 February 2018

Yongzhuo Gao, Zhijiang Du, Xueshan Gao, Yanyu Su, Yu Mu, Li Ning Sun and Wei Dong

This paper aims to present an open-architecture kinematic controller, which was developed for articulated robots, facing the demands of various applications and low cost…

Abstract

Purpose

This paper aims to present an open-architecture kinematic controller, which was developed for articulated robots, facing the demands of various applications and low cost on robot system.

Design/methodology/approach

A general approach to develop this controller is described in hardware and software design. The hardware consists of embedded boards and programable multi-axes controller (PMAC), connected with ethernet, and the software is implemented on a robot operating system with MoveIt!. The authors also developed a teach pendant running as a LAN node to provide a human–machine interface (HMI).

Findings

The proposed approach was applied to several real articulated robot systems and was proved to be effective and portable. The proposed controller was compared with several similar systems to verify its integrality and flexibility. The openness of this controller was discussed and is summarized at the end of this paper.

Practical implications

The proposed approach provided an open and low-complex solution for experimental studies in the lab and short-run production in small workshops.

Originality/value

Several contributions are made by the research. The actuation model and communication were implemented to integrate the trajectory planning module and PMAC for setting up the physical interface. Method and program interface based on kinematics was provided to generate various interpolations for trajectory planning. A teach pedant with HMI was developed for controlling and programing the robot.

Details

Industrial Robot: An International Journal, vol. 45 no. 2
Type: Research Article
ISSN: 0143-991X

Keywords

1 – 10 of 189