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Article
Publication date: 5 June 2019

Apostolos Koukouselis, Konstantinos Chatziioannou, Euripidis Mistakidis and Vanessa Katsardi

The design of compliant towers in deep waters is greatly affected by their dynamic response to wave loads as well as by the geometrical and material nonlinearities that…

Abstract

Purpose

The design of compliant towers in deep waters is greatly affected by their dynamic response to wave loads as well as by the geometrical and material nonlinearities that appear. In general, a nonlinear time history dynamic analysis is the most appropriate one to be applied to capture the exact response of the structure under wave loading. However, this type of analysis is complex and time-consuming. This paper aims to develop a simplified methodology, which can adequately approximate the maximum response yielded by a dynamic analysis by means of a static analysis.

Design/methodology/approach

Various types of time history dynamic analysis are first applied on a detailed structural model, ranging from linear to fully nonlinear, that are used as reference solutions. In the sequel, a simplified analysis model is formulated, capable of reproducing the response of the entire structure with significantly reduced computational cost. In the next stage, this model is used to obtain the linear and nonlinear response spectra of the structure. Finally, these spectra are used to formulate a simplified design approach, based on equivalent static loads.

Findings

This simplified design approach produces good results in cases that the response is mainly governed by the first eigenmode, which is the case when compliant towers are considered.

Originality/value

The present paper borrows ideas from the area of earthquake engineering, where simplified methodologies can be used for the design of a certain class of structures. However, the development of a simplified methodology for the approximation of the dynamic behavior of offshore structures under wave loading is a much more complex problem, which, to the authors’ knowledge, has not been addressed till now.

Details

Engineering Computations, vol. 36 no. 4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 13 June 2016

Lei Wang, Xiaojun Wang and Xiao Li

– The purpose of this paper is to focus on the influences of the uncertain dynamic responses on the reconstruction of loads.

Abstract

Purpose

The purpose of this paper is to focus on the influences of the uncertain dynamic responses on the reconstruction of loads.

Design/methodology/approach

Based on the assumption of unknown-but-bounded (UBB) noise, a time-domain approach to estimate the uncertain time-dependent external loads is presented by combining the inverse system method in modern control theory and interval analysis in interval mathematics. Inspired by the concept of set membership identification in control theory, an interval analysis model of external loads time history, which is indeed a region or feasible set containing all possible loads being consistent with the bounded structural acceleration responses is established and further solved by two interval algorithms.

Findings

Unlike traditional loads identification methods which only give a point estimation, an interval estimation of external loads time history, which is a region containing all the possible loads being consistent with the uncertain structural responses, is determined. The correlation characteristics among the responses of acceleration, velocity, and displacement are also discussed in consideration of the UBB uncertainty.

Originality/value

For one hand, the solution of the inverse problem in original system is transformed to the solution of the direct problem in inverse system; for another, the authors deal with the uncertainty by use of interval analysis method, and the identified interval process, which contains any possible external loads time history being consistent with the bounded structural responses can be approximately obtained.

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Article
Publication date: 11 November 2020

Duncai Lei, Xiannian Kong, Siyu Chen, Jinyuan Tang and Zehua Hu

The purpose of this paper is to investigate the dynamic responses of a spur gear pair with unloaded static transmission error (STE) excitation numerically and…

Abstract

Purpose

The purpose of this paper is to investigate the dynamic responses of a spur gear pair with unloaded static transmission error (STE) excitation numerically and experimentally and the influences of the system factors including mesh stiffness, error excitation and torque on the dynamic transmission error (DTE).

Design/methodology/approach

A simple lumped parameters dynamic model of a gear pair considering time-varying mesh stiffness, backlash and unloaded STE excitation is developed. The STE is calculated from the measured tooth profile deviation under the unloaded condition. A four-square gear test rig is designed to measure and analyze the DTE and vibration responses of the gear pair. The dynamic responses of the gear transmission are studied numerically and experimentally.

Findings

The predicted numerical DTE matches well with the experimental results. When the real unloaded STE excitation without any approximation is used, the dynamic response is dominated by the mesh frequency and its high order harmonic components, which may not be result caused by the assembling error. The sub-harmonic and super-harmonic resonant behaviors are excited because of the high order harmonic components of STE. It will not certainly prevent the separations of mesh teeth when the gear pair is under the condition of high speed and heavy load.

Originality/value

This study helps to improve the modeling method of the dynamic analysis of spur gear transmission and provide some reference for the understanding of the influence of mesh stiffness, STE excitation and system torque on the vibration behaviors.

Details

Engineering Computations, vol. 38 no. 6
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 21 June 2011

Jianjun Wang, Yizhong Ma and Guojin Su

The purpose of this paper is to propose a new method of robust parameter design for dynamic multi‐response system. The objectives are to resolve the correlations among…

Abstract

Purpose

The purpose of this paper is to propose a new method of robust parameter design for dynamic multi‐response system. The objectives are to resolve the correlations among multiple responses and the uncertainty of system with incomplete information.

Design/methodology/approach

First, desirability function is used to measure dynamic system sensitivity and system variation, and principal component analyses on the two indices are conducted. Second, the grey relational grade (GRD) between principal component sequences of the two indices and their respective ideal sequences, gained by grey relational analysis, is converted to an integrated GRD (IGRD) index by means of TOPSIS method, and then the optimal level combination of controllable factors is identified based on the IGRD index.

Findings

It was found that the optimal factor level combination obtained by the proposed method is nearest the ideal solution and farthest from the negative ideal solution. The validity and superiority of the proposed method are confirmed through two illustrative examples.

Research limitations/implications

It should be noted that the proposed method fails to consider the interaction effects between controllable factors and noise factors.

Originality/value

The method proposed in the paper effectively integrates several common methods to optimize a dynamic multiple responses system based on Taguchi's robust parameter design. These methods do not involve complicated mathematical theory, and are therefore easy for practitioners to use in engineering practice.

Details

Asian Journal on Quality, vol. 12 no. 1
Type: Research Article
ISSN: 1598-2688

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Article
Publication date: 13 November 2017

Zhiwei Wang, Yi Liu and Feng Wang

The purpose of this paper is to establish a simplified model of the closed hydrostatic guideway for the rapid analysis of static and dynamic characteristics. Further, the…

Abstract

Purpose

The purpose of this paper is to establish a simplified model of the closed hydrostatic guideway for the rapid analysis of static and dynamic characteristics. Further, the influence of compressibility and dynamic frequency are taken into consideration in the new dynamic model.

Design/methodology/approach

The new model is based on the second kind of Lagrange equation. In this model, the closed hydrostatic guideway is supported by 12 pads, and each oil pad is equivalent to a nonlinear spring-damper system. The equivalent spring coefficient and damper coefficient of the oil pad are extracted by the three different equivalent methods. Finally, the validation experiments of step load response and dynamic stiffness are conducted on a hydrostatic guideway.

Findings

For solving the step response, the linear spring-damper model and the nonlinear spring-damper Model 1 are better than the nonlinear spring-damper Model 2. The accuracy of the three methods are very high for static stiffness calculation. For the calculation of dynamic stiffness, the nonlinear spring-damper Model 2 is better than the nonlinear spring-damper Model 1. The linear spring-damper model has low precision for dynamic stiffness calculation, especially at high frequency. The accuracy of the new model is validated by experiments.

Originality/value

The equivalent method of nonlinear spring-damper system has higher accuracy. Different equivalent methods should be adopted for different load types. The computational speeds of the new dynamic model with the three methods are much better than finite element method (about ten times).

Details

Industrial Lubrication and Tribology, vol. 69 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 11 February 2021

Guichen Zhang, Heng Peng, Hongtao Zhang, Juzhen Tang and Yinghua Liu

The safety assessment of engineering structures under repeated variable dynamic loads such as seismic and wind loads can be considered as a dynamic shakedown problem. This…

Abstract

Purpose

The safety assessment of engineering structures under repeated variable dynamic loads such as seismic and wind loads can be considered as a dynamic shakedown problem. This paper aims to extend the stress compensation method (SCM) to perform lower bound dynamic shakedown analysis of engineering structures and a double-closed-loop iterative algorithm is proposed to solve the shakedown load.

Design/methodology/approach

The construction of the dynamic load vertexes is carried out to represent the loading domain of a structure under both dynamic and quasi-static load. The SCM is extended to perform lower bound dynamic shakedown analysis of engineering structures, which constructs the self-equilibrium stress field by a series of direct iteration computations. The self-equilibrium stress field is not only related to the amplitude of the repeated variable load but also related to its frequency. A novel double-closed-loop iterative algorithm is presented to calculate the dynamic shakedown load multiplier. The inner-loop iteration is to construct the self-equilibrated residual stress field based on the certain shakedown load multiplier. The outer-loop iteration is to update the dynamic shakedown load multiplier. With different combinations of dynamic load vertexes, a dynamic shakedown load domain could be obtained.

Findings

Three-dimensional examples are presented to verify the applicability and accuracy of the SCM in dynamic shakedown analysis. The example of cantilever beam under harmonic dynamic load with different frequency shows the validity of the dynamic load vertex construction method. The shakedown domain of the elbow structure varies with the frequency under the dynamic approach. When the frequency is around the resonance frequency of the structure, the area of shakedown domain would be significantly reduced.

Research limitations/implications

In this study, the dynamical response of structure is treated as perfect elastoplastic. The current analysis does not account for effects such as large deformation, stochastic external load and nonlinear vibration conditions which will inevitably be encountered and affect the load capacity.

Originality/value

This study provides a direct method for the dynamical shakedown analysis of engineering structures under repeated variable dynamic load.

Details

Engineering Computations, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 7 August 2017

Esmaeil Salahshoor and Saeed Ebrahimi

The purpose of this paper is to investigate the effect of joint clearance on the behavior of a needle driver mechanism (a slider-crank linkage) of a typical sewing machine…

Abstract

Purpose

The purpose of this paper is to investigate the effect of joint clearance on the behavior of a needle driver mechanism (a slider-crank linkage) of a typical sewing machine with an imperfect joint between the coupler and the slider (including needle).

Design/methodology/approach

In order to model the clearance, the momentum exchange approach is used. The Lankarani and Nikravesh’s continuous contact force model is used to model the contact force, and the modified Coulomb’s friction law represents the friction between sliding members. The penetration force applied on the needle by fabric is chosen based on an experimental data in the literature. The dynamic response is validated for the existing properties in the literature without considering the penetration force.

Findings

It is shown that the clearance joint made considerable effect on the dynamic response of the system. The rough changes of the needle acceleration and jerk are obvious. The base reaction force changed roughly and did not vary as smooth as that of the mechanism with ideal joint. So, clearance joint in the mechanism could lead to an undesirable vibration in the system. Furthermore, the crank driver must provide a non-smooth moment on the crank to keep the crank rotational velocity constant. Moreover, reducing the clearance size sufficiently could make the dynamic response closer to that of the mechanism with ideal joint. In addition, smoother crank moment could be required if the clearance size is reduced sufficiently. Furthermore, the rough change of the base reaction force which can represent the vibration caused by the mechanism on the fixed frame could be reduced if the clearance size is small enough.

Originality/value

Lockstitch sewing machine is one of the most common apparel industrial machines. The needle driver mechanism of a sewing machine could have an important role for proper stitch forming. On the other hand, clearances are inevitable in assemblage of mechanisms to allow the relative motion between the members. This clearance is due to machining tolerances, wear, material deformations, and imperfections, and it can worsen mechanism performance such as precision, dynamic behavior and vibration. Unfortunately, despite the importance of the dynamic behavior of the needle driver mechanism from practical point of view, very little publications have focused especially on the investigation of the effect of clearance joint on the dynamic behavior of the sewing machine which could lead to undesired vibration of the system and shorter lifetime as a result. In this paper, the dynamic behavior of the system including, needle velocity and acceleration, crank moment and base reaction force was compared with that of the ideal mechanism. Finally, the effect of clearance size on the dynamic behavior of the system was investigated.

Details

International Journal of Clothing Science and Technology, vol. 29 no. 4
Type: Research Article
ISSN: 0955-6222

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Article
Publication date: 22 October 2019

Xiantao Zhang and Wei Liu

In the coupling of aircraft pipeline structures, current research works mainly focus on fluid-solid coupling effects or a single part of structure vibration like a…

Abstract

Purpose

In the coupling of aircraft pipeline structures, current research works mainly focus on fluid-solid coupling effects or a single part of structure vibration like a pipeline. Because of the clamp, the pipe vibration caused by fluid pulsation was transmitted to the body, and the body vibration was also transmitted to the pipe structure. Thus, the relationship between the airframe and the pipeline system cannot be separated, and the influence of airframe needs to be considered when coupling structure under vibration. The paper aims to discuss these issues.

Design/methodology/approach

This paper aims to investigate the influence of pipeline layouts on airframe-clamps-pipeline (ACP) structure’s dynamic response by experiment and simulation method. First, ACP structures are established including three parts. The natural frequencies and mode shapes are obtained by hammering experiment. The mode results are in agreement with numerical simulation. By using electromagnetic vibration shaker, extinction is applied on ACP structure, and then the dynamic responses of structure can be obtained by test equipments. The influence principle of pipeline layouts is obtained by dynamic response analysis. The present study provides a method for pipeline layout design in aerospace engineering.

Findings

Under the ACP’s first-order resonance frequency excitation, the maximum stress increases when the Z-shaped pipeline bending position changes from 1/2 to 1/5. The opposite way occurs under the only pipeline resonance frequency excitation. The stress amplitudes near both sides (inner and outer) of the clamp on the plate surface change with the excitation frequency. Under the ACP’s first-order resonance frequency excitation, the outer side stress is larger than the inner side stress, but under the only pipeline resonance frequency excitation, the inner side stress is larger than the outer side stress.

Originality/value

The study of the effect of pipeline layout parameters on ACP structure provides a method for pipeline layout design in aerospace engineering.

Details

Multidiscipline Modeling in Materials and Structures, vol. 16 no. 2
Type: Research Article
ISSN: 1573-6105

Keywords

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Article
Publication date: 12 November 2010

Wei Liu, Yongshou Liu and Zhufeng Yue

Pressure pulsations and vibration working condition lead to dynamic troubles in hydraulic devices. It is highly desirable to be able to estimate the durability at the…

Abstract

Purpose

Pressure pulsations and vibration working condition lead to dynamic troubles in hydraulic devices. It is highly desirable to be able to estimate the durability at the design stage so that appropriate maintenance period can be determined for safety and reliability. The purpose of this paper is to propose a quantitative evaluation method for pulsation and vibration based on reliability.

Design/methodology/approach

Pressure pulsations are approximately treaded as a stationary random process. The principle of transform function and fluid network chain rules are used to disassemble the hydraulic power unit into the series‐system. Mean square deviation of dynamic stress under the pumping source white noise exciting was calculated based on frequency responses. Statistical regularity of displacement and stress responses of pipelines under external random vibration are obtained by the spectrum analysis. Both the first‐passage failure criterion and fatigue damage accumulation failure criterion are adopted to analyze the dynamic pressure reliability of hydraulic pipelines.

Findings

The terminal joint, bellow pipe and pipe clamps are verified as the weak location of the pipelines. The mean square deviations of pulsations and vibration response influence the pipelines reliability. The results indicated that the preventative design method of controlling the pressure below 10 per cent of rated pressure does not meet the security specification of the hydraulic power unit.

Originality/value

The paper proposes a quantitative evaluation method for random pressure pulsation and external vibration based on reliability, which provides a new approach for the safety assessment and design of hydraulic pipelines.

Details

Multidiscipline Modeling in Materials and Structures, vol. 6 no. 4
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 1 February 1989

Harn C. Chen and Robert L. Taylor

The Lanczos vectors and the Ritz vectors have been used for computing the dynamic response of linear structures. Although the procedures of using these two sets of vectors…

Abstract

The Lanczos vectors and the Ritz vectors have been used for computing the dynamic response of linear structures. Although the procedures of using these two sets of vectors appear similar to the procedure of using the eigenvectors to find an approximate solution, the fundamental mechanisms of the three are different. We compare the three sets of vectors in detail to show some of the important differences in the hope that this comparison will be helpful to the use of the Lanczos vectors or the Ritz vectors for computing dynamic responses.

Details

Engineering Computations, vol. 6 no. 2
Type: Research Article
ISSN: 0264-4401

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