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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 investigating the…

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: 1 August 2016

Wenling Lu and David A. Whidbee

This paper aims to examine the characteristics of banks that were the target of intervention in the form of bailout or failure during the financial crisis and, of those subjected…

Abstract

Purpose

This paper aims to examine the characteristics of banks that were the target of intervention in the form of bailout or failure during the financial crisis and, of those subjected to intervention, what characteristics distinguish those that received bailout funds from those that were deemed failures.

Design/methodology/approach

The study estimates a series of logit regressions in an effort to identify the causes of regulatory intervention while controlling for bank-level characteristics and the economic and regulatory environment.

Findings

The empirical results indicate that many of the same characteristics associated with banks receiving bailout funds are similar to the characteristics associated with failed banks. However, non-performing loans increased the likelihood of failure, but reduced the likelihood of a bank receiving Capital Purchase Program (CPP) funds, suggesting that regulatory authorities discriminated in their use of CPP funds based on the quality of a bank’s asset portfolio. Further, those banks located in states with limits on de novo branching and those banks that are part of a multi-bank holding company structure were less likely to fail but were more likely to receive CPP funds.

Originality/value

This paper provides a comprehensive analysis of regulatory intervention in the banking industry during the late 2000s financial crisis and the impact of different banking organizational structures, economic circumstances, and financial fragility on the likelihood of a bank failing or receiving bailout funds.

Details

Journal of Financial Economic Policy, vol. 8 no. 3
Type: Research Article
ISSN: 1757-6385

Keywords

Article
Publication date: 4 September 2023

Xuanzhi Li, Suduo Xue, Xiongyan Li, Guanchen Liu and Renjie Liu

Instantaneous unloading with equal force is usually used to simulate the sudden failure of cables. This simulation method with equivalent force requires obtaining the magnitude…

Abstract

Purpose

Instantaneous unloading with equal force is usually used to simulate the sudden failure of cables. This simulation method with equivalent force requires obtaining the magnitude and direction of the force for the failed cable in the normal state. It is difficult, however, to determine the magnitude or direction of the equivalent force when the shape of the cable is complex (space curve). This model of equivalent force may be difficult to establish. Thus, a numerical simulation method, the instantaneous temperature rise method, was proposed to address the dynamic response caused by failures of the cables with complex structural form.

Design/methodology/approach

This method can instantly reduce the cable force to zero through the instantaneous temperature rise process of the cable. Combined with theoretical formula and finite element model, the numerical calculation principle and two key parameters (temperature rise value and temperature rise time) of this method were detailed. The validity of this approach was verified by comparing it with equivalent force models. Two cable-net case with saddle curved surfaces were presented. Their static failure behaviors were compared with the dynamic failure behaviors calculated by this method.

Findings

This simulation method can effectively address the structural dynamic response caused by cable failure and may be applied to all cable structures.

Originality/value

An instantaneous temperature rise method (ITRM) is proposed and verified. Its calculation theory is detailed. Two key parameters, temperature rise value and temperature rise time, of this method are discussed and the corresponding reference values are recommended.

Details

Engineering Computations, vol. 40 no. 9/10
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 July 2014

Fábio Ribeiro Soares da Cunha, Tobias Wille, Richard Degenhardt, Michael Sinapius, Francisco Célio de Araújo and Rolf Zimmermann

This paper aims to present a new robustness-based design strategy for thin-walled composite structures under compressive loading, which combines strength requirements in terms of…

Abstract

Purpose

This paper aims to present a new robustness-based design strategy for thin-walled composite structures under compressive loading, which combines strength requirements in terms of the limit and ultimate load with robustness requirements evaluated from the structural energy until collapse.

Design/methodology/approach

In order to assess the structural energy, the area under the load-shortening curve between several characteristic points such as local buckling, global buckling, onset of degradation and collapse load is calculated. In this context, a geometrically nonlinear finite element analysis is carried out, in which the ply properties are selectively degraded by progressive failure.

Findings

The advantage of the proposed methodology is observed by analyzing unstiffened composite plates under compressive loading, wherein the lightest plate that satisfies both strength and robustness requirements can be attained.

Practical implications

As a practical implication, this methodology gives a new argument to accept the collapse load close to the ultimate load once robustness is ensured.

Originality value

The structural energy is employed to investigate the robustness of thin-walled composite structures in postbuckling, and new energy-based robustness measures are proposed. In the design of composite structures, this innovative strategy might lead to a more robust design when compared to an approach that only accounts for the ultimate load.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 86 no. 4
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 1 March 1984

Dan M. Frangopol

The paper attempts to establish the connection between structural reliability and structural optimization for the particular case of plastic structures. Along this line, the paper…

Abstract

The paper attempts to establish the connection between structural reliability and structural optimization for the particular case of plastic structures. Along this line, the paper outlines a reliability‐based optimization approach to design plastic structures with uncertain interdependent strengths and acted on by random interdependent loads. The importance of such interdependencies, and of some of the other statistical parameters used as input data in probabilistic computations, is demonstrated by several examples of sensitivity studies on both the probability of collapse failure as well as the reliability‐based optimum solution.

Details

Engineering Computations, vol. 1 no. 3
Type: Research Article
ISSN: 0264-4401

Article
Publication date: 8 July 2022

Da Teng, Yun-Wen Feng, Jun-Yu Chen and Cheng Lu

The purpose of this paper is to briefly summarize and review the theories and methods of complex structures’ dynamic reliability. Complex structures are usually assembled from…

Abstract

Purpose

The purpose of this paper is to briefly summarize and review the theories and methods of complex structures’ dynamic reliability. Complex structures are usually assembled from multiple components and subjected to time-varying loads of aerodynamic, structural, thermal and other physical fields; its reliability analysis is of great significance to ensure the safe operation of large-scale equipment such as aviation and machinery.

Design/methodology/approach

In this paper for the single-objective dynamic reliability analysis of complex structures, the calculation can be categorized into Monte Carlo (MC), outcrossing rate, envelope functions and extreme value methods. The series-parallel and expansion methods, multi-extremum surrogate models and decomposed-coordinated surrogate models are summarized for the multiobjective dynamic reliability analysis of complex structures.

Findings

The numerical complex compound function and turbine blisk are used as examples to illustrate the performance of single-objective and multiobjective dynamic reliability analysis methods. Then the future development direction of dynamic reliability analysis of complex structures is prospected.

Originality/value

The paper provides a useful reference for further theoretical research and engineering application.

Details

International Journal of Structural Integrity, vol. 13 no. 5
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 12 December 2023

Muzamil Ahmad Rafiqii, M.A. Lone and M.A. Tantray

This study aims to provide a review for scour in complex rivers and streams with coarser bed material, steep longitudinal bed slopes and dynamic environments, in the interest of…

Abstract

Purpose

This study aims to provide a review for scour in complex rivers and streams with coarser bed material, steep longitudinal bed slopes and dynamic environments, in the interest of the safety and the economy of hydraulic structures. The knowledge of scour in such geographical complexities is very crucial for a comprehensive understanding of scour failures and for establishing definitive criteria to bridge this major research gap.

Design/methodology/approach

The existing available literature shows significant work done in case of silt, sand and small sized coarser bed material but any substantial work for bed material of gravel size or above is lacking, resulting in a wide gap. Though some researchers have attempted to explore possibilities of refining the existing models by adding pier size, shape, sediment non-uniformity and armouring effects, which otherwise have been given a miss by the various researchers, including the pioneer in the field Lacey–Inglis (1930). But still, a rational model for scour estimation in such complex conditions for global use is yet to come. This is because all the parameters governing the scour have not been studied properly till date as is evident from the globally available literature and is witnessed in the field too, in recurrent failure of hydraulic structures especially bridges.

Findings

The researchers presume that the finer materials move only as a result of erosion. However, in actual field conditions, it has been observed that the large-sized stones also roll down and cause huge erosion along the river bed and damage the hydraulic structures, especially in the steep river/stream beds along hilly slopes. This fact has been overlooked in the models available globally and has been highlighted only in the current work in an attempt to recognize this major research gap. A study carried out on a number of streams globally and in Jammu and Kashmir, India also, has shown that in steep river and stream beds with bed material consisting of gravel size or greater than gravel, large scour holes ranging from 1 m to 5 m were created by furious floods, and due to other unknown forces along the channel path and near foundations of hydraulic structures.

Originality/value

To the best of the authors’ knowledge, this work is purely original.

Details

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

Keywords

Article
Publication date: 2 October 2017

Hossein Nematiyan Jelodar

Analysis of designing and controlling the failure of marine structures attached to the bottom of the sea under dynamic load obtained from the sea waves is one of the main…

Abstract

Purpose

Analysis of designing and controlling the failure of marine structures attached to the bottom of the sea under dynamic load obtained from the sea waves is one of the main engineering challenges in recent years. The circumstances of the onshore marine structures have their own complexity and the difficulty due to the effect of hydrodynamic factors and dynamic responses which are dominant in the marine environment. The paper aims to discuss these issues.

Design/methodology/approach

The structure elements are composed of the metal pipe with a length of 5 m, outside diameter of 20 cm and thickness of 1.5 mm. the failure control with a safety factor of 2 indicates the absence of the above marine structure failure. It has been diagnosed to be trustworthy and reliable.

Findings

In this study, the control of marine steel structure failure with the height of 60 m under the dynamic load of the sea water waves having sinusoidal shape in the Caspian Sea has been studied and analyzed.

Originality/value

In this paper, the minimum and maximum internal force and movement in six directions of freedom were obtained for each element. To analyze and control the failure, the combination of stresses caused by static and dynamic loads has been used. According to the regulation of 10-360-AISC, the control was conducted.

Details

International Journal of Structural Integrity, vol. 8 no. 5
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 17 August 2021

Amit Chandra, Anjan Bhowmick and Ashutosh Bagchi

The study investigates the performance of a three-story unprotected steel moment-resisting frame (SMRF) designed for high seismic demand in the fire-only (FO) and post-earthquake…

Abstract

Purpose

The study investigates the performance of a three-story unprotected steel moment-resisting frame (SMRF) designed for high seismic demand in the fire-only (FO) and post-earthquake uniform and traveling fires (PEF). The primary objective is to investigate the effects of seismic residual deformation on the structure's performance in horizontally traveling fires. The traveling fire methodology, unlike conventional fire models, considers a spatially varying temperature environment.

Design/methodology/approach

Multi-step finite element simulations were carried out on undamaged and damaged frames to provide insight into the effects of the earthquake-initiated fires on the local and global behavior of SMRF. The earthquake simulations were conducted using nonlinear time history analysis, whereas the structure in the fire was investigated by sequential thermal-structural analysis procedure in ABAQUS. The frame was subjected to a suite of seven ground motions. In total, four horizontal traveling fire sizes were considered along with the Eurocode (EC) parametric fire for a comparison. The deformation history, axial force and moment variation in the critical beams and columns of affected compartments in the fire heating and cooling regimes were examined. The global structural performance in terms of inter-story drifts in FO and PEF scenarios was investigated.

Findings

It was observed that the larger traveling fires (25 and 48%) are more detrimental to the case study frame than the uniform EC parametric fire. Besides, no appreciable difference was observed in time and modes of failure of the structure in FO and PEF scenarios within the study's parameters.

Originality/value

The present study considers improved traveling fire methodology as an alternate design fire for the first time for the PEF performance of SMRF. The analysis results add to the much needed database on structures' performance in a wide range of fire scenarios.

Details

Journal of Structural Fire Engineering, vol. 12 no. 4
Type: Research Article
ISSN: 2040-2317

Keywords

Article
Publication date: 23 August 2013

Rosario Borrelli, Francesco Di Caprio, Umberto Mercurio and Fulvio Romano

The main objective of this work is to assess the current capabilities of different commercial finite element (FE) codes in simulating the progressive damage of composite structures

Abstract

Purpose

The main objective of this work is to assess the current capabilities of different commercial finite element (FE) codes in simulating the progressive damage of composite structures under quasi-static loading condition in post-buckling regime.

Design/methodology/approach

Progressive failure analysis (PFA) methodologies, available in the investigated FE codes, were applied to a simple test case extracted from literature consisting in a holed composite plate loaded in compression.

Findings

Results of the simulations are significantly affected by the characteristic parameters needed to feed the degradation models implemented in each code. Such parameters, which often do not have a physical meaning, have to be necessarily set upon fitting activity with an experimental database at coupon level. Concerning the test case, all the codes were found able to capture the buckling load and the failure load with a good accuracy.

Originality/value

This paper would to give an insight into the PFA capabilities of different FE codes, providing the guidelines for setting the degradation model parameters which are of major interest.

Details

International Journal of Structural Integrity, vol. 4 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

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