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Article
Publication date: 12 May 2021

P.S. Liu and X.M. Ma

The purpose of this paper is to provide a summarization and review of the present author's main investigations on failure modes of reticular metal foams under different loadings…

Abstract

Purpose

The purpose of this paper is to provide a summarization and review of the present author's main investigations on failure modes of reticular metal foams under different loadings in engineering applications.

Design/methodology/approach

With the octahedral structure model proposed by the present authors themselves, the fundamentally mechanical relations have been systematically studied for reticular metal foams with open cells in their previous works. On this basis, such model theory is continually used to investigate the failure mode of this kind of porous materials under compression, bending, torsion and shearing, which are common loading forms in engineering applications.

Findings

The pore-strut of metal foams under different compressive loadings will fail in the tensile breaking mode when it is brittle. While it is ductile, it will tend to the shearing failure mode when the shearing strength is half or nearly half of the tensile strength for the corresponding dense material and to the tensile breaking mode when the shearing strength is higher than half of the tensile strength to a certain value. The failure modes of such porous materials under bending, torsional and shearing loads are also similarly related to their material species.

Originality/value

This paper presents a distinctive method to conveniently analyze and estimate the failure mode of metal foams under different loadings in engineering applications.

Details

Multidiscipline Modeling in Materials and Structures, vol. 17 no. 4
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 1 November 2022

Yongliang Wang and Xin Zhang

Hydrofracturing technology has been widely used in tight oil and gas reservoir exploitation, and the fracture network formed by fracturing is crucial to determining the resources…

Abstract

Purpose

Hydrofracturing technology has been widely used in tight oil and gas reservoir exploitation, and the fracture network formed by fracturing is crucial to determining the resources recovery rate. Due to the complexity of fracture network induced by the random morphology and type of fluid-driven fractures, controlling and optimising its mechanisms is challenging. This paper aims to study the types of multiscale mode I/II fractures, the fluid-driven propagation of multiscale tensile and shear fractures need to be studied.

Design/methodology/approach

A dual bilinear cohesive zone model (CZM) based on energy evolution was introduced to detect the initiation and propagation of fluid-driven tensile and shear fractures. The model overcomes the limitations of classical linear fracture mechanics, such as the stress singularity at the fracture tip, and considers the important role of fracture surface behaviour in the shear activation. The bilinear cohesive criterion based on the energy evolution criterion can reflect the formation mechanism of complex fracture networks objectively and accurately. Considering the hydro-mechanical (HM) coupling and leak-off effects, the combined finite element-discrete element-finite volume approach was introduced and implemented successfully, and the results showed that the models considering HM coupling and leak-off effects could form a more complex fracture network. The multiscale (laboratory- and engineering-scale) Mode I/II fractures can be simulated in hydrofracturing process.

Findings

Based on the proposed method, the accuracy and applicability of the algorithm were verified by comparing the analytical solution of KGD and PKN models. The effects of different in situ stresses and flow rates on the dynamic propagation of hydraulic fractures at laboratory and engineering scales were investigated. when the ratio of in situ stress is small, the fracture propagation direction is not affected, and the fracture morphology is a cross-type fracture. When the ratio of in situ stress is relatively large, the propagation direction of the fracture is affected by the maximum in situ stress, and it is more inclined to propagate along the direction of the maximum in situ stress, forming double wing-type fractures. Hydrofracturing tensile and shear fractures were identified, and the distribution and number of each type were obtained. There are fewer hydraulic shear fractures than tensile fractures, and shear fractures appear in the initial stage of fracture propagation and then propagate and distribute around the perforation.

Originality/value

The proposed dual bilinear CZM is effective for simulating the types of Mode I/II fractures and seizing the fluid-driven propagation of multiscale tensile and shear fractures. Practical fracturing process involves the multi-type and multiscale fluid-driven fracture propagation. This study introduces general fluid-driven fracture propagation, which can be extended to the fracture propagation analysis of potential fluid fracturing, such as other liquids or supercritical gases.

Article
Publication date: 1 September 1956

A.E. Johnson

In previous paragraphs of the paper, use has been made for various purposes of the results of investigations carried out for the Panel on a number of disk materials. In this…

Abstract

In previous paragraphs of the paper, use has been made for various purposes of the results of investigations carried out for the Panel on a number of disk materials. In this section a detailed description of this work is given.

Details

Aircraft Engineering and Aerospace Technology, vol. 28 no. 9
Type: Research Article
ISSN: 0002-2667

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 seismic…

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

Keywords

Article
Publication date: 2 March 2015

Jie Zhang, Jing Liu, Qian Hu, Feng Huang, ZhaoYang Cheng and JunTao Guo

The aim of this paper was to clarify the influence of tensile stress on the electrochemical behavior of X80 steel in a simulated acid soil solution and attempt to understand…

Abstract

Purpose

The aim of this paper was to clarify the influence of tensile stress on the electrochemical behavior of X80 steel in a simulated acid soil solution and attempt to understand mechanistic aspects of the corrosion behaviors of X80 under these conditions.

Design/methodology/approach

The electrochemical behavior of X80 steel at various tensile stresses was investigated in a simulated acid soil solution using electrochemical impedance spectroscopy, potentiodynamic scan measurements and surface analysis techniques.

Findings

The results show that as tensile stress was increased, the open-circuit potential decreased, the reaction activity increase, the reaction resistance (Rct)value became smaller by degrees, the corrosion product film resistance (Rf) first decreased and then increased and polarization current densities changed conversely. The corrosion product film was compact and continuous under the low stress, whereas it was relatively loose under high-stress conditions. Tensile stress promotes the movement of dislocations, which become active points when they move to the steel surface. The increase in the number of active points enhances the anodic dissolution rate and promotes the formation of corrosion product film whose blocking effect can decrease the dissolution rate. The corrosion rate of the specimen is determined by these two effects.

Originality/value

This research provides an essential insight into the mechanism of the electrochemical behavior of X80 steel in acid soil environments.

Details

Anti-Corrosion Methods and Materials, vol. 62 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 30 August 2022

Dorcas Kaweesa, Lourdes Bobbio, Allison M. Beese and Nicholas Alexander Meisel

This study aims to investigate the tensile strength and elastic modulus of custom-designed polymer composites developed using voxel-based design. This study also evaluates…

Abstract

Purpose

This study aims to investigate the tensile strength and elastic modulus of custom-designed polymer composites developed using voxel-based design. This study also evaluates theoretical models, such as the rule of mixtures, Halpin–Tsai model, Cox–Krenchel model and the Young–Beaumont model and the ability to predict the mechanical properties of particle-reinforced composites based on changes in the design of rigid particles at the microscale within a flexible polymer matrix.

Design/methodology/approach

This study leverages the PolyJet process for voxel-printing capabilities and a design of experiments approach to define the microstructural design elements (i.e. aspect ratio, orientation, size and volume fraction) used to create custom-designed composites.

Findings

The comparison between the predictions and experimental results helps identify appropriate methods for determining the mechanical properties of custom-designed composites ensuring informed design decisions for improved mechanical properties.

Originality/value

This work centers on multimaterial additive manufacturing leveraging design freedom and material complexity to create a wide range of composite materials. This study highlights the importance of identifying the process, structure and property relationships in material design.

Article
Publication date: 8 October 2019

Hongru Ma, Xiaobin Deng, Xiaoliang Shi, Guanchen Lu, Hongyan Zhou, Yuan Chen and Zhenyu Yang

This paper aims to explore the damage mechanism of a lubricating film on the worn surface of solid self-lubricating composites under different loads.

Abstract

Purpose

This paper aims to explore the damage mechanism of a lubricating film on the worn surface of solid self-lubricating composites under different loads.

Design/methodology/approach

By comparing the actual stress with the strength, it is possible to determine the approximate wear state of the lubricating film. To prove the validity of the mathematical model that can predict the initiation of micro cracks or even the failure of the lubricating film, M50-5 Wt.% Ag self-lubricating composites (MA) was prepared. Tribological tests of the composites against Si3N4 ceramic balls were conducted at room temperature from 2 to 8 N. The electron probe microanalysis images of the lubricating film verify the wear state of the lubricating film.

Findings

The study found that the back edge of the contact area is the most vulnerable to destruction. The tensile stress and the equivalent shear stress have a positive correlation with load and friction coefficient. When the load is 4 N, an intact lubricating film covers the worn surface because the tensile stress and the equivalent shear stress are below the tensile strength and the shear strength, respectively; under other working conditions, the lubricating film is destroyed.

Originality/value

This paper has certain theoretical guidance for the study of tribological properties of solid self-lubricating composites. Moreover, this mathematical model is appropriate to be applied for the other composites.

Article
Publication date: 22 June 2022

Ryan R. Ford, Akhilesh Kumar Pal, Scott C.E. Brandon, Manjusri Misra and Amar K. Mohanty

The fused filament fabrication (FFF) process is an additive manufacturing technique used in engineering design. The mechanical properties of parts manufactured by FFF are…

Abstract

Purpose

The fused filament fabrication (FFF) process is an additive manufacturing technique used in engineering design. The mechanical properties of parts manufactured by FFF are influenced by the printing parameters. The mechanical properties of rigid thermoplastics for FFF are well defined, while thermoplastic elastomers (TPE) are uncommonly investigated. The purpose of this paper is to investigate the influence of extruder temperature, bed temperature and printing speed on the mechanical properties of a thermoplastic elastomer.

Design/methodology/approach

Regression models predicting mechanical properties as a function of extruder temperature, bed temperature and printing speed were developed. Tensile specimens were tested according to ASTM D638. A 3×3 full factorial analysis, consisting of 81 experiments and 27 printing conditions was performed, and models were developed in Minitab. Tensile tests verifying the models were conducted at two selected printing conditions to assess predictive capability.

Findings

Each mechanical property was significantly affected by at least two of the investigated FFF parameters, where printing speed and extruder temperature terms influenced all mechanical properties (p < 0.05). Notably, tensile modulus could be increased by 21%, from 200 to 244 MPa. Verification prints exhibited properties within 10% of the predictions. Not all properties could be maximized together, emphasizing the importance of understanding FFF parameter effects on mechanical properties when making design decisions.

Originality/value

This work developed a model to assess FFF parameter influence on mechanical properties of a previously unstudied thermoplastic elastomer and made property predictions within 10% accuracy.

Details

Rapid Prototyping Journal, vol. 28 no. 10
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 August 1998

D. Mukherjee, R. Rajmohan, B. Rathapan, V. Rajkumar and S. Raman

The paper discusses the aspect of probable stress induced embrittlement of 304 stainless steel stresses originating from thermal exposure, uniaxial tension, and reverse bending…

Abstract

The paper discusses the aspect of probable stress induced embrittlement of 304 stainless steel stresses originating from thermal exposure, uniaxial tension, and reverse bending, which have been simulated on the surface of SS plates of 1mm thickness, using conventional techniques. The physical and electrochemical properties of the treated SS materials have been followed up as a function of the corroding medium and also the type and extent of the stress interaction.

Details

Anti-Corrosion Methods and Materials, vol. 45 no. 4
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 1 November 1948

A.E. Johnson and D.C. Herbert

THE work described in this paper was undertaken to investigate the behaviour of a magnesium alloy beam clastically and plastically deformed by a uniform bending moment at room…

Abstract

THE work described in this paper was undertaken to investigate the behaviour of a magnesium alloy beam clastically and plastically deformed by a uniform bending moment at room temperature. The object of the work was to obtain relations between stresses and strains in the beam, to afford a basis for design, in cases where it is required to submit magnesium alloy structures to bending stresses exceeding the elastic limit.

Details

Aircraft Engineering and Aerospace Technology, vol. 20 no. 11
Type: Research Article
ISSN: 0002-2667

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