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1 – 10 of over 2000
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

Article
Publication date: 29 March 2022

Jun Yao, Ruochen Ding, Kailun Li, Baorui Du, Lu Zhao and Yixiang Yuan

The purpose of this paper is to identify the energy absorption characteristics of arch micro-strut (ARCH) lattice structure (different from traditional straight micro-strut…

Abstract

Purpose

The purpose of this paper is to identify the energy absorption characteristics of arch micro-strut (ARCH) lattice structure (different from traditional straight micro-strut lattice structure) under high-speed impact, and promote the development of special-shaped micro-strut lattice structure.

Design/methodology/approach

The study serves to study the anti-impact and energy absorption characteristics of ARCH lattice structure under different strain rates and different unit layers of lattice structure. In this paper, quasi-static compression and Hopkinson compression bar experiments are used for comparative analysis.

Findings

The results show that the ARCH lattice structure has obvious strain rate effect. When the strain rate is low, the number of layers of lattice structure has a great influence on the mechanical properties. With the increase of strain rate, the influence of the number of layers on the mechanical properties gradually weakens. So the ARCH lattice structure with fewer layers (less than five layers) should be selected as the impact energy absorbing materials at lower impact rate, while at higher impact rate, the number of layers can be selected according to the actual requirements of components or devices space size.

Originality/value

This study shows that Arch lattice structure has excellent energy absorption performance, and provides a theoretical reference for the application of ARCH lattice structure in energy-absorbing materials. ARCH lattice structure is expected to be applied to a variety of energy absorption and anti-impact components or devices, such as aircraft black box fall buffer components, impact resistant layer of bulletproof and landing buffer device.

Details

Rapid Prototyping Journal, vol. 28 no. 8
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 28 February 2023

Sudipta Pramanik, Kay-Peter Hoyer and Mirko Schaper

The purpose of this study is to investigate the manufacturability of Fe-3Si lattice structures and the resulting mechanical properties. This study could lead to the successful…

Abstract

Purpose

The purpose of this study is to investigate the manufacturability of Fe-3Si lattice structures and the resulting mechanical properties. This study could lead to the successful processing of squirrel cage conductors (a lattice structure by design) of an induction motor by additive manufacturing in the future.

Design/methodology/approach

The compression behaviour of two lattice structures where struts are arranged in a face-centred cubic position and vertical edges (FCCZ), and struts are placed at body-centred cubic (BCC) positions, prepared by laser powder bed fusion (LPBF), is explored. The experimental investigations are supported by finite element method (FEM) simulations.

Findings

The FCCZ lattice structure presents a peak in the stress-strain curve, whereas the BCC lattice structure manifests a plateau. The vertical struts aligned along the compression direction lead to a significant increase in the load-carrying ability of FCCZ lattice structures compared to BCC lattice structures. This results in a peak in the stress-strain curve. However, the BCC lattice structure presents the bending of struts with diagonal struts carrying the major loads with struts near the faceplate receiving the least load. A high concentration of geometrically necessary dislocations (GNDs) near the grain boundaries along cell formation is observed in the microstructure.

Originality/value

To the best of the authors’ knowledge, this is the first study on additive manufacturing of Fe-3Si lattice structures. Currently, there are no investigations in the literature on the manufacturability and mechanical properties of Fe-3Si lattice structures.

Article
Publication date: 16 January 2007

X. Guo, W. Li, B. Gu and Y. Qiu

This study sets out to compare the response of three‐dimensional (3D) woven composites subjected to high strain rate (HSR) compression loading with the dynamic response.

Abstract

Purpose

This study sets out to compare the response of three‐dimensional (3D) woven composites subjected to high strain rate (HSR) compression loading with the dynamic response.

Design/methodology/approach

The 3D composites were manufactured using Kevlar woven fabrics with epoxy resin system utilising vacuum bag moulding approach. Samples were subjected to HSR compression loading in three directions using a modified split Hopkinson's pressure bar.

Findings

Peak stress and stiffness of 3D composites were higher for dynamic loading when compared with static loading in case of both in‐plane direction and out‐of‐plane direction. The peak stress and modulus increased with the increase in strain rate for both in‐plane direction and out‐of‐plane direction. Peak stress and dynamic modulus were higher when the samples were loaded in the fill direction compared with the warp direction loading. The failure strain in through‐the‐thickness direction was far higher than in in‐plane warp and fill direction.

Research limitations/implications

Other strength parameters of 3D composites could be studied.

Practical implications

The study provided the strength comparison of 3D composites in different situations.

Originality/value

The paper provide data on 3D composites for engineering applications.

Details

Pigment & Resin Technology, vol. 36 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 25 January 2024

Shrushti Maheshwari, Zafar Alam and Sarthak S. Singh

The purpose of this study is to experimentally investigate the large deformation compression characteristics of fused deposition modelling (FDM)-printed poly lactic acid (PLA)…

70

Abstract

Purpose

The purpose of this study is to experimentally investigate the large deformation compression characteristics of fused deposition modelling (FDM)-printed poly lactic acid (PLA), considering the combined effect of infill density and strain rate, and to develop a constitutive viscoplastic model that can incorporate the infill density to predict the experimental result.

Design/methodology/approach

The experimental approach focuses on strain rate-dependent (2.1 × 10−4, 2.1 × 10−3, and 2.1 × 10−2 s−1) compression testing for varied infill densities. Scanning electron microscopy (SEM) imaging of compressed materials is used to investigate deformation processes. A hyperelastic-viscoplastic constitutive model is constructed that can predict mechanical deformations at different strain rates and infill densities.

Findings

The yield stress of PLA increased with increase in strain rate and infill density. However, higher degree of strain-softening response was witnessed for the strain rate corresponding to 2.1 × 10−2 s−1. While filament splitting and twisting were identified as the damage mechanisms at higher strain rates, matrix crazing was observed as the primary deformation mechanism for higher infill density (95%). The developed constitutive model captured yield stress and post-yield softening behaviour of FDM build PLA samples with a high R2 value of 0.99.

Originality/value

This paper addresses the need to analyse and predict the mechanical response of FDM print polymers (PLA) undergoing extensive strain-compressive loading through a hyperelastic-viscoplastic constitutive model. This study links combined effects of the printing parameter (infill density) with the experimental parameter (strain rate).

Article
Publication date: 1 August 2003

Masayoshi Akiyama, Yutaka Neishi, Yoshitaka Adachi and Kenjiro Terada

Observation by optical microscopy and EBSP have made it clear that the trigger for the grain coarsening phenomenon of austenite stainless steel BS304S31 may be the stacking faults…

Abstract

Observation by optical microscopy and EBSP have made it clear that the trigger for the grain coarsening phenomenon of austenite stainless steel BS304S31 may be the stacking faults concentrating selectively in a thin layer lying just beneath the grain boundary. When macroscopic plastic strain reached 6 percent, selective concentration of stacking faults was observed. When it reached 20 percent, the distribution of stacking faults became uniform in each grain. After these specimens were heated, concentration of stacking faults disappeared, and grain coarsening occurred at the point with 6 percent strain, but no grain coarsening occurred at the point with 20 percent strain. In order to investigate this concentration of stacking faults, an attempt was made to analyze the deformation in each crystal by using image‐based FEM. The result suggested that there is a possibility that plastic strain concentrates in the vicinity of the grain boundary when the macroscopic plastic strain is small.

Details

Engineering Computations, vol. 20 no. 5/6
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 19 November 2021

Marcelo Greco and Daniel Henrique Nunes Peixoto

In this paper the use of classical strain measures in analysis of trusses at finite deformations will be discussed. The results will be compared to the ones acquired using a novel…

Abstract

Purpose

In this paper the use of classical strain measures in analysis of trusses at finite deformations will be discussed. The results will be compared to the ones acquired using a novel strain measure based on the Hyperbolic Sine function. Through the evaluation of results, algebraic development and graph analysis, the properties of the Hyperbolic Sine strain measure will be examined.

Design/methodology/approach

Through graph plotting, comparisons between the novel strain measure and the classic ones will be made. The formulae for the implementation of the Hyperbolic Sine strain measure into a positional finite element method are developed. Four engineering applications are presented and comparisons between results obtained using all strain measures studied are made.

Findings

The proposed strain measure, Hyperbolic Sine, has objectivity and symmetry. The linear constitutive model formed by the Hyperbolic Sine strain and its conjugated stress presents an increasing stiffness, both in compression and tension, a behavior that can be useful in the modeling of several materials.

Research limitations/implications

The structural analysis performed on the four examples of trusses in this article did not consider the variation of the cross-sectional area of the elements or the buckling phenomenon, moreover, only elastic behavior is considered.

Originality/value

The present article proposes the use of a novel strain measure family, based on the Hyperbolic Sine function and suitable for structural applications. Mathematical expressions for the use of the Hyperbolic Sine strain measure are established following the energetic concepts of the positional formulation of the finite element method.

Details

Engineering Computations, vol. 39 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 8 January 2020

Ante Džolan, Mladen Kožul, Alen Harapin and Dragan Ćubela

This paper aims to present an approach for the numerical simulation of concrete shrinkage. First, some physical mechanisms of shrinkage are described and then the developed…

Abstract

Purpose

This paper aims to present an approach for the numerical simulation of concrete shrinkage. First, some physical mechanisms of shrinkage are described and then the developed numerical model for the analysis of shrinkage of spatial three-dimensional structures using thermal analogy is presented. Results of the real behavior of structures because of concrete shrinkage using the developed numerical model are compared with the experimental and it is clearly shown that the developed numerical model is an efficient tool in predicting the time-dependent behavior of all concrete structures.

Design/methodology/approach

In this paper, Fib Model Code 2010 to predict shrinkage deformation of concrete is used, and it was incorporated in the three-dimensional numerical model using the thermal analogy. Mentioned three-dimensional numerical model uses the modified Rankine material law to describe concrete behavior in tension and modified Mohr-Coulomb material law to describe concrete behavior in compression. The developed three-dimensional numerical model successfully analyzes the behavior of reinforced and/or prestressed concrete structures including time-dependent deformations of concrete as well.

Findings

Results are shown in this paper clearly demonstrate the reliability of the developed numerical model in predicting the shrinkage strain, as well as its impact on concrete and reinforced concrete structures. The results obtained using the developed numerical model are in better agreement with the experimental results, than the results obtained using the numerical models from literature that also use the Fib Model Code 2010 to predict the shrinkage strain. So, it can be concluded that for a real simulation of concrete structures, alongside the model for predicting the shrinkage strain, the models for concrete behavior in tension and compression have a very important role.

Originality/value

Results of the developed three-dimensional numerical model were compared with experimental results from literature and with theoretical foundations, and it can be talked that this numerical model presents a good tool for analysis of reinforced and prestressed concrete structures including shrinkage deformation of concrete. Results obtained using the developed three-dimensional numerical model are better agreed with experimental than results of other numerical model from literature.

Details

Engineering Computations, vol. 37 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 8 January 2020

Paola Ginestra, Stefano Pandini and Elisabetta Ceretti

The purpose of this paper is to focus on the production of scaffolds with specific morphology and mechanical behavior to satisfy specific requirements regarding their stiffness…

176

Abstract

Purpose

The purpose of this paper is to focus on the production of scaffolds with specific morphology and mechanical behavior to satisfy specific requirements regarding their stiffness, biological interactions and surface structure that can promote cell-cell and cell-matrix interactions though proper porosity, pore size and interconnectivity.

Design/methodology/approach

This case study was focused on the production of multi-layered hybrid scaffolds made of polycaprolactone and consisting in supporting grids obtained by Material Extrusion (ME) alternated with electrospun layers. An open source 3D printer was utilized, with a grain extrusion head that allows the production and distribution of strands on the plate according to the designed geometry. Square grid samples were observed under optical microscope showing a good interconnectivity and spatial distribution of the pores, while scanning electron microscope analysis was used to study the electrospun mats morphology.

Findings

A good adhesion between the ME and electrospinning layers was achieved by compression under specific thermomechanical conditions obtaining a hybrid three-dimensional scaffold. The mechanical performances of the scaffolds have been analyzed by compression tests, and the biological characterization was carried out by seeding two different cells phenotypes on each side of the substrates.

Originality/value

The structure of the multi-layered scaffolds demonstrated to play an important role in promoting cell attachment and proliferation in a 3D culture formation. It is expected that this design will improve the performances of osteochondral scaffolds with a strong influence on the required formation of an interface tissue and structure that need to be rebuilt.

Details

Rapid Prototyping Journal, vol. 26 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 22 March 2013

Dalibor Petković, Mirna Issa, Nenad D. Pavlović and Lena Zentner

The aim of this paper is to investigate implementations of carbon‐black filled silicone rubber for tactile sensation.

Abstract

Purpose

The aim of this paper is to investigate implementations of carbon‐black filled silicone rubber for tactile sensation.

Design/methodology/approach

The sensor‐elements for this tactile sensing structure were made by press‐curing from carbon‐black filled silicone rubber.

Findings

The behaviour of the silicone rubber shows strong non‐linearity, therefore, the sensor cannot be used for accurate measurements. The greatest advantage of this material lies in its high elasticity.

Originality/value

A new method for artificial tactile sensing skin for robotic applications.

Details

Sensor Review, vol. 33 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

1 – 10 of over 2000