Search results

1 – 10 of 39
Per page
102050
Citations:
Loading...
Access Restricted. View access options
Article
Publication date: 1 October 2018

Gregory Taylor, Xin Wang, Leah Mason, Ming C. Leu, K. Chandrashekhara, Timothy Schniepp and Ross Jones

The purpose of this paper is to study the flexural behavior of additively manufacture Ultem 1010 parts. Fused deposition modeling (FDM) process has become one of most widely used…

377

Abstract

Purpose

The purpose of this paper is to study the flexural behavior of additively manufacture Ultem 1010 parts. Fused deposition modeling (FDM) process has become one of most widely used additive manufacturing methods. The process provides the capability of fabricating complicated shapes through the extrusion of plastics onto a print surface in a layer-by-layer structure to build three-dimensional parts. The flexural behavior of FDM parts are critical for the evaluation and optimization of both material and process.

Design/methodology/approach

This study focuses on the performance of FDM solid and sparse-build Ultem 1010 specimens. Flexure tests (three-point bend) are performed on solid-build coupons with varying build orientation and raster angle. These parameters are investigated through a full-factorial design of experiments (DOE) to determine optimal build parameters. Air gap, raster width and contour width are held constant. A three-dimensional nonlinear finite element model is built to simulate the flexural behavior of the FDM parts.

Findings

Experimental results include flexure properties such as yield strength and modulus, as well as analysis of the effect of change in build parameters on material properties. The sparse-build FDM parts chosen from the experimental tests are simulated based on this developed model. Thermo-mechanical simulation results show that the finite element simulation and experimental tests are in good agreement. The simulation can be further extended to other complicated FDM parts.

Originality/value

From the DOE study, sparse-build coupons with specific build parameters are fabricated and tested for the validation of a finite element simulation.

Details

Rapid Prototyping Journal, vol. 24 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

Access Restricted. View access options
Article
Publication date: 27 April 2020

Myranda Spratt, Sudharshan Anandan, Rafid Hussein, Joseph W. Newkirk, K. Chandrashekhara, Misak Heath and Michael Walker

The purpose of this study is to analyze the build quality and compression properties of thin-walled 304L honeycomb structures manufactured by selective laser melting. Four…

134

Abstract

Purpose

The purpose of this study is to analyze the build quality and compression properties of thin-walled 304L honeycomb structures manufactured by selective laser melting. Four honeycomb wall thicknesses, from 0.2 to 0.5 mm, were built and analyzed.

Design/methodology/approach

The density of the honeycombs was changed by increasing the wall thickness of each sample. The honeycombs were tested under compression. Differences between the computer-assisted design model and the as-built structure were quantified by measuring physical dimensions. The microstructure was evaluated by optical microscopy, density measurements and microhardness.

Findings

The Vickers hardness of the honeycomb structures was 209 ± 14 at 50 g load. The compression ultimate and yield strength of the honeycomb material were shown to increase as the wall thickness of the honeycomb samples increased. The specific ultimate strength also increased with wall thickness, while the specific yield stress of the honeycomb remained stable at 42 ± 2.7 MPa/g/cm3. The specific ultimate strength minimized near 0.45 mm wall thickness at 82 ± 5 MPa/g/cm3 and increased to 134 ± 3 MPa/g/cm3 at 0.6 mm wall thickness.

Originality/value

This study highlights a single lightweight metal structure, the honeycomb, built by additive manufacturing (AM). The honeycomb is an interesting structure because it is a well-known building material in the lightweight structural composites field but is still considered a relatively complex geometric shape to fabricate. As shown here, AM techniques can be used to make complex geometric shapes with strong materials to increase the design flexibility of the lightweight structural component industry.

Details

Rapid Prototyping Journal, vol. 26 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

Access Restricted. View access options
Article
Publication date: 11 February 2020

Rafid Hussein, Sudharshan Anandan, Myranda Spratt, Joseph W. Newkirk, K. Chandrashekhara, Misak Heath and Michael Walker

Honeycomb cellular structures exhibit unique mechanical properties such as high specific strength, high specific stiffness, high energy absorption and good thermal and acoustic…

255

Abstract

Purpose

Honeycomb cellular structures exhibit unique mechanical properties such as high specific strength, high specific stiffness, high energy absorption and good thermal and acoustic performance. This paper aims to use numerical modeling to investigate the effective elastic moduli, in-plane and out-of-plane, for thick-walled honeycombs manufactured using selective laser melting (SLM).

Design/methodology/approach

Theoretical predictions were performed using homogenization on a sample scale domain equivalent to the as-manufactured dimensions. A Renishaw AM 250 machine was used to manufacture hexagonal honeycomb samples with wall thicknesses of 0.2 to 0.5 mm and a cell size of 3.97 mm using 304 L steel powder. The SLM-manufactured honeycombs and cylindrical test coupons were tested using flatwise and edgewise compression. Three-dimensional finite element and strain energy homogenization were conducted to determine the effective elastic properties, which were validated by the current experimental outcomes and compared to analytical models from the literature.

Findings

Good agreement was found between the results of the effective Young’s moduli ratios numerical modeling and experimental observations. In-plane effective elastic moduli were found to be more sensitive to geometrical irregularity compared to out-of-plane effective moduli, which was confirmed by the analytical models. Also, it was concluded that thick-walled SLM manufactured honeycombs have bending-dominated in-plane compressive behavior and a stretch-dominated out-of-plane compressive behavior, which matched well with the simulation and numerical models predictions.

Originality/value

This work uses three-dimensional finite element and strain energy homogenization to evaluate the effective moduli of SLM manufactured honeycombs.

Details

Rapid Prototyping Journal, vol. 26 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

Access Restricted. View access options
Article
Publication date: 1 June 1997

Jaroslav Mackerle

Gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the…

6101

Abstract

Gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the theoretical as well as practical points of view. The range of applications of FEMs in this area is wide and cannot be presented in a single paper; therefore aims to give the reader an encyclopaedic view on the subject. The bibliography at the end of the paper contains 2,025 references to papers, conference proceedings and theses/dissertations dealing with the analysis of beams, columns, rods, bars, cables, discs, blades, shafts, membranes, plates and shells that were published in 1992‐1995.

Details

Engineering Computations, vol. 14 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

Access Restricted. View access options
Article
Publication date: 17 October 2008

Zhihui Gao, Chao Yun and Yushu Bian

The purpose of this paper is to examine a new idea of vibration control which minimizes joint‐torques and suppresses vibration of the flexible redundant manipulator.

379

Abstract

Purpose

The purpose of this paper is to examine a new idea of vibration control which minimizes joint‐torques and suppresses vibration of the flexible redundant manipulator.

Design/methodology/approach

Using the kinematics redundancy feature of the flexible redundant manipulator, the self‐motion in the joint space can be properly chosen to both suppress vibration and minimize joint‐torques.

Findings

The study shows that the flexible redundant manipulator still has the second optimization feature on the premise of vibration suppression. The second optimization feature can be used to minimize joint‐torques on the premise of vibration suppression.

Research limitations/implications

To a flexible redundant manipulator, its joint‐torques and vibration can be reduced simultaneously via its kinematics redundancy feature.

Practical implications

The method and algorithm discussed in the paper can be used to minimize joint‐torques and suppress vibration for the flexible redundant manipulator.

Originality/value

The paper contributes to the study on improving dynamic performance of the flexible redundant manipulator via its kinematics redundancy feature. The second optimization capability of the flexible redundant manipulator is discovered and used to both minimize joint‐torques and suppress vibration.

Details

International Journal of Intelligent Computing and Cybernetics, vol. 1 no. 4
Type: Research Article
ISSN: 1756-378X

Keywords

Access Restricted. View access options
Article
Publication date: 23 August 2013

Namita Nanda, S.K. Sahu and J.N. Bandyopadhyay

– The purpose of this paper is to study the nonlinear forced vibration responses of delaminated composite shells in hygrothermal environments.

153

Abstract

Purpose

The purpose of this paper is to study the nonlinear forced vibration responses of delaminated composite shells in hygrothermal environments.

Design/methodology/approach

Finite element method using an eight-noded C0 continuity, isoparametric quadrilateral element is employed. The theoretical formulations are based on the first order shear deformation theory and von Kármán type nonlinear kinematics. For modeling the delamination, multipoint constraint algorithm is incorporated in the finite element code.

Findings

The effect of delaminations on the nonlinear transient response of delaminated composite shells is dependent not only on the size but also on the location of the delaminations and hygrothermal environments.

Research limitations/implications

The present study is limited to cylindrical and spherical shells having rectangular planform containing single delamination. Studies on different shell forms having non rectangular planforms containing multiple delaminations can be taken up for future research.

Originality/value

Nonlinear transient response of delaminated shells in hygrothermal environments is studied for the first time. It will assist researchers of nonlinear dynamic behavior of elastic systems.

Details

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

Keywords

Access Restricted. View access options
Article
Publication date: 1 August 2010

Namita Nanda, S.K. Sahu and J.N. Bandyopadhyay

The purpose of this paper is to study the nonlinear forced vibration response of delaminated composite shells in hygrothermal environments.

550

Abstract

Purpose

The purpose of this paper is to study the nonlinear forced vibration response of delaminated composite shells in hygrothermal environments.

Design/methodology/approach

Finite element method using an eight‐noded C0 continuity, isoparametric quadrilateral element is employed. The theoretical formulations are based on the first‐order shear deformation theory and von Kármán type nonlinear kinematics. For modeling the delamination, multipoint constraint algorithm is incorporated in the finite element code.

Findings

The paper finds that the effect of presence of delaminations on the nonlinear transient response of composite shells is dependent not only on the size, but also on the location of the delaminations and the hygrothermal environments.

Research limitations/implications

The present study is limited to cylindrical and spherical shells having rectangular planform containing single delamination. Studies on different shell forms having non‐rectangular planforms containing multiple delaminations can be taken up for future research.

Originality/value

The value in this paper lies in that nonlinear transient response of delaminated shells in hygrothermal environments is studied for the first time. It will assist researchers of nonlinear dynamic behavior of elastic systems.

Details

International Journal of Structural Integrity, vol. 1 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

Access Restricted. View access options
Article
Publication date: 1 February 2005

L. Ravi Kumar, P.K. Datta and D.L. Prabhakara

To predict the critical flutter load and frequencies of doubly curved panels using first‐order shear deformation theory considering the effects of shear deformation and rotary…

836

Abstract

Purpose

To predict the critical flutter load and frequencies of doubly curved panels using first‐order shear deformation theory considering the effects of shear deformation and rotary inertia.Design/methodology/approach – A finite element analysis procedure is based on the extension of dynamic, shear deformable theory initially according to Sanders' theory, which can be reduced to Love's and Donnell's theories by means of tracers.Findings – Flutter is observed to be more common than divergence under follower loading; the magnitude of the flutter load is gradually decreasing with the increasing cut‐out size; load bandwidth and type of load conditions have significant influence on flutter and divergence characteristics of both isotropic and laminated curved panels; damping is perceived to have significant effect on flutter behaviour; the effect of direction control parameter with damping significantly affects the critical load.Practical implications – The practical behaviour of follower forces involving: aerodynamic drag; engine thrust; cantilever pipe conveying fluid; gas turbine rotor; automatic control system application; and automobile disk brakes can be monitored more successfully.Originality/value – Will assist students of elastic systems, both conservative and non‐conservative.

Details

Aircraft Engineering and Aerospace Technology, vol. 77 no. 1
Type: Research Article
ISSN: 0002-2667

Keywords

Access Restricted. View access options
Article
Publication date: 6 July 2015

Litesh N Sulbhewar and P. Raveendranath

Piezoelectric extension mode smart beams are vital part of modern control technology and their numerical analysis is an important step in the design process. Finite elements based…

180

Abstract

Purpose

Piezoelectric extension mode smart beams are vital part of modern control technology and their numerical analysis is an important step in the design process. Finite elements based on First-order Shear Deformation Theory (FSDT) are widely used for their structural analysis. The performance of the conventional FSDT-based two-noded piezoelectric beam formulations with assumed independent linear field interpolations is not impressive due to shear and material locking phenomena. The purpose of this paper is to develop an efficient locking-free FSDT piezoelectric beam element, while maintaining the same number of nodal degrees of freedom.

Design/methodology/approach

The governing equations are derived using a variational formulation to establish coupled polynomial field representation for the field variables. Shape functions based on these coupled polynomials are employed here. The proposed formulation eliminates all locking effects by accommodating strain and material couplings into the field interpolation, in a variationally consistent manner.

Findings

The present formulation shows improved convergence characteristics over the conventional formulations and proves to be the most efficient way to model extension mode piezoelectric smart beams, as demonstrated by the results obtained for numerical test problems.

Originality/value

To the best of the authors’ knowledge, no such FSDT-based finite element with coupled polynomial shape function exists in the literature, which incorporates electromechanical coupling along with bending-extension and bending-shear couplings at the field interpolation level itself. The proposed formulation proves to be the fastest converging FSDT-based extension mode smart beam formulation.

Details

Engineering Computations, vol. 32 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

Access Restricted. View access options
Article
Publication date: 1 February 1994

W. Wagner and F. Gruttmann

In this paper we derive a simple finite element formulation forgeometrical nonlinear shell structures. The formulation bases on a directintroduction of the isoparametric finite…

219

Abstract

In this paper we derive a simple finite element formulation for geometrical nonlinear shell structures. The formulation bases on a direct introduction of the isoparametric finite element formulation into the shell equations. The element allows the occurrence of finite rotations which are described by two independent angles. A layerwise linear elastic material model for composites has been chosen. A consistent linearization of all equations has been derived for the application of a pure Newton method in the nonlinear solution process. Thus a quadratic convergence behaviour can be achieved in the vicinity of the solution point. Examples show the applicability and effectivity of the developed element.

Details

Engineering Computations, vol. 11 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

1 – 10 of 39
Per page
102050