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Article
Publication date: 15 November 2013

Mohd Hafizi Shamsudin, Jingjing Chen and Christopher B. York

The purpose of this paper is to investigate the buckling strength of simply supported plates with mechanical extension-twisting coupling. Bounds of the compression…

Abstract

Purpose

The purpose of this paper is to investigate the buckling strength of simply supported plates with mechanical extension-twisting coupling. Bounds of the compression buckling strength are presented for a special sub-class of extension-twisting coupled laminate that is free from the thermal distortions that generally arise in this class of coupled laminate as a result of the high temperature curing process. These special laminates are generally referred to as hygro-thermally curvature-stable (HTCS).

Design/methodology/approach

This paper gives an overview of the methodology for developing laminates with extension-twisting coupling properties, which are derived from a parent laminate with HTCS properties. A closed form buckling solution is applicable for this special class of coupled laminate, which facilitates an assessment of compression buckling strength performance for the entire laminate design space.

Findings

Extension-twisting coupled laminates have potential applications in the design of aero-elastic compliant rotor blades, where the speed of the rotating blade, and the resulting centrifugal force, can be used to control blade twist. Extension-twisting coupling reduces the compression buckling performance of the blade, which represents an important static design constraint. However, the performance has been shown to be higher than competing designs with extension-shearing coupling in many cases.

Originality/value

Bounds of the buckling curves have been presented for the entire HTCS laminate design space, possessing extension-twisting and shearing-bending coupling, in which the laminates contain standard ply angle orientations and up to 21 plies. These laminates can be manufactured without the undesirable thermal warping distortions that generally affect this class of coupled laminate, and in particular, those containing angle plies only; previously thought to be the only form of laminate design from which this particular type of mechanical coupling can be derived.

Details

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

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Article
Publication date: 1 December 2004

Martin Goosey and Mark Poole

With the ever increasing demands for high performance electronic devices there is a need for circuit board laminates that have enhanced properties when compared to…

Abstract

With the ever increasing demands for high performance electronic devices there is a need for circuit board laminates that have enhanced properties when compared to conventional materials such as the widely used epoxide‐based FR4 laminates. Equipment manufacturers require boards with better mechanical stability and improved electrical characteristics. At the same time, new environmental legislation is set to drive electronics assembly temperatures much higher as manufacturers start to use lead‐free soldering processes. The legislation is also raising questions about the long‐term viability of brominated resins as the basis for imparting flame retardancy to laminates. Fortunately, laminate manufacturers have responded to these challenges by developing and introducing a wide range of new laminates that address these issues. This paper describes some of these challenges and gives an introduction to the new high performance laminates that are finding increasing use. It also highlights the need for chemical processes used in the manufacture of interconnects with laminates to be specifically optimised for the chosen substrate material.

Details

Circuit World, vol. 30 no. 4
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 30 August 2013

M.P. Jenarthanan and R. Jeyapaul

The purpose of this paper is to report the preparation, characterisation and machinability of resin hybrid GFRP composites, which are made of glass fibre and the mixture…

Abstract

Purpose

The purpose of this paper is to report the preparation, characterisation and machinability of resin hybrid GFRP composites, which are made of glass fibre and the mixture of epoxy & polyester resin.

Design/methodology/approach

Resin hybrid GFRP laminates containing 0, 20 and 40wt% of polyester resin with the epoxy resin are prepared by conventional hand layup technique using glass fibre as the reinforcement. The variation of break load and shear strength for three different combinations of epoxy and polyester resin are studied by ASTM. A plan of experiment based on Taguchi was established with prefixed cutting parameters and the machining was performed. A stylus type profilometer to examine the surface roughness and shop microscope to examine the delamination of resin hybrid GFRP laminates were used. An analysis of variance (ANOVA) was performed to investigate the cutting characteristics of resin hybrid GFRP composite materials using solid carbide end mill. The correlation was obtained by multiple‐variable linear regression using Minitab 14 software.

Findings

Taguchi analysis reveals that the resin hybrid GFRP laminate provides better machinability in terms of surface roughness and delamination when compared to homogenous GFRP laminates (pure epoxy resin). Polyester resin enhances the machinability of the GFRP laminates.

Research limitations/implications

The machinability of the resin hybrid GFRP laminates can be improved further by modifying the polyester resin percentage.

Originality/value

The resin hybrid GFRP laminates so developed can be used in aircraft and aerospace applications to increase the shear and work of fracture properties.

Details

Pigment & Resin Technology, vol. 42 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 March 1991

V. Fronz

For TAB tapes and flex circuitry, laminates with adhesives (3‐layer laminates) are commonly used. The drawbacks of adhesives are well known. Adhesiveless flexible…

Abstract

For TAB tapes and flex circuitry, laminates with adhesives (3‐layer laminates) are commonly used. The drawbacks of adhesives are well known. Adhesiveless flexible copper‐polyimide laminates (2‐layer laminates) could avoid such disadvantages. Two‐layer thin film laminates may be produced using sputtering technology. Good adhesion strength between the copper and the polyimide film may be achieved by means of special plasma treatment. The advantages and disadvantages of 2‐layer flexible thin film laminates are discussed in this paper, along with their different production methods. The adhesion strength of 2‐layer laminates in comparison with 3‐layer laminates will be pointed out. Future uses of 2‐layer flexible thin film laminates will be considered, along with their benefits.

Details

Circuit World, vol. 17 no. 4
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 9 April 2021

Ashok Magar and Achchhe Lal

The prediction of accurate failure strength and a composite laminate failure load is of paramount importance for reliable design. The progressive failure analysis helps to…

Abstract

Purpose

The prediction of accurate failure strength and a composite laminate failure load is of paramount importance for reliable design. The progressive failure analysis helps to predict the ultimate failure strength of the laminate, which is more than the first ply failure (FPF) strength. The presence of a hole in the laminate plate results in stress concentration, which affects the failure strength. The purpose of the current work is to analyze the stress variation and progressive failure of a symmetric laminated plate containing elliptical cutouts under in-plane tensile loading. The effect of various parameters on FPF and last ply failure (LPF) strength is studied.

Design/methodology/approach

The ply-by-ply stresses around elliptical cutouts are obtained analytically using Muskhelishvili's complex variable formulation. To predict the progressive failure, Tsai–Hill (T-H) and Tsai–Wu (T-W) failure criteria are used, and depending on the mode of failure, lamina modulus is degraded.

Findings

The study has revealed that fiber orientation and stacking sequence for given loading have the most significant effect on the laminate's failure strength.

Originality/value

Complex variable method and conformal mapping are simple and proficient for studying failure analysis of a laminated plate with elliptical cutout.

Details

International Journal of Structural Integrity, vol. 12 no. 4
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 21 February 2020

Changsheng Wang, Xiao Han, Caixia Yang, Xiangkui Zhang and Wenbin Hou

Numerous finite elements are proposed based on analytical solutions. However, it is difficult to find the solutions for complicated governing equations. This paper aims to…

Abstract

Purpose

Numerous finite elements are proposed based on analytical solutions. However, it is difficult to find the solutions for complicated governing equations. This paper aims to present a novel formulation in the framework of assumed stress quasi-conforming method for the static and free vibration analysis of anisotropic and symmetric laminated plates.

Design/methodology/approach

Firstly, an initial stress approximation ruled by 17 parameters, which satisfies the equilibrium equations is derived to improve the performance of the constructed element. Then the stress matrix is treated as the weighted function to weaken the strain-displacement equations. Finally, the Timoshenko’s laminated composite beam functions are adopted as boundary string-net functions for strain integration.

Findings

Several numerical examples are presented to show the performance of the new element, and the results obtained are compared with other available ones. Numerical results have proved that the new element is free from shear locking and possesses high accuracy for the analysis of anisotropic and symmetric laminated plates.

Originality/value

This paper proposes a new QC element for the static and free vibration analysis of anisotropic and symmetric laminated plates. In contrast with the complicated analytical solutions of the equilibrium equations, an initial stress approximation ruled by 17 parameters is adopted here. The Timoshenkos laminated composite beam functions are introduced as boundary string-net functions for strain integration. Numerical results demonstrate the new element is free from shear locking and possesses high accuracy for the analysis of anisotropic and symmetric laminated plates.

Details

Engineering Computations, vol. 37 no. 6
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 26 February 2020

Sagar Dnyandev Patil, Yogesh J. Bhalerao and Adik Takale

The purpose of this paper is to analyze the significance of disparate design variables on the mechanical properties of the composite laminate. Four design variables such…

Abstract

Purpose

The purpose of this paper is to analyze the significance of disparate design variables on the mechanical properties of the composite laminate. Four design variables such as stacking sequence, stacking angle, types of resins and thickness of laminate have been chosen to analyze the impact on mechanical properties of the composite laminate. The detailed investigation is carried out to analyze the effect of a carbon layer in stacking sequence and investigate the impact of various resins on the fastening strength of fibers, stacking angles of the fibers and the thickness of the laminate.

Design/methodology/approach

The Taguchi approach has been adopted to detect the most significant design variable for optimum mechanical properties of the hybrid composite laminate. For this intend, L16 orthogonal array has been composed in statistical software Minitab 17. To investigate an effect of design variables on mechanical properties, signal to noise ratio plots were developed in Minitab. The numerical analysis was done by using the analysis of variance.

Findings

The single parameter optimization gives the optimal combination A1B1C4D2 (i.e. stacking sequence C/G/G/G, stacking angle is 00, the type of resin is newly developed resin [NDR] and laminate thickness is 0.3 cm) for tensile strength; A4B2C4D2 (i.e. stacking sequence G/G/G/C, stacking angle is 450, the type of resin is NDR and laminate thickness is 0.3 cm) for shear strength; and A2B3C4D2 (i.e. stacking sequence G/C/G/G, stacking angle is 900, the type of resin is NDR and thickness is 0.3 cm) for flexural strength. The types of resins and stacking angles are the most significant design variables on the mechanical properties of the composite laminate.

Originality/value

The novelty in this study is the development of new resin called NDR from polyethylene and polyurea group. The comparative study was carried out between NDR and three conventional resins (i.e. polyester, vinyl ester and epoxy). The NDR gives higher fastening strength to the fibers. Field emission scanning electron microscope images illustrate the better fastening ability of NDR compared with epoxy. The NDR provides an excellent strengthening effect on the RCC beam structure along with carbon fiber (Figure 2).

Details

World Journal of Engineering, vol. 17 no. 2
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 16 November 2012

Allen F. Horn, Patricia A. LaFrance, John W. Reynolds and John Coonrod

The purpose of this paper is to help high frequency circuit designers understand how to choose the best permittivity value for a laminate material for accurate modeling.

Abstract

Purpose

The purpose of this paper is to help high frequency circuit designers understand how to choose the best permittivity value for a laminate material for accurate modeling.

Design/methodology/approach

In this paper, experimental measurements of the performance of simple circuits are compared to various mathematical and software models.

Findings

Higher permittivity values were obtained using samples with bonded copper foil compared to samples etched free of foil. These higher values yielded better agreement between measured and modelled performance using current automated design software. High profile foil on thin laminates was found to increase the surface impedance of the conductor and change the propagation constant and apparent permittivity of the laminate by 15 percent or more. It was also demonstrated that, under some circumstances, the anisotropy of the substrate could result in differences in measured and modelled performance.

Research limitations/implications

Only a limited number of circuit laminate materials were closely examined. Future work should include a wider variety of laminates.

Originality/value

The paper details the magnitude of the effects of test method, conductor profile and substrate anisotropy on the values of a material's permittivity best suited for circuit design purposes.

Details

Circuit World, vol. 38 no. 4
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 9 April 2018

Patryk Adam Jakubczak, Jaroslaw Bienias, Radoslaw Mania and Krzysztof Majerski

The purpose of the study was to develop the forming methodology for FML laminates with complex shapes, based on aluminium and epoxy-glass composite.

Abstract

Purpose

The purpose of the study was to develop the forming methodology for FML laminates with complex shapes, based on aluminium and epoxy-glass composite.

Design/methodology/approach

The subject of research encompassed Al/GFRP fibre metal laminates. Autoclave process has been selected for FML profiles production. The manufacturing process was followed by quality analysis for laminates produced.

Findings

The achievement of high stability and dimensional tolerance of thin-walled FML laminates is ensured by developed technology. The values of selected sections angles are significantly limited as a result of forming of FML laminates through the components performing. Failure to adhere to technological recommendations and to high regime of developer technology may lead to the occurrence of defects in FML.

Practical implications

Thin-walled composite structures could be applied in light-weight constructions, such as aircraft structures, which must meet rigorous requirements with regard to operation under complex load. The development of this type of technology may contribute to increased importance of FML sections in research area and finally to increased scope of their applications.

Originality/value

The production of thin-walled FML profiles with complex geometry, which would be characterized by dimensional stability and repeatable structural quality free of defects, is associated with many problems. No studies have been published so far on an effective forming process for FML laminates with complex shapes. Developed methodology has been verified through quality evaluation of produced profiles by means of non-destructive and destructive methods. The development of this type of technology may contribute to increased importance of FML, e.g. in aerospace technology.

Details

Aircraft Engineering and Aerospace Technology, vol. 90 no. 3
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 8 August 2016

Sunil Bhat and S. Narayanan

Since failure of laminated composites by delaminations is common, the purpose of this paper is to present a numerical procedure to check the stability of delaminations in…

Abstract

Purpose

Since failure of laminated composites by delaminations is common, the purpose of this paper is to present a numerical procedure to check the stability of delaminations in fiber metal laminate (Glare), with different possible damage configurations, under uni-axial tension. Deformation behavior of the laminate is also examined. Influence of the type and the extent of damage, represented by varying sizes and number of delaminations, on delamination driving force and laminate deformation is found.

Design/methodology/approach

Delaminated Glare is modeled by finite element method. Interface cohesive elements are used to model the delaminations. Finite element results provide the deflection/deformation characteristics of the laminate. Driving forces of delaminations are estimated by J integrals that are numerically obtained over cyclic paths near delamination tips. Laminates with different types of delaminations are also fabricated and externally delaminated for measurement of their interlaminar fracture toughness. The delamination is considered to be stable if its driving force is less than corresponding interlaminar fracture toughness of the laminate.

Findings

Delaminations are found to be stable in laminates with lower number of delaminations and unstable in laminates with higher number of delaminations. Increase in size of delaminations increases the deformations but reduces the delamination driving force whereas increase in number of delaminations increases both deformations and driving forces. The trends change in case of laminates with symmetrical damage. Shape of delamination is also found to influence the deformations and driving forces. The finite element model is validated.

Research limitations/implications

There is scope for validating the numerical results reported in the paper by theoretical models.

Practical implications

Checking the stability of delaminations and their effect on deformation behavior of the laminate helps is assessment of safety and remaining life of the laminate. If failure is predicted, preemptive action is taken by using repair patch ups at identified critical locations in order to avoid failures in service conditions.

Originality/value

The paper offers the following benefits: use of cohesive zone method that is readily possible in finite element procedures and is relatively simple, fast and reasonably accurate is demonstrated; suitability of using J integrals over paths crossing non-homogeneous and property mismatched material layers is tested; and influence of the type and the extent of damage in the laminate on its deformation behavior and delamination driving forces is found. This type of work has not been reported so far.

Details

International Journal of Structural Integrity, vol. 7 no. 4
Type: Research Article
ISSN: 1757-9864

Keywords

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