Search results

1 – 10 of 46
Per page
102050
Citations:
Loading...
Access Restricted. View access options
Article
Publication date: 6 April 2012

Annapurna Addagarla and N. Siva Prasad

Out‐of‐plane displacement (warpage) is one of the major thermomechanical reliability concerns for board‐level electronic packaging. The warpage and residual stresses can cause…

397

Abstract

Purpose

Out‐of‐plane displacement (warpage) is one of the major thermomechanical reliability concerns for board‐level electronic packaging. The warpage and residual stresses can cause unreliability in the performance of electronic chip. An accurate estimation of the distortion and the residual stresses will help in selecting right combination of material for soldering and to determine the better assembly procedure of the chip. The purpose of this paper is to create a 3D nonlinear finite element model to predict the warpage, bending stresses, shear and peel stresses in a flip‐chip on board (FCOB).

Design/methodology/approach

A 3D finite element procedure has been developed considering the material nonlinearity during solidification for a FCOB assembly. Finite element results have been compared with the experimental values.

Findings

The present finite element method gives better approximation of residual warpage and stresses compared to analytical models available in the literature.

Originality/value

The 3D finite element approach considering the elasto‐plastic and temperature‐dependent material properties has not been attempted by any authors. Experiments have been conducted for the comparison of finite element values. The finite element results compare better than the methods available in the literature. Hence a better method for estimating the deformation and residual stresses in flip‐chip assembly has been suggested.

Details

Soldering & Surface Mount Technology, vol. 24 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

Access Restricted. View access options
Article
Publication date: 1 November 2011

R.S. Sudheesh and N. Siva Prasad

The purpose of this paper is to study the effect of trailing liquid nitrogen (LN2) heat sink on arc welding of mild steel plates. The effect on temperature field, stress and…

525

Abstract

Purpose

The purpose of this paper is to study the effect of trailing liquid nitrogen (LN2) heat sink on arc welding of mild steel plates. The effect on temperature field, stress and distortions are studied using experimental and numerical methods.

Design/methodology/approach

The methodology consists of experimental and numerical methods. The temperature measured at a point near the arc is used to estimate the cooling capacity of the heat sink using inverse heat transfer (IHT) method. The estimated cooling flux is applied to the finite element model to study the stress and distortions using LN2 heat sink. The stresses are measured using X‐ray diffraction technique and the distortions using dial gauges.

Findings

IHT method has been employed in estimating the cooling capacity of the LN2 jet. This has been applied to welding to study the effect on weld induced stresses and distortions. The method can be extended to calculate the heat removal rate in various manufacturing processes where cooling is employed.

Research limitations/implications

The lack of temperature dependent material properties resulted in deviation of stresses between analytical results and experiment values.

Originality/value

IHT method developed for heat removal capacity of trailing heat sink is a contribution. The estimated heat flux shows good agreement in analytical and experimental temperature values. These temperatures have been extended to calculate stresses and out of plane distortions in welding and there is a reasonable agreement between finite element analysis and experimental results.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 21 no. 8
Type: Research Article
ISSN: 0961-5539

Keywords

Access Restricted. View access options
Article
Publication date: 30 May 2024

Baharak Hooshyarfarzin, Mostafa Abbaszadeh and Mehdi Dehghan

The main aim of the current paper is to find a numerical plan for hydraulic fracturing problem with application in extracting natural gases and oil.

37

Abstract

Purpose

The main aim of the current paper is to find a numerical plan for hydraulic fracturing problem with application in extracting natural gases and oil.

Design/methodology/approach

First, time discretization is accomplished via Crank-Nicolson and semi-implicit techniques. At the second step, a high-order finite element method using quadratic triangular elements is proposed to derive the spatial discretization. The efficiency and time consuming of both obtained schemes will be investigated. In addition to the popular uniform mesh refinement strategy, an adaptive mesh refinement strategy will be employed to reduce computational costs.

Findings

Numerical results show a good agreement between the two schemes as well as the efficiency of the employed techniques to capture acceptable patterns of the model. In central single-crack mode, the experimental results demonstrate that maximal values of displacements in x- and y- directions are 0.1 and 0.08, respectively. They occur around both ends of the line and sides directly next to the line where pressure takes impact. Moreover, the pressure of injected fluid almost gained its initial value, i.e. 3,000 inside and close to the notch. Further, the results for non-central single-crack mode and bifurcated crack mode are depicted. In central single-crack mode and square computational area with a uniform mesh, computational times corresponding to the numerical schemes based on the high order finite element method for spatial discretization and Crank-Nicolson as well as semi-implicit techniques for temporal discretizations are 207.19s and 97.47s, respectively, with 2,048 elements, final time T = 0.2 and time step size τ = 0.01. Also, the simulations effectively illustrate a further decrease in computational time when the method is equipped with an adaptive mesh refinement strategy. The computational cost is reduced to 4.23s when the governed model is solved with the numerical scheme based on the adaptive high order finite element method and semi-implicit technique for spatial and temporal discretizations, respectively. Similarly, in other samples, the reduction of computational cost has been shown.

Originality/value

This is the first time that the high-order finite element method is employed to solve the model investigated in the current paper.

Details

Multidiscipline Modeling in Materials and Structures, vol. 20 no. 4
Type: Research Article
ISSN: 1573-6105

Keywords

Access Restricted. View access options
Article
Publication date: 25 July 2024

Reza Masoumzadeh, Mostafa Abbaszadeh and Mehdi Dehghan

The purpose of this study is to develop a new numerical algorithm to simulate the phase-field model.

58

Abstract

Purpose

The purpose of this study is to develop a new numerical algorithm to simulate the phase-field model.

Design/methodology/approach

First, the derivative of the temporal direction is discretized by a second-order linearized finite difference scheme where it conserves the energy stability of the mathematical model. Then, the isogeometric collocation (IGC) method is used to approximate the derivative of spacial direction. The IGC procedure can be applied on irregular physical domains. The IGC method is constructed based upon the nonuniform rational B-splines (NURBS). Each curve and surface can be approximated by the NURBS. Also, a map will be defined to project the physical domain to a simple computational domain. In this procedure, the partial derivatives will be transformed to the new domain by the Jacobian and Hessian matrices. According to the mentioned procedure, the first- and second-order differential matrices are built. Furthermore, the pseudo-spectral algorithm is used to derive the first- and second-order nodal differential matrices. In the end, the Greville Abscissae points are used to the collocation method.

Findings

In the numerical experiments, the efficiency and accuracy of the proposed method are assessed through two examples, demonstrating its performance on both rectangular and nonrectangular domains.

Originality/value

This research work introduces the IGC method as a simulation technique for the phase-field crystal model.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 34 no. 9
Type: Research Article
ISSN: 0961-5539

Keywords

Access Restricted. View access options
Article
Publication date: 13 September 2021

Vijaya Prasad B., Arumairaj Paul Daniel, Anand N. and Siva Kumar Yadav

Concrete is a building material widely used for the infrastructural development. Cement is the binding material used for the development of concrete. It is the primary cause of CO2

199

Abstract

Purpose

Concrete is a building material widely used for the infrastructural development. Cement is the binding material used for the development of concrete. It is the primary cause of CO2 emission globally. The purpose of this study is to develop sustainable concrete material to satisfy the present need of construction sector. Geopolymer concrete (GPC) is a sustainable concrete developed without the use of cement. Therefore, investigations are being conducted to replace the cement by 100% with high calcium fly ash (FA) as binding material.

Design/methodology/approach

High calcium FA is used as cementitious binder, sodium hydroxide (NaOH) and sodium silicates (Na2SiO3) are used as alkaline liquids for developing the GPC. Mix proportions with different NaOH molarities of 4, 6, 8 and 10 M are considered to attain the appropriate mix. The method of curing adopted is ambient and oven curing. Workability, compressive strength and microstructure characteristics of GPC are analysed and presented.

Findings

An increase of NaOH in the mix decreases the workability. Compressive strength of 29 MPa is obtained for Mix-I with 8 M under ambient curing. A polynomial relationship is obtained to predict the compressive strength of GPC. Scanning electron microscope analysis is used to confirm the geo-polymerisation process in the microstructure of concrete.

Originality/value

This research work focuses on finding some alternative cementitious material for concrete that can replace ordinary portland cement (OPC) to overcome the CO2 emission owing to the utilisation of cement in the construction industry. An attempt has been made to use the waste material (high calcium FA) from thermal power plant for the production of GPC. GPC concrete is the novel building material and alternative to conventional concrete. It is the ecofriendly product contributing towards the improvement of the circular economy in the construction industry. There are several factors that affect the property of GPC such as type of binder material, molarity of activator solution and curing condition. The novelty of this work lies in the approach of using locally available high calcium FA along with manufactured sand for the development of GPC. As this approach is rarely investigated, to prove the attainment of compressive strength of GPC with high calcium FA, an attempt has been made during the present investigation. Other influencing parameter which affects the strength gain has also been analysed in this paper.

Details

Journal of Engineering, Design and Technology , vol. 20 no. 2
Type: Research Article
ISSN: 1726-0531

Keywords

Access Restricted. View access options
Article
Publication date: 31 January 2022

Akash Gupta and Manjeet Singh

The purpose of this study is to check the reliability of a multi-pin joint to be a fail-safe joint by considering different geometric and material parameters. The pin joints are…

63

Abstract

Purpose

The purpose of this study is to check the reliability of a multi-pin joint to be a fail-safe joint by considering different geometric and material parameters. The pin joints are made of uni-directional fiberglass that has been impregnated with epoxy composites incorporating 3% nano-clay.

Design/methodology/approach

This study incorporates the analysis of multi-pin joints experimentally, numerically and statistically using the Weibull approach. During analyses, geometrical parameters edge to diameter (E:D), longitudinal pitch to diameter (F:D), side edge to diameter (S:D) and transverse pitch to diameter (P:D) were analyzed using the Taguchi method with a higher-the-better L16 orthogonal array.

Findings

This study aims to develop multi-pin laminated joints to attain higher reliability, which have been designated as fail-safe joints for the intended application and which have higher joint strength. The study reveals that to achieve 99% reliability or 1% probability of failure using the Weibull approach, 24.4% load decrement from the experimental result recorded for three-pin joint configuration at E:D = 4, F:D = 5, S:D = 4 and P:D = 5. Similarly, for the four-pin configuration at E:D = 4, F:D = 4, S:D = 4 and P:D = 5, 23.07% of load decrement observed from the experimental result implies that the expected load with a 99% reliability offers a safe load.

Originality/value

A reliability analysis on multi-pin joints was not conducted in structural application. Composite materials are used because of high reliability and high strength-to-weight ratio. So, in the present work, reliability of the multi-pin joint is analyzed using Weibull distribution.

Details

World Journal of Engineering, vol. 20 no. 4
Type: Research Article
ISSN: 1708-5284

Keywords

Access Restricted. View access options
Article
Publication date: 28 September 2012

Kondapalli Siva Prasad, Chalamalasetti Srinivasa Rao and Damera Nageswara Rao

The purpose of this paper is to optimize the fusion zone grain size and hardness using Hooke and Jeeves Algorithm.

139

Abstract

Purpose

The purpose of this paper is to optimize the fusion zone grain size and hardness using Hooke and Jeeves Algorithm.

Design/methodology/approach

Experiments are conducted as per four factors, five levels response surface method based central composite design matrix. Empirical relations for predicting grain size and harness are developed. The effect of welding variables on grain size and hardness are studies. Grain size and hardness are optimised using Hooke and Jeeves Algorithm.

Findings

The developed empirical relations can be effectively used to predict grain size and hardness values of micro plasma arc welded Inconel 625 sheets. The values of grain size and hardness obtained by Hooke and Jeeves Algorithm matches with experimental values with great accuracy.

Research limitations/implications

The developed mathematical models are valid for 0.25 mm thick Inconel 625 sheets only.

Practical implications

In the present paper only four important factors namely peak current, back current, pulse rate and pulse width are considered, however one may consider other parameters like plasma gas flow rate, shielding gas flow rate, etc.

Originality/value

The present work is very much useful to sheet metal industries manufacturing metal bellows, diaphragms, etc.

Details

Multidiscipline Modeling in Materials and Structures, vol. 8 no. 3
Type: Research Article
ISSN: 1573-6105

Keywords

Access Restricted. View access options
Article
Publication date: 11 December 2024

Gollapalli Shankar and Siva Reddy Sheri

This research investigates the impact of Dufour effects and viscous dissipation on unsteady magnetohydrodynamic (MHD) natural convection in an incompressible, viscous, and…

8

Abstract

Purpose

This research investigates the impact of Dufour effects and viscous dissipation on unsteady magnetohydrodynamic (MHD) natural convection in an incompressible, viscous, and electrically conductive fluid over a vertically oscillating flat plate. The study highlights the significance of magnetic fields in influencing thermal and mass transfer, particularly in the context of thermal radiation. Computational fluid dynamics method including finite difference or finite element techniques can be used to crack the governing equations of the fluid flow. In this work, we used the finite element method (FEM) numerical technique to analyze the numerical behavior of unsteady boundary layer flow of Casson fluid with natural convection past an oscillating vertical plate. Key parameters such as skin friction, temperature, concentration, velocity and Sherwood numbers are derived and analyzed. The results demonstrate that viscous dissipation significantly elevates the fluid temperature, while an increase in the radiation parameter is associated with a decrease in internal friction at the plate. These findings provide critical insights into the interplay between thermal radiation and magnetic fields in MHD flows, with potential applications in engineering systems involving heat and mass transfer, such as cooling systems and material processing. This study underscores the importance of understanding these dynamics for optimizing the performance of MHD applications in various industrial settings.

Design/methodology/approach

The mainly authorized and energetic FEM to explain the non-linear, dimensionless partial differential equations (11–13) via equation with boundary conditions (14) makes use of Bathe (36), Reddy (37), Connor (38) and Chung (39). Following are the key steps that make up the method: discretize the domain, derivation of element equation, assembly of element equation, imposition of boundary condition and solution of assembly equation.

Findings

This study examined the impact of viscid dissipative radiation and the Dufour effect on unsteady one-dimensional MHD natural convective flow of a viscous, incompressible, electrically conducting fluid past an infinite moving vertical flat plate with a chemical reaction. Numerically solving the governing equations using the FEM approach is efficient and precise, aiming to be applied to fluid mechanics and related problems. Along with their effects on temperature, concentration and velocity, the following parameters are included: the mass Grashof number, the Soret number, the Grashof number, the Prandtl number, chemical reaction, the Schmidt number, radiation and the Casson parameter. Both the Grashof numbers of thermal and mass rates (Gr, Gm) make an increment in the velocity region. The velocity decreases with an increase in the magnetic parameter. The velocity increases with an increase in the permeability of the porous medium parameter. The temperature flow rate is higher for both Dufour and Viscid dissipation, while a decrement is noted of both Prandtl number and radiation effects. The decrementing behavior of the concentration region is observed at supreme inputs of chemical reaction coefficient and Schmidt number.

Originality/value

This is an original paper and not submitted anywhere.

Details

Multidiscipline Modeling in Materials and Structures, vol. 21 no. 2
Type: Research Article
ISSN: 1573-6105

Keywords

Access Restricted. View access options
Article
Publication date: 15 November 2017

Dagmar Daubner-Siva, Claartje J. Vinkenburg and Paul G.W. Jansen

The purpose of this paper is to adopt a paradox lens for dovetailing the human resource management sub-domains of talent management (TM) and diversity management (DM), in the…

2096

Abstract

Purpose

The purpose of this paper is to adopt a paradox lens for dovetailing the human resource management sub-domains of talent management (TM) and diversity management (DM), in the attempt to create closer alignment between the two.

Design/methodology/approach

The authors review paradox theory, TM and DM literatures and formulate a paradox that becomes apparent when considering TM and DM simultaneously.

Findings

The authors coin this tension as the “exclusion-inclusion paradox,” highlighting that TM and DM reflect contradictory, yet interrelated principles: organizations promote exclusion through a TM architecture that focuses on the identification and development of a few selected employees, while simultaneously, organizations promote inclusion, in the attempt to minimize existing inequalities for traditionally marginalized groups.

Practical implications

Once uncovered, the exclusion-inclusion paradox enables organizational actors to make choices on whether to respond actively or defensively to the paradox. The authors argue for active responses in order to work through the paradox.

Originality/value

This is the first paper adopting a paradox lens in order to interweave the DM literature with TM literature in the attempt to explain how DM and TM constitute contradicting yet interrelated principles.

Details

Journal of Organizational Effectiveness: People and Performance, vol. 4 no. 4
Type: Research Article
ISSN: 2051-6614

Keywords

Access Restricted. View access options
Article
Publication date: 23 October 2015

Ibraheem A. Samotu, Fatai O. Anafi, Muhammad Dauda, Abdulkarim S. Ahmed, Raymond B. Bako and David O. Obada

The general-purpose engine lathe is the most basic turning machine tool. As with all lathes, the two basic requirements for turning are a means of holding the workpiece while it…

67

Abstract

The general-purpose engine lathe is the most basic turning machine tool. As with all lathes, the two basic requirements for turning are a means of holding the workpiece while it rotates as well as a means of holding cutting tools and moving them relatively to the workpiece. In this paper, we present the results of finite element analysis (FEA) performed to investigate nature of stress and their distribution at optimum point along the two turning tables of a micro-controller based versatile machine tool desktop learning module. Commercial Autodesk Inventor was used to create both three-dimensional (3D) and 2D models as well as performing simulation. Dynamics simulation generated the motion load expected to act on the tables when used for real-life operation which were in turn used to perform the FEA. The motion of the DC stepper motor driving the tables and other parts of the module is designed to be controlled by programmable chips. Before creating FEA simulation for the tables, numerical divergence were prevented by varying the mesh settings to obtain the settings at which the results of the analyses converges which was obtained at 0.03 average element size and 0.04 minimum element size. Finite element analysis carried out on the tables shows that aluminium alloy 4032-T6 chosen will serve in the fabrication of physical prototype. FEA revealed the nature and level of stresses that will be experienced on the tables, it also revealed region where these stresses will concentrate on them. The analysis also estimated the expected weight of the turning tables 1&2 to be 1.23536 and 0.257182 kg respectively and show that the minimum factor of safety was constantly 15 ul within the tables which means that they will not fail during operation.

Details

World Journal of Engineering, vol. 12 no. 5
Type: Research Article
ISSN: 1708-5284

Keywords

1 – 10 of 46
Per page
102050