International Journal of Computational Materials Science and Surface Engineering (10 papers in press)
Modelling and optimization of adhesive bonded joint strength of composites for aerospace applications
by Hanumantharaya R, Irappa Sogalad, S. Basavarajappa, Manjunath Patel G C
Abstract: In recent past, adhesive bonding gain much attention world-wide in joining of engineered parts namely, automotive and aerospace structures. The strength of adhesive bonded composite joints is studied by conducting experiments based on the matrices of central composite design. The collected data was analyzed using response surface methodology. The mathematical model was established to express the load carrying capacity and joint strength as a function of input variables. Further, Analysis of variance was carried out to ensure good fit to the experimental data. Moreover, the statistical methods determine significant interaction effects among the factors. Finally, genetic algorithm was used to locate the optimum points of joint strength for the set of inputs i.e. 40 mm overlap length, 0.2 mm adhesive thickness and 4.526
Keywords: Composite bonded joint; Response surface methodology; Central composite design; and Genetic algorithm.
Effect of cutting parameters on surface roughness in ultra-high precision turning of a contact lens polymer
by Muhammad Mukhtar Liman, Khaled Abou-El-Hossein, Lukman N. Abdulkadir, Peter O.,. Babatunde, Abubakar I.,. Jumare
Abstract: This paper studies the effect of cutting parameters on surface generation in ultra-precision turning of a contact lens polymer. Contact lens manufacture requires high accuracy and surface integrity. Surface roughness is generally used to measure the index quality of a turning process. It has been an important response because it has direct influence toward the part performance and the production cost. Hence, choosing optimal cutting parameters will not only improve the quality measure but also the productivity. This research work is therefore aimed at investigating the effect of cutting parameters (cutting speed, feed rate and depth of cut) on surface roughness of ONSI-56 contact lens polymer with a monocrystalline diamond cutting tool. In this work, cutting speed (A) is found to be the most dominant factor having the highest degree of significance followed by the square of the cutting speed (A2) and the feed rate (B). However, interaction between cutting speed and feed rate (AB) has the lowest degree of significance on the surface roughness.
Keywords: ANOVA; Cutting parameters; Contact lenses; Surface roughness.
Mechanical and Wear Surface Characterization of Aluminum Hybrid Nanocomposite
by Manivannan I, Ranganathan S, Gopalakannan S, Suresh S, Candane D
Abstract: The newly engineered metal matrix nanocomposite (MMNC) of Al 6061 reinforced with 0.4 wt % SiC and 0.5 wt % Gr hybrid nanocomposites were synthesized by ultrasonic assisted stir casting method. The pin-on-disc equipment were conducted on the prepared samples to investigate the tribological behavior of the hybrid nanocomposite. The hybrid nanocomposite and wear surfaces have been characterized by Field Emission Scanning Electron Microscope (FESEM) equipped with an Energy Dispersive Spectrometer (EDS),Optical Microscope (OM) and 3D profilometer to understand the wear mechanisms. This study shows the effectiveness of incorporation of graphite in the hybrid nano composite for reduction of friction, wear and surface roughness. With the introduction of nanoSiC and Gr particles in to matrix alloy, the number and depth of grooves in worn surface of hybrid nanocomposites decreased. The Al/0.4SiC/0.5Gr hybrid nano-composite showed superior tribological properties and self-lubricating ability compared to the matrix alloy.
Keywords: Al6061; Nano SiC; Graphite; Ultrasonic assisted casting; Wear; Friction; Surface roughness.
Effect of weld parameters on joint strength of 904L grade steel using resistance spot welding
by Vivek Kalyankar, Nitin Chouhan
Abstract: Experimental investigation on resistance spot welding of 904L super austenitic stainless steel, which is finding its considerable applicability in automobile sector, is presented in this work. However, joining of this material involves difficulties due to complex working range of process parameters leading to critical mechanical and metallurgical changes in the weld joint. More focus is given on effect of important process parameters like weld time, current, electrode pressure and squeeze time on strength of weld joint. A mathematical model is proposed to understand the combined effect of multiple processing parameters on tensile shear strength (TSS) which can be beneficial to scientific community to get enhanced results. For the present setup, more significant parameter is electrode pressure followed by other parameters. TSS decreases with increase in electrode pressure up to certain level and then starts increasing while TSS increases with increase in squeeze time and subsequently it remains constant.
Keywords: 904L stainless steel; Resistance spot welding; Tensile shear strength; Weld time; Electrode pressure; Weld current; Squeeze time.
Influences of Tool Rotational Speed on Microstructural Characteristics and Mechanical Properties of Friction Stir Welded AA2014-T6 Aluminium Alloy
by Chinnasamy Rajendran, R. Mannoj Guru, S. Kavin, P. Navanithan, P. Nishanth Kalathil
Abstract: Friction stir welding (FSW) is a promising solid-state welding process for precipitation hardening and high strength aluminum alloys. An experimental and theoretical investigation was carried out to check the significance of tool rotation speed on microstructural characteristics and tensile properties of high-strength alloy AA2014. FSW joints were made with varying tool rotation speed from 1100 rpm to 1900 rpm with an equal increment of 200 rpm, while the other parameters such as welding speed, shoulder diameter and tool tilt angle were kept constant. The strength of FSW joints was correlated with microhardness, microstructure and fractographs. The joint fabricated with the tool rotation speed of 1500 rpm, welding speed of 50 mm/min, shoulder diameter of 6 mm and tool tilt angle of 1.5
Keywords: Friction stir welding; AA2014; Tool rotational speed; Tensile properties; Microstructure.
Molecular dynamic study of combined effects of diamond tool rake angle and duncut/Redge ratio on nanomachining behavior of monocrystalline optical silicon
by Lukman N. Abdulkadir, Khaled Abou-El-Hossein, Muhammad M. Liman, Peter B. Odedeyi, Abubakar I. Jumare
Abstract: Silicon shows ductility under contact loading due to influence of tool geometry and cutting parameters. Of the tool geometries, edge radius and rake angle have been proven to significantly affect ductile regime machining of silicon. Molecular dynamics (MD) study of the effects of edge radius, rake angle and d_uncut/R_edge ratio (at uncut chip thickness above and below edge radius) on optical silicon nanomachining was conducted using a multi-body potential function. It was observed that the stress state of silicon in the machining zone was within experimental reported range and increased with increase in rake angle and decrease in d_uncut/R_edge ratio causing increased compression of in-depth residual stress. Larger rake angle tool experienced slightly stronger cutting resistance from the workpiece than that with the smaller rake angle (with the same edge radius) causing the specific cutting energy (SCE), cutting and thrust forces to increase. The kinetic friction was however high at high d_uncut/R_edge ratio, reducing as the rake angle increases due to increase in thrust forces. Furthermore, the excessive negative effective rake angle created due to edge roundness at low d_uncut/R_edge ratio and high rake angle was observed to be responsible for increase in phase change at the cutting region. This led to a decrease in chip length and thickness, while the ploughing ahead of the tool and subsurface deformation underneath the machined surface increased.
Keywords: Molecular dynamics; potential function; optical silicon; rake angle; d_uncut/R_edge ratio plastic deformation; subsurface deformation.
Thermo-mechanical Evaluation of Plasma Sprayed YSZ based Multi-layered Thermal Barrier Coatings
by Debasish Das, Rajeev Verma, Vipul Kumar Pathak
Abstract: The multi-layered YSZ, NiCoCrAlY, Cr2O3 and Al2O3 coatings of varying thickness (200
Keywords: Thermal barrier coatings; diesel engine; thermal cycling; lattice strain.
Selection of Process Parameters of AISI 304 for Laser Processing of Materials
by Paramasivan Kalvettukaran, Sandip Das, Sundar Marimuthu, Dipten Misra
Abstract: This paper describes numerical simulation of laser processing of AISI 304 sheet metal and statistical analysis to develop mathematical relations for determination of the limiting values of the process parameters such that the material temperature remains above or below the specified maximum temperature, depending upon the specific requirement. The statistical software Design-Expert 7.0 is used to create the design layout and to obtain the final regression equation. The simulations layout is designed based on a central composite design (CCD) with four factors and five levels. Laser power, scanning speed, spot diameter and plate thickness are considered as input variables, while maximum temperature of the plate is considered as the response from the model. The simulations are carried out through finite element package COMSOL MULTIPHYSICS
Keywords: Laser material processing; Numerical simulation; Regression equation; Solidus temperature; Liquidus temperature.
Multiple welding simulated microstructure and corrosion resistance of super austenitic stainless steel 254SMo welding heat-affected zone
by Guannan Zhang Guannan Zhang
Abstract: This paper studies the effects of thermal cycle and heat input on microstructure, grain size, precipitated phase and corrosion properties in the simulated heat-affected zone of super austenitic stainless steel 254SMo. The results show that the microstructure grains in the heat affected zone gradually grow up, the pitting corrosion resistance decreases continuously and intergranular corrosion resistance firstly decreases and then increases with the thermal cycle and heat input increase. The precipitated phase appears in the heat-affected zone at the multiple thermal cycles and high heat input.
Keywords: super austenitic stainless steel; simulated heat-affected zone; thermal cycles; heat inputs; precipitated phase; corrosion resistance
Special Issue on: ICPNS'2016 Physical and Numerical Simulation of Materials Processing
The study on kinetics of metadynamic recrystallization of a Nb-V microalloyed non-quenched and tempered steel
by Liwen Zhang, Wenfei Shen, Chi Zhang, Yingnan Xia, Xinhua Shi, Fei Xia
Abstract: The metadynamic recrystallization (MDRX) behavior of a Nb-V microalloyed non-quenched and tempered steel was investigated by isothermal hot compression tests on Gleeble-1500 thermal-mechanical simulator. Compression tests were performed using double hit schedules at temperatures of 1273-1423 K, strain rates of 0.01-5 s-1, initial grain sizes of 92-149 μm and inter-pass time of 0.5-10 s. The effects of deformation parameters, including deformation temperature, strain rate, initial grain size and inter-pass time, on MDRX softening fraction were analyzed. The experimental results show that MDRX softening fraction increases with the increasing of deformation temperature, strain rate and inter-pass time, while it decreases with the increasing of initial grain size. Based on the experimental results, the kinetic model of MDRX for the tested steel was established. A good agreement between the experimental and predicted MDRX softening fraction was obtained, which indicates that the established kinetic model can precisely predict the MDRX softening fraction for the hot deformed tested steel.
Keywords: Metadynamic recrystallization, Nb-V microalloyed steel, Non-quenched and tempered steel, Hot compression