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Open access

K. Shunmugesh and K. Panneerselvam

Abstract

Carbon Fiber Reinforced Polymer (CFRP) is the most preferred composite material due to its high strength, high modulus, corrosion resistance and rigidity and which has wide applications in aerospace engineering, automobile sector, sports instrumentation, light trucks, airframes. This paper is an attempt to carry out drilling experiments as per Taguchi’s L27 (313) orthogonal array on CFRP under dry condition with three different drill bit type (HSS, TiAlN and TiN). In this research work Response Surface Analysis (RSA) is used to correlate the effect of process parameters (cutting speed and feed rate) on thrust force, torque, vibration and surface roughness. This paper also focuses on determining the optimum combination of input process parameter and the drill bit type that produces quality holes in CFRP composite laminate using Multi-objective Taguchi technique and TOPSIS. The percentage of contribution, influence of process parameters and adequacy of the second order regression model is carried out by analysis of variance (ANOVA). The results of experimental investigation demonstrates that feed rate is the pre-dominate factor which affects the response variables.

Open access

A. Jasik

Abstract

The paper presents the results of numerical calculations of temperature and thermal stress distribution in thermal barrier coatings deposited by thermal spraying process on the nickel based superalloy. An assumption was made to apply conventional zirconium oxide modified with yttrium oxide (8YSZ) and apply pyrochlore type material with formula La2Zr2O7. The bond coat was made of NiCoCrAlY. Analysis of the distribution of temperature and stresses in ceramic coatings of different thicknesses was performed in the function of bond-coat thickness and the type of ceramic insulation layer. It was revealed that the thickness of NiCrAlY bond-coat has not significant influence on the stress distribution, but there is relatively strong effect on temperature level. The most important factor influenced on stress distribution in TBC system is related with type and properties of ceramic insulation layer.

Open access

P. L. Żak, D. Kalisz and G. Rączkowski

Abstract

Presented work focused on the movement of SiC particles in the vicinity of the solidification front in AZ91/(SiC)P composite. Authors describe the mathematical model that governs this phenomenon. On the base of following numerical model own computer program was prepared. The behavior of a particle moving parallel to the solidification front was analyzed. Three variants of local velocity gradient of liquid metallic phase were analyzed for a particle of radius 10, 50 and 100 μm. At a bigger velocity gradient the SiC particle was observed to go down quicker and to move towards the solidification front. This effect was stronger for SiC particles, which had a bigger radius, i.e. 100 and 50 μm

Open access

B. Szczucka-Lasota and J. Piwnik

Abstract

Thermally spraying with micro-jet cooling is an innovate technology. It is possible to get fine dispersive structure of coatings during the shorter time in comparable to the classical high velocity oxygen fuel process (HVOF). It corresponds with good corrosion-erosion properties of structure. In the paper the parameters of the spraying with micro-jet cooling process are presented. The selected properties of coatings obtained by hybrid method are presented. The results of wear tests for hybrid and HVOF coating are compared. Results of investigation are very optimistic. The presented technology should be adapted to the actual production of protective coating for machines and construction working in wear conditions.

Open access

M.S. Uddin, Y.W. Liu and S. Shankar

Abstract

This paper presents a numerical modelling and optimization of a new ‘star-like’ geometric texture shape with an aim to improve tribological performance. Initial studies showed that the triangle effect is the most dominant in reducing the friction. Motivated with this, a ‘star-like’ texture shape consisting of a series of triangular spikes around the centre of the texture is proposed. It is hypothesised that by increasing the triangular effect on a texture shape, the converging micro-wedge effect is expected to increase, hence increasing the film pressure and reducing the friction. Using the well-known Reynolds boundary conditions, numerical modelling of surface texturing is implemented via finite difference method. Simulation results showed that the number of apex points of the new ‘star-like’ texture has a significant effect on the film pressure and the friction coefficient. A 6-pointed texture at a texture density of 0.4 is shown to be the optimum shape. The new optimum star-like texture reduces the friction coefficient by 80%, 64.39%, 19.32% and 16.14%, as compared to ellipse, chevron, triangle and circle, respectively. This indicates the potential benefit of the proposed new shape in further enhancing the hydrodynamic lubrication performance of slider bearing contacts.

Open access

M. Soliman, H. Palkowski and A. Nofal

Abstract

Ductile iron was subjected to a total true strain (φt) of 0.3 either by applying φt in the austenite region or by apportioning it through applying a true strain of 0.2 in the austenite region before quenching to austempering temperature (TA) of 375°C, where a true strain of 0.1 is applied (ausforming). Additionally, two types of matrices were produced in the ductile iron, namely ausferritic and ferritic-ausferritic matrices. The ferrite is introduced to the matrix by intercritical annealing after austenitization. Dilatometric measurements as well as microstructure examination showed a fast ausferrite transformation directly after applying φA and that the introduction of ferrite to the matrix resulted in a remarkable acceleration of the ausferrite formation. The transformation kinetics, microstructure evolution, hardness and compression properties are studied.

Open access

M. Akbarzadeh, M. Zandrahimi and E. Moradpour

Abstract

Molybdenum disulfide (MoS2) is one of the most widely used solid lubricants applied in different ways on the surfaces under friction. In this work, AISI 316 austenitic stainless steel was coated with MoS2, using thermo-diffusion method at different temperatures and times. Coatings properties were investigated using SEM, EDX, XRD and FTIR, Hardness Tester and Roughness tester. The results illustrated the formation of a uniform layer on the surface, containing MoS2 and MoO3-X phases. The thickness, grain size and the hardness of the coatings were 20-50 μm, 400-1000 nm and 350- 550 HV respectively. Friction tests carried out using ball-on-disc method under normal loads of 10 N under ambient conditions showed values of the friction coefficient 0.30-0.40. In addition, the kinetics of diffusion layers between the substrate and the coating were also investigated. It was found that there at steady temperature there is a parabolic relationship between the thickness of the diffusion layer and the treatment time. The activation energy for the process was estimated to be 143 kJ mol−1. Depending on the treatment time and temperature, the thicknesses of diffusion layer varied between 0.5 and 2.5 microns.

Open access

T. Sadowski and P. Golewski

Abstract

The contemporary demands in different branches of engineering require application of new multi-component materials and structural systems. Appropriately chosen joining technology can offer significant enhancement of structural system performance in terms of effectiveness, reliability, safety and other design criteria. The modern applications of complex joints are of great technological interest as they permit to combine and to enhance the individual effects of each kind of joint. This is of great importance for modern applications in different branches of engineering: aerospace, mechanical and civil. Therefore in this paper we will focus on the analysis of mechanical response of adhesive joint of aluminium strips reinforced by rivets. The aim of the paper is to investigate experimentally the mechanical behaviour of adhesive joint of aluminium strips reinforced by rivets for industrial applications in aerospace. The considered joint was subjected to uniaxial loading. The tests in this paper were performed for: • classical adhesive joint in order to investigate material parameters for numerical modelling of the hybrid joint • hybrid joining of the structural elements in order to investigate the reinforcement effect. The experiments with application of digital image ARAMIS system allowed for on-line monitoring of the deformation process of the considered joining elements. The particular distributions of displacement fields at the joint surface were estimated for any stage of loading process. Numerical modelling was performed for experimentally investigated specimens. The materials parameters, necessary for calculation, were estimated from experiments. FEA modelling was done with the help of ABAQUS code.

Open access

F. Kováč, I. Petryshynets and P. Horňak

Abstract

This work investigates the microstructure and texture evolution in grain-oriented electrotechnical steel with a new inhibition system based on vanadium carbides nano-particles. The novel approach for the preparation of this steel with appropriate final magnetic properties combines not only nanoinhibitors based on the vanadium carbides precipitations but also includes straininduced grain growth mechanism in combination with dynamic continuous annealing during the secondary recrystallization. The experimental grain-oriented steel with proposed new chemical composition was prepared in laboratory conditions. The texture analysis has shown that suggested procedure led the formation of sufficiently strong {110}<001> Goss texture during the short time period of a final annealing process, which is comparable to that obtained in the conventionally treated grain-oriented steels.

Open access

E. Hadasik, D. Kuc, T. Mikuszewski and I. Schindler

Abstract

The paper analyses the characteristics of plasticity and microstructure of magnesium alloys with lithium meant for hot plastic working with different lithium content. The alloys were prepared in conditions of vacuum smelting. Achieved ingots were subject to hot extrusion. Tests on Gleeble simulator were conducted to assess the susceptibility of tested alloys to plastic forming in conditions of hot plastic working. For tested alloy the activation energy was marked for hot plastic deformation and plasticity characteristics in function of Zener-Hollomon parameter. After the analysis of the influence of temperature on the deformability of tested alloys it was stated that the alloy containing 8%Li (LAZ831) has better susceptibility to plastic treatment than alloy containing 4%Li (LAZ431), but higher than in case of classic magnesium alloys - AZ31.