International Journal of Materials and Structural Integrity (12 papers in press)
Deformational inhomogeneity in Al-8Mg alloy microhardness study
by Swami Naidu Gurugubelli, A.V.S.S.K.S. Gupta, N.R.M.R. Bhargava
Thermal cycling reliability of lead-free package stackable very thin fine pitch ball grid array (PSvfBGA) assemblies with reworkable edge and corner bond adhesives
by Hongbin Shi, Toshitsugu Ueda
Constant-pressure molecular dynamics simulation of thermal bubble nucleation in rough wall nanochannels
by Min Chen, Dawei Jiang, Kunpeng Jiang
Triaxial tests on weak planes damage of hard brittle shale of Longmaxi formations in south Sichuan Basin,China
by Yi Ding, Xiangjun Liu, Wei Zeng
Abstract: In the petroleum field, rock mechanical properties are a significant parameter for design of drilling operations. Shale formation has a high risk of wellbore instability in drilling. To reduce this risk, more investigations on shale should be conducted. Therefore, in this paper, by using X-ray diffraction and electron microscope scanning test, the mineral composition and microstructure of brittle shale of the Longmaxi formation have been analysed. Based on the triaxial compression tests, rock mechanical parameters in variable time have been discussed when shale is in the external force condition. In particular, considering shale failure along a weak plane, change laws of shale mechanical properties, such as stress, strain, structure integrity and elastic parameters, have been analysed. This work offers comprehensive exploration on shale mechanical properties. Mechanical parameters of shale in this study can provide reference for engineering design, and more importantly, establish the foundation for investigation of rock damage in the future.
Keywords: shale; triaxial tests; rock mechanics; weak plane damage.
Environment friendly milling of Inconel-625
by Pragat Singh, J.S. Dureja, Harwinder Singh, Manpreet S. Bhatti
Abstract: Inconel 625, having wide industrial applications, exhibits poor machinability because of rapid work-hardening and poor thermal conductivity. Therefore, cutting fluids are used to remove heat and provide lubrication in the cutting zone, but their application poses serious environmental and health hazards, hence the need to minimise their use. The nanoparticle-based minimum quantity lubrication (NMQL) technique provides an effective alternative to flooded cooling-machining of Inconel and stainless steel. The current study evaluates the performance of NMQL in terms of tool wear and surface finish during face milling of Inconel 625. To enhance thermal conductivity of MQL, soluble multi-walled carbon nanotubes (1% wt.) were mixed in vegetable oil. Cutting parameters were optimised to minimise tool wear and surface roughness, and validation tests were also conducted under flooded and dry conditions to compare their performance with NMQL machining. The performance of the cutting tool during NMQL machining was found to be 15.56% and 3.45% better than dry and flooded machining, respectively, on the basis of tool wear and 14.06% and 59.02% improved over flooded and dry machining, respectively, in terms of surface roughness.
Keywords: Inconel 625; face milling; minimum quantity lubrication; nanoparticle-based minimum quantity lubrication; multi-walled carbon nanotubes; tool wear; surface roughness; environment friendly machining.
Modelling and characterization of a magneto-rheological elastomer isolator device under impact loadings using interpolated multiple adaptive neuro-fuzzy inference system structure
by Mohd Sabirin Rahmat, Khisbullah Hudha, Zulkiffli Abd Kadir, Nur Rashid Mat Nuri, Noor Hafizah Amer, Shohaimi Abdullah
Abstract: This paper presents the modelling and characterisation of a magneto-rheological elastomer isolator device (MREID) under impact loading using the adaptive neuro-fuzzy inference system (ANFIS) technique. The characterisation of an MREID under impact loading was performed using an impact pendulum test rig, and the data obtained from the experimental work was processed in the form of force-velocity and force-displacement characteristics. In order to predict MREID behaviour in simulation analysis, multiple ANFIS models were proposed. A single ANFIS model was represented as a single kinetic energy produced by the impact mass used in experimental work. The experimental data was then used to train the ANFIS in predicting MREID behaviour and validating its performance. For verification, the prediction model, a parametric model (namely, the modified Bouc-Wen model) was developed, and the models were compared. The proposed interpolated multiple ANFIS model predicted the behaviour of the MREID with a high level of accuracy. The proposed model produced a better prediction than the modified Bouc-Wen model.
Keywords: magnetorheological elastomer; isolator device; impact loading; ANFIS; Bouc-Wen MRE modelling.
Factors influencing the interference of inner surface parallel biaxial cracks in thick-walled pipes
by Xiaofeng Qin, Feng Li, Xingguo Zhao
Abstract: The present work provides insights into the factors that influence the interference of inner surface biaxial cracks in a thick-walled cylinder under internal pressure by the finite element method. An interaction impact factor λ is defined based on theoretical formula of stress intensity factor of a single axial crack and factors such as angles, ratio of crack length to wall thickness, and ratio of outer diameter to wall thickness, which probably have an effect on the interference of two parallel axial cracks. The present work reveals there is a critical angle determining the closure and opening effect between the biaxial cracks. When the angle between biaxial cracks is larger than the critical value, the opening effect will be strengthened with the increase of angle, ratio of crack length to wall thickness, and ratio of outer diameter to wall thickness. The closure effect will be strengthened with the increase of angle, ratio of crack length to wall thickness and ratio of outer diameter to wall thickness when the angle between the biaxial cracks is smaller than the critical value.
Keywords: stress intensity factor; biaxial cracks; interaction impact factor; thick-walled pipe.
Study on the adsorption of methylene blue by NaOH KH550 modified bagasse
by Xuanjun Dai, Jiyuan Zhu
Abstract: The chemical composition, thermal stability and crystallinity of NaOH/KH550 modified bagasse were studied using the infrared spectroscopic analysis, thermogravimetric analysis and x-ray diffractometry. After modification, the hemicellulose was removed and KH550 was grafted onto the surface of the bagasse fibre effectively. Then, the modified bagasse was used as the adsorbent of methylene blue (MB) for the adsorption study. According to the results, the initial concentration of MB ranged from 10 to 200 mg/L at room temperature (25 ℃). The removal rate of MB could reach 94% under the conditions of adsorbent dosage greater than or equal to 4 g/L, solution pH from 8 to 12 and an adsorption time longer than 60 minutes. Furthermore, the adsorption isotherm model and adsorption kinetic model of modified bagasse for MB were studied, and the results showed that the adsorption isotherm accorded with the Freundlich model and the adsorption kinetic model accorded with a pseudo-second-order kinetic equation.
Keywords: bagasse; coupling reagent; characterisation; methylene blue; adsorption.
Effect of high temperature on fly ash based alkali-activated concrete compared with Portland cement concrete
by Sonal Thakkar, Urmil Dave, Jay Patel
Abstract: Sustainability and durability of concrete structures is an issue in todays world. This paper presents comparative study of effect of high temperature on fly ash based alkali-activated concrete, activated with sodium based activators and Ordinary Portland cement concrete for same grade. Residual compressive strength, split tensile strength, flexural strength, bond strength and modulus of elasticity were evaluated for both concrete at temperatures of 27
Keywords: high temperature; alkali activated concrete; fly ash; ordinary Portland cement concrete; residual mechanical properties.
Flexural fatigue analysis of fibre-reinforced polymer concrete composites under non-reversed loading
by Raman Bedi, S.P. Singh
Abstract: Results of an investigation on the flexural fatigue performance of Polypropylene Fibre-Reinforced Polymer Concrete Composites (PFRPCC) are presented. Flexural fatigue lives of PFRPCC beams at different stress levels were obtained using a 100 kN MTS servo-controlled actuator. The specimens incorporated three weight fractions, i.e. 0.5%, 1.0% and 2.0%, of polypropylene fibres. It has been established using a graphical goodness of fit procedure that the fatigue life distributions of PFRPCC at various stress levels approximately follow the two-parameter Weibull distribution with correlation coefficient exceeding 0.9. The results of the graphical goodness of fit procedure have been reinforced with the help of the Kolmogorov-Smirnov goodness of fit test and the Anderson-Darling test of goodness of fit.The fatigue strength prediction models, particularly representing S-N relationships, have been examined and the material coefficients have been obtained for PFRPCC containing different weight fractions of fibres. Furthermore, using Weibull distribution, probability of failure has been incorporated into the fatigue life data of PFRPCC to develop S-N-Pf relationships, both graphically and analytically. The two million cycle endurance limits for PFRPCC containing different amounts of fibres have also been obtained.
Keywords: polymer concrete composites; fatigue; statistical properties/methods; Weibull distribution; probability of failure.
A new simple formulation for instantaneous coil diameter of a SMA helical spring
by Santhanam Ranganathan, M.S. Sivakumar, Y. KRISHNA
Abstract: Helical coil tension springs made of shape memory alloy (SMA) materials generally undergo large deflection under loading, during which their mean coil diameter changes noticeably. In the design of these helical coil springs, it is necessary to identify the real behaviour which may be affected by the variation in actual coil diameter. Therefore, a simple formulation is proposed in this paper for predicting instantaneous coil diameter. The predictions from the present formulation match very closely with experimental measurements. The proposed formulation is relatively easy to adopt for design calculations. The effects of varying coil diameter on the spring characteristics are also discussed. This is very general and can be used for any helical spring that undergoes small or large deflections, although the proposed formulation is derived for an SMA helical spring.
Keywords: shape memory alloy; SMA; helical coil tension springs; instantaneous coil diameter; large deflection.
Effects of two-step heat treatment on the structure of cotton-derived activated carbon fibres
by Tsuyoshi Yoda, Keita Shibuya, Kazuma Miura, Hideki Myoubudani
Abstract: Activated carbon fibres (ACFs), a novel material, has attracted considerable research attention. The pore structures found on the surfaces of ACFs are strongly related to their functionality. Herein, ACFs were prepared via a two-step thermal treatment of cotton. The diameters and width distributions of thus-prepared ACFs were characterised using scanning electron microscopy (SEM). SEM analysis also revealed that the pore structures on the surfaces of the cotton-derived ACFs were activated by carbon dioxide. Successful adsorption functionality of these ACFs was characterised using a methylene blue solution. The effects of the two-step thermal treatment and potential applications of this methodology are also discussed. The proposed method can be used on other fibre products or industrial waste materials generated during the manufacture of cloth and fibres, and the generated ACFs can be used for energy-storage applications.
Keywords: activated carbon fibre; scanning electron microscope; thermal treatment; activation; pore structure; methylene blue; adsorption; cotton.