International Journal of Materials and Structural Integrity (9 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
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.
Compressive strength enhancement of concrete using fly ash as a partial replacement of fine aggregate and model development
by H.M.A. Mahzuz, Md. Jahid Hasan
Abstract: Fly ash is well known as a Supplementary Cementitious Material (SCM) and for its very fine well-rounded particles. Miniature gaps left in the concrete affect the concrete adversely. Fly ashs miniature and well-rounded shape can easily fill these gaps additionally offering some extra binding. The aim of this study was to use fly ash as a percentage of fine aggregate (FA). To observe the effect on a number of variations, three weight based ratios 1:1.25:2.5, 1:1.5:3 and 1:2:3 have been considered. For each ratio the fly ash varied as 0%, 10%, 20% and 30% of the FA. The curing period has been set at 28 days. The water-cement ratio (W/C) has been kept constant at 0.5. After going through all the processes and procedures the resulting data have revealed that the optimum compressive strength of the concrete lies at 10% of fly ash content. A nonlinear relationship has been perceived within the resulting compressive strength and elasticity varying with different fly ash quantity. Finally a nonlinear regression model has been suggested to mathematically describe the findings.
Keywords: concrete; fly ash; compressive strength; elasticity; nonlinear regression.
Mechanics of contact interaction and deformation of main pipelines in the conditions of extreme external actions
by Nikolay Makhutov, Mikhail Gadenin, Alexander Cherniavsky, Oleg Cherniavsky, Vladimir Nadein
Abstract: Formulation and solution of a task for the composite engineering-geological interacting of a pipeline and a soil are considered. Finite element method is used for numerical analysis of the task, accounting for large displacements and corresponding strains under changing boundary conditions. The capability of the limit state reaching in the pipeline with loss of form stability is shown to depend on the pad layer and the pipe properties. It is demonstrated also that safety maintenance could be provided by usage of ribs, formed on a pipe by a cyclic thermomechanical actions.
Keywords: structural material; deformation; strength; contact interaction; pipeline integrity; seismic steadiness; modeling; finite element method.
Changing the physical and chemical properties of alkaline soil stabilised with industrial waste material tile dust
by Jasbir Saini, Dharmender Kumar Soni, A.K. Mandal
Abstract: Various construction and post-construction damages have been reported in various research works concerning alkaline soil, owing to its irregular behaviour, especially its lower bearing capacity in natural conditions. Further, the soil strength gets decreased on soaking. In Haryana, alkaline soil deposits occur in extensive areas, which are related to certain geotechnical issues such as collapse upon wetting and susceptibility to strength loss. Owing to these characteristics, some of the roads constructed on alkaline soils in Kurukshetra have worsened because of cracking and ravelling. The important objective of this research work is the improvement of the load-bearing capacity of roads constructed on Kurukshetra alkaline soils by tile dust. Soil samples from the Pehowa-Kurukshetra road were collected and tested for enhancement of their properties by tile dust at different dosages ranging from 2 to 12%. The evaluation of the load-bearing capacity of stabilised soil mixtures is done using standard Proctor tests, performed to evaluate the compaction behaviour. The test results indicated that the maximum dry density gets minimised and the optimum moisture content gets increased with the supplementary admixture. Other tests, including the California Bearing Ratio test (CBR) and unconfined compression tests (UCS), are done for evaluating the strength properties of alkaline soil. Chemical tests due to the reaction in submerged conditions were performed in CSSRI lab in Karnal Haryana, and the following tests for pH, ECe, sodium, potassium, calcium, and magnesium were performed in saturated and submerged conditions after 30 days. These samples are put in a container for 30 days in both conditions to evaluate the chemical changes due to admixing of tile dust in alkaline soil. The test results specify that the tile dust significantly enhances the performance of the soil. Thereby, the improved soil is used as a good sub-base in flexible pavements in construction work.
Keywords: alkaline soil; stabilisation; industrial and agricultural waste.