NOPR Collection:

Ionic transport in sodium phosphate glasses doped with chlorides of Co, Cd and Ag

2010-03-10T16:30:31Z

Title: Ionic transport in sodium phosphate glasses doped with chlorides of Co, Cd and Ag Authors: Das, S S; Srivastava, Vibha; Singh, P Abstract: Several samples of sodium phosphate glasses doped with different concentrations of chlorides of cadmium and cobalt along with samples of undoped sodium phosphate glass have been prepared. Sodium phosphate glasses doped with varying amounts of AgCl have also been prepared to see the role of Ag⁺ ion in modifying the conductivity of sodium phosphate glass. These glasses have been characterized by elemental analysis, X-ray diffraction, IR spectra, differential scanning calorimetry, transference number measurements and electrical conductivity studies. All the glasses are found to be essentially ionic conductors. The undoped sodium phosphate glass has low σ value in comparison to the doped ones. The values of ionic conductivity in Na₂O‑P₂O₅‑CdCl₂ and Na₂O-P₂O₅-CoCl₂ glasses are maximum for 1% CdCl₂ and 5% CoCl₂ doped ones respectively. However, in the case of Na₂O-P₂O₅-AgCl glass the σ values go on increasing with the increasing concentrations of the dopant AgCl and the following sequence is observed. σ (-CdCl₂) < σ(-CoCl₂) < σ (-AgCl) These results have been explained on the basis of changes in the structure of sodium phosphate glass matrix by the addition of different dopant cations, viz; Cd²⁺, Co²⁺and Ag⁺. Page(s): 455-461

Elastic property evaluation of jute-glass fibre hybrid composite using experimental and CLT approach

2010-03-08T16:30:42Z

Title: Elastic property evaluation of jute-glass fibre hybrid composite using experimental and CLT approach Authors: Ahmed, K Sabeel; Vijayarangan, S Abstract: Elastic properties are the basic quantities that are required during design and optimization of a laminated structure. Though the literature on elastic properties of conventional single fibre composite is well published, the same is scanty in the case of natural and hybrid composites. This work is focused on evaluation of in-plane elastic properties of untreated woven jute and jute-glass fabric hybrid polyester composites, under tension. The specimens have been fabricated by hand-lay-up technique with different relative weight fraction of jute and glass fibre. Theoretically, the laminate elastic properties are predicted by using the classical lamination theory (CLT) and rule of hybrid mixture model, using the resin and fibre properties together with the volume fraction (micromechanics). Experimentally, the elastic properties have been evaluated by tension test in warp and weft direction and in-plane shear test as per ASTM standards. The results indicated that the Young’s modulus in both warp and weft direction improve by the inclusion of glass fibre, where as Poisson’s ratio is decreased. Prediction by CLT and model showed close agreement with experimental values with a maximum deviation of about 20%. The possible causes for this deviation are discussed. Page(s): 435-442

Investigation of low cycle fatigue crack opening size and closure stress

2010-03-08T16:30:35Z

Title: Investigation of low cycle fatigue crack opening size and closure stress Authors: Daunys, M; Taraškevičius, A Abstract: In the recent years, a number of studies on the fatigue crack opening and crack closure load have been carried out. Present investigation serves as an intermediate point to complete a failure prediction model with a more practical value for determination of leak before the break (LBB) problem in pressure vessels and pipes. An attempt has been made to solve this problem by using analytical, numerical and experimental methods. Method of linear fracture mechanics at analytical investigation by using the analogy between the stress strain state at stress concentrator and the crack tip and strain intensity factor is adapted to the nominal elastic-plastic loading. Investigation has showed that numerical results are in good agreement with the experimental results. However, the proposed analytical model satisfactorily matches with the experiment in the middle of the crack, which is acceptable for LBB conception, and incorrect at the crack tip, which is non-acceptable for the fracture mechanics conception. Page(s): 417-425

Determination of the effect of temperature and relative humidity on the friction coefficient of V-belt mechanism

2010-03-09T16:30:33Z

Title: Determination of the effect of temperature and relative humidity on the friction coefficient of V-belt mechanism Authors: Cengiz, Abdulkadir; Uçar, Mehmet Abstract: In the V-belt drive system, temperature and humidity are the most effective parameters affecting the slippage. This study is done in two stages. Firstly, experimental study has been carried out and the effect of temperature, relative humidity on the slippage between V-belt and pulley has been analyzed. At the second stage, non-linear regression analysis has been carried out to get a prediction equation for determining of friction coefficient between V-belt and pulley at the different temperature and humidity. In the analysis MATLAB Statistics Toolbox was used. At the result of the analysis the prediction equation has been obtained with 0.995 correlation coefficient. It has been seen that increase of temperature and humidity leads to decrease in the coefficient of friction (slippage raises). In high humidity conditions, slip quantity raises rapidly when temperature is 60-80°C. Page(s): 405-410