Bivariate generalized linear exponential Weibull distribution provide an alternative for bivariate generalized exponential, bivariate generalized linear exponential and bivariate generalized Rayleigh models as it is quite flexible in nature. In this paper we study the bivariate generalized linear exponential Weibull distribution by using concomitants of generalized order statistics. The expressions for product and single moments were obtained which are derived by using concomitants of generalized order statistics. These moments used to obtain mean and variances for different sets of parameters. Additionally, we employ the ranked set sampling method to obtain more informative samples from this distribution. Within the ranked set sampling framework, we construct the best linear unbiased estimator for estimating the parameter associated with the study variable. Finally, the practical applicability of the proposed model is demonstrated through three real-life bivariate datasets, namely, cable-insulation data consisting of breakdown voltage and breakdown time, sandstone data consisting of P‑wave velocity and unconfined compressive strength, and American Football League match data from 1986 comprising two types of scoring times.
Demands for high-performance WC-Co cemented carbide tools have been significantly increased in high-end manufacturing industries such as precision and micro-machining. WC-Co and WC-TiC-TiN-Co cemented carbides were subjected to nitriding heat treatment, and their microstructures and properties were analyzed in order to explore the effect and strengthening mechanism of the nitriding process on the surface properties of the two alloys. The results show that no significant phase changes were observed on the surface of WC-Co, while a cermet layer consisting of rich-TiCN and rich-TiN cermet was formed on the surface of WC-TiC-TiN-Co after nitriding heat treatment. For mechanical properties, the hardness of WC-Co is less affected by nitriding heat treatment, while the surface hardness of WC-TiC-TiN-Co increases from 1589.3 kgf/mm2 to 1838.2 kgf/mm2, increasing by 15.7
The thermal conductivity and compressive strength of foam concrete (FC) with densities of 300, 400, 500, 700, and 900 kg/m3 were investigated, and its pore structure was characterized using X‑ray computed tomography. Through numerical simulations using COMSOL Multiphysics, theoretical estimates, and experimental testing, the thermal conductivity of composite panels was determined, and simulation errors were compared with theoretical errors. The results indicate that FC gradually improves as their density increases. The fitted empirical formula can predict the performance of FC, and the simulation error within a 10
This study investigates the creep of axisymmetrically loaded hollow cylinders made of functionally graded material. A self-consistent scalar model is used to simulate material creep. The nonlinear initial-boundary-value creep problem is solved by a numerical-analytical method based on the combined application of the Ritz and Runge-Kutta-Merson methods with automatic time-step selection. Creep problems are solved for functionally graded cylinders based on aluminum reinforced with silicon carbide (Al-SiC) particles subjected to constant internal pressure. The content of ceramic SiC particles varies linearly in the radial direction. Material creep is described by Norton’s law.
This paper presents results from a study on how conical indenter tip size affects local edge-damage characteristics and fracture resistance in edge-chipping tests on technical and optical glasses. It is shown that the fracture resistance of glass is not a constant value and depends on several factors, such as the type, shape, and size of the indenter’s active part, the level of applied force, the range of fracture distance, the method used to approximate the empirical data, and their scatter. The ability to resist chipping is affected by a scale (or size) effect caused by the indenter tip size. This requires a detailed clarification of how this effect manifests so it can be effectively accounted for in design calculations and in the certification and comparative evaluation of materials. The work consisted of a comprehensive study of the edge chipping of glass specimens using conical diamond indenters with different spherical tip radii (r = 11, 100, 200, 400, and 800 μm). Based on fractographic analysis of the fractured edge zones, we established patterns in how the typical character of glass edge damage changes with indenter tip radius. As the radius increases, the study shows a transition from elastic-plastic deformation of the glass, with chips forming through the development of a median semicircular crack, to fully elastic fracture, in which chipping results from the propagation of a quasi-conical crack. The geometric tip size of the Rockwell indenter (r = 200 μm) is found to be critical for this change in the local edge damage. The fracture resistance of glass increases substantially with indenter radius, which is regarded as the main parameter reflecting the scale effect in chipping. The data justify the choice of indenter type and confirm the validity and effectiveness of applying the fracture resistance criterion for brittle materials.
