Band 25, Heft 5-6

An outline of the modified Mindlin plate theory, which deals with bending deflection as a single variable, is presented. Shear deflection and cross-section rotation angles are functions of bending deflection. A new four-node rectangular finite element of moderately thick plate is formulated by utilizing the modified Mindlin theory. Shape functions of total (bending+shear) deflections are defined as a product of the Timshenko beam shape functions in the plate longitudinal and transversal direction. The bending and shear stiffness matrices, and translational and rotary mass matrices are specified. In this way conforming and shear-locking-free finite element is obtained. Numerical examples of plate vibration analysis, performed for various combinations of boundary conditions, show high level of accuracy and monotonic convergence of natural frequencies to analytical values. The new finite element is superior to some sophisticated finite elements incorporated in commercial software.

The aim of this paper is to study the behaviour of reflection of SV- wave at a free surface under the effects of magnetic field, initial stress, rotation and voids. When a SV- wave is incident on the free surface of an elastic half space, two damped P-waves and a SV-wave is reflected. Among of these waves, P-waves are only affected by magnetic field and rotation whereas SV-wave is influenced by rotation, initial stress and magnetic field. Numerical computations are performed for the developed amplitude ratios of P-, SV- and magneto-elastic waves. This study would be useful for magneto-elastic acoustic device field and further study about nature of seismic waves.

The so-called indentation size effect (ISE) observed mainly in nanoindentation measurements with prismatic tips, is theoretically modeled in this article with the use of gradient theory. It is shown that the ISE, i.e. the dependence of the calculated hardness value on the indentation depth, is rather an artifact of the geometry of the tip used, than a phenomenon related to the material tested. The model predictions are compared with nanoindentation measurements of Al specimens.

The paper describes a different condition of pouring temperature by sand and permanent mould to produce A356-6 wt% TiB 2 metal matrix composites by in-situ method salt metal reaction route. The observation of SEM micrographs shows particle distribution of the TiB 2 and it appears in hexagonal shape in Al matrix. The results of X-ray diffraction (XRD) analysis confirmed the formation of those TiB 2 particulates and the results showed TiB 2 particles are homogeneously dispersed throughout the matrix metal. Subsequent structure-property evaluation studies indicated sub-micron size reinforcement of in-situ formed TiB 2 particles with improved physical and mechanical properties as compared to sand and permanent mould of Al-TiB 2 composites. From, the permanent mould Al-TiB 2 composite has an advantage of increase the properties over sand mould Al-TiB 2 composite.

In nuclear power plants, modified 9Cr-1Mo ferritic steel (Grade 91 or P91) is used for constructing steam generators (SG’s) whereas austenitic stainless steel (AISI 316LN) is a major structural member for intermediate heat exchanger (IHX). Therefore, a dissimilar joint between these materials is unavoidable. In this investigation, dissimilar joints were fabricated by Shielded Metal Arc Welding (SMAW) process with Inconel 82/182 filler metals. Transverse tensile properties and Charpy V-notch impact toughness for different regions of dissimilar joints of modified 9Cr-1Mo ferritic steel and AISI 316LN austenitic stainless steel were evaluated as per the standards. Microhardness distribution across the dissimilar joint was recorded. Microstructural features of different regions were characterized by optical and scanning electron microscopy. The transverse tensile properties of the joint is found to be inferior to base metals. Impact toughness values of different regions of dissimilar metal weld joint (DMWJ) is slightly higher than the prescribed value. Formation of a soft zone at the outer edge of the HAZ will reduce the tensile properties of DMWJ. The complex microstructure developed at the interfaces of DMWJ will reduce the impact toughness values.

Since its inception no one has done analysis and design of FSW tool. Initial dimensions of FSW tool are decided by educated guess. Optimum stresses on tool pin have been determined at optimized parameters for bead on plate welding on AZ31B–O Mg alloy plate. Fatigue analysis showed that the chosen FSW tool for the welding experiment has not ∞ life and it has determined that the life of FSW tool is 2.66×10 5 cycles or revolutions. So one can conclude that any arbitrarily decided FSW tool generally has finite life and cannot be used for ∞ life. In general, one can determine the suitability of tool and its material to be used in FSW of the given workpiece materials in advance by this analysis in terms of fatigue life of the tool.

A preliminary constitutive model is suggested for fresh mortar by taking into account the rheological properties of the base matrix (concrete matrix), as well as the interaction of the aggregates (concrete suspensions). The model may be applicable for interventions in monuments and restoration/protection of objects of cultural heritage.