A Relational Database Interface for Design Expert Systems

Most of the software so far developed that is based on expert systems uses a rule-based representation of the domain knowledge. Expert System applications in the engineering design process, however, frequently require access to a large static knowledge base that is easily represented in a database. This article presents the details of a relational database module to represent such static knowledge that is callable as a function by a rule-based expert system. The software implemented on a microcomputer using a C compiler, can be accessed by any inference engine with external C function calling capability. It has been used in developing an expert system for the design of steel structural elements.     

Effect of an external electrostatic field on ultrasonic machining of a dielectric material—an experimental study

The paper deals with the experimental study of the effect of an applied electrostatic field on ultrasonic machining of glass. Cylindrical cavities are machined in glass specimens (? 1-3 mm thick), both without and in the presence of a field. It is found that the time required for a 0-38 mm deep cut is reduced by about 10-20% due to the presence of a field. Further, the tool penetration rate is found to increase with the penetration of the tool into the workpiece. Using the analysis of variance technique, the observed data are analysed to show that the change in the rate of machining in the two cases is not due to chance but due to the presence of the field.     

Effect of rolling deformation and solution treatment on microstructure and mechanical properties of a cast duplex stainless steel

The present study deals with the effect of rolling deformation and solution treatment on the microstructure and mechanical properties of a cast duplex stainless steel. Cast steel reveals acicular/Widmanst?tten morphology as well as island of austenite within the $\boldsymbol\delta $ -ferrite matrix. Hot rolled samples exhibit the presence of lower volume percent of elongated band of $\boldsymbol\delta $ -ferrite ( $\boldsymbol\sim $ 40%) and austenite phase which convert into finer and fragmented microstructural constituents after 30% cold deformation. By the solution treatment, the elongated and broken crystalline grains recrystallize which leads to the formation of finer grains (<10? $\boldsymbol\mu $ m) of austenite. X-ray diffraction analysis has corroborated well with the above-mentioned microstructural investigation. Enhancement in hardness, yield strength and tensile strength values as well as drop in percent elongation with cold deformation increases its suitability for use in thinner sections. 30% cold rolled and solution treated sample reveals attractive combination of strength and ductility (25·22?GPa%). The examination of fracture surface also substantiates the tensile results. The sub-surface micrographs provide the potential sites for initiation of microvoids.     

Microstructure‐texture‐fracture toughness property correlation in annealed Al‐6Mg alloy with minor scandium and zirconium additions

The effect of minor addition of scandium and zirconium on the fracture toughness (FT) behaviour of aluminium‐6 wt% magnesium alloy is studied. Texture measurement and transmission electron microscopy have revealed that the evolution of texture in cast alloys after annealing is decided by the morphology and character of the precipitates. It is further demonstrated that the said minor addition influences the FT behaviour of Al‐6Mg alloy by manipulating in‐plane anisotropy as decided by the precipitate morphology. Textural situation in annealed state has also been related to the FT behaviour.     

A MODEL FOR ANALYSIS OF ARBITRARY COMPOSITE AND POROUS MICROSTRUCTURES WITH VORONOI CELL FINITE ELEMENTS

The Voronoi Cell Finite Element Model (VCFEM) has been successfully developed for materials with arbitrary microstructural distribution. In this method, the finite element mesh evolves naturally by Dirichlet Tessellation of the microstructure. Composite VCFEM for small deformation plasticity has been developed by expressing the element stresses in terms of polynomial expansions of location co-ordinates. Though this works well for discrete composites with inclusions, its effectiveness diminishes sharply for porous materials with voids. The effect worsens sharply with voids of arbitrary shapes. To overcome this limitation, a new way of defining stress functions is introduced in this paper. Based on a transformation method similar to the Schwarz–Christoffel conformal mapping, it introduces reciprocal stress functions that are derived to incorporate shape effects. Several numerical experiments are conducted to establish the strength of this formulation. The effect of various microstructural morphologies on the overall response and local variables are studied.     

R–S ADAPTED ARBITRARY LAGRANGIAN–EULERIAN FINITE ELEMENT METHOD FOR METAL-FORMING PROBLEMS WITH STRAIN LOCALIZATION

In this paper, an adaptive Arbitrary Lagrangian–Eulerian (ALE) finite element method is developed for solving large deformation problems with applications in metal-forming simulation. The ALE mesh movement is coupled with r-adaptation of automatic node relocation, to minimize element distortion during the process of deformation. Strain localization is considered in this study through the constitutive relations for ductile porous materials. Prediction of localized deformation is achieved through a multilevel mesh superimposition method, termed as s-adaptation. The model is validated by comparison with established results and codes, and a few metal-forming problems are simulated to test its effectiveness.     

Synthesis and 980°C Phase Development of Some Mullite Gels

Earlier works of mullitization through the gel route have been reviewed and the results show 980°C DTA and crystalline phases. Some Al₂O₃-SiO₂ gels have been synthesized by using different precursors and by varying pH and water content during the gelification process. Thermal changes of these coherent gels were studied by DTA and X-ray powder diffractometry. The results demonstrate that two types of aluminosilicate gels form. The first type produces orthorhombic mullite directly on heating at 980°C, whereas the second type forms cubic mullite first at 980°C and then transforms to the orthorhombic variety on further heating. Lastly, the cause of the 980°C exotherm is explained with reference to kaolinite.     

Numerical simulation with finite element and artificial neural network of ball indentation for mechanical property estimation

A combined mechanical property evaluation methodology with ABI (Automated Ball Indentation) simulation and Artificial Neural Network (ANN) analysis is evolved to evaluate the mechanical properties for Carbon Manganese Steel (SA-333 Grade-6) and Stainless Steel (SS-304LN). The experimental load deflection data is converted into meaningful mechanical properties for these materials and their evaluated property is verified with experimental tensile specimen results. An ANN database is generated with the help of contact type finite element analysis by numerically simulating the ABI process for various magnitudes of yield strength (σ _yp ) (200 MPa–400 MPa) with a range of strain hardening exponent (n) (0.05–0.5) and strength coefficient (K) (600 MPa–1600 MPa). For the present problem, a ball indenter of 1.57 mm diameter having Young’s modulus higher than test piece is used to minimize the error due to indenter deformation. Test piece dimension is kept large enough in comparison to the indenter configuration in the simulation to minimize the deflection at the outer edge of the test piece. Further, this database after the neural network training; is used to analyse measured material properties of different test pieces. The ANN predictions are reconfirmed with contact type finite element analysis for an arbitrary selected test sample. The methodology evolved in this work can be extended to predict material properties for any irradiated nuclear material in the service. Extensions of the ABI tests and the associated database analysis could lead to evaluation of the indentation energy to fracture needed for the structural integrity assessment of aged components.     

Preparation of novel CdS-graphene/TiO2 composites with high photocatalytic activity for methylene blue dye under visible light

In this study, CdS combined graphene/TiO₂ (CdS-graphene/TiO₂) composites were prepared by a sol–gel method to improve on the photocatalytic performance of TiO₂. These composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and transmission electron microscopy (TEM). The photocatalytic activities were examined by the degradation of methylene blue (MB) under visible light irradiation. The photodegradation rate of MB under visible light irradiation reached 90·1% during 150 min. The kinetics of MB degradation were plotted alongside the values calculated from the Langmuir–Hinshelwood equation. 0·1 CGT sample showed the best photocatalytic activity, which was attributed to a cooperative reaction between the increase of photo-absorption effect by graphene and photocatalytic effect by CdS.     

A comprehensive literature review and analysis of the design,balancing and scheduling of assembly systems

This paper reports the results of a comprehensive review and analysis of the assembly line balancing literature. Quantitative developments and qualitative issues are addressed at both the strategic and tactical levels. The numerous quantitative and qualitative factors which the literature mentions could impact the design, balancing and scheduling of assembly systems are organized into an eight-level hierarchical, factor/decision taxomony. This comprehensive taxonomy is used to assess our progress in assembly system design and operation. Finally, from the results of the literature review and progress assessment, suggestions for future research on socio-technical assembly systems are offered.