Advanced Materials and Processes Research Institute
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Microstructural Alterations Through Heat Treatment and Its Influence on Wear Response of a Silicon Containing Zinc-Based Alloy Under Different Test Conditions.
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A comparative evaluation of the theoretical failure criteria for workability in cold forging.
No full textThis paper evaluates various theoretical failure criteria pertaining to workability in cold forging reported in the published literature for their reliability and sensitivity in predicting the occurrence of ductile fracture in metalworking. Finite element (FE) simulation of the published upsetting experiments on cylindrical test specimens was performed to determine the threshold values attained by various criteria at the fractured locations, for a wide variety of materials. A comparison of the experimental threshold values of different criteria, with those obtained through FEA of complex metalworking processes at fracture was also made. A statistical analysis of the results revealed that none of the criteria are truly friction and geometry-independent for universal application. Nevertheless, within a family of processes such as upsetting, the criteria depending on cumulative specific plastic energy adjusted suitably with the maximum tensile stress, are the most reliable ones in the estimation of workability limits
Preparation and characterization of penta alkyds based on mahua oil.
No full textA medium oil length alkyd resin is prepared from mahua oil (a non-traditional oil), pentaerythritol and phthalic anhydride. The alkyd was characterized by IR analysis. Other properties viz. , viscosity, specific gravity, acid number, saponification value etc. were determined. Film characteristics of the resin like drying time, thickness, scratch hardness, impact resistance and adhesion were also assessed. The performance of the resin was found to be comparable to a commercial resin. Penta alkyd developed using mahua is of non-drying nature. It can be used as a baking system by curing with melamine at 140oC for 4 hr. The baked film offers good mechanical properties as well as resistance to water and alkali. Combination of ester gum with mahua alkyd gives an air dying resin
CAE for forging of titanium alloy aero-engine disc and integration with CAD-CAM for publication of the dies.
No full textTitanium alloy aero-engine turbine discs are subjected to stringent quality requirements pertaining to dimensional tolerances and mechanical properties. Therefore, the forging process of the disc is meticulously designed. This paper primarily deals with computer-aided engineering (CAE) of the die profile as well as the process design for the forging and in addition briefly addresses the integration of CAE with computer-aided design–computer-aided manufacturing (CAD–CAM) for the fabrication of the dies. The CAE involves study of (i) mechanics of the material flow using large deformation FEA for streamlined flow and (ii) the mechanisms of deformation using dynamic materials modelling (DMM) technique for the process optimization. In addition, concurrent modelling using DMM as well as finite element modelling (FEM) facilitates understanding the development of microstructure at different locations in the forged component. The predicted flow pattern and the load-stroke values are found to be in good agreement with the experimental results. The results of the CAE are fed to a CAD environment and finally linked to CAM for the fabrication (precision machining) of the dies. This integrated approach is cost effective and time saving
High Stress Abrasive Wear Mechanism of LM13-SiC Composite Under Varying Experimental Conditions
No full textAn attempt has been made to understand the mechanism of material removal during two-body abrasive wear of Al-alloy (LM13)-SiC composite under varying experimental conditions through the wear surface and subsurface examination. It has been noted that the mechanisms of material removal during the wear process are primarily cutting and plowing, which lead to formation of continuous wear grooves. In the composite, SiC particles act as protrusions over the surface and protect the matrix from wear. But at higher applied load, coarser abrasive size, and larger sliding distances, some of the SiC particles get fractured into fine particles and scooped off from the wear surface leading to a higher wear rate. The subsurface studies show severe plastic deformation and finally formation of a mechanically mixed layer (MML) over the plastically deformed zone. The MML gets fractured during the wear process and finally removed by the formation of lateral and transverse cracking. The cracks are generally initiated at the interface of MML and the plastically deformed zone and propagate along the weaker region in MML. The material removal mechanism has been schematically presented in order to have a better understanding
Dynamic materials Modelling and finite element simulation of titanium alloy turbine disc forging
No full textTitanium alloy turbine discs for aeroengines are normally produced by forging to near net shape at high temperature followed by machining. Since titanium alloys exhibit limited workability and the microstructural development during forging is highly sensitive to the processing temperature and strain rate, the selection of the processing conditions becomes very important. In this study, a processing map for Ti alloy 685 is developed using dynamic materials modelling (DMM), which suggests good workability in the α–β phase field at 960°C and at strain rates less than 10–2 s–1. In addition, a large deformation finite element analysis (FEA) of isothermal disc forging is carried out, to design the die profile that renders streamlined flow during forging. The computed distribution of strain and strain rate in the deforming billet integrated with the results of DMM aids in designing the forging scheme to achieve uniform microstructure in the final component. In this context, the importance of upsetting prior to forging is also discussed. The paper includes experimental validation of the FEA–DMM integrated approach
Dynamic Viscoelasticity of Hybrid Kevlar and Glass Fiber Reinforced LLDPE in the Molten State
No full textKevlar and glass fibers were used to reinforce linear low density polyethylene (LLDPE), and composite sheets of 0.8, 1.5 and 2.5 mm thicknesses were obtained by using a compression molding technique. Dynamic viscoelastic properties of non-hybrid and hybrid composites of various compositions at 200°C are evaluated. Storage modulus (G′) and loss modulus (G″) increase with angular frequency (ω) and reinforcement. Replacement of glass fiber by Kevlar at constant loading of fibers in LLDPE increases the value of G′, G″ and η′. The fractured surface of composite shows the gradient orientation of fibers particularly in 2.5 mm thick sheet. Top and bottom layers show relatively two-dimensional orientation as compared to the middle layer, which shows random orientation. The orientation of fibers decreases G′ and η′ of Kevlar fiber and hybrid fiber hybrid fiber reinforced LLDPE composites. The effect of change in distance between parallel plate of rheometer (change in strain amplitude) on dynamic rheological properties is studied and reported here