Development of a model for friction stir weld quality assessment using machine vision and acoustic emission techniques

The surface texture of friction stir weld is related to internal structure of weld. The statistical image parameters along good and defect weld regions are quantitatively evaluated for quality from the weld bead images, which are processed and analyzed using machine vision technique and X-ray radiography. The weld strength obtained along the weld regions showing similar variations in Acoustic Emission (AE) data, which was acquired during welding and image data of the weld bead are analyzed to assess the weld quality. The combined model developed using limiting values of image data and AE data along different regions of weld evaluate the weld quality more reliably. © 2015 Elsevier B.V. All rights reserved

Numerical Simulation of Double Action Powder Compaction Process

The extensive utilization of aluminum reinforced with silicon carbide composites in different structural applicationshas motivated the need to find a cost effective technological production method for these composites. Homogeneity, machinability, and interfacial reaction of the constituents represent the large problems pertaining to these composites. Production of a homogenous, high strength and near net shape structural components made from aluminum-silicon carbide composites can be achieved using powder metallurgy (PM) technology. In the present work double acting compaction process is simulated for four cases of different compositions and compaction densities. The compact pressures and relative densities are plotted. The simulation parameters derived are presented

Thermomechanical modeling and Evaluation to study peak temperature and Flow stress of Friction Stir welds of Aluminum Alloy 6061

This work involves three-dimensional thermomechanical modeling of Friction Stir Welding (FSW) process using general purpose Finite Element Analysis (FEA) simulation tool ‘Altair Hyperworks’ from the combined complementary effort of experimental evaluation and numerical modeling to understand FSW process. Thermal and mechanical behavior of the material which are mutually dependent are coupled together to simulate the FSW process model similar to the real time to evaluate the peak temperature and flow stress. The heat generation is governed by friction between tool and workpiece, plastic deformation and the temperature imposed subsequently on the material. The temperature distribution in the workpiece during FSW process of butt joining of aluminum alloy 6061-T6 is experimentally measured from the devised thermocouple layout at different locations on the workpiece in the welding direction. The temperature history and normal force predicted from simulated model is compared with that of experimental values and is found to be in good agreement validating the numerical model. Parametric study to determine the effects of tool rotational and traverse speed on the performance of weld is carried out by predicting peak temperatures, flow stress, strain rate and normal force. The peak temperature during welding is found to be increase as tool rotation speed is increased at constant traverse speed leading to formation of defects due to lower flow stress and high strain rate. On the other hand as the tool traverse rate is increased the total heat input decreased which decreases weld temperature at constant rotational speed increasing the flow stress leading to formation of defects. This provides better insight about the peak temperature, flow stress and strain rate developed at different tool speeds by numerical modeling without conducting costlier experiments. The results predicted from the numerical modeling leads to the better understanding of effect of flow stress and strain rate on normal force which can be measured during FSW to aid the assessment of weld performance

Effects of Magnetic field and Viscous Dissipation on Oberback Convection in a Chiral Fluid and Mass Transfer Flow through porous media

A chiral molecule is a type of molecule that lacks an internal plane of symmetry and thus has a non-superposable mirror image of a molecule. Chiral fluid is a fluid which has molecules and exhibits the chirality. The influence of viscous dissipation on convective flow, heat transfer, and mass transfer through viscous incompressible chiral fluid through a vertical porous layer immersed in porous medium in the presence of a uniform magnetic field is investigated. The coupled non-linear equations governing the motion are solved analytically using the regular perturbation method with Eckert number Ecas perturbation parameter. The effect of magnetochiral number M, porous parameter σ, Grashof number Gr, Eckert number E, and Schmidt number Sc on velocity, temperature distribution, mass flow rate, skin friction and rate of heat transfer are depicted graphically and some important conclusions are drawn

Application of acoustic emission technique for online monitoring of friction stir welding process during welding of AA6061-​T6 aluminum alloy

Acoustic Emission (AE) technique has been successfully used to monitor processes like metal cutting, grinding and electron beam welding as a nondestructive evaluation method. Friction Stir Welding (FSW) is a solid state welding that avoids problems assocd. with fusion welding and is used in aerospace industries. An attempt has been made to study the application of AE technique to monitor FSW process by identifying the occurrence of defect while welding is in progress and suggest means to rectify the defect. In this study, aluminum alloy AA6061-​T6 has been used as work piece material. It was obsd. that the nature of AE signals produced during welding are helpful in identifying the occurrence of defects produced. The values of a few AE parameters derived from AE signals were found to be helpful in developing a model for online monitoring of FSW process to produce defect free welds. The model has been successfully validated

IoT Based Smart Manufacturing system-Case Studies

Manufacturing now a days growing and becoming more complex, automated and computerized. Smart manufacturing is an emerging form of production manufacturing asset of today and in the future with involvement of smart sensors, actuators, communication technology, smart consumer devices like smart phones and tablets and data-intensive modeling. This paper will highlight a review of IoT application in smart manufacturing. Case studies on advanced techniques used in manufacturing industries for different operation such as Monitoring and controlling of smart equipment, IoT based Smart factory connectivity for industries, Hazardous Gas Detection, Electromyogram (EMG) monitoring system, and Tool wears characterization, Defect predictive in a manufacturing system, Machinery Health monitoring are presented

A Review on Challenges and Opportunities for Implementing Industry 4.0 in India

The globalization and the competitiveness are enforcing organizations to readdress and innovate their production processes. The world is entering a new era of industrial emanating technology in automation and data exchange through the use of Internet of Things called fourth technological revolution or Industry 4.0. It represents the amalgamation of tools already used in the past such as big data; cloud, robot, 3D printing, simulation, etc. are now connected into an internet to transmit digital data. For the implementation of this new paradigm, there are many opportunities and also many challenges. This paper highlights brief introduction on challenges and opportunities for implementation of Industry 4.0 in India

In-situ microcompression high cycle fatigue tests: Up to 1 kHz frequencies and 10 million oscillation cycles

Nanomechanical tests are moving beyond hardness and modulus to encompass host of different mechanical properties like strain rate sensitivity 1,2, stress relaxation 3, creep and fracture toughness by taking advantage of focused ion beam milled geometries and well known stress state during testing. Adding high cycle fatigue (HCF) properties to this list will be useful to extend the gamut of properties studied at the micro/nanoscale. There have been several reports of repeated impact and sinus mode (also referred to as “continuous stiffness mode”) nanoindentation tests for studying the contact fatigue properties of films and coatings. Though promising for studying contact fatigue properties, these measurements suffer from low oscillation frequencies (less than ~ 50 Hz) and, consequently, long duration tests. Merle et al. 4 reported micropillar compression-compression fatigue tests on nanocrystalline Cu at 40Hz and required ~ 7 hours to reach 1 million cycles. For a technique like nanoindentation that typically comprises of thermal drift rates of ~ 3nm/min at room temperature, this amounts to a total displacement drift of 1.2µm over the entire duration of the test (7 hours). Therefore, pushing the frequencies of sinus oscillation tests higher seems to be the key towards minimizing artefacts of measurements and to reach high cycle contact fatigue regime in shorter time spans. This presentation will report the development of micropillar HCF tests with oscillation frequencies up to 1kHz and compression-compression fatigue tests up to 10 million cycles. Micropillar HCF tests performed on single crystal silicon (reference sample, does not exhibit fatigue at high frequencies) showed no change in unloading stiffness over 10 million cycles, suggesting the reliability of the developed experimental technique. The associated instrumentation and technique development, design of the fatigue tests at the micron scale, data analysis methodology, experimental protocol and challenges will be discussed. Compression-compression high cycle micropillar fatigue of nanocrystalline nickel will be presented and the experimental results will be discussed in light of existing literature data, particularly the operative deformation mechanism(s). The fatigue tests were performed both below and above the 0.2% offset yield strength. Prolonged fatigue tests resulted in grain growth and microstructural changes in nanocrystalline nickel. The associated changes in mechanical deformation data (unloading stiffness, load and displacement amplitudes) will be discussed. The convolution of time dependent plasticity in such tests will be addressed by comparing both load and displacement controlled fatigue tests at high frequencies. It is hoped that this study will pave way for routine high cycle fatigue tests of metals at the micron scale and provide clues for designing similar indentation based fatigue tests. Please click Additional Files below to see the full abstract

High strain rate plasticity in microscale glass

Understanding the materials behavior at high strain rates is critical for the design of structures subjected to accidental overloads such as crash testing of vehicles and impact resistance of surface coatings. From a scientific perspective, experimental determination of high strain rate properties at the micro- and nano-scale will allow the bridging of time scales between atomistic simulations and experiments, leading to a direct comparison between the two methods. Despite many efforts to expand the range of micro and nanomechanical testing in terms of forces, temperatures and loading conditions, the achievable strain rates are still around 10-5 s-1 to 10-2 s-1. This limited range of strain rates is primarily due to lack of testing platforms capable of simultaneous high-speed actuation and high-speed sensing of microscale displacements and millinewton loads. This presentation will report, a piezo-based experimental methodology for conducting high strain rate in situ micropillar compression testing at rates upto ~2000/s inside a scanning electron microscope (SEM), including a brief overview of the advantages and challenges of microscale high strain rate testing compared to traditional macroscale, Kolsky bar based, high strain rate testing. Please click Additional Files below to see the full abstract