A Finite Element Approach to Conduct Machinability Studies on Age-Hardened AA6061 Matrix Hybrid Composites

AA6061, a popular structural material, has found widespread usage in the automotive and aerospace domains. The current work explored the effect of the improvement of mechanical properties on the machinability of AA6061 through finite element analysis. Three compositions of AA6061 containing 2 wt.% graphite and 0, 2, 4 wt.% granite dust were fabricated by stir casting.  In the current work, a finite element model of a slab milling cutter with eight teeth was designed with high-speed steel (HSS) as the tool material. The LS-DYNA module of ANSYS was used for simulation of the milling operation, selecting two peripheral speeds for the cutter during the machining of the workpiece. Surface milling was carried out on the cast slabs of the three compositions to study chip formation. At higher cutting speeds, there was an increase in the von Mises stress as well as material deformation. An increase in the weight fraction of the ceramic fillers led to a corresponding increase in the von Mises stress and material deformation. The experimental results from face milling of the three compositions showed that the surface roughness increased with an increase in the content of ceramic fillers and a decrease in chip size

A Finite Element Approach to Conduct Machinability Studies on Age-Hardened AA6061 Matrix Hybrid Composites

AA6061, a popular structural material, has found widespread usage in the automotive and aerospace domains. The current work explored the effect of the improvement of mechanical properties on the machinability of AA6061 through finite element analysis. Three compositions of AA6061 containing 2 wt.% graphite and 0, 2, 4 wt.% granite dust were fabricated by stir casting.  In the current work, a finite element model of a slab milling cutter with eight teeth was designed with high-speed steel (HSS) as the tool material. The LS-DYNA module of ANSYS was used for simulation of the milling operation, selecting two peripheral speeds for the cutter during the machining of the workpiece. Surface milling was carried out on the cast slabs of the three compositions to study chip formation. At higher cutting speeds, there was an increase in the von Mises stress as well as material deformation. An increase in the weight fraction of the ceramic fillers led to a corresponding increase in the von Mises stress and material deformation. The experimental results from face milling of the three compositions showed that the surface roughness increased with an increase in the content of ceramic fillers and a decrease in chip size

Performance Evaluation of Homogeneous Charge Compression Ignition Combustion Engine â A Review

The development of HCCI combustion technology has been drawing a great deal of attention from researchers. This survey explains ongoing research methodologies and results. HCCI combustion, other than conventional combustion, is purely based on chemical kinetics. At present the automobile sector faces the problem of emissions and needs to develop clean technologies. However, HCCI operation still has issues such as ignition control, combustion phasing control, operating range control, cold start, and UHC (unburned hydrocarbon) and CO (carbon monoxide) emissions. The challenge is to overcome these problems without compromising other engine parameters and performance. For HCCI, the mixture preparation is especially important, while the compression ratio, IVC (inlet valve closure) timing, inlet pressure, inlet temperature and EGR play a very prominent role in controlling it. This paper will go through a detailed discussion of all the above conditions

Effect of V-shaped Ribs on Internal Cooling of Gas Turbine Blades

Thermal efficiency and power output of gas turbines increase with increasing turbine rotor inlet temperature. The rotor inlet temperatures in most gas turbines are far higher than the melting point of the blade material. Hence the turbine blades need to be cooled. In this work, simulations were carried out with the leading edge of gas turbine blade being internally cooled by coolant passages with V-shaped ribs at angles of 30°, 45° or 60° and at three aspect ratios (1:1, 1:2 and 2:3). The trailing edge of the blade was cooled by cylindrical and triangular pin-fin perforations in staggered and inline arrangements. Numerical analyses were carried out for each configuration of the cooling passages. The best cooling passages for leading edge and trailing edge were deduced by comparing the results of these analyses. It was found that using V-shaped ribs and fins induces a swirling flow, which in turn increases the velocity gradient and hence produces an improvement in heat transfer. The results show that under real time flow conditions, the application of V-shaped ribs and pin-fin perforations is a very promising technique for improving blade life

Progress of auxetic and semi-auxetic materials

Auxetic materials with negative Poisson\u27s ratios, display the unique behavior owing to their micro-structure or geometrical build. Auxetic materials resist deformities when subjected to uniaxial, biaxial, and shearing stresses. Cellular based materials are known for their excellent impact and shock energy absorption. When foams are incorporated with auxetic geometry, their impact energy absorption increases. Combination of auxetic materials with conventional materials yield semi-auxetic materials. Ideally, layered structures where facing materials are metallic sheets sandwiching polymeric foam cores are popular. The auxetic materials can be combined with conventional materials to obtain P-N-P and N-P-N semi-auxetic sandwiched structures with diverse potential in several applications like automotive, aerospace, sports equipment, and protective armors

Effect of CNT-based resin modification on the mechanical properties of polymer composites

In this study an attempt was made to explore the possibility of substituting 3D E-glass fabric with eco-friendly basalt fabric along with the modification of resin using MWCNTs, a material system about which very limited information exists. The study involved comparing the mechanical properties of two sets of composites. The first set was comprised of 3D orthogonally woven E-glass-reinforced epoxy composites, basalt-reinforced epoxy composites, and hybrid 3D E-glass orthogonally woven/basalt-reinforced epoxy composites while the second set of composites was the same as the first but prepared with resin modified with Multi Walled Carbon Nanotubes (MWCNTs). All the composites were fabricated by hand lay-up and compression molding techniques. To modify the resin for the second set of composites, MWCNTs were dispersed into the epoxy resin with acetone as a surfactant by magnetic stirring and ultra-sonification. Mechanical tests included tensile, flexural, and low velocity impact strength which were evaluated as per standards. Scanning electron microscopy (SEM) was employed to study the fractured surfaces. Results showed that resin modification did not yield any positive results on the mechanical properties of the composites. The highest tensile (364.4 MPa) and flexural strength (345.3 MPa) was obtained for 3D E-glass composites followed by basalt composites and hybrid 3D E-glass/basalt composites while the highest impact strength of 198.42 kJ/m2 was exhibited by the hybrid 3D E-glass/basalt composites. SEM micrographs showed de-bonding between the modified matrix and fiber which was seen as one of the primary causes for relatively poor performance of the composites prepared with modified resin. Fiber breakage, matrix cracking, fiber pull-out, and delamination were the other modes of failure. Results suggest that hybridization with basalt fibers is a much safer, more cost effective, and eco-friendly option over resin modification

Influence of fabric orientation and compression factor on the mechanical properties of 3D E-glass reinforced epoxy composites

3-D E-glass fabric reinforced epoxy composites at 6 mm thickness were fabricated for various orientations of the binder yarn viz. 0°, 30°, 45°, 60° and 90° respectively. Tensile, flexural, interlaminar shear stress tests were conducted to ascertain the influence of binder yarn orientation on the mechanical properties of the composites. The composites with 0° binder yarn orientation showed the best strength followed by 90° whilst the others showed highly depleted traits in comparison. Shear stress induced at the interface of each lamina was seen as the major reason for drop in the strength. A secondary study was carried out to explore the effect of compression factor during fabrication on the mechanical properties of the composites. Laminates with varying thickness namely, 4 mm, 5 mm and 7 mm but, with same number of plies of 3D E-glass fabric at 0° orientation were fabricated. The test results were compared with the results of 6 mm composites from the primary study. The results showed that, compression factor affected the mechanical properties of the composites and had a direct relation with increasing compression factor up to a certain value beyond which a drop in properties was seen. Composites pressed to a thickness of 5 mm showed the best properties. Drop in properties was attributed to close packing of reinforcement and crushing of fibres leading to inefficient stress transfer. Scanning electron microscopy was employed to understand the modes of failure. The major failure modes observed were delamination, matrix cracking and debonding. Based on the results obtained, these composites can be seen as a material system for applications like ballistic armours, structural renovations and automobile components

The scope of acoustic impedance matching of hybrid fiber metal laminates for shielding applications

In a multi-layered shielding material, the sequence of the arrangement of the layers affects the extent of insulation to acoustic waves. In the current work, hybrid composite laminates have been taken up comprising 10 sequences, employing metallic faceplate (AA6061), paperboard, ballistic-grade aramid, and ultra-high molecular weight polyethylene (UHMWPE) fabrics with an epoxy binder. In the theoretical studies, an analytical model for the transmission loss function has been developed by incorporating the multiple wave reflection principle in combination with interface-wise acoustic impedance grading. The analytical model has been validated using the transmission loss functions from numerical and experimental studies on the different sequences. The numerical simulation has been carried out using the harmonic acoustic analysis module, on Ansys R19.0. The experimentation has been carried out on an impedance tube. The results from the analytical model are in good agreement with the experimental and numerical simulation results, the analytical model can be used for predicting the transmission losses of composite laminates

Effect of B₄C/Gr on Hardness and Wear Behavior of Al2618 Based Hybrid Composites through Taguchi and Artificial Neural Network Analysis

Artificial neural networks (ANNs) have recently gained popularity as useful models for grouping, clustering, and analysis in a wide range of fields. An ANN is a kind of machine learning (ML) model that has become competitive with traditional regression and statistical models in terms of useability. Lightweight composite materials have been acknowledged to be the suitable materials, and they have been widely implemented in various industrial settings due to their adaptability. In this research exploration, hybrid composite materials using Al2618 reinforced with B4C and Gr were prepared and then evaluated for hardness and wear behavior. Reinforced alloys have a higher (approximately 36%) amount of ceramic phases than unreinforced metals. With each B4C and Gr increase, the wear resistance continued to improve. It was found that microscopic structures and an appearance of homogenous particle distribution were observed with an electron microscope, and they revealed a B4C and Gr mixed insulation surface formed as a mechanically mixed layer, and this served as an effective insulation surface that protected the test sample surface from the steel disc. The ANN and Taguchi results confirm that load contributed more to the wear rate of the composites

Experimental investigation into mechanical properties of coconut shell powder modified epoxy/ 3d E-glass composites

The aim of this research work was to investigate the influence of resin modification with Coconut Shell Powder (CSP) on the tensile, flexural and impact properties of composites reinforced with 3D E-glass orthogonally woven fabric. The composites were fabricated using a combination of hand lay-up and press moulding techniques. Three different proportion of CSP namely, 0.5%, 1.5% and 3% by weight of resin were considered for modifying the epoxy resin. The properties of these composites were determined and compared with composites fabricated without coconut shell powder. Additionally, to ascertain the effect of dispersion technique on the mechanical properties of the composites, their tensile strengths were compared with composites fabricated with epoxy in which CSP was added to the resin and mixed mechanically. Improved mechanical properties were obtained for composites fabricated with modified resin and an increasing trend was observed with increase in proportion of CSP with the highest properties obtained for composites with 3% CSP content showing an increase of about 117%, 87% and 39% in tensile, flexural and impact strengths respectively over the composites without CSP. Tensile strengths of composites prepared by mechanical dispersion of CSP were lower than the resin modified composites having the same CSP content, showing a drop of about 53% and 25% thereby proving the efficacy of resin modification process. Scanning Electron Microscopy (SEM) was employed to analyse the characteristics of the CSP and to investigate the various failure modes