Sustainable machining necessitates energy-efficient processes, longer tool lifespan, and greater surface integrity of the products in modern manufacturing. However, when considering Ti6Al4V alloy, ...these objectives turn out to be difficult to achieve as titanium alloys pose serious machinability challenges, especially at elevated temperatures. In this research, we investigate the optimal machining parameters required for turning of Ti6Al4V alloy. Turning experiments were performed to optimize four response parameters, i.e., specific cutting energy (SCE), wear rate (
R
), surface roughness (
R
a
), and material removal rate (MRR) with uncoated H13 carbide inserts in the dry cutting environment. Grey relational analysis (GRA) combined with the analytic hierarchy process (AHP) was performed to develop a multi-objective function. Response surface optimization was used to optimize the developed multi-objective function and determine the optimal cutting condition. As per the ANOVA, the interaction of feed rate and cutting speed (f × V) was found to be the most significant factor influencing the grey relational grade (GRG) of the multi-objective function. The optimized machining conditions increased the MRR and tool life by 34% and 7%, whereas, reducing the specific cutting energy and surface roughness by 6% and 2% respectively. Using Taguchi-based GRA by analytic hierarchy process (AHP) weights method, the benefits of high-speed machining Ti6Al4V through multi-response optimization were achieved.
In this study, experimental research has been done to investigate and analyze the effects of fiber hybridization and stacking configurations on the impact performance of carbon/flax bio-hybrid ...composite laminates. A total of four composite laminates with pure carbon, sandwich, symmetric, and asymmetric stacking configurations were manufactured and investigated in terms of low-velocity impact test with varying energies between 30J and 75J. Both qualitative and quantitative analysis were performed to analyze the damage and failure patterns in the composite layups and were compared with the pure carbon-based layup to identify the effects stacking configuration. The experimental findings showed the symmetric layup having a consistent distribution of flax fiber layers, showed the most enhanced performance as compared to the carbon-based layup Moreover, damage and failure modes differed among layups and increased with varying impact energies. Furthermore, to enable the thorough comparison of the configurations, Composite Performance Index (CPI) was developed, which suggests that bio-hybrid configurations when designed optimally with a suitable number of evenly distributed flax layers, can equal or exceed the performance of a pure carbon fiber configuration.
This research focuses on the study of the effects of processing conditions on the Johnson–Cook material model parameters for orthogonal machining of aluminum (Al 6061-T6) alloy. Two sets of ...parameters of Johnson–Cook material model describing material behavior of Al 6061-T6 were investigated by comparing cutting forces and chip morphology. A two-dimensional finite element model was developed and validated with the experimental results published literature. Cutting tests were conducted at low-, medium-, and high-speed cutting speeds. Chip formation and cutting forces were compared with the numerical model. A novel technique of cutting force measurement using power meter was also validated. It was found that the cutting forces decrease at higher cutting speeds as compared to the low and medium cutting speeds. The poor prediction of cutting forces by Johnson–Cook model at higher cutting speeds and feed rates showed the existence of a material behavior that does not exist at lower or medium cutting speeds. Two factors were considered responsible for the change in cutting forces at higher cutting speeds: change in coefficient of friction and thermal softening. The results obtained through numerical investigations after incorporated changes in coefficient of friction showed a good agreement with the experimental results.
Tungsten inert gas (TIG) welding is type of arc welding with area of applications in food industry, pharmaceutical industry, chemical plants, marine, aerospace, medical devices, and implants, etc. ...TIG welding process involve several parameters. Many parameters are controllable by the operator, and these parameters have a direct or indirect impact on the microstructure and mechanical properties of the joints. In the present study, three TIG welding parameters, arc current, voltage, and shielding gas flow rate, were changed up to three levels and their effects on surface roughness, hardness and tensile strength were investigated. Experiments were carried out on a 3 mm thick plate of austenitic stainless steel AISI 316L utilizing a TIG welding equipment and were designed according to Taguchi L9 orthogonal array (OA). ER308L was used as filler material. Results were analyzed using signal to noise S/N ratio and analysis of variance. It was observed that, for optimization of each response, arc current is the most influential factor. Minimum surface roughness was achieved at parametric combination of current 125 A, voltage 18 V and gas flow rate 12 L/min. Maximum hardness was achieved at parametric combination of current 125 A, voltage 20 V and gas flow rate 9 L/min. Maximum tensile strength was achieved at parametric combination of current 100 A, voltage 18 V and gas flow rate 6 L/min.
This research investigates the effects of fiber hybridization on the mechanical performance of carbon/flax bio‐hybrid laminates. The study comprised of manufacturing and analyzing five distinct ...composite laminates, comprising pure carbon and various carbon/flax configurations with symmetric and asymmetric layups. The laminates were subjected to uniaxial tensile and low‐velocity impact testing at energy levels from 30 to 75 J. Quantitative and qualitative analyses were conducted to assess the damage/failure patterns to determine the changes due to hybridization and stacking sequence. The experimental results revealed that integrating flax layers into different bio‐hybrid configurations significantly influences their strength, stiffness and impact resistance. One of symmetric layups, having uniform distribution of flax layers throughout thickness, demonstrated the most enhanced performance. To facilitate comprehensive comparison, two indices were developed: Composite‐Performance Index (CPI) and Cost‐Effectiveness Index (CEI). These indices indicate that bio‐hybrid configurations, optimally designed with appropriate number of evenly distributed flax layers, can match or surpass performance of pure carbon layup. The study concludes that incorporating flax into carbon fiber laminates can yield substantial benefits in impact performance with slight compromise in tensile strength and stiffness. However, the overall cost efficiency of bio‐hybrid composites is superior, considering both tensile strength and impact performance.
Highlights
Effect of fiber hybridization on the mechanical performance of hybrid laminates was studied.
Carbon/Flax composites exhibited slightly lower tensile strength compared to carbon‐based layup.
Symmetric layups with evenly distributed flax layers showed enhanced impact performance.
Cost efficiency of bio‐hybrid composites is superior for both tensile and impact performance.
Flowchart for investigating the effect of fibre hybridization on the tensile and low velocity impact behaviour of carbon/flax bio‐hybrid composites.
This paper proposes a multi-scale analysis technique based on the micromechanics of failure (MMF) to predict and investigate the damage progression and ultimate strength at failure of laminated ...composites. A lamina’s representative volume element (RVE) is developed to predict and calculate constituent stresses. Damages that occurred in the constituents are calculated using separate failure criteria for both fiber and matrix. Subsequently, the volume-based damage homogenization technique is utilized to prevent the localization of damage throughout the total matrix zone. The proposed multiscale analysis procedure is then used to investigate the notched and unnotched behavior of three multi-directional composite layups, 30, 60, 90, −60, 302S, 0, 45, 90, −452S, and 60, 0, −603S, subjected to static tension and compression loading. The specimen is fabricated from unidirectionally reinforced composite (IM7/977-3). The prediction of ultimate strength at failure and equivalent stiffness are then benchmarked against the experimental test data. The comparative analysis with various failure models is also carried out to validate the proposed model. MMF demonstrated the capability to correctly predict the ultimate strength at failure for a range of multidirectional composites laminates under tensile and compressive load. The numerically predicted findings revealed a good agreement with the experimental test data. Out of the three investigated composite layups, the simulated results for the quasi-isotropic 0, 45, 90, −452S layup agreed extremely well with the experimental results with all the percentage errors within 10% of the measured failure loads.
Voids are one of the many material defects present at the microscopic length scale. They are primarily responsible for the formation of cracks and hence contribute to ductile fracture. Circular voids ...tend to deform into elliptical voids just before their coalescence to form cracks. The principle aim of this study is to investigate the effect of void shape on the micro-mechanism of void growth by using Discrete Dislocation Plasticity simulations. For voided crystals, conventional DDP produces a continuous slip step throughout the material even if a dislocation escapes from a non-convex domain. To overcome this issue, the Extended Finite Element Method (XFEM) is used here to incorporate the displacement discontinuity. Different aspect ratios of elliptical voids are considered under uniaxial and biaxial deformation boundary conditions. The results suggest that voids having the largest surface area tend to have maximum growth rate as compared to void with lower surface area, i.e. “larger is faster”. Under biaxial loading, a higher magnitude of strain hardening, and void growth rate are observed as compared to uniaxial loading. The results also suggest that the orientation of slip planes as well as voids, affect the overall plastic behavior of the voided-ductile material. Furthermore, circular void tends to induce minimum growth rate but have the maximum strain hardening effect as compared to other void shapes under both loading conditions. The results of this study provide a deeper understanding of ductile fracture with applications in manufacturing industry, aerospace industry and in the design of nano/micro-electromechanical devices i.e. NEMS/MEMS.
•Discrete Dislocation Plasticity does not correctly deal with dislocation escape through non-convex material discontinuities.•A new superposition scheme is proposed, that couples Discrete Dislocation Plasticity and the Extended Finite Element Method.•Using this method, the deformation response of a voided crystal, with a variable aspect ratio of the void, is studied.•Voids with a larger surface area tend to grow faster as compared to voids with smaller surface areas.•Circular voids, having the minimum surface area, tend to induce minimum deformation but maximum strain hardening effect.
High temperature shape memory alloys Ti50Ni25Pd25 and Ti50Ni20Pd25Cu5 were developed, characterized, and tensile tested in both martensite ( Mf − 50°C) and austenite ( Af + 50°C) phases. The ...transformation temperatures of ternary Ti50Ni25Pd25 alloy were increased by 11 to 12.5°C by substitution of Ni with 5 at% Cu. At the same time, transformation heat absorbed and released during forward and reverse martensitic transformation was also increased. In the martensite phase, the mechanical properties, that is, the stress for reorientation of martensite variants and fracture stress, were increased by 33 and 60 MPa, respectively, whereas the fracture strain was decreased by 1.5%. In the austenite phase, the critical stress for slip and fracture stress were increased by 62 and 40.9 MPa, respectively, whereas the fracture strain was decreased by 1.2%. The increase in both stresses was attributed to the solid solution strengthening by substitution of Ni atoms with relatively greater atomic radius of copper (Cu) atoms. The overall results suggest that the addition of 5 at% Cu in place of Ni in Ti50Ni25Pd25 alloy is very beneficial to improving the mechanical and shape memory properties and increasing the transformation temperatures.
Finite element (FE) modeling of tailor welded blanks (TWBs) is a complex phenomenon compared to FE modeling of monolithic sheets due to the change of mechanical properties caused by the welding ...process. This complexity involves modeling different zones generated due to the heat effect. Research on the formability of steel TWBs with dissimilar thicknesses and strength produced by manual tungsten inert gas (TIG) welding technique and formed by single point incremental forming (SPIF) involving base sheets, weld nugget (WN), and heat affected zone (HAZ) is presented, numerically. The materials selected for the study included deep drawing quality (DDQ) steel (DC06) and stainless steel (SS) (AISI 201). Variable wall angle truncated pyramid was used as test geometry, and FE software Abaqus (dynamic explicit solver) was used for the analysis. Thickness profiles and state of stress and strain in both the cases of thickness and strength differential were analyzed. A decrease in thickness was observed at the corners in both cases. However, this decrease was more prominent in the case of strength differential. The symmetry of the pattern on both sides with minimum and maximum values of stress towards the thinner side was observed in the case of thickness differential. Variation in stress was more prominent towards the side of high-strength material along maximum value in the case of strength differential. Equivalent plastic strain observed was more linear and higher towards the sides of thicker sheet and material having less strength in the case of thickness differential and strength differential, respectively. Research investigations may be applied in a similar fashion for the precise study of formability characteristics of various kinds of TWBs being used in multiple industries including automotive, vessel, and medical.
The effect of nano particle inclusion and the stacking sequence/metal volume fraction on the tensile strength and energy absorption properties of Fiber Metal Laminates (FML) is investigated. The FML ...structure is composed of lightweight thin sheets of aerospace grade aluminum alloy 7075 and unidirectional glass fiber composite sheets with Araldite LY5052 thermoset epoxy system as the matrix. The volume fraction of aluminum sheets in the FML structure was varied by increasing the number of aluminum sheets from 2 to maximum 4. In the second batch, the epoxy matrix is reinforced with of multi-walled carbon nano tubes and nano diamond particles together, each with 0.15 wt%. The purpose is to enhance the properties of the epoxy matrix to facilitate higher inter-laminate adhesion (FRP and aluminum). The results of the tensile testing show that with the increase of the metal volume fraction, the tensile strength as well energy absorbing capability (toughness) both are increased. The inclusion of the nano-reinforcements has increased the tensile strength and the toughness of the FML structure as compared to that of the FMLs without nano particles. The strength-to-weight ratio of FML structures is also increased after the inclusion of nano reinforced as desired for aerospace applications.
PDF
