This paper investigates the effect of plasticity ball burnishing on characteristics of surface integrity, residual stress and hardness of laser direct energy deposited (DEDed) Stellite 21 alloys, with a focus on the burnishing directional effect on surface and microstructural deformation. The results demonstrated that the burnishing improved surface finish, reducing Sa and Sz by 24% and 47%, respectively. The burnishing flattened and modified the cellular/columnar grains at a depth of 50 µm, with the most notable changes observed on the cross-sectional plane normal to the burnishing direction. Compared to the ground surface, the burnishing introduced higher and deeper compressive stresses along normal to the burnishing/grinding direction (−1341 MPa and 61 µm) as compared to that along the burnishing direction (−449 MPa and 56 µm). Likewise, the burnishing increased the full width at half maximum (FWHM) in the same fashion by broadening XRD peaks along normal to the burnishing direction. Due to higher grain modification and dislocation density, the burnishing has improved microhardness at a depth of 320 µm by 26% along normal to the burnishing direction. These findings demonstrate that the plasticity ball burnishing has a directional effect on plastic deformation and can be considered a plausible technique for tailored surface integrity, residual stress and hardness, which potentially improve the service performance of DEDed Stellite 21 alloy components.

This paper presents the effect of ball burnishing on the surface integrity and residual stress of laser-direct energy-deposited (DED) 316 L alloys, with a particular focus on surface modification characteristics across two directional planes relative to the burnishing direction. The results show that the burnishing significantly improved surface finish, reducing Ra and Sa by 76% and 51%, respectively. Additionally, the burnishing altered the grain structure from cellular/columnar to equiaxed within 50 μm deep from the top surface, with the most pronounced changes occurring in the cross-sectional plane normal to the burnishing direction. The process also converted tensile stresses into compressive stresses, with the peak compressive stress being 99% higher than that of the ground surface. Notably, the compressive stress was higher along normal to the burnishing direction compared to the burnishing direction itself. Furthermore, the burnishing increased the full width at half maximum (FWHM) by broadening X-ray diffraction (XRD) peaks, with the greatest increase observed at a depth of 68 μm, confirming the severe grain alternations. Due to grain modification and dislocation movement, the burnishing increased microhardness by 32% at the top surface, with a hardened layer extending up to 400 μm in depth. The improvement in hardness was more significant on the plane normal to the burnishing direction.

This study investigates the influence of ball burnishing (BB) path strategies on the surface integrity and functional performance of laser-cladded Inconel 718. Three BB strategies—(1) BB-Longitudinal, (2) BB-Transverse, and (3) BB-Crosshatch—relative to the laser scan trajectory were evaluated and compared against ground surfaces as a baseline. Post-processing BB treatment were demonstrated to be effective in modifying the subsurface layer of the cladded Inconel 718 material, extending to depths of up to 100 µm, increasing dislocation density by over 2.5 times, and enhancing hardness from 260 HV5 (ground) to as high as 461 HV5. These microstructural improvements led to significant gains in corrosion and impact resistance, despite a rise in surface roughness from Ra 0.35 µm (ground) to up to 2.38 µm for BB-Longitudinal surfaces. Impact testing revealed up to 35% reduction in indentation volume, particularly with BB-Transverse and BB-Crosshatch strategies. Nonetheless, sliding wear tests did not confirm improvements in wear resistance, as wear depths exceeded the hardened layer and abrasive wear remained dominant. Electrochemical testing in 3.5 wt.% NaCl solution showed a positive shift in corrosion potential (Ecorr) exceeding 200 mV compared to the ground condition, indicating reduced corrosion susceptibility for BB-Longitudinal condition. Among the tested strategies, BB-Transverse offered the most balanced enhancements, highlighting the complex interplay between laser cladding heterogeneities and post-processing response in optimizing surface and mechanical properties of Inconel 718 claddings.

This paper investigates the axial deformation characteristics and crashworthiness of thin-walled metal tubes (TWT) reinforced with Polyetherketoneketone (PEKK) honeycomb lattice structures consisting of bio-inspired hierarchical cellular topological features. Experimentally validated numerical results revealed that the specific energy absorption capacity (SEA) of these composite structures increased with filler volume corresponding to a specific cellular topology. This includes the bio-inspired hierarchical sparse (BHS) topology, which registered a remarkable improvement in SEA over the hollow tube of 202%. In contrast, the central (BHC) topology deformed in an unstable hex-dominated pattern and triggered catastrophic failure of the composite in global bending mode. Furthermore, rigid cells were shown to drastically increase the initial peak force (IPF), while cells with low stiffness were beneficial for maintaining a low level of IPF and moderately improving SEA. Moreover, the rib and wall thickness of the BHS honeycomb cells were suitably tailored to increase the SEA by 2.1%, while simultaneously reducing the IPF by 3.7%. These findings suggest that multi-functional mechanical attributes of PEKK hierarchical honeycomb lattice fillers can mutually benefit thin-walled tubes with superior energy absorption capability and lightweight features over conventional lattice-filled tubes or a hollow tube.

Laser metal deposition (LMD) as an additive manufacturing (AM) is widely used to repair and extend wear and fatigue life of the critical components. This paper has investigated the application of ball burnishing (BB) to improve surface integrity and high-cycle fatigue resistance of LMDed AISI 431 alloys. Results showed that the BB treated samples exhibited significant surface finish improvement by lowering roughness by 91 %. Microhardness increased from 490 to 530 HV0.1, an increase by 10 % with a modified depth of 400 mu m from the top surface. XRD results showed a peak shift and increase in FWHM by up to 17 %. This had been corroborated by EBSD exhibiting a 20 % increase in dislocation density and 24 % increase in localised misorientation within microstructure. As a result, the overall high cycle fatigue strength of the burnished sample increased by 50 %, and the cracks initiated from sub-surface level defects at a depth of 350 mu m below the top surface, delaying the crack propagation and fracture failure. The findings clearly highlight that the burnishing treatment can be a plausible approach in improving the dynamic fatigue resistance and the overall service life of LMDed AISI 431 steel alloys components in engineering applications.

The aim of this paper is to investigate the effect of plasticity burnishing on the surface properties and antifouling resistance of UHMWPE. Ball burnishing experiments at different pressures (44-131 bar) and path strategies (1: Single Parallel and 2: Cross Parallel) were conducted. The treated surface was characterised in terms of surface roughness, surface topography, and contact angle (CA) to evaluate its surface wettability. Microhardness, wear and impact resistance were measured to assess mechanical integrity. Results show that as the burnishing pressure increased, surface roughness decreased. Strategy 2 demonstrated the most significant reduction in surface roughness. No clear relationship between burnishing pressure and CA was found. However, Strategy 2 with relatively higher pressure generated specific surface micro-texture that was responsible for higher CA over Strategy 1. Marine salt spray tests demonstrated improved water adsorption stably, creating a uniform hydration layer on the surface treated with Strategy 2. Consequently, in-field marine fouling test results revealed an improved antifouling resistance of the burnished surface. The burnishing increased microhardness, wear and impact resistance. Improvement in surface integrity was attributed to stretching and plastic yielding of entangled macromolecular chains and crystals networks in UHMWPE. The findings indicate that ball burnishing with appropriate path pattern and pressure could be a viable route to improve surface wettability and antifouling resistance.

In this study, thin-walled tubes were circumferentially strengthened by plasticity ball burnishing of critical locations determined from buckling mode analysis. Axial crush test results revealed that the surface-treated (ST) tubes increased localized yield strength, attained superior crashworthiness performance, and triggered predictable deformation modes according to the buckling modes of the tubes. Numerical analysis was performed and successfully validated with the experiment at 90% prediction accuracy. The treated tube ST-4 with the 12th buckling mode outperformed a conventional tube with an increase in specific energy absorption (SEA) and crush force efficiency (CFE) by up to 70% while sustaining a low increase in initial peak force (IPF). Furthermore, the tube demonstrated a greater rate of energy dissipation compared to tubes with conventional surface-treated patterns at the same level of surface-treated area. The crashworthiness performance improved as the surface-treated area ratio increased. A theoretical model was developed for the surface-treated tube based on fundamental deformation kinematics, predicting mean crushing force and total energy absorption with acceptable accuracy. The findings strongly suggest that the proposed surface-enhanced tubes have great potential to be used as energy-absorbing structures in crashworthiness applications.

In this study, a laser surface pre-treatment strategy was applied to aluminium 7075-T6 alloy, in which the laser power, speed and frequency were varied to determine the best modified surface property in terms of surface wettability. Surface texture, topography, roughness, contact angle and adhesive bonding strength of the treated surface were measured and characterised. Results showed that the laser-treated surface at a laser power of 30 W, speed of 1.2 m/s and frequency of 8 kHz provided the highest surface wettability by showing the lowest contact angle of 17 & DEG;, which was attributed to the deeper surface cavities and higher surface roughness. The laser treatment increased the adhesion strength up to 8.5 MPa which was 45% higher than that of the untreated surface (of 5.9 MPa). Its adhesion strength nearly matched with that of the oxalic acid treatment. The laser-treated failed specimen shows predominantly adhesion-cohesion failure mode with a strong interfacial bonding. FTIR spectra confirmed the presence of required functional chemical groups of the adhesive after curing, demonstrating a strong bonding force and affinity between the adhesive and the modified surface. The findings clearly indicate that the laser surface pre-treatment would be a viable surface modification strategy without environmental and health hazard to provide adequate strength in the adhesively bonded joints.

High heat generation with the consequent increase in temperature is still a limiting factor for productivity and quality in machining processes, mainly because it strongly affects the tool's life and the quality of the workpiece. Cutting fluids in abundance (CFA), often named flood cooling, is the standard machining cooling technique used industrially. However, CFA poses significant environmental hazards while incurring mounting manufacturing costs. To address this, the current paper focuses on a comprehensive performance evaluation of a novel internally cooled tool (ICT) while machining grey cast iron -GCI. Designed and built in-house, the ICT system can internally circulate the coolant through a specifically modified insert, effectively removing the heat from the interface. The machining tests followed a full factorial Design of Experiment-DoE (23) with two quantitative input variables, the depth of cut (doc) (1.0 and 2.0 mm) and the cutting speed (vc) (100 and 150 m/min) and one qualitative variable, the cutting atmosphere (ICT or CFA). The feed rate was maintained constant at 0.1 mm/rev. The response variables were cutting force, tool wear mechanisms, and surface integrity in terms of roughness, microhardness, and microstructure. The main results indicated that, compared to CFA, ICT increased cutting force by 42 %. ICT also increased peak microhardness by 22 % at 500 mu m from the top surface. It also induced grain modification at 4 mm depth, indicating that ICT caused a work-hardening effect in the subsurface. These results were an indication that ICT could effectively take heat away at the cutting zone. Statistical analysis on surface roughness showed that the significant variables were the cutting speed and its interaction with the at-mosphere, where increasing the cutting speed was the dominant parameter. ICT reduced the roughness at higher cutting speeds, as opposed to CFA. The predominant wear mechanisms were adhesion and abrasion, along with plastic deformation for both ICT and CFA. Finally, the ICT system showed to be a promising eco-friendly tech-nique with high cooling capacity, presenting some advantages compared to CFA, with similar machining performance.

The measurement of cutting force is one of the key factors in determining the tool condition and improving machine reliability. Therefore, the cutting force measurement becomes crucial to improve the machining process. The cutting force can be measured with piezoelectric as well as piezoresistive transducers. The force measuring transducers with later ones are cost-effective and can be easily installed in any small/medium-scale enterprise. For this approach, the selection of sensing elements is essential. The various mechanical ring elements were used for sensing the deformation. The low-cost device can be affordable in small-scale industries. Along with cutting force, it is suggested to measure the vibration signals to analyze the machining dynamics of the process. The salient features and diverse force measuring transducers were discussed in this article. This paper aims to briefly review the existing design and performance of dynamometers used in modern manufacturing.

Herein, the influence of the grinding–burnishing on surface integrity, mechanical properties, and corrosion performance of Stellite 21 alloys coating deposited by laser cladding is investigated. The as‐clad specimens are first ground followed by further modification by ball burnishing at forces of 424 N and 509 N. Results show that the grinding–burnishing enhances surface finish by lowering Ra from 2.6 to 0.73 μm and Rz from 13 to 4.9 μm, respectively. Surface porosity is found to decrease from 3.8% to 0.9%. Hardness is increased from 609 HV to 702 HV, with a surface alteration as deep as 250 μm, while wear resistance increases by reducing worn volume from 4.15 to 2.95 mm3. Because of high hardness, the grinding–burnishing increases impact resistance by lowering indent depth by 20%. Grains flatten and surface undulations are remarkably reduced due to burnishing. Finally, grinding–burnishing at 509 N improves the corrosion resistance by increasing positive corrosion potential from −0.41 to −0.14 V and lowering corrosion current density from 6.34 × 10−4 A cm−2 to 2.19 × 10−5 A cm−2, as compared to grinding. This synergistic grinding–burnishing can be a plausible post‐treatment route for the laser‐clad alloys.

The present paper aims to provide an overview of the current state-of-the-art mechanical surface modification technologies and their response in terms of surface roughness, surface texture, and microstructural change due to cold work-hardening, affecting the surface integrity and corrosion resistance of different Mg alloys. The process mechanics of five main treatment strategies, namely, shot peening, surface mechanical attrition treatment, laser shock peening, ball burnishing, and ultrasonic nanocrystal surface modification, were discussed. The influence of the process parameters on plastic deformation and degradation characteristics was thoroughly reviewed and compared from the perspectives of surface roughness, grain modification, hardness, residual stress, and corrosion resistance over short- and long-term periods. Potential and advances in new and emerging hybrid and in-situ surface treatment strategies were comprehensively eluded and summarised. This review takes a holistic approach to identifying the fundamentals, pros, and cons of each process, thereby contributing to bridging the current gap and challenge in surface modification technology for Mg alloys. To conclude, a brief summary and future outlook resulting from the discussion were presented. The findings would offer a useful insight and guide for researchers to focus on developing new surface treatment routes to resolve surface integrity and early degradation problems for successful application of biodegradable Mg alloy implants.

The ceramic materials prove to be better alternative to metallic and polyethylene implants. The AZ31 alloy exhibits better biocompatible properties compared with existing metallic implants. The present study investigated the friction and wear rate properties of silicon nitride (Si3N4), Alumina (Al2O3), zirconia (ZrO2) and zirconia toughened alumina (ZTA) against AZ31 for 2 km under bio-lubricants using ball-on-disc (B-o-D) tribometer. The bio-lubricants considered for the current study include Ringer's solution, distilled water, saline solution and phosphate buffer saline (PBS). The B-o-D load of 20 N which equals the gait load of normal walking is taken into consideration for current study. Amongst the ceramic materials considered, ZTA and Si3N4 ceramic biomaterials showed better tribological behaviour for PBS bio-lubricant and comparatively maximum wear rate was observed for alumina-AZ31 combination for all bio-lubricants. Amongst the bio-lubricants, distilled water and saline solution exhibited poor tribological phenomenon compared with PBS bio-lubricant. The silicon nitride and ZTA showed better tribological behaviour for PBS bio-lubricant thus proving as potential materials for joint replacement in combination with AZ31.

Edge loading leads to high contact stress at the rim of the contact. This is due to less radial clearance and excessive lateral head displacement which potentially causes implant failure. The ceramic implants have a high possibility of fracture compared with metallic implants because of above-said reasons. The present study focuses on the investigation of contact stress for the combined effect of radial clearance (0.05-0.75 mm) and micro-lateralisation conditions (1-2.5 mm) for Metal-on-Metal (M-o-M) and Ceramic-on-Ceramic (C-o-C) pairs. The contact stresses are analysed for round corners of the acetabulum cup geometry for the above-said combinations with four different arc radii (1- 4mm). Finite element modeling (FEM) of femur head with half of the acetabulum cup is considered for the current study. Contact stress values obtained for 2 mm and 4 mm round corner geometry are quite low when compared with 1 and 3 mm round corners even for larger radial clearances and high lateral head displacements. The study also showed von Mises stress value obtained for M-o-M pair is quite low for 4 mm round corner for larger radial clearance and high lateral head displacements. Similarly, in C-o-C pair the compressive stress values are minimum for 4 mm round corner. Since the stress values were minimum for 4 mm round corner geometry, it clearly indicates that even edge loading occurs and the round corner geometry would be very helpful in reducing the stress for both M-o-M and C-o-C pairs.

This paper presents the influence of the grinding-burnishing on surface integrity and corrosion performance of the laser-cladded AISI 431 alloys. As-cladded specimens were first ground followed by ball burnishing. To evaluate surface alteration and performance enhancement, six major properties were measured and analyzed in terms of surface roughness, porosity, microhardness, wear, and impact and corrosion resistance. Results showed that grinding-burnishing significantly improved the surface finish by lowering R-a and R-z by up to 29% and 41%, respectively, compared with grinding. Surface porosity was found to decrease by 18%. Maximum surface microhardness increased by 32% when grinding-burnishing, with a modified depth of up to 250 mu m, while wear resistance in terms of volume loss increased by up to 38%. Because of hardness improvement, the grinding-burnishing increased the impact resistance by lowering the maximum indent depth by 29%. The corrosion resistance improved by increasing positive corrosion potential from -0.31 V (grinding) to -0.21 V (grinding-burnishing) and lowering corrosion current density from 1.18 x 10(-3) A.cm(-2) (for grinding) to 2.1 x 10(-5) A.cm(-2) (grinding-burnishing). Burnishing further induced grain modification in terms of grain deformation and flattening within microstructure, but no grain refinement was observed. XRD results however showed lattice deformation indicating potential compressive residual stress generated by burnishing. Overall, it is imperative to say that the combined grinding-burnishing can be a viable surface modification technique to extend functional service life of the laser-cladded components.

This study investigated the perforation resistance behaviour of metal–plastic laminates (MPLs) when they are indented by different nose shapes. Aluminium (Al) and HDPE (high-density polyethylene) layers were bonded with a suitable adhesive in an alternative manner to prepare bilayer and trilayer MPL configurations. Quasi-static perforation experiments were performed with hemispherical, conical and blunt indenters. The effects of nose shape, layer configuration and adhesive on the force–deformation profile, perforation resistance capacity and failure mechanisms were evaluated. The results indicate that for a monolithic layer, the blunt indenter showed the highest perforation energy capacity. The conical and blunt indenters facing Al backed by HDPE gave higher perforation energy. The hemispherical indenter facing HDPE backed by Al was found to be more effective in perforation resistance. Trilayer Al–HDPE–Al showed higher perforation resistance than HDPE–Al–HDPE. Circumferential cracking, radial symmetric cracking and shear plugging were the main failure modes for Al under hemispherical, conical and blunt indenters, respectively. The adhesive contributed to an increase in the perforation energy and peak force to failure in laminates. The adhesive was shown to detach from the Al surface after Al fracturing through crack propagation, and this effect was more pronounced when the indenter faced HDPE at the front of the laminate.

Hip simulator, pin-on-disc (POD) and finite element analysis (FEA) are widely used approaches to estimate in-vitro wear of implants. While former two are shown to be widely employed for predicting wear under lubricated and non-lubricated conditions, which are often not suitable for assessing wear in the event of extensive changes of hip design parameters. The parameters like radial clearance, edge loading, acetabulum cup thickness, femur head diameter and cup inclination angle have impact on wear. This article focuses on computational approaches involved in predicting hip wear of hard bearing biomaterials i.e. metal-on-metal (M-o-M), Ceramic-on-ceramic (C-o-C) and PCD-PCD (poly crystalline diamond) for human hip prosthesis. The limitations on reliability of FEA tool based on various parameters like meshing, modeling approaches and experimentally determined friction and wear coefficients from POD or hip simulator are reviewed. The continuous evolutions of modeling techniques developed using FEA tool are motivating the researchers, to improve these techniques further to predict contact stress and wear of implants in better way.

The target of this paper incorporates rehabilitation of /u/ sound in Bangladeshi adult speakers of English in classroom practice. The phoneme /u/ is a short vowel and /u:/, a long vowel in English phonemic inventory. But long and short vowel distinction is not a phonemic feature in Bangla. That is why, many Bengali speakers of English pronounce /u/উ/ in both the cases as there is /উ /u/ sound in Bengali language. This creates problem for the listeners specifically the native speakers to understand the speech of the Bengali adult speakers of English and the comprehensibility level of their pronunciation is very low. The researcher, from his practical experience, finds that Phonological establishment of /উ /u/ sound in the tertiary level students of Bangladesh is one of the main reasons of this problem. This paper is a pedagogically designed lesson plan to rehabilitate the fossilized /u/উ / sound in Bengali speakers by applying Audio Articulation Method in the class hour. By operating various kinds of drills such as, interaction drill, substitution drills, minimal pairs, tongue twister etc in the class hour, the teachers can conduct the class to rehabilitate the fossilized sounds in the learners and both the trainers and trainees in Bangladesh can get the chance to defossilize the fossilized sound by these drillings.

The role of composite materials has been extremely significant for the human race since the primitive civilizations to the modern day. They have simply been indispensable in the field of materials. The idea of combining materials to form composites is to obtain materials with superior characteristics like enhanced strength, resistance to corrosion, flexible designs, higher durability, better strength-to-weight ratios, etc. The main advantage of composites is that the material properties can be tailored as per the desired applications. The research and advancements on composites has spread its applications across diverse fields such as medical, construction, automobile, aerospace, oil and gas, household products, and so on. Rockets is one such application that would not be possible without the advent of composite materials. As a researcher, it is essential to understand what composites are or how these have evolved since their first usage. Therefore, this chapter completely focuses on the basic topics like introduction of composites and the history and evolution of composites. A brief discussion is also done on the properties and applications of composite materials.

Surface of an implant plays a key role in determining the performance as several events are associated with the surface. Modifying the surface with a bioactive coating or/and mechanical treatment can profoundly affect the success of the implant.