The integration of sustainable waste-derived reinforcements into polymer composites is an effective strategy for improving performance while reducing environmental impact. In this study, rice husk biochar was investigated as a particulate reinforcement for epoxy composites, and its influence on mechanical, tribological, and thermal behaviour was systematically evaluated. Epoxy composites containing different weight fractions of rice husk biochar were fabricated and characterised. Tensile strength increased from 22.7 MPa for neat epoxy to 29.2 MPa at 9 wt.% biochar, accompanied by an increase in elongation at break from 0.8% to 1.31%, indicating improved stress transfer and reduced brittleness. Flexural strength similarly improved from 58 MPa to 70.1 MPa, confirming enhanced resistance to bending-induced failure. Fracture-surface analysis revealed suppression of cleavage-dominated river patterns and increased crack deflection in biochar-reinforced composites. Dry sliding wear analysis showed that intermediate biochar content increased wear mass loss (0.76 mg at 6 wt.%) due to particle pull-out and third-body abrasion, whereas higher filler loading promoted more stable surface interaction. Thermogravimetric analysis demonstrated improved thermal stability of biochar-reinforced epoxy composites at elevated temperatures, particularly in the 400 °C–550 °C range, attributed to char-mediated thermal shielding. Overall, the results demonstrate that rice husk biochar provides multifunctional enhancement of epoxy composites by improving mechanical performance and high-temperature thermal resistance, while introducing content-dependent tribological effects, highlighting its potential as a sustainable reinforcement for epoxy-based non-load bearing structural applications.

3D printing offers the ability to fabricate lightweight structural profiles with controlled infill and geometry. This study examines the mechanical behaviour of 3D-printed polylactic acid (PLA) structures with a 10% infill density under four load conditions (10, 15, 20, and 25 N). Four designs (M1, M2, M3, and M4), representing commonly used structural profiles found in beam and column applications, were analysed using ANSYS finite element simulations. Each design was evaluated under roller and nodal boundary conditions to study deformation, stress, and strain responses. Three-point flexural tests were also carried out on all four designs, and the measured peak flexural stress and apparent flexural modulus were compared with the simulated stiffness values. Both the simulations and experimental results showed that Design M3 exhibited the highest stiffness and more consistent behaviour compared to the other designs, while Design M4 showed higher deformation and lower bending resistance. Roller supports generally reduced deformation through better load distribution, whereas nodal supports increased local stiffness in selected designs. Although the magnitude of stiffness differed between simulation and experiment, the ranking of the designs remained consistent. Overall, the study confirms that the geometry plays an important role in their load-bearing performance, and the numerical model provides a reliable tool for comparing and selecting suitable designs before fabrication.

Wire-arc additive manufacturing (WAAM) has garnered attention in academia and industry and has huge potential because of its ability to fabricate complex geometry and economic viability compared to other metal additive manufacturing (MAM) processes. Its unparalleled design freedom, ability to manufacture near-net shaped components, less material wastage, ability to produce large components with a variety of materials, and flexibility in influencing material properties by varying the process parameters makes WAAM promising for industry. Ti–6Al–4V is the most prevalent titanium alloy because of its exceptional material properties and extensive application in aerospace industry, the marine sector, and bio-medical implants, among others. However, its use is limited due to its poor wear behavior due to oxidation, delamination, and spalling. Thus, it is crucial to improve the wear resistance of Ti–6Al–4V by surface engineering, manufacturing processes, and post-process treatments. In this review, we aim to provide a brief introduction to popular MAM processes, process parameters of WAAM, and path planning that influence the material properties and explore the wear behavior of the Ti–6Al–4V alloy in different environmental conditions, process parameters, and post-processing treatments. Due to the dearth of literature available on the wear behavior of the Ti–6Al–4V alloy manufactured using WAAM, the wear behavior of Ti–6Al–4V manufactured by L-PBF, SLM, and other conventional methods is reviewed. Additionally, this review paves the path of future exploration of the wear characteristics of the Ti–6Al–4V alloy manufactured by WAAM.