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Fibre-reinforced composites are widely utilised in weight-sensitive engineering applications due to their superior structural stiffness and lightweight characteristics. In this study, the impact of embedding fibrous z-pins on the tensile and vibrational properties of co-cured glass/epoxy laminates was investigated through experimental methods. The fibrous pins were embedded at three different volume fractions (0.5%, 2.0% and 4.0%) to examine the failure behaviour of the laminated composites. The experimental findings revealed that the tensile strength and modulus of composite laminates decreased as the volume fraction of fibrous pins increased, which indicates stress concentration around the pins and potential fibre disruption. Specifically, the results of the tensile tests demonstrated that including 4.0 vol.% composite fibrous pins led to a reduction of 45.81% in the tensile strength of the composite laminate compared to unpinned laminates. Fracture analysis of the failed specimens indicated that the insertion of fibrous pins resulted in damage to the matrix material, fibre discontinuity, fibre distortion, the formation of resin-rich areas, and a decrease in the in-plane volume content of fibres. Moreover, the experimental modal analysis revealed that fibrous pin insertion reduced the structural stiffness of the laminated composites. Interestingly, the 4.0 vol.% fibrous pin-embedded samples exhibited higher modal damping due to the increased energy-dissipating behaviour of the laminated composites. The present study suggests that z-pin incorporation can be strategically employed to achieve a balance between stiffness and damping, potentially leading to composites optimised for specific noise reduction applications.

Adhesively bonded joints are typically prone to failure at overlapping ends due to high shear and peel stresses. Several methods have been developed to reduce the shear stress and improve the strength of adhesive joints. One potential approach is to modify the overlapping area into a joggle and wavy form configuration, which reduces the stress concentration and enhances the performance of adhesive joints. The present study investigated the impact of joggle and wavy-shaped overlapping areas on the load-carrying behaviour of additive-manufactured lap joints. Adhesive joints with joggle and wavy design configurations were fabricated with Acrylonitrile butadiene styrene through a fused deposition modelling approach. Shear analysis revealed that the joggle and wavy-shaped design significantly improved the structural integrity of the joints, with load-carrying capacities enhanced by 65.91% and 55.45%, respectively, compared to single-lap joints. Failure surface examination showed that the single lap joint failed in adhesive mode, while the joggle and wavy joint failed in cohesive mode. Experimental free vibrational analysis revealed that the joggle and wavy-shaped 3D printed adhesive joints had a higher natural frequency than single lap joints. The proposed joint design configurations and findings can be used to fabricate 3D-printed adhesive joints with better structural integrity.

In the current study, mechanical properties of hot pressed, solution treated and aged austenitic stainless steels (21-4N) for were evaluated by varying the percentage of yttria addition. The milled powders were vacuum hot pressed at 1,200°C with a pressure level of 56 MPa with a holding period of 2 hrs under the vacuum level of 10-2 torr. Hot pressed samples were solution treated at 1,200°C for a period of 2 hrs and immediately subjected to water quenching to dissolve more grain boundary carbides. Further, to achieve the desired hardness samples were aged at 750°C held for 4 hrs followed by air cooling. Optical micrographs and SEM-EDS studies reveal austenitic grain with grain boundary carbides in the hot pressed condition. After solution treatment these precipitates disappears which was confirmed through SEM-EDS. Austenitic stainless steel containing 0.3 wt% yttria has attained higher tensile strength of 598 MPa in the age hardened condition.

Ferritic oxide dispersion-strengthened (ODS) steels containing Fe–17Cr–0.89Mn–0.89Si–0.25Y2O3–1.5ZrO2–3Al (wt%) was prepared through mechanical alloying, and X-ray diffractogram was used to analyze crystallite size for different time intervals during milling. Milled powders were consolidated at three different temperatures 1050 °C, 1100 °C and 1170 °C at three different pressure levels of 30, 40 and 60 MPa at different cooling rates 5 °C/min, 25 °C/min, 50 °C/min. Optimization of three parameters, namely sintering pressure, sintering temperature and rate of cooling, was done in this current study through design of experiments. Analysis of variance technique inclusive of signal-to-noise ratio was employed to optimize the processing parameters through L9orthogonal array which predicts the response variable like density, tensile strength and hardness in the present study. Density and mechanical properties of powder metallurgy component are governed by sintering parameters. From the results, it is observed that in sintering pressure increases the mechanical properties and density. Samples sintered at 1170 °C with the pressure level of 60 MPa and rate of cooling 50 °C/min exhibit higher sintered density, hardness and tensile strength than the other sintered conditions. Sintering pressure is the most prevailing factor followed by the vacuum hot pressing inducing density and mechanical properties. Analysis of variance and Taguchi method were used to find the optimum parameters for attaining the superior mechanical properties of the 17Cr ferritic ODS steel.

The wear behaviour of AISI 316LN austenitic stainless steel has been studied by varying the duration of nitriding. AISI 316LN steel was nitrided using salt bath nitriding which consist of a mixture of 70:30 ratio of alkaline cynates and carbonates. Nitriding was carried out for two time durations namely 60 min and 100 min. Pin-on-Disc wear test were carried out for both the untreated and treated sample at room temperature. The wear parameters were changed to understand the wear mechanism of AISI 316LN steel along with the nitrided sample by varying the sliding distance for 250 m, 500 m and 1000 m. Due to the presence of different wear mechanism the rate of wear varies as a function of sliding distance. For untreated sample the wear mechanism was dominant with adhesion, abrasion and plastic deformation. An optical micrograph, X-ray diffraction analysis, wear morphology, hardness measurement and surface roughness were carried out. Due to the presence of compound layer as a result of nitriding AISI 316LN austenitic stainless steel, the mechanism of wear was restricted to abrasive wear. Untreated specimens have more significant wear loss when compared to treated specimen as work hardening and an increase in hardness of wear track resulted in material pull out. Stability of the compound layer is achieved as a result of longer duration of nitriding. Abrasive wear is resisted to a greater extend due the availability of compound layer. AISI 316LN steel which was nitrided for 100 min exhibited a more stable compound layer when compared to the same nitrided for 60 min.