Residual stresses introduced by Double-Sided Dimpling (DSD) before drilling a through-thickness hole can improve fatigue strength. However, each subsequent operation modifies the initial stress field following DSD, so that reliable prediction of residual stress redistribution is essential for strength and durability assessment. This study presents an experimental–computational framework for validating both the formation and redistribution of DSD-induced residual stresses in an AA2024-T4 aluminum alloy plate. A controlled residual stress field was produced by DSD and characterized by neutron diffraction. The measured elastic strain distributions were used to validate a previously developed analytical ‘autoplug’ model and a finite element model of the DSD process. The results confirmed the characteristic self-equilibrated stress state described by the ‘autoplug’ model, including a tensile hoop stress maximum at the elastic–plastic boundary. To examine the stress evolution during material removal, the specimen was subsequently cut centrally into two halves using wire electrical discharge machining. A second neutron diffraction campaign provided volume-averaged measurements of the redistributed elastic strain field. Comparison with finite element predictions showed that the model accurately captures stress redistribution caused by the formation of a new free surface and the associated elastic strain relief. The proposed Rational Experimental–Computational Correlation framework provides a reliable basis for predicting residual stress evolution beyond the initial DSD stage. The validated finite element model provides a predictive numerical framework for the DSD process and enables future analysis of drilling-induced stress redistribution in mechanically strengthened components.
Carbon-fibre-reinforced polyether ether ketone (CF/PEEK) offers a lightweight alternative to metallic fastening components, but its vibration response and mechanical performance can be further tailored through particulate reinforcement. This study investigates TiB 2 -reinforced CF/PEEK hybrid composites and their application in lightweight polymer bolts, with particular emphasis on the relationship between TiB 2 content, microstructural evolution, mechanical behaviour, thermal stability, and dynamic response. TiB 2 was incorporated at 1–4 wt.% through melt compounding followed by low-speed planetary milling and compression moulding. The resulting composites were evaluated using microstructural, mechanical, thermal, and vibration characterization, while hybrid polymer bolts were assessed through frequency-response and impact-hammer testing. TiB 2 incorporation improved hardness and compressive strength, with maximum values of 106 HRM and 359.97 MPa, respectively, at 4 wt% TiB 2 for the 450CA30 configuration. For the dynamically investigated 3 wt% TiB 2 configuration, the damping ratio increased from 0.88 to 0.94 for 450CA30 and from 0.86 to 0.91 for 150CA30, accompanied by substantial attenuation of resonance response. The 3 wt% TiB 2 hybrid bolts also exhibited tensile-strength improvements of approximately 4.5% and 3.5% for 450CA30 and 150CA30, respectively. The principal novelty of this work lies in demonstrating the potential of TiB 2 -reinforced CF/PEEK as a lightweight polymeric fastening material with experimentally verified vibration-attenuation capability at the bolted-joint level. The results establish a composition–microstructure–property–dynamic-response relationship and identify 3 wt% TiB 2 as a promising configuration among those subjected to dynamic testing, while acknowledging that definitive dynamic optimization requires characterization of higher TiB 2 loadings.
Fe(iron) is beneficial in die-cast aluminum alloys, but its Fe-rich phases are highly detrimental to ductility, which limits the tolerable Fe content. In this study, a strategy of partially substituting Mn with Fe combined with Al-SrRE composite modification is proposed to improve the mechanical properties. Under a constant total (Mn + Fe) content, the effects of Fe content on the three-dimensional (3D) morphological evolution of Fe-rich phases and the mechanical properties of Al-7Si-0.2 Mg-xFe-(0.8-x)Mn alloy were investigated using OM, SEM, EDS, DSC, and synchrotron radiation X-ray computed tomography (SRXCT). The results show that with increasing Fe content and decreasing Mn content, the morphology of the Fe-rich phases evolves: needle-like + Chinese-script -* Chinese-script -* needle-like + Chinese-script -* coarse needle-like. When both Fe and Mn contents reach 0.40%, corresponding to an Mn/Fe ratio of approximately 1, the Fe-rich phases are dominated by fine and compact Chinese-script structures with a multi-branched polyhedral 3D morphology. At this composition, the alloy achieves the optimal mechanical properties, with a tensile strength of 176 MPa and an elongation of 9.6%, respectively. DSC results and thermodynamic calculations indicate that when the contents of Fe and Mn are close, the precipitation temperature range of the Fe-rich phases overlaps with the alpha-Al eutectic reaction. The competitive growth between them promotes the formation of fine and compact Fe-rich phases, which is the main reason for achieving a good combination of strength and ductility. This study provides new insight for the highvalue utilization of recycled aluminum with high Fe content.
