The thermo-mechanical response of power module heat sinks under cyclic loading conditions plays a critical role in determining the structural reliability of automotive electronic systems. This study investigates the deformation behaviour of a dual-plate aluminium heat sink subjected to combined thermal and power cycling representative of service conditions. An experimental approach based on distributed resistive strain gauges was employed to capture local strain evolution at selected locations across the structure. A controlled zero-balancing procedure was implemented to isolate the contribution of assembly-induced preload from thermally driven deformation. The instrumented module was first exposed to climatic chamber cycles in the range -40 $^\circ \text{C}$ to 75 $^\circ\text{C}$, followed by power thermal cycling endurance tests designed to reproduce operational loading sequences. The measurements reveal a stable and repeatable strain response governed by the interaction between non-uniform thermal expansion and discrete mechanical constraints. The heat sink exhibits compressive states at low temperature and progressively transitions to tensile deformation as temperature increases, with limited hysteresis during cyclic loading. Spatial variations in strain are observed across the structure, reflecting the influence of fastening conditions, thermal gradients, and structural coupling within the assembly. A simplified finite element representation is used to support the interpretation of the experimental observations and to provide qualitative insight into the deformation pattern and constraint effects. The results show that the dominant contribution to the overall strain field originates from assembly preload, while thermal cycling induces a consistent and largely elastic response without evidence of critical deformation anomalies under the investigated conditions. The study provides an experimentally grounded assessment of thermo-mechanical behaviour in power module heat sinks and offers practical guidance for measurement strategies and structural evaluation under coupled thermal and operational loading.

Friction stir welding of thin AA2024-T4 sheets is characterized by complex thermo–mechanical interactions arising from rapid heat dissipation, steep thermal gradients, and severe plastic deformation. In the present study, a coupled thermo–mechanical finite element model based on the coupled Eulerian–Lagrangian approach was developed in ABAQUS/Explicit to investigate material flow behavior, temperature evolution, strain distribution, and mechanical performance during friction stir welding of 2 mm-thick AA2024-T4 sheets. A systematic experimental campaign was conducted using rotational speeds ranging from 1000 to 1600 rpm and traverse speeds between 100 and 300 mm/min, corresponding to rotational-to-traverse speed ratios (ω/v) of 3.33–16.0 mm⁻¹. Thermal histories acquired using embedded K-type thermocouples and mechanical characterization through tensile and hardness testing were employed for model validation. Excellent agreement was achieved between numerical predictions and experimental measurements, with deviations limited to 3.2% for peak temperature and 1.5% for ultimate tensile strength, while coefficients of determination (R²) exceeding 0.985 were obtained for all validated responses. The thermo–mechanical simulations revealed pronounced localization of equivalent plastic strain within the stir zone and demonstrated that the spatial distribution of strain and heat generation strongly governed hardness evolution and joint performance. An optimum welding condition was identified at ω = 1400 rpm and v = 300 mm/min, corresponding to an ω/v ratio of 4.67 mm⁻¹, under which a maximum joint efficiency of 88% was achieved. Furthermore, the developed framework enabled quantitative correlation between process parameters, thermo–mechanical fields, and resulting mechanical properties, thereby providing mechanistic insight into defect suppression and weld quality enhancement in thin-sheet friction stir welding. The validated numerical framework is expected to serve as a reliable predictive tool for process optimization and performance assessment of high-strength aerospace aluminum alloys subjected to friction stir welding.

Forest residues generated from logging operations, forest maintenance, and wood-processing activities represent an increasingly important secondary biomass resource for sustainable material engineering. The heterogene-ous composition of these residues, together with their high lignocellulosic content, creates significant opportunities for their integration into wood-based composites and bio-derived adhesive systems. However, variability in species, morphology, moisture sensitivity, and chemical composition still limits their large-scale and standardized industrial utilization. This review investigates the valorization pathways of forest management residues within engineered wood-based material systems, with particular emphasis on wood–plastic composites, fiberboards, veneer-based products, and bio-adhesives derived from lignin and tannin fractions. The reviewed studies were identified through a structured survey of recent scientific literature focusing on the processing, classification, physicochemical characteristics, and engineering applications of forest biomass residues. Different utilization strategies were examined according to the geometrical form of the biomass, including fibers, particles, powders, and chemically extracted constituents used for adhesive formulation. The reviewed literature showed that forest residues were successfully incorporated into thermoplastic and thermosetting composite systems, where they contributed to stiffness enhancement, material lightweighting, and partial substitution of petroleum-derived constituents. Lignin- and tannin-based bio-adhesives also demonstrated promising potential for reducing formaldehyde dependence in wood panel manufacturing, although challenges related to reactivity, water resistance, and compositional variability remained significant. The findings further indicated that hybrid biomass systems, adhesive-free densified boards, and integrated biorefinery approaches have progressively expanded the technological possibilities for circular biomass utilization. The study demonstrates that forest residues can serve as multifunctional feedstocks for sustainable wood-based engineering materials when supported by appropriate material selection, traceability, and process integration strategies. The review also provides critical insights into the current limitations, scalability challenges, and future research directions associated with the transition toward low-emission and circular lignocellulosic material systems.