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Abstract Continuous efforts are underway for the reduction of the structural weight of transit through the introduction of a multi-material metal-composites system. There are major challenges in joining dissimilar materials to result in optimum structural integrity. The conventional joining techniques have limitations in terms of preparation time, weight penalty resulting from adhesives, and uncertainty in joint integrity. Recently adoption of macro scale mechanical interlocking in the adhesive joining resulted in significant improvement of joint performance. This made mechanical interlocking gain an attention for hybrid joining. In this study, fastenerless method of mechanical interlocking based on Japanese wood joining craft is considered for joining carbon fiber-reinforced polyamide thermoplastic composite to aluminum. Different interlocking joining designs (IJDs) were developed. The joints were obtained by force-fitting the male into the female counterpart. Here the male and female segments joined at macro level with no joining integrity at the interface. Further, these joints were tested and evaluated for tensile strength. A finite element analysis (FEA) model is developed for stress analysis and studying failure mechanisms of the IJDs. It was observed that the geometry of IJD dictates the failure mode and material composition governs the maximum strength achieved by a particular IJD. Each IJD showed higher load capacity with metal as a female counterpart to the composite compared to other way round. 

Sheet Molding Compound (SMC) is a widely used composite material, particularly in automotive applications, due to its cost-effectiveness, lightweight properties, and adaptability for complex shapes. While E-glass is commonly used as reinforcement in SMC, its strength and stiffness are limited compared to carbon fiber (CF). Previous research has focused on continuous-discontinuous SMC hybrids, combining continuous CF with glass fiber substrates, but these approaches are costly and complex to manufacture. This study explores a novel discontinuous-discontinuous hybrid SMC that combines E-glass SMC (G-SMC) with recycled carbon fiber (rCF) mats, aiming to enhance mechanical properties without a significant cost increase. Two materials were produced, one with and one without rCF, and were tested for flexural, tensile, interlaminar shear, and impact properties. Failure mechanisms were also examined through digital imaging. This approach demonstrates the potential for a cost-effective and practical SMC hybrid suitable for commercial applications in the automotive industry. 

This study addresses an existing gap in the literature by providing a comparative analysis of various adhesive model representation approaches, using cohesive zone models—both local and continuum models. Through a systematic investigation of stress distribution and force–displacement characteristics across different modeling techniques, we reveal the advantages and limitations of each method. This study provides a comparison of various adhesive modeling approaches, including single-row cohesive elements, interfacial elements, middle cohesive elements, and single-row continuum solid elements, highlighting their effects on stress distribution and failure modes in single lap joints across a range of adherend thicknesses and overlap lengths. The findings demonstrate that the choice of modeling techniques yields a similar prediction of failure modes in single lap joints under tensile loading. Consequently, choosing among these methods can be guided by the level of detail in capturing localized damage mechanisms. The results offer a foundation for informed decision making in adhesive modeling, with implications for improving joint design and reliability in real-world applications.