Abstract
SCULPTROL has developed an innovative, sustainable, and cost-effective process chain utilizing rolling technologies to create sculptures on metal sheets for multi-material bonding applications. The sculpted surfaces enhance bonding strength between different materials by promoting adhesive and mechanical interlocking at the interfaces through protrusions. In comparison to existing technologies, such as those utilizing electron beams or additive manufacturing solutions, SCULPTROL presents an alternative that addresses the primary limitations of conventional methods. This approach offers a robust, scalable solution that is suitable for mass production and the fabrication of large, high-value components. The sculpting process is achieved through rolling—an inherently efficient forming process designed for high production rates and ease of operation. This process eliminates the need for additional manufacturing steps to create protrusions or pins, resulting in significant cost savings and reduced emissions compared to competing solutions. Two viable methods have been demonstrated: 1. The use of an external flat shaped plate to generate protrusions through simple cylindrical rolls; 2. The development of specialized laminating rolls equipped with interchangeable inserts, capable of producing various types of protrusions. To support these methods, a reliable digital twin was generated using FEM simulation (QformUk code). This digital twin enables virtual analysis of the manufacturability of sculptured sheets, including aspects such as protrusion patterns, size, shape, and inclination. The insights gained from these simulations allowed the optimal design of both the plates and the roll insert configurations. Cavities in plates and inserts were created using several technologies, including conventional drilling, EDM, water jet cutting, and laser machining. The goal of the tooling process is to generate specifically designed shaped cavities (high aspect ratio holes), which can be replicated as protrusions or pins in the forming material through the application of thermomechanical deformation. The tools were employed to produce sculptured sheets using different alloys, including AA3105, AA1050, and AZ31, with various pattern configurations. Sculptured sheets were then applied and tested in multimaterial joints. In the frame of multi-materials, the most promising combinations for hybrid structures in several sectors (aerospace, automotive, electrical and packaging, etc) are MetalMetal and Metal-Fibre Reinforced Composites (FRC). Among metal-metal joints, similar and dissimilar metal joints were investigated, while pre-preg carbon-vynilester SMC over aluminum sculptured sheets were produced and tested for the metal/FRC joints. Metal-Metal joints were successfully produced with different final properties depending on process temperature and reduction ratios.A response surface analysis model was created, suggesting its effectiveness in predicting bond strength indicated as the width-normalized peak force required to initiate cracking in the interface layer of the peel tests. Metal-Fibre Reinforced Composites (FRC) joints were then experimentally tested in single lap-shear configuration and pull out condition in order to develop and validate innovative FEM simulation of the joint behaviour in the elasto-plastic domain thus enabling the generalization of the results to any possible joint pattern and load configuration. Test results showed an increase of 120% of the load carried out by the joint (80% of the stress) compared to not sculptured surfaces and an even more remarkable increase of the 250% of the energy absorbed before joint failure. RESULTS ACHIEVED The main achievements of the project, compared to the previous state of the art, can be summarized as follows: Innovative Protrusion Generation Techniques - Introduction of an external shaped plate method and dedicated laminating rolls with interchangeable inserts, enhancing flexibility in design and production. Enhanced Bonding Strength - Development of sculpted surfaces that improve adhesive and mechanical interlocking, resulting in superior bonding strength between multi-materials. - Sculptured surfaces offer a potential solution to the low adhesion of pre-preg carbon–vinylester SMC to metal substrates. - Mechanical hybridization significantly enhances joint strength and modifies the failure progression of SLJs, improving both structural robustness (+120% of the load carried) and energy absorption before joint failure (+250% increment). - Improved bonding in metal/metal joints is achieved when proper process parameters and reduction rates are selected. Cost and Resource Efficiency - Significant reduction in manufacturing costs through minimized production steps and faster production rates compared to additive methods. Advanced Simulation and Design - Creation of a reliable digital twin using FEM simulation (QformUk code) for virtual analysis of manufacturability, leading to optimized design configurations for plates and roll inserts. - Development of elasto-plastic simulations of metal/FRP joints beyond the state of the art, including the damage behaviour of both metals and adhesive interface. - Elasto-plastic simulations of metal/FRP joints allow the results to be extended to different geometric joint configurations commonly found in industrial production. Versatile Tooling Technologies - Comparison of multiple technologies (EDM, water jet cutting, and laser machining) with conventional CNC drilling for the manufacturing of tool cavities, enabling high precision and design adaptability. Scalability for Mass Production - Establishment of a manufacturing process that is easily scalable, making it suitable for highvolume production of high-value components. Application to Different Materials The project involved the use of the following materials: -metals: AA3105, AA1050, AZ31 -FRC: carbon-vinyl-easter SMC (STR120N131)
Dettagli del progetto
Responsabile scientifico: Lorenzo Donati
Strutture Unibo coinvolte:
Dipartimento di Ingegneria Industriale
Coordinatore:
ALMA MATER STUDIORUM - Università di Bologna(Italy)
Contributo totale di progetto: Euro (EUR) 197.488,00
Contributo totale Unibo: Euro (EUR) 67.860,00
Durata del progetto in mesi: 24
Data di inizio
28/09/2023
Data di fine:
28/02/2026
