Abstract

The main objective of this work was to show the technical viability of a traditional Sheet Moulding Compound process hybridized with Carbon fibre prepreg reinforcements, in a demonstrative car seat structure. The new reinforced seat is lighter, has better mechanical resistance to impact and the typical carbon fibre visual aspect in the reinforced areas. Currently, the seat structure is composed by the hybrid solution with the matrixes of both materials being epoxy, therefore compatible which promotes a good adhesion under the correct processing conditions. To ensure the viability of this hybridization, an extensive laboratorial test campaign was conducted in a laboratorial hot plate press to study the Sheet Moulding Compound flow dynamics during the moulding process and how it interacts with the prepreg preforms. The cure process of both materials was also analysed to establish the optimal temperature profiles. Finally, mechanical tests were performed according to ASTM D 5868-01 to evaluate the mechanical properties of the bonding between the two materials. The reinforced car seat prototype was validated according to the ECE-R17 and FMVSS202a impact tests on the head rest and a 25% reduction in overall weight was achieved. The life-cycle cost and the visual aspect benefits are expected to compensate the slightly higher manufacturing cost in relation to the original part due to the cost of the prepreg material. Further research will be needed to in terms of process automation to ensure the required process quality.

Abstract

Lightening vehicles has been and continues to be one of the main objectives of the automotive industry. On one hand, to reduce fuel consumption in internal combustion vehicles, and, on the other hand, to try to maximize the autonomy of electric vehicles. In this aspect, composite polymeric materials, such as Sheet Molding Compound (SMC) materials, play a decisive role; however, their use in structural parts requires appropriate design and simulation techniques. In order to maximize design possibilities, in the conceptualization phases of the product development process, topology optimization tools open many possibilities. Nevertheless, the use of this technique in SMC materials generates certain uncertainties due to the nature of the material.

In this context, in this work a metal part has been replaced by a version of it in SMC and topological optimization tools have been used in the conceptual design stage. The possible variants have been analyzed when entering the mechanical data of the material, due to its anisotropic nature, as well as the influence of temperature on them, due to the fact that in the working environment the piece is subjected to 130 ºC. To do this, samples of material have been molded and a mechanical characterization has been carried out to understand the behavior of the material with respect to fiber orientation and temperature. Then, using the PTC Creo design tool, a topological optimization and subsequent adaptation were carried out to improve the processability of the component. The most promising versions have been virtually validated using finite elements with Abaqus software.

In conclusion, this work has demonstrated the viability of using topology optimization techniques in the conceptual design of components with SMC materials. Furthermore, in combination with simulation techniques using finite elements, they have proven to be tools that reduce and perfect product development in composite materials.

Abstract

In recent times, polymer matrix composite material technologies have undergone a true revolution driven by the boom in demand, especially in the transportation and energy sectors. Composites are increasingly being incorporated due to the significant weight reduction they offer in structural components, which leads to lower energy consumption in transportation systems. Ambitious EU sustainability policies (such as the EU Green Deal and the New Industrial Strategy) further accelerate this shift towards efficient and sustainable solutions, with a major impact on the transportation sector—particularly in the automotive industry, both for conventional and emerging propulsion systems. The use of lightweight materials is expected to increase from the current 30% to 70% by 2030, with composites representing approximately 20%.

However, the automotive sector is one of the most demanding in terms of processing times. Therefore, optimizing and monitoring process parameters through embedded sensors in molds is seen as a valuable tool to adjust processing times and enable continuous quality control of components.

This paper presents the results obtained within the framework of the COMPCERTO project, which aims to develop solutions that support the optimization of manufacturing structural components through thermforming processes using Sheet Molding Compound (SMC) materials. The project involves the implementation of sensors to monitor curing, pressure, and temperature within the molds, enabling the acquisition of representative real-time data at critical points during the thermoforming process in the press.

In order to determine the most suitable manufacturing parameters, preliminary tests are conducted to optimize the curing cycle. Based on the results, a Design of Experiments (DoE) is proposed. Finally, mechanical, thermal, and microstructural characterizations are performed on the samples defined in the DoE. This will generate a database that helps correlate real-time process data with potential defects in SMC parts.

Abstract

In recent times, polymer matrix composite material technologies have undergone a genuine revolution, driven by the surge in demand—particularly in the transportation and energy sectors. Composites are being increasingly incorporated due to the significant weight reduction they enable in structural components, which in turn leads to a decrease in energy consumption in transportation as a result of this weight savings. Ambitious EU sustainability policies (such as the EU Green Deal or the New Industrial Strategy) are further accelerating this shift toward efficient and sustainable solutions, with a significant impact on the transportation sector, especially the automotive industry—both in conventional and emerging propulsion systems (the use of lightweight materials is expected to increase from the current 30% to 70% by 2030, with composites accounting for approximately 20%). However, the automotive sector is one of the most demanding in terms of processing times. Therefore, the optimization and monitoring of processing parameters through embedded sensors in molds is presented as a valuable tool for adapting processing times and enabling continuous quality control of parts. This paper presents the results obtained within the framework of the COMPCERTO project, which aims to develop solutions that facilitate the optimized manufacturing of components with structural requirements through Sheet Molding Compound (SMC) thermoforming processes. To achieve this, the implementation of sensors for monitoring curing, pressure, and temperature in molds is proposed, enabling the acquisition of representative values at critical points and in real time for the phenomena occurring during the thermoforming of parts in the press. Preliminary tests are carried out to optimize the curing cycle in order to determine the most suitable manufacturing parameters, and based on the results, a Design of Experiments (DoE) is proposed. Finally, mechanical, thermal, and microstructural characterizations are performed on the tests defined in the DoE. This will generate a database that serves to correlate the real-time data obtained from the parts with potential defects in the SMC components.