Accurate Assessment of the Tensile Strength of High-Performance Carbon Fibre Unidirectional Composites for Hydrogen Storage Applications
Topic(s) : Experimental techniques
Co-authors :
Wajih AKLEH (FRANCE), Xavier GABRION (FRANCE), Violaine GUICHERET-RETEL , Dominique PERREUX , Vincent PLACET , Benjamin SALA , Frédéric THIEBAUDAbstract :
The global shift towards cleaner energy due to climate change and pollution has stimulated extensive research into hydrogen as a promising alternative to traditional energy sources [1]. Storage options for hydrogen require high-performance storage vessels that can withstand extreme conditions of low temperatures, elevated pressures, and cyclic filling and emptying, all leading to a degradation of the tank structure. Consequently, storage vessel design is central in hydrogen research.
The mechanical characterisation of high-performance carbon fibre unidirectional composites is of crucial importance for the design of structures, particularly in the context of aviation applications such as type IV hydrogen tanks for aircraft. This is essential to ensure that structures are properly designed up to safety measures without over-dimensioning, which can result from underestimating the strength of the used materials. As part of the Clean Aviation - CAVENDISH project, the work of this thesis focuses on addressing the challenges associated with the mechanical characterisation of these composites.
Standardised mechanical characterisation methods, such as ASTM D3039 [2] and ASTM D2290 [3] for rectangular and ring specimens, respectively, are widely used. However, these standards may not provide accurate representations of the material strength due to non-uniform and non-homogeneous stress states within the composites. Concentrations of stress [4] and mixed loading [5] can lead to unreliable results, highlighting the need for alternative characterisation methods.
The work of this thesis begins with a detailed review of the current literature in this field, building upon recent research [6] and applying it to the studied material. The aim is to determine stress concentration factors along the tensile-loaded rectangular specimens through finite element analysis. This analysis will help identify a combination of parameters, including specimen geometry, tab design, and tab material properties, that ensures repeatable failure within the gauge length of the specimen.
Simultaneously, mechanical tests are conducted on both rectangular and ring specimens to validate the numerical results and provide insights into the mechanical behaviour of the composites. These experiments will contribute to the development of improved characterisation techniques that accurately capture the mechanical properties of high-performance carbon fibre unidirectional composites.
Preliminary numerical results reveal a consistent trend with the literature regarding end tab parameters, indicating that similar results can be expected experimentally. Additionally, for the ring specimens, it is anticipated that digital image correlation will effectively define the stress states, enabling accurate prediction of failure, and thus the implementation of the proper modifications to the applied characterisation techniques.
The mechanical characterisation of high-performance carbon fibre unidirectional composites is of crucial importance for the design of structures, particularly in the context of aviation applications such as type IV hydrogen tanks for aircraft. This is essential to ensure that structures are properly designed up to safety measures without over-dimensioning, which can result from underestimating the strength of the used materials. As part of the Clean Aviation - CAVENDISH project, the work of this thesis focuses on addressing the challenges associated with the mechanical characterisation of these composites.
Standardised mechanical characterisation methods, such as ASTM D3039 [2] and ASTM D2290 [3] for rectangular and ring specimens, respectively, are widely used. However, these standards may not provide accurate representations of the material strength due to non-uniform and non-homogeneous stress states within the composites. Concentrations of stress [4] and mixed loading [5] can lead to unreliable results, highlighting the need for alternative characterisation methods.
The work of this thesis begins with a detailed review of the current literature in this field, building upon recent research [6] and applying it to the studied material. The aim is to determine stress concentration factors along the tensile-loaded rectangular specimens through finite element analysis. This analysis will help identify a combination of parameters, including specimen geometry, tab design, and tab material properties, that ensures repeatable failure within the gauge length of the specimen.
Simultaneously, mechanical tests are conducted on both rectangular and ring specimens to validate the numerical results and provide insights into the mechanical behaviour of the composites. These experiments will contribute to the development of improved characterisation techniques that accurately capture the mechanical properties of high-performance carbon fibre unidirectional composites.
Preliminary numerical results reveal a consistent trend with the literature regarding end tab parameters, indicating that similar results can be expected experimentally. Additionally, for the ring specimens, it is anticipated that digital image correlation will effectively define the stress states, enabling accurate prediction of failure, and thus the implementation of the proper modifications to the applied characterisation techniques.