The paper presents technological, experimental and numerical studies aimed at the development of ... more The paper presents technological, experimental and numerical studies aimed at the development of a morphing nozzle in composite material with a deformable divergent section, which is designed to control the vector of thrust in rockets without using mechanisms or localized flexible joints. The nozzle design is characterized by corrugated composite walls and longitudinal elements that make possible a separation of load paths involved in bending response, bearing of internal pressures and related force resultants. Mechanical requirements and conditions of pressure, temperature and gas velocity in the morphing part of the nozzle are defined by selecting and investigating two potential application scenarios. Thereafter, both technological aspects and the assessment of mechanical performances are addressed by designing, manufacturing and testing a composite demonstrator with morphing capabilities. A lightweight and flexible thermal protection system is proposed, designed and numerically analyzed. Finally, a virtual demonstrator of the composite morphing nozzle is developed. Results point out the possibility of manufacturing composite elements with axial load bearing capability that may undergo significant bending deformation without failures. The integration of a flexible thermal protection systems leads to a promising concept for the development of innovative morphing nozzle for rocket engine applications.
Abstract The paper presents a new bi-phasic approach to model delamination and transverse crackin... more Abstract The paper presents a new bi-phasic approach to model delamination and transverse cracking in the matrix of composite laminates by using a single constitutive law, based on a decomposition of the composite stiffness properties into idealized fibre and matrix phases. The decomposition is used in finite element models where membrane elements representing the fibre phase are embedded in a three-dimensional mesh that models the matrix phase. A single constitutive law is applied to the matrix phase by combining a Cohesive Zone Model, which models delamination between plies, with an intralaminar damage law, aimed at modelling a transverse matrix cracking within the plies. All the theoretical aspects of decomposition and constitutive law are described. Then, the numerical experimental correlations are presented considering delamination tests and the evolution of the transverse matrix cracking in cross-ply specimens, with a statistical distribution of strength properties, also in the presence of interactions between matrix cracking and delamination. The approach provides the possibility to efficiently simulate both individual delaminations and transverse cracks with a model using a single layer of elements per ply, without introducing interface elements. Moreover, it also provides new possibilities to control the interaction between intralaminar and interlaminar damage phenomena.
The paper presents technological, experimental and numerical studies aimed at the development of ... more The paper presents technological, experimental and numerical studies aimed at the development of a morphing nozzle in composite material with a deformable divergent section, which is designed to control the vector of thrust in rockets without using mechanisms or localized flexible joints. The nozzle design is characterized by corrugated composite walls and longitudinal elements that make possible a separation of load paths involved in bending response, bearing of internal pressures and related force resultants. Mechanical requirements and conditions of pressure, temperature and gas velocity in the morphing part of the nozzle are defined by selecting and investigating two potential application scenarios. Thereafter, both technological aspects and the assessment of mechanical performances are addressed by designing, manufacturing and testing a composite demonstrator with morphing capabilities. A lightweight and flexible thermal protection system is proposed, designed and numerically analyzed. Finally, a virtual demonstrator of the composite morphing nozzle is developed. Results point out the possibility of manufacturing composite elements with axial load bearing capability that may undergo significant bending deformation without failures. The integration of a flexible thermal protection systems leads to a promising concept for the development of innovative morphing nozzle for rocket engine applications.
Abstract The paper presents a new bi-phasic approach to model delamination and transverse crackin... more Abstract The paper presents a new bi-phasic approach to model delamination and transverse cracking in the matrix of composite laminates by using a single constitutive law, based on a decomposition of the composite stiffness properties into idealized fibre and matrix phases. The decomposition is used in finite element models where membrane elements representing the fibre phase are embedded in a three-dimensional mesh that models the matrix phase. A single constitutive law is applied to the matrix phase by combining a Cohesive Zone Model, which models delamination between plies, with an intralaminar damage law, aimed at modelling a transverse matrix cracking within the plies. All the theoretical aspects of decomposition and constitutive law are described. Then, the numerical experimental correlations are presented considering delamination tests and the evolution of the transverse matrix cracking in cross-ply specimens, with a statistical distribution of strength properties, also in the presence of interactions between matrix cracking and delamination. The approach provides the possibility to efficiently simulate both individual delaminations and transverse cracks with a model using a single layer of elements per ply, without introducing interface elements. Moreover, it also provides new possibilities to control the interaction between intralaminar and interlaminar damage phenomena.
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Papers by Chiara Mirani