A generalized global-local defect/damage initiation model for launcher composite structures pre-sizing
Topic(s) : Material and Structural Behavior - Simulation & Testing
Co-authors :
Alexy TAILLEUR (FRANCE), Kevin MATHIS (FRANCE), Ange ROGANI (FRANCE), Pablo NAVARRO (FRANCE), Steven MARGUET , Jean-François FERREROAbstract :
COLIBRI is a platform developed and used by CNES for designing and dimensioning space launchers’ composite structures [1]. This tool is composed of three modules: technology pre-selection, pre-sizing and dimensioning. Defects and damages in composite structures are currently taken into account during the final stage. Thus, the selected structure is optimal to meet the specifications but is not necessarily the most efficient to support defects or damage. Therefore, it is necessary to address defects and damage as early as possible in the development stages of the structure.
The objective of this work is to develop a defect/damage initiation and propagation numerical model for launcher composite structures at pre-sizing stage. The structures optimized in COLIBRI have large dimensions and performing damage calculations on those whole structures is not a feasible solution during the pre-sizing step. The approach proposed in this paper is based on submodeling. It allows to circumvent this problem and to significantly reduce the calculation time while keeping the desired accuracy. Indeed, in large-scale structures such as those optimized in COLIBRI, damage initiation and propagation are generally local phenomena that are mainly triggered in areas of preexisting defects, manufacturing imperfections and accidental/service damage or inefficient maintenance [2].
The proposed methodology consists on a one way shell-to-solid submodeling where defects such as porosity, matrix cracking and delamination have been inserted. The presence of these defects plays a predominant role in the initiation and propagation of damage [3,4]. The methodology developed focuses on the initiation of damage in the presence of defects. The approach adopted is therefore unidirectional: the information flows from the "global" model to the distinct "local" model. It is realized through the numerical solver Nastran only and presents a huge flexibility. The theory is generalized to thin and thick plates by including the effects of transverse shear strain for any symmetric laminate. It also works for flat, cylindrical and spherical structures. Compared to a refined global 3D model of the structure, the results obtained with the global 2D / local 3D process demonstrate an excellent correlation for both displacement and stress fields while being less time consuming.
This numerical model will be compared with a future experimental campaign conducted on coupon test using a prepreg made of carbon fibres and cyanate ester thermoset matrix which has been previously characterized for the study. These tests will allow to set up the test-calculation dialogue for the validation of the model. Eventually, this numerical model will be included in the optimization process and the best architecture will be determined with respect to the specifications and its tolerance to damage in the presence of defects.
The objective of this work is to develop a defect/damage initiation and propagation numerical model for launcher composite structures at pre-sizing stage. The structures optimized in COLIBRI have large dimensions and performing damage calculations on those whole structures is not a feasible solution during the pre-sizing step. The approach proposed in this paper is based on submodeling. It allows to circumvent this problem and to significantly reduce the calculation time while keeping the desired accuracy. Indeed, in large-scale structures such as those optimized in COLIBRI, damage initiation and propagation are generally local phenomena that are mainly triggered in areas of preexisting defects, manufacturing imperfections and accidental/service damage or inefficient maintenance [2].
The proposed methodology consists on a one way shell-to-solid submodeling where defects such as porosity, matrix cracking and delamination have been inserted. The presence of these defects plays a predominant role in the initiation and propagation of damage [3,4]. The methodology developed focuses on the initiation of damage in the presence of defects. The approach adopted is therefore unidirectional: the information flows from the "global" model to the distinct "local" model. It is realized through the numerical solver Nastran only and presents a huge flexibility. The theory is generalized to thin and thick plates by including the effects of transverse shear strain for any symmetric laminate. It also works for flat, cylindrical and spherical structures. Compared to a refined global 3D model of the structure, the results obtained with the global 2D / local 3D process demonstrate an excellent correlation for both displacement and stress fields while being less time consuming.
This numerical model will be compared with a future experimental campaign conducted on coupon test using a prepreg made of carbon fibres and cyanate ester thermoset matrix which has been previously characterized for the study. These tests will allow to set up the test-calculation dialogue for the validation of the model. Eventually, this numerical model will be included in the optimization process and the best architecture will be determined with respect to the specifications and its tolerance to damage in the presence of defects.