Method for simulating the behavior of a bonded joint of two parts

1. A computer-aided method aiding in a design of a structural joint of two composite material parts ( 11 , 15 ) with an adhesive material layer ( 13 ), comprising the following steps:

a) providing a Finite Element Model with information for analyzing said structural joint;

b) providing a calculation model for calculating deformations of the adhesive material layer ( 13 ) when it is subjected to tensile/peel and shear stresses, including a plastic behavior of an adhesive of a linear type under tension/peeling and of a non-linear type under shearing; and

c) simulating a behavior of said structural joint as bonded by applying the calculation model to obtain failure indices of each failure mode,

wherein plastification criteria taking into account hydrostatic stress simulate in an approximate manner the effect that the tensile stresses have in the plastification process based on generation and coalescence of microcavities when large volumetric deformations occur in the adhesive material layer, and

wherein said method includes calculating rigidity matrices of each element, and once the rigidity matrix of each element has been calculated in local axes, it is changed to global axes, after which the rigidity matrices of all the elements are assembled in order to obtain a global rigidity matrix of the structure.

2. The computer-aided method according to claim 1 , wherein said two composite material parts ( 11 , 15 ) are simulated using two-dimensional elements and said adhesive layer ( 13 ) is simulated sing spring elements ( 1 , 2 ).

3. The computer-aided method according to claim 1 , wherein said two composite material parts ( 11 , 15 ) are a panel and a stiffening element of an aeronautical structure and a thickness of said adhesive material layer ( 13 ) is less than 1 mm.

4. A system having a processor and a memory coupled to said processor to aid in a design of a structural joint of two composite material parts ( 11 , 15 ) with an adhesive material layer ( 13 ), using a computer-implemented Finite Element Model of said structural joint, comprising:

a computer-implemented modulus containing a parametric definition of certain features of said joint and which allows using said processor providing input data of said Finite Element Model;

wherein said Finite Element Model comprises a calculation model for calculating using said processor deformations of said adhesive material layer ( 13 ) when it is subjected to tensile/peel and shear stresses, including a plastic behavior of an adhesive of a linear type under tension/peeling and of a non-linear type under shearing and which allows simulating a behavior of said structural joint as bonded to obtain failure indices of each failure mode,

wherein plastification criteria taking into account hydrostatic stress simulate in an approximate manner the effect that the tensile stresses have in the plastification process based on generation and coalescence of microcavities when large volumetric deformations occur in the adhesive material layer, and

wherein said system calculates rigidity matrices of each element, and once the rigidity matrix of each element has been calculated in local axes, it is changed to global axes, after which the rigidity matrices of all the elements are assembled in order to obtain a global rigidity matrix of the structure.

5. The system according to claim 4 , wherein said two composite material parts ( 11 , 15 ) are a panel and a stiffening element of an aeronautical structure and the thickness of said adhesive material layer ( 13 ) is less than 1 mm.

6. The computer-aided method according to claim 2 , wherein said two composite material parts ( 11 , 15 ) are a panel and a stiffening element of an aeronautical structure and a thickness of said adhesive material layer ( 13 ) is less than 1 mm.