Simulation Tool for Damage in Composite Laminates

A computerized method of simulating damage growth in composite laminates having a plurality of interfaces between adjacent layers of fibers disposed in a matrix material, the method comprising:

• forming a finite element model of a composite material, the finite element model comprising a plurality of nodes and having a region having a single layer of shell or plate elements comprising a composite stiffness matrix corresponding to a plurality of layers of fibers disposed in a matrix material;
• storing the finite element model in computer memory;
• using a computer to determine a finite element solution to the finite element model subjected to a load;
• if the finite element model has a delamination crack, providing separate stiffness matrices corresponding to laminate layers on each side of the delamination crack;
• predicting the spatial orientation of microcracks that precede the delamination front to thereby determine if the delamination front migrates via a matrix crack to a new interface;
• if the delamination migrates to a new interface, split one or more adjacent shell elements in the direction of growth to form new shell elements, the new shell elements having stiffness matrices that are modified from those of the current interface split location to correspond to a new interface location that is offset from the current interface to thereby account for migration of the delamination to the new interface by providing a stiffness discontinuity at a boundary between adjacent shell elements thereby modeling the matrix crack.

A computerized method of simulating damage growth in composite laminates having a plurality of interfaces between adjacent layers of fibers disposed in a matrix material, the method comprising:

• forming a finite element model of a composite material, the finite element model comprising a plurality of nodes and having a region having a single layer of shell or plate elements comprising a composite stiffness matrix corresponding to a plurality of layers of fibers disposed in a matrix material;
• storing the finite element model in computer memory;
• using a computer to determine a finite element solution to the finite element model subjected to a load;
• using a computer to evaluate at each load step in a numerical finite element solution procedure if a delamination crack exists in the finite element mesh and/or if a delamination crack forms according to a predefined damage initiation criteria;
• if a delamination crack forms or is already present, determining the location in the laminate including a present interface;
• if a delamination crack does not form, or if a delamination crack does not exist, repeat the step of determining a finite element solution;
• if a delamination crack forms or already exists, providing separate stiffness matrices corresponding to laminate layers on each side of the delamination crack;
• predicting the spatial orientation of microcracks that precede the delamination front and evaluating if an adjacent layer of fibers arrests the microcracks to thereby determine if the delamination front remains in the current interface or migrates in a direction that is traverse to the elements through at least one of the adjacent layers of fibers via a matrix crack to a new interface;
• if the delamination grows and migrates to a new interface, split one or more adjacent shell elements to form new shell elements having stiffness matrices to thereby account for migration of the delamination to the new interface.