Numerical method for fracture modelling of lattice interface materials in composite structures
Topic(s) : Material and Structural Behavior - Simulation & Testing
Co-authors :
Michelle HEDVARD (GERMANY), Philipp WEISSGRAEBER (GERMANY)Abstract :
The low weight-to-stiffness and weight-to-strength ratios are some of the key parameters when selecting fiber reinforced polymers for structural design. In the assembly process of composite members, bonding is a commonly used method. Manufacturing tolerances can result in thick bond lines, as experienced for wind turbine blades where the bond lines can be several centimetres thick and is prone to fail [1]. Filling the bond lines with bulk adhesives add a significant amount of mass, increasing the overall weight of the final structure.
Mechanical metamaterials (also known as architected materials) are proposed to replace current joint adhesives in thick bond lines [2]. Their tunable material properties provide opportunities for anisotropic properties, low weight-to-stiffness and weight-to-strength ratios, good energy absorption capabilities etc. [3]. In addition, some mechanical metamaterials exhibit toughening effects during the damage process [4]. The wide range of design options for the specific geometry of the metamaterial allows the bondline interface to be designed for the specific purpose of the structure, here referred to as architected interfaces. At the same time, a metamaterial such as a lattice structure reduces the amount of material used per volume compared to a homogeneous material. Mechanical metamaterials are currently mainly studied at infinite length scales, where boundary effects are neglected. Therefore, a better understanding of confined metamaterials is needed to utilize the advantage of the architected interfaces.
In this work, a numerical model is presented for the study of architected interfaces confined by composite materials in a double cantilever beam setup under different loading conditions. Due to the loading configurations and bending deformation of the substrate structures, the interface material is locally subjected to tensile and compressive loading states. To account for buckling failure in case of compressively loading the effect of deformations due to substrate deformation is taken into account. The interface is represented by a lattice structure modelled using beam elements. Damage to the lattice structures is incorporated into the material model by introducing complete softening of the lattice material when failure occurs. Examples of results for confined metamaterials under different loading conditions are presented. The proposed method contributes to a better understanding of the behavior and damage of architected interfaces.
Mechanical metamaterials (also known as architected materials) are proposed to replace current joint adhesives in thick bond lines [2]. Their tunable material properties provide opportunities for anisotropic properties, low weight-to-stiffness and weight-to-strength ratios, good energy absorption capabilities etc. [3]. In addition, some mechanical metamaterials exhibit toughening effects during the damage process [4]. The wide range of design options for the specific geometry of the metamaterial allows the bondline interface to be designed for the specific purpose of the structure, here referred to as architected interfaces. At the same time, a metamaterial such as a lattice structure reduces the amount of material used per volume compared to a homogeneous material. Mechanical metamaterials are currently mainly studied at infinite length scales, where boundary effects are neglected. Therefore, a better understanding of confined metamaterials is needed to utilize the advantage of the architected interfaces.
In this work, a numerical model is presented for the study of architected interfaces confined by composite materials in a double cantilever beam setup under different loading conditions. Due to the loading configurations and bending deformation of the substrate structures, the interface material is locally subjected to tensile and compressive loading states. To account for buckling failure in case of compressively loading the effect of deformations due to substrate deformation is taken into account. The interface is represented by a lattice structure modelled using beam elements. Damage to the lattice structures is incorporated into the material model by introducing complete softening of the lattice material when failure occurs. Examples of results for confined metamaterials under different loading conditions are presented. The proposed method contributes to a better understanding of the behavior and damage of architected interfaces.