Characterization of Singular Stress States due to Geometry, Material, or Boundary Condition Discontinuities.
Analysis and evaluation of singular stress states, i.e., with unbounded stresses around points called singularities, due to a discontinuity in geometry, material (isotropic or anisotropic), or boundary/interface conditions: cracks, cracks in a perfect or imperfect interface, cracks terminating at an interface, corners in a single material or multiple materials joined with different boundary, contact, or interface conditions. Determination of singularity orders and development of methods for calculating the **generalized stress intensity factors** associated with the mentioned singular states.
Development and Computational Implementation of New Fracture Mechanics Methods for Predicting Damage Initiation and Growth in Composite Materials, Joints, and Structures.
Development and computational implementation of new fracture mechanics methods: **Finite Fracture Mechanics (FFM)**, the **Linear Elastic Brittle Interface Model (LEBIM)**, the combination of FFM with LEBIM, cohesive zone models, variational fracture mechanics models such as **”phase fields”**, and others.
Fundamentals and Applications of the Boundary Element Method (BEM).
Theoretical and computational implementation developments of the **Boundary Element Method (BEM)** for the numerical solution of: generalized plane strain problems in anisotropic materials, axisymmetric problems, three-dimensional problems for transversely isotropic materials, elastic and thermo-elastic friction contact problems (with conforming and non-conforming meshes), problems in materials with gradually varying properties, and problems in viscoelastic materials. Methods to guarantee the uniqueness of the numerical solution in the collocational and symmetric Galerkin BEM. Calculation of stresses and potential gradient on the boundary and in the domain.
Multiscale Study of Damage Initiation and Growth in Composite Materials, Joints, and Structures.
Study and prediction of damage mechanisms in composite material laminates at the micro-mechanical level: **damage between fibers** under transverse loads, and at the meso-mechanical level: **intralaminar damage and delamination**. Study and prediction of failure at the macro-mechanical level of composite specimens, joints, and structures: **debonding** between different parts of a joint or structure. Implementation of progressive damage criteria in finite element method computational codes.
Design, Analysis, and Prediction of Failure Load for Composite Material Structures.
Application of finite element method computational codes to the design, analysis, and prediction of failure load for various composite structures primarily used in the aeronautical and renewable energy sectors, with special attention to the **post-buckling behavior** of composite panels, where the damage mechanisms indicated in the previous section are modeled.
Adhesive Joints
Study of the stress states in adhesive joints of composite material and/or metal to establish **design criteria** based on the singular stress states existing in adhesive joints. Characterization of material parameters in the presence of singular stress states. Generation of an **engineering-use design procedure** for joints.
Manufacturing of Composite Materials
Fluid-thermo-mechanical modeling, characterization, and optimization of the **ultrasonic compaction process** for coupling with out-of-autoclave manufacturing systems. Characterization of rapid curing systems using radiation. Manufacturing of carbon fiber and fiberglass parts using **Additive Layer Manufacturing (ALM)** techniques with a 3D printer.
Testing of Composite Specimens, Joints, and Structures.
Experimental characterization of long-fiber reinforced composite material properties at the micro-mechanical level: **single fiber testing**, determination of fiber-matrix interface mechanical properties. Experimental characterization of mechanical properties of composite laminates: **off-axis testing**, **Iosipescu testing**, fatigue testing, etc. Experimental characterization of mechanical properties of interfaces between laminates and adhesives. Experimental determination of failure load for specimens, joints, and also **full-scale structures**.