Improving the efficiency of aerospace structures involves reducing their weight and maintaining their safety throughout their life cycle. To avoid oversizing, a deep knowledge of the damage mechanism in composite materials is crucial, and interlaminar fracture, or delamination, is one of the most critical mechanisms. Understanding delamination behavior and characterizing the Interlaminar Fracture Toughness (IFT) of composites is key to designing safe and efficient structures. Standard tests to quantify IFT are restricted to unidirectional (UD) specimens with delamination propagation parallel to the fiber. However, structures are built using Multi-Directional (MD) laminates, where delamination may appear at any interface and propagate in any direction, and IFT may differ from that obtained by standard tests, leading to oversized, inefficient structures. The main problems that prevent IFT test for MD laminates are: elastic couplings, thermal residual stress, finite width effects, and delamination migration. Currently, there is no understanding of whether migration can be reliably avoided in mode I tests, while it can be prevented in mode II and mixed mode I/II tests. This work aims to understand and, if possible, prevent the crack migration mechanism in Mode I test with Fully-Uncoupled Multi-Directional (FUMD) specimens, which have recently been proposed to solve problems of couplings, residual stresses, and finite width. Since crack migration depends on the shear stress state at the tip of the delamination, often causing delamination to progress toward an off-axis ply, it is essential to comprehend such stress state. Our goal is to identify specific FUMD specimens that will redirect the delamination toward a 0º ply instead. To achieve this, we are developing simplified models to quickly analyze and visualize the shear stress state. These models will help determine whether crack propagation is directed toward the upper or lower ply. This work will provide significant insights into the feasibility of conducting pure Mode I fracture toughness tests for non-UD interfaces.